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Showing papers in "Innovative Food Science and Emerging Technologies in 2005"


Journal ArticleDOI
TL;DR: In this paper, the microstructure, stickiness, hygroscopicity and solubility of powder mango juice were analyzed using a mini-spray dryer of laboratorial scale.
Abstract: This work aimed the induction of crystallization on powder mango juice during the process of spray drying and the correlation of the microstructure of the powder obtained with the functional properties of stickiness and solubility. To perform this work, we used mango juice with 12 °Brix. Before being dehydrated, the juice undertook addition from the following carriers: maltodextrin, gum arabic and starch waxy in the concentration of 12%. The solution also received addition of crystalline cellulose in the concentrations of 0, 3, 6 and 9%. The powder was obtained through the use of a mini-spray dryer of laboratorial scale. Analyses of microstructure, stickiness, hygroscopicity and solubility were performed on the obtained powder. The microstructure analyses showed that the powders of the mango juices obtained through spray drying using the carriers maltodextrin, gum arabic, starch waxy without the addition of cellulose presented surfaces of amorphous particles. The analysis XRD showed that when 3, 6 and 9% of cellulose were added, the particles showed half-crystalline surfaces. The value of stickiness decreased in terms of the concentration of cellulose reaching values of 0.15, 0.22 and 0.11 Kg-f for maltodextrin, gum arabic and starch waxy, respectively. The functional property of solubility is affected when 9% of cellulose is added reaching the values of 72, 71 and 31% for the carriers maltodextrin, gum arabic and starch wax, respectively.

738 citations


Journal ArticleDOI
TL;DR: In this article, the microencapsulation of d-limonene by spray drying was investigated with respect to the effects of emulsion droplet size, powder particle size, as well as to the effect of various kinds of matrices (gum arabic, maltodextrin, and modified starch) on its stability.
Abstract: The microencapsulation of d -limonene by spray drying was investigated with respect to the effects of emulsion droplet size, powder particle size, as well as to the effects of various kinds of matrices (gum arabic, maltodextrin, and modified starch) on its stability. It was realized by studying release characteristics and oxidative stability during storage. The release and the oxidation decreased deeply with an increase in powder and emulsion particle size for gum arabic and maltodextrin materials. Further, the distributions of emulsion size in the powder showed an increase in the fraction of large emulsion droplets and changed to a bimodal distribution. However, the modified starch HI-CAP 100 showed a higher stability of encapsulated d -limonene than the others. The influence of powder and emulsion size on its encapsulated flavor as well as the change in the emulsion size during storage could not be observed. Industrial Relevance Spray drying is a common and useful unit operation for microencapsulation of food ingredients. Data on emulsion droplet size and on powder size on product stability provide conflicting results which makes a systematic study regarding these factors highly relevant. The data suggest that an optimal size of flavour powder should be selected for high retention during spray drying, stability during storage and for the ability to control release of flavour.

329 citations


Journal ArticleDOI
TL;DR: In this article, a modified atmosphere packaging (MAP) was used for the preservation of the texture of the cherries in a 16-day storage at 1 °C and 90% RH.
Abstract: Sweet cherry shows severe problems for commercialisation mainly due to incidence of decay and a fast loss of sensory quality, both for fruit and stem. A package has been developed based on the addition of eugenol, thymol, menthol or eucalyptol (pure essential oils) separately to trays sealed with polypropylene bags to generate a modified atmosphere (MAP). In addition, cherries in MAP (without essential oils) were selected and served as controls. All cherries were stored during 16 days at 1 °C and 90% RH. Steady-state atmosphere was reached after 9 days of cold storage with 2–3% of CO2 and 11–12% of O2 with no significant differences between treated and control, with the exception of eucalyptol, in which significant increases in CO2 and decreases of O2 were obtained. When fruit quality parameters were determined, those treated with eugenol, thymol or menthol showed benefits in terms of reduced weight loss, delayed colour changes and maintenance of fruit firmness compared with control. Stem remained green in treated cherries while they became brown in control. However, cherries packaged with eucalyptol behaved even worst than control cherries, with generation of off-flavours, loss of quality and stem browning. Finally, the microbial analysis showed that all essential oils reduced moulds and yeasts and total aerobic mesophilic colonies by 4- and 2-log CFU compared with control, respectively. In conclusion, the use of MAP in combination with eugenol, thymol or menthol is an effective tool on maintaining cherry fruit quality and reducing the occurrence of decay. Industrial relevance The data presented in this work suggest that the use of pure essential oils (eugenol, thymol or menthol) in combination with modified atmosphere packaging (MAP) is an innovative and useful tool as alternative to the use of synthetic fungicides in fruits and vegetables, especially for those which are highly perishable and have a short shelf-life, as cherries. These compounds have been included in the list of generally recognized as safe (GRAS) compounds by FDA. As far as we know, this is the first paper dealing on the use of natural antifungal compounds and MAP and that these combined technologies confer benefits in fruit storage and retailing, with reduction in spoilage microorganisms, maintenance of cherry quality attributes and extension of shelf-life. The effects of these natural compounds on individual microorganisms, both responsible for spoilage and food-borne pathogens, as well as the minimum concentration to gain effectiveness deserve further research.

293 citations


Journal ArticleDOI
TL;DR: In this paper, two different options for the combined recovery of pectin and phenolic compounds from mango peels, a byproduct of industrial mango processing, were developed, which can easily be integrated in an existing pectins and polyphenols extraction process.
Abstract: Two different options for the combined recovery of pectin and phenolic compounds from mango peels, a byproduct of industrial mango processing, were developed. After extraction of dried mango peels with diluted sulfuric acid, the phenolic compounds were adsorbed using a styrene–divinylbenzene copolymerisate resin, and pectin was obtained from the effluent by precipitation with ethanol. Phenolic compounds were recovered from the resin with methanol and the eluate was lyophilized (Process I). Alternatively, the pectin was precipitated by adding the crude extract to ethanol. After removal of the organic solvent, the phenolic compounds were obtained from the aqueous phase of the precipitation bath using the adsorbent resin as described before (Process II). While in total, 129.4 mg/g polyphenols were detected in the lyophilizate obtained from Process I, only 71.0 mg/g dm could be recoverd from Process II. The profiles of the polyphenols were almost identical, revealing that during pectin precipitation preferential adsorption of polyphenolic compounds to the pectin may be excluded. Besides the characterization of the pectins and the phenolic compounds, investigations into the influence of the drying temperature on the polyphenolic content of the peels were carried out, indicating a significant loss of flavonol glycosides depending on heat exposure. On the other hand, some xanthone glycosides were formed during the drying process. Furthermore, antioxidative capacities of the lyophilized eluates were investigated using the DPPH, TEAC and FRAP assays. The antioxidative capacity of the extracts exceeded that of mangiferin and quercetin 3-O-glucoside, respectively, thus demonstrating mango peels to be a suitable source of health-beneficial compounds. The lyophilizates obtained from Process I showed higher antioxidative capacities in all three assays. These findings indicate a correlation between the amount of phenolic compounds and the antioxidative capacity. Industrial relevance Byproducts of mango processing amount to 35–60% of the total fruit weight. Their complete exploitation for further product recovery is a promising measure from both an environmental and economic point of view. In our previous study mango peels were found to be a rich source of pectin, with a high degree of esterification and phenolic compounds, like flavonol O- and xanthone C-glycosides. Therefore, two alternative processes for the combined recovery of pectin and polyphenols, which can easily be integrated in an existing pectin production process, were developed in the present study.

292 citations


Journal ArticleDOI
TL;DR: The inactivation of microorganisms of importance to shellfish, particularly viruses, the commercial HP processing of oysters and the advantages of HP technology as they pertain to the seafood industry are reviewed.
Abstract: Many commercially important shellfish are filter feeders and, as a consequence, concentrate microbes from the surrounding waters. Shellfish may be relayed or depurated to reduce the level of microbial contamination, but the efficiency of these purification practices, particularly in relation to viruses and indigenous marine bacteria, is questionable. Therefore additional processing is necessary to ensure the safety of shellfish for human consumption. In recent years high pressure (HP) processing has been investigated as an alternative method for food preservation. HP technology allows inactivation of microorganisms while maintaining sensory and nutritional properties of foods. Currently, HP processing has several commercial food applications, including oysters. As well as enhancing safety and extending shelf-life, HP treatment has the additional advantage of shucking or opening shellfish, making this technology particularly beneficial to the shellfish processing industry and consumers alike. Industrial relevance High pressure (HP) processing is increasingly being used in the commercial processing of oysters, due to its minimal effects on sensory and nutritional quality, the opening or shucking of oysters during treatment, and the reduction of levels of Vibrio vulnificus , a pathogen of concern particularly in the US. However, little is known of the efficacy of HP treatment in reducing other pathogens in shellfish such as human enteric viruses, which are the predominant cause of shellfish-borne disease. This article reviews the inactivation of microorganisms of importance to shellfish, particularly viruses, the commercial HP processing of oysters and the advantages of HP technology as they pertain to the seafood industry.

226 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the feasibility of encapsulation of a vegetable oil (ISIO4®, 5% w/w dry matter) used as a model into a mixture of maltodextrin and acacia gum.
Abstract: Many active components (anti-oxidants, aromas) are lipophilic substances, available in liquid form and have to be protected from the environment. Encapsulation of oil drops into a solid matrix is regarded as an efficient protection method and a means of formulating liquid compounds in a solid dosed form. The aim of this study is to investigate the feasibility of encapsulation of a vegetable oil (ISIO4®, 5% w/w dry matter) used as a model into a mixture of maltodextrin and acacia gum. Encapsulation was completed in three stages, i.e. emulsification, spray drying and fluid bed agglomeration. Optimal operating conditions for spray drying and agglomeration were identified. Powders were characterized before and after agglomeration in terms of oil content and protection (dispersion into the matrix, surface oil content, oxidation) and powder handling properties (flowability, wettability, friability). The proposed encapsulation method provided powders where oil droplets were well dispersed and protected (oil droplets diameter lower than 1 μm in reconstituted emulsions, less than 2% of the total oil content at the particle surface, oil oxidation lowered compared to unprotected oil). Agglomeration did not change oil encapsulation properties of the spray-dried powder but considerably improved its wettability. Industrial relevance Encapsulation of active components finds many applications in food industry for aromas, vitamins, anti-oxidants, etc. used in powdered foods (soups, instant drinks and sauces), prepared meals and food complements with a market in constant increase. It is also widely used in pharmaceutical, chemical and cosmetics industries where products are different but techniques are similar. This study aimed to test the combination of spray drying and fluidised bed agglomeration to encapsulate sensitive lipid-based compounds into dosed powders to provide protection and storage stability and render their use easier.

196 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of lemon albedo on chemical, physicochemical and sensory properties of beef burgers were investigated using a ranking test, and the results showed significant differences on redness and hardness.
Abstract: Citrus fruits constitute an underused source of fibre and antioxidants, particularly albedo, and the potential for its use is explored. Lemon albedo was prepared from pith following four different methods either cooking or/and drying and mincing. These ingredients were added at 0%, 2.5%, 5% and 7.5% levels to a beef burger mix and the burgers were evaluated for quality attributes including: compositional analysis, cooking characteristics, fat oxidation, pH, physical tests (included colour and texture profile analysis) and a range of sensory attributes using a ranking test. The type of albedo slightly influenced the lipid oxidation and pH of samples, while the cooking properties were significantly improved by some of the added treatment materials with average increments of 5.5–11% on treatment meat patties when compared with control samples. Instrumental colour testing showed some differences on lightness, yellowness and redness, while hardness, gumminess, springiness and chewiness were in general, consistently higher as albedo concentration increased. The dry ingredient also had a stronger effect. The sensory evaluation highlighted significant differences on redness and hardness. Samples were also ranked distinctly in relation to their overall acceptance where only treatments with raw albedo compared poorly to the rest of samples, which indicates potential to develop this material as a food ingredient. Industrial relevance Citrus fruits are mainly used for juice, oil and pectin production and are underutilized sources for dietary fibre and antioxidants. This work examined the effects of lemon albedo on chemical, physicochemical and sensory properties of beef burgers especially to improve cooking properties. Besides reduced cooking losses citrus fibre seems to have potential as alternative to conventional fillers in meat product.

191 citations


Journal ArticleDOI
TL;DR: In this paper, the microencapsulation of l-menthol was studied by spray drying, using gum arabic (GA) and modified starch (CAPSUL, HI-CAP 100) as capsule materials.
Abstract: The microencapsulation of l-menthol was studied by spray drying, using gum arabic (GA) and modified starch (CAPSUL, HI-CAP 100) as capsule materials. The results showed a higher retention of l-menthol with the increasing of initial solid concentration. HI-CAP 100, showed a higher retention than the other capsule materials. However, it also showed a higher residue of l-menthol on the surface of powder especially at the high concentration of l-menthol in the feed emulsion. That might be from the interaction between the wall materials and l-menthol which can re-crystallize to form whisker after the spray drying. Furthermore, the release characteristics of l-menthol were also investigated. The release rate increased upon elevation of relative humidity and temperature. The activation energies of the release of l-menthol from GA wall matrices at 75 and 83%RH were 140 and 48 kJ/mol, respectively. Industrial relevance Controlled release of food constituents is currently receiving highest interest. This study aimed to better understand some of the processing and storage conditions. Decrease in emulsion droplet size led to increased flavor retention during spray drying. Interesting electron-micrographs of the spray dried capsules are provided as well as data on water absorption isotherms and release rate constants vs. storage temperatures. Clear industrially relevent data regarding capsule size, matrix, material, water activity and temperature during storage are provided.

189 citations


Journal ArticleDOI
TL;DR: In this article, a kinetic study of post processing quality loss was conducted after high pressure processing (600 MPa, 40 °C, 4 min) or thermal pasteurization (80 °C and 60 s) of fresh Navel orange juice.
Abstract: A kinetic study of post processing quality loss was conducted after high pressure processing (600 MPa, 40 °C, 4 min) or thermal pasteurisation (80 °C, 60 s) of fresh Navel orange juice. Selection of processing conditions was mainly based on pectin methylesterase inactivation. Ascorbic acid loss, colour, viscosity and sensory characteristics were measured during storage at different isothermal conditions (0–30 °C). Increased shelf life (based on ascorbic acid retention) was achieved for high pressurised compared to thermally pasteurised juice, ranging from 49% (storage at 15 °C) to 112% (storage at 0 °C). Activation energy values for ascorbic acid loss were 68.5 and 53.1 kJ/mol, respectively, for high pressurised and thermally treated juice. High pressure processing resulted in better retention of flavour of untreated juice and superior sensory characteristics compared to thermal pasteurisation. Colour change was linearly correlated to ascorbic acid loss for both types of processing. Slightly higher apparent viscosity values were determined for high pressurised juice. Industrial relevance Application of high hydrostatic pressure on orange juice industry. Fresh orange juice is a product of high commercial and nutritional value due to its rich vitamin C content and its desired sensory characteristics. High Hydrostatic Pressure (HHP) is an alternative non-thermal technology that has been proposed for application on orange juice. Such a treatment denaturates enzymes and eliminates microorganisms responsible for spoilage of orange juice without detrimental effects on the sensory and nutritional quality of juice. The effect of HHP on the stability of fresh orange juice has been studied by different research groups, while orange juices processed with the new technology have already been commercially available in Japan, U.S.A., Mexico and Europe. However, a systematic kinetic approach of the effect of HHP on different quality indexes (not only microbial spoilage) immediately after processing, as well as during a long term storage of the processed orange juice is needed, in order to achieve an optimal process design and a successful application of the new technology in orange juice industry. Such kinetic data for parameters related to the quality and nutritional value of fresh orange juice were gathered in the present work providing therefore industry with useful information for the HHP stabilization of orange juice and the production of a high quality product. Due to the great benefits of HHP compared to the conventional pasteurization that emerged from this work regarding the quality, shelf life and nutritional characteristics of fresh orange juice, HHP technology is an advantageous alternative process for high valued products like orange juice.

178 citations


Journal ArticleDOI
TL;DR: In this article, the authors present a novel way of using permeate (clear juice) as well as retentate (pulpy juice) for microbial stabilisation and concentration.
Abstract: Melon juice obtained from fruits discarded by exporters was first clarified by crossflow microfiltration and then concentrated by osmotic evaporation (OE). The resulting clarified melon juice was highly similar to the initial juice, except for insoluble solids and carotenoids, which were concentrated in the retentate. Average permeation flux was relatively high (about 80 L h −1 m −2 ), with continuous extraction of retentate at a volumetric reduction ratio of 3. After concentration of the clarified melon juice to as much as 550 g kg −1 of total soluble solids using a continuous feed-and-bleed procedure of OE, we found that almost the entire composition of the product was preserved. This integrated membrane process permitted two valuable products to be obtained: a clarified concentrate of melon juice that had not undergone any thermal treatment, and a glowing-orange retentate that was enriched in provitamin A. Industrial relevance The increasing quality demand for fresh fruits results in an increase in rejected melons. Juice processing could overcome the product losses occurring but thermal sensitivity of melon juice flavour prohibits conventional thermal processing. Interestingly this paper attempts to use membrane processes for microbial stabilisation and concentration. The authors present a novel way of using permeate (clear juice) as well as retentate (pulpy juice). Enzyme activities in the products during and after processing may need some attention prior to industrial application of the process.

142 citations


Journal ArticleDOI
TL;DR: In this paper, the authors compared the efficacy of cold and warm tap water with and without chlorination in washing uncut carrots during the production of shredded, packaged carrots while operating on pilot-plant scale under conditions of industrial practice.
Abstract: Different applications of cold and warm tap water (4 °C and 50 °C) with and without chlorination, respectively, in the washing of uncut peeled carrots ( Daucus carota L.) were conducted, and their effects on sensory and microbiological properties during storage for 9 days at 4 °C were assessed. To minimise cross-contamination of almost sterile inner root parts with the highly contaminated outer cortex during processing the peeled carrots were washed prior to cutting. The washing treatments were carried out using a commercial processing line, thus facilitating the scale-up to industrial production. Populations of aerobic mesophilic bacteria, lactic acid bacteria and enterobacteria on these minimally processed carrots were determined, and the sensorial quality of shredded carrots was evaluated by a sensory panel throughout storage. Additionally, colour, texture, sugars, and trichloromethanes were analysed. Washing uncut carrots with cold chlorinated water (200 mg/l, 4 °C) and warm tap water (50 °C) ensured sugar retention and reduced aerobic mesophilic bacteria by 1.7 and 2.0 log 10 colony forming units per gram (cfu/g), respectively, while washing with warm chlorinated water (200 mg/l) resulted in a 2.3 log 10 cfu/g reduction. By-product formation due to chlorination was negligible. Sensorial properties of the latter samples were slightly affected. It was shown that both washing uncut knife-peeled carrots with cold chlorinated water (4 °C) and warm tap water (50 °C), respectively, provided good microbiological safety paired with improved sensorial properties. Moreover, fresh-like character of the products was retained, as indicated by the persisting respiration of the living tissues. Industrial relevance Minimally processed vegetables are an increasing market. Shelf-life extension and consumer safety are of immense relevance for the fresh-cut industry; therefore, the application of antimicrobial agents such as chlorine is widespread. However, various consumer groups object to the use of chlorinated water. The present study aimed at comparing the efficacy of cold and warm tap water with and without chlorination, respectively, in washing uncut carrots during the production of shredded, packaged carrots while operating on pilot-plant scale under conditions of industrial practice. In view of microbial reduction and maintenance of sensory properties, the use of cold chlorinated water and warm tap water, respectively, proved to be effective for washing peeled carrots. By-product formation due to chlorination was negligible.

Journal ArticleDOI
TL;DR: In this article, an interesting approach using leafy vegetable extract with antioxidative properties to prevent oxidative damage during storage of heated oils has been presented, where the ethanol extracts of leafy vegetables were added to refined sunflower and groundnut oils heated to frying temperature and stored for 4 weeks, analyzed for peroxide value that indicates the oxidative state of oils.
Abstract: The investigation was undertaken with an objective of analyzing the antioxidant capacity of leafy vegetables (LV) and testing their efficacy on storage of heated oils. Four leafy vegetables viz., cabbage ( Brassica oleracea var. capitata), coriander leaves ( Coriandrum sativum ), hongone ( Alternanthera sessilis ), and spinach ( Spinacia oleracea ) were analyzed for antioxidant activity by standard methods. The ethanol extracts of LV were added to refined sunflower and groundnut oils heated to frying temperature and stored for 4 weeks, analyzed for peroxide value that indicates the oxidative state of oils. The polyphenol content ranged from 5 mg in cabbage to 69.5 mg in spinach. Reducing power of the leafy vegetables indicative of electron donating property for termination of free radical chain reactions followed the order—spinach Industrial relevance This paper presents an interesting approach using leafy vegetable extract with antioxidative properties to prevent oxidative damage during storage of heated oils. The temperature stability of antioxidants from leavy vegetables would allow to produce highly useful antioxidantive extracts from vegetable processing wastes.

Journal ArticleDOI
TL;DR: The pH of the treatment medium plays an important role in determining this target bacterial strain, and the combination of PEF and subsequent holding under acidic conditions has been proven to be an effective method in order to achieve a higher level of microbial inactivation.
Abstract: The objective was to evaluate and compare the pulsed electric field (PEF) resistance of four Gram-positive (Bacillus subtilis, Listeria monocytogenes, Lactobacillus plantarum, Staphylococcus aureus) and four Gram-negative (Escherichia coli, E. coli O157:H7, Salmonella serotype Senftenberg 775W, Yersinia enterocolitica) bacterial strains under the same treatment conditions. Microbial characteristics such as cell size, shape or type of the cell envelopes did not exert the expected influence on microbial PEF resistance. The most PEF resistant bacteria depended on the treatment medium pH. For instance, L. monocytogenes, which showed the highest PEF resistance at pH 7.0, was one of the most sensitive at pH 4.0. The most PEF resistant strains at pH 4.0 were the Gram-negatives E. coli O157:H7 and S. Senftenberg. A subsequent holding of PEF-treated cells in pH 4.0 for 2 h increased the degree of inactivation up to 4 extra Log10 cycles depending on the bacterial strain investigated. Under these treatment conditions, the most PEF resistant bacterial strains were still the pathogens S. Senftenberg and E. coli O157:H7. Industrial relevance The design of appropriate food preservation processes by PEF requires the selection of an adequate target bacterial strain, which should correspond to the most PEF resistant microorganism contaminating food. This study indicates that the pH of the treatment medium plays an important role in determining this target bacterial strain. On the other hand, the combination of PEF and subsequent holding under acidic conditions has been proven to be an effective method in order to achieve a higher level of microbial inactivation.

Journal ArticleDOI
TL;DR: In this article, the effect of pressure at different temperature (10, 25, and 60 °C) and pH (7.6 and 8.8) levels on selected properties of egg white solutions (turbidity, solubility, residual denaturation enthalpy, surface hydrophobicity, sulfhydryl content, susceptibility to enzymatic hydrolysis and trypsin inhibition activity).
Abstract: A study was conducted on the effect of pressure at different temperature (10, 25, and 60 °C) and pH (7.6 and 8.8) levels on selected properties of egg white solutions (turbidity, solubility, residual denaturation enthalpy, surface hydrophobicity, sulfhydryl content, susceptibility to enzymatic hydrolysis and trypsin inhibition activity). The pressure-induced changes in these properties were dependent on the pressure and temperature applied and the pH. The most pronounced changes were observed in the pressure range of 400–700 MPa. Pressure induced an increase in turbidity, surface hydrophobicity, exposed SH content and susceptibility to enzymatic hydrolysis, while it resulted in a decrease in protein solubility, total SH content, denaturation enthalpy and trypsin inhibitory activity. Industrial relevance Egg white is a multifunctional food ingredient with unique properties. Since pressure can induce changes in protein functionality it is of industrial relevance to explore the impact of pressure at different temperatures on egg white properties. Pressure induced changes were pronounced and also dependent on pH and temperature thus offering the potential for a wide range of p, T and pH combinations for monitoring of unique egg white protein functionality.

Journal ArticleDOI
TL;DR: In this paper, the use of two techniques to control the release of the chosen active compound (lysozyme) from a polymeric material into the foodstuff is proposed: a monolayer cross-linked PVOH film and a multilayer structure made of crosslinked PVO layers are developed and studied.
Abstract: Active packaging materials able to release antimicrobial compounds into foodstuff can be used in order to avoid or slow down the bacterial growth during storage. In this work the use of two techniques to control the release of the chosen active compound (lysozyme) from a polymeric material into the foodstuff is proposed: a monolayer cross-linked PVOH film and a multilayer structure made of cross-linked PVOH layers are developed and studied. Lysozyme release tests into water were performed in order to compare the release kinetics from the investigated films. Results suggest that by means of both structures it is possible to control the rate at which lysozyme is released from the PVOH film. The antimicrobial activity of lysozyme released from the investigated films was tested against a suspension of Micrococcus lysodeikticus. Results show that the incorporation of lysozyme into PVOH does not lead to a loss of activity of the enzyme. Industrial relevance The increased use of gently processed foods requires packaging to be an integral part of the preservation concept. Consequently additional antimicrobial activity from the packaging material can aid in shelf life extension. This paper concentrates on the release rate of lysozyme, a naturally occuring antimicrobial agent (eg. salvia, mothers milk, raw milk), from multilayer films. A comperision of mono- and multilayer films containing lysozyme regarding their effectiveness on M. lysodeikticus as target organism was also performed. Both aims were met leading to a controlled release of lysozyme with no loss of activity.

Journal ArticleDOI
TL;DR: It was shown that the effect of HP on cells of a single species can vary; some HP-induced sublethal injury is irreversible, allowing the sensitisation of Gram-negative bacteria to nisin post HP treatment, and a combination of hurdles may allow lower pressures and shorter treatment times without compromising product safety.
Abstract: The behaviour of both Gram-negative and Gram-positive bacteria associated with milk, in response to application of high pressure (HP) combined with nisin, was evaluated. Escherichia coli, Pseudomonas fluorescens, Listeria innocua, and Lactobacillus viridescens grown separately in skim milk were pressure-treated at 250–500 MPa for 5 min at 20 °C in the presence of 0, 250, or 500 IU/ml nisin. Combining HP and nisin gave a greater inactivation of all four bacteria than when either was applied individually. A reduction of ≥ 8 log of L. viridescens and L. innocua in milk was achieved at 500 MPa for 5 min at 20 °C, in the presence of 500 IU/ml nisin. The Gram-negative bacteria were more sensitive to HP, either alone or in combination with nisin, than Gram-positive bacteria. Treatment at 400 MPa for 5 min with 500 IU/ml nisin, or at 250 MPa for 5 min with 500 IU/ml nisin, gave a > 8 log reduction of E. coli and P. fluorescens, respectively. By adding nisin to cell suspensions after HP treatment, it was shown that the effect of HP on cells of a single species can vary; some HP-induced sublethal injury is irreversible, allowing the sensitisation of Gram-negative bacteria to nisin post HP treatment. Reversible membrane damage in P. fluorescens caused by HP was demonstrated using fluorescent dye uptake before, after, or during HP treatment. Industrial relevance The synergistic microbial inactivation that can be achieved by HP treatment in the presence of nisin has applications not only for liquid milk but many other dairy and low-acid products. Such a combination of hurdles may allow lower pressures and shorter treatment times without compromising product safety.

Journal ArticleDOI
TL;DR: In this paper, the effects of different high pressure processing (HPP) treatments on EVOH-based packaging materials were studied and they were compared with the morphological effects produced by a more traditional food preservation technology, i.e. sterilization.
Abstract: The effects of different high pressure processing (HPP) treatments on EVOH-based packaging materials were studied and they were compared with the morphological effects produced by a more traditional food preservation technology, i.e. sterilization. The samples were high pressure processed at 400 and 800 MPa, during 5 and 10 min at two different temperatures, 40 and 75 °C. Sterilization was carried out in an autoclave at 120 °C during 20 min. Oxygen barrier and morphological properties of the treated packaging structures were analyzed and compared with those of the untreated samples. The results proved that HPP scarcely affects packaging materials, especially when compared with the detrimental consequences of retorting. Industrial relevance Although commercial food products are being high pressure processed packaged in flexible packaging materials relatively little information is available regarding the impact on high pressure. This paper addresses critical issues such as pressure effects on permeability and morphology of EVOH-based packaging structures which are essential to be able to assure food safety during pressure treatment and storage. A slight increase in crystalline morphology resulting in better barrier properties could be found after pressure treatment.

Journal ArticleDOI
TL;DR: In this paper, high pressure processing at moderate pressures and storage at refrigeration temperatures have been evaluated as a means of maximizing microbial inactivation while maintaining consumer acceptability of the product.
Abstract: Navel orange juices subjected to high pressure processing (HPP) and temperature treatment (TT) were stored at 4 and 10 °C for up to 12 weeks to establish the shelf-life of such products. The processed juices and a control juice, stored at − 20 °C, were assessed by a trained sensory panel and a consumer acceptance panel at 0, 1, 2, 4, 8 and 12 weeks or until such time that the juices were considered unfit for consumption. Untreated juice stored at 4 °C was similarly assessed for up to 2 weeks and untreated juice stored at 10 °C was assessed for up to 1 week. The volatile components of corresponding juices were isolated by SPME and the extracts were analyzed by GC–MS. Twenty key aroma compounds were selected for quantification and these data were used to monitor the change in volatile content of the juices during storage. The study showed that the odor and flavor of the HPP juice was acceptable to consumers after storage for 12 weeks at temperatures up to 10 °C. However, only the TT juice stored at 4 °C was acceptable after the same length of storage. Industrial relevance Orange juice is a sensitive product subject to a high microbial load that can tolerate only moderate heat treatment without the destruction of the product’s delicate aroma and flavor characteristics. High pressure processing at moderate pressures and storage at refrigeration temperatures have been evaluated as means of maximizing microbial inactivation while maintaining consumer acceptability of the product. The sensory and analytical data presented demonstrate that high pressure processing with refrigeration can extend the shelf-life of orange juice while maintaining consumer acceptability.

Journal ArticleDOI
TL;DR: In this article, the effectiveness of RF heating in inactivating surrogates of both Listeria and Escherichia coli cells in milk under continuous flow conditions was evaluated using a 2 kW, 27.12 MHz RF heater.
Abstract: Using a 2 kW, 27.12 MHz RF heater, studies were conducted to evaluate the effectiveness of RF heating in inactivating surrogates of both Listeria and Escherichia coli cells in milk under continuous flow conditions. Depending on product residence time and RF power level, RF heating was found to be capable of inactivating both Listeria and E. coli in milk, with E. coli being the more heat sensitive of the two. For a total residence time of 55.5 s (i.e., 29.5 and 26 s in the applicator and holding tube, respectively), up to 5- and 7-log reductions were found for heating Listeria and E. coli, respectively at 1200 W, and an applicator tube exit temperature of approximately 65 °C. This study demonstrates that RF heating could be used to effectively pasteurize milk by manipulating incident power levels and flow rate. While these studies have been conducted under mild fluid flow (laminar) conditions, further studies are necessary to justify its industrial application using more realistic flow conditions. Industrial relevance Radio frequency (RF) heating can provide rapid heating. Compared to the microwave, RF has the added advantage of higher penetration depth. These advantages could be harnessed for pasteurizing large volume liquid foods and, most importantly, RF heating could potentially replace traditional heat exchangers that are easily fouled by products such as milk. This study demonstrates the effectiveness of using RF heating under mild flow conditions to inactivate microorganisms that could contaminate milk.

Journal ArticleDOI
TL;DR: HHP treatment of whey protein concentrate (WPC) yields increases in the number of binding sites for an aromatic hydrophobic probe, while aliphatichydrophobic binding affinity of WPC is enhanced after come-up time or 10 min of HHP treatment.
Abstract: The objective of this study was to evaluate the influence of high hydrostatic pressure (HHP) treatments on hydrophobicity of whey protein concentrate (WPC) An increase in binding affinity or decrease in apparent dissociation constant indicates increased hydrophobicity, which is positively correlated with functional properties The effects of HHP treatment (600 MPa, 50 °C, 0 to 30 min) on intrinsic fluorescence of WPC and the binding properties of WPC for aromatic 1-anilino-naphthalene-8-sulfonate (ANS) and aliphatic cis-parinaric acid (CPA) probes were studied HHP treatment of WPC resulted in an increase in intrinsic tryptophan fluorescence intensity and a 4 nm red shift after 30 min of treatment, which indicated changes in the polarity of tryptophan residues microenvironment of whey proteins from a less polar to a more polar environment There was an increase in the number of binding sites of WPC for ANS from 016 to 110 per molecule of protein after HHP treatment for 30 min No significant changes in the apparent dissociation constant of WPC for ANS were observed after HHP treatment, except for an increase from 18 × 10−5 M to 33 × 10−5 M after 30 min of HHP treatment There were no significant changes in the number of binding sites of WPC for CPA However, increased binding affinities of WPC for CPA were observed after the come-up time or 10 min of HHP treatment, with a decrease of apparent dissociation constant from 22 × 10−7 M to 11 × 10−7 M The binding sites of WPC may become more accessible to the aliphatic hydrophobic probe CPA after the come-up time or 10 min of HHP treatment These results indicate that HHP treatment of WPC yields increases in the number of binding sites for an aromatic hydrophobic probe, while aliphatic hydrophobic binding affinity of WPC is enhanced after come-up time or 10 min of HHP treatment Industrial Relevance Text The functionality of protein molecules depends on hydrophobic, electrostatic, and steric parameters of the protein structure Modifications of proteins that enhance hydrophobicity show promise for improving functional properties of foods An increase in binding affinity or decrease in apparent dissociation constant indicates increased hydrophobicity High hydrostatic pressure (HHP) affects the hydrophobicity of beta-lactoglobulin (β-LG), the primary protein in whey, and increases the binding affinity of β-LG for 1-anilino-naphthalene-8-sulfonate and cis-parinaric acid However, little work has been done regarding the effects of HHP on whey protein concentrate (WPC) hydrophobicity and flavor-binding properties, and whether the presence of multiple proteins in WPC has significant influence on the behavior of whey proteins during HHP treatments WPC is a good candidate for testing the practical utility of the application of HHP to modify the functional properties of a complex protein system since it is in the form that the ingredient is utilized in a number of food applications The current work describes the effects of HHP on hydrophobicity of WPC and potential applications

Journal ArticleDOI
TL;DR: In this paper, the effect of three different mono-polar pulse shapes on treatment chamber corrosion was investigated and the relationship between dissolved metals in sodium chloride and the transferred charge was derived.
Abstract: Liquid pumpable food is mostly pasteurised by heat treatment. In the last decennia there is an increasing interest in so-called Pulsed Electric Field (PEF) treatment. During this treatment food is pumped between two metal electrodes and exposed to short high electric field pulses, typical 2-4 kV mm-1 during 1-10 μs. During this treatment the stainless steel electrodes are in direct contact with the food product. Associated with the charge that has to be exchanged at the interface of electrode and food, electrode material may be transferred from electrode to food. This transfer of material may cause serious electrode corrosion and adds metals to the food. The magnitude of material transfer depends on many factors such as current magnitude, pulse duration, pulse shape and fluid constitution. In this contribution the effect of three different mono-polar pulse shapes on treatment chamber corrosion is investigated. Experiments are carried out in an aqueous sodium chloride solution. The experiments showed that due to PEF treatment dissolved metals are present in the liquid. The four main elements of stainless steel, iron, chromium, nickel and manganese, have been considered in particular. These elements could only be detected in the liquid when it was repeatedly exposed to a Pulsed Electric Field treatment, which was realised by repeatedly circulating. From the experiments a relationship between dissolved metals in sodium chloride and the transferred charge is derived. With these values an upper limit for dissolved metals caused by PEF treatment can be defined. © 2005 Elsevier Ltd. All rights reserved.

Journal ArticleDOI
TL;DR: The effects of cold and warm, chlorinated water as well as warm water without chlorination for pre-washing trimmed, cored iceberg lettuce heads was assessed regarding the shelf-life and physiological properties of the resulting ready-to-use (RTU) produce as discussed by the authors.
Abstract: The effects of cold and warm, chlorinated water as well as warm water without chlorination for pre-washing trimmed, cored iceberg lettuce heads was assessed regarding the shelf-life and physiological properties of the resulting ready-to-use (RTU) produce On a pilot-plant scale, lettuce heads were shredded with or without pre-washing (50 °C, no chlorine; 4 and 50 °C, 200 mg/l free chlorine; 60 s) After shredding, lettuce was washed for 90 s (tap water, 4 °C), spin-dried, packaged in 200 g consumer-sized bags, and stored at 4 °C for ≤ 9 days Samples were analyzed for their headspace O 2 and CO 2 levels, sensory properties, microbiological status, and phenylalanine ammonia-lyase (PAL) activity at regular intervals throughout processing and storage Parallelly, instrumental color and texture measurements were performed All pre-washing procedures of lettuce heads lowered the initial counts of total aerobic bacteria, pseudomonades, and Enterobacteriaceae by ≥ 163, ≥ 155, and ≥ 185 log 10 cfu/g, respectively, while the single-wash of shredded lettuce in tap water without any pre-washing resulted in significantly smaller reduction rates (023, 011, and 071 log 10 cfu/g, respectively) During storage, all pre-washing procedures had a persistent effect on bacterial counts of the RTU lettuce Furthermore, all pre-washing procedures delayed vascular tissue browning at cut edges and retarded the decline in the overall visual quality of the samples Whereas wound-induced PAL synthesis was reduced by the use of warm water (± chlorine), O 2 depletion and CO 2 evolution in the corresponding bags were slightly enhanced, thus proving that processing kept the food as a living tissue Industrial relevance Ready to use fresh like produce is getting increasing attention and industrial relevance The aim of this study was to specifically overcome problems associated with product heterogeneity Interestingly, the use of warm tap water without chlorination as a pre-washing step proved as effective alternative to the application of cold chlorinated water without substantially compromising vitality and freshness of the product

Journal ArticleDOI
TL;DR: In this article, a method for formulating free, solved and water-dispersible phytosterols allows for their incorporation into almost all kinds of foods as well as beverages.
Abstract: Phytosterols can significantly reduce cholesterol levels in humans. However, their dose response is strongly formulation dependent. Due to their insolubility in water and poor solubility in oil and their surface activity, the formulation in functional foods of unesterified non-crystalline phytosterols with an expected dose response even higher than the esterified phytosterols commonly applied today proved problematic. Supersaturating phytosterols with a crystallization inhibitor in the oil phase of an o/w emulsion in a special process combines high phytosterol concentrations with the potential of strongly increased dose response. In two formulations, no crystallization was observable in stability investigations over a period of 60 days. Industrial relevance Compared to actual formulations as phytosterol fatty acid esters in fat-based foods, the method describe here for formulating free, solved and water-dispersible phytosterols allows for their incorporation into almost all kinds of foods as well as beverages. Additionally, the expected to dose–response to phytosterol formulated according to this method is expected to exceed by far that of phytosterol fatty acid esters. Combined with the comparably high concentration in the new, water-dispersible formulations, the method yields the opportunity of producing a wide variety of functional foods with phytosterols highly effective in lowering the risk for cardiovascular diseases.

Journal ArticleDOI
TL;DR: In this article, the effect of metal dissolving during a monopolar pulse shape, generated by a pulse forming network, was investigated with single and repeated PEF treatments in orange juice.
Abstract: In the last decennia, there is an increasing interest in pulsed electric field (PEF) treatment. The product is often treated in a continuous flow treatment chamber with stainless steel electrodes and exposed to short pulsed electric fields, typically 2-4 kV mm-1 during 1-10 μs. Due to direct contact of the treatment chamber electrodes with the food product, the main elements of these stainless steel electrodes are able to dissolve in the treated product. The magnitude of the material transfer depends on many factors such as current magnitude, pulse duration, pulse shape, and product constitution. In this contribution, the effect of metal dissolving during a monopolar pulse shape, generated by a pulse forming network, is investigated. Experiments are carried out with single and repeated PEF treatments in orange juice. These experiments showed that, due to PEF treatment, dissolved metals are present in the juice. The four main elements of stainless steel, iron, chromium, nickel, and manganese, have been considered in particular. The metal concentrations found do not exceed the legislation values for fruit juices and the EU Drinking Water Directive [EU Drinking Water Directive, http://www.europe.eu.int/. for human consumption. From the experiments, a relationship between dissolved metals in orange juice and the transferred charge is derived. In addition, a lifetime prediction of the treatment chamber caused by release of metals has been made. © 2005 Elsevier Ltd. All rights reserved.

Journal ArticleDOI
TL;DR: In this article, the effects of high pressure phase transitions of water on plant tissue material depending on the processing conditions were investigated and the results showed that phase transition of ice I to ice III resulted in the lowest damaging effect on the tissue compared to the other phase transition processes investigated.
Abstract: To design and optimize high pressure processes at low temperatures, a quantification of the effects of different processing steps on the food structure is required. Beside pressure-shift freezing, the processes of freezing to ice III and ice V, as well as storage at −27 °C and 250 MPa up to 24 h (metastable liquid state of water) of potato samples were examined. Analyses of the structural changes of the plant tissue included impedance measurements, texture analysis, color measurements and the evaluation of the optical appearance. Storage at subzero temperatures without phase transitions resulted in low membrane damage; however, cell lysis was triggered. Freezing to ice III resulted in the lowest damaging effect on the tissue compared to the other phase transition processes investigated. Samples frozen to ice V and pressure-shift frozen were more deteriorated compared to those frozen to ice III. However, considerable improvements compared to conventional freezing were found. The direction of solid–solid phase transitions (phase transition of ice I to ice III or phase transition of ice III to ice I) influenced the result of high pressure–low temperature processing significantly. Industrial relevance It was previously shown that pressure supported phase transitions of ice I like pressure shift freezing are able to preserve the fragile stucture of biological samples like food better than conventional freezing. The present study extends the knowledge of pressure supported phase transitions to a higher pressure domain with the participation of other ice modifications. The authors demonstrate the influences of high pressure phase transitions of water on plant tissue material depending on the processing conditions. The study opens the way to new industrial processing concepts based on high pressure low temperature applications.

Journal ArticleDOI
TL;DR: The process developed is considered suitable for being scaled up to industrial-scale production thus opening an avenue for large-scale cactus pear fruit processing.
Abstract: Since no process has yet been established for the production of cactus pear juice, the present work aimed at the development of a betalain-based colouring foodstuff from Opuntia ficus-indica cv. ‘Gialla’ and cv. ‘Rossa’ of two seasons applying unit operations typical for fruit juice production. Complete separation of the peels from the pulp and removal of seeds were achieved by carborundum peeling of the frozen fruits and subsequent passing through a finisher. Furthermore, for improved filtration of cactus pear juice different enzyme preparations were tested to degrade pectic-like substances. To monitor quality changes in the course of processing, juice samples were analysed after each processing step in terms of colour and selected chemical parameters. While lightness (L*) and chroma (C*) increased during processing for both cultivars, hue angle (h°) remained unchanged for the yellow cultivar ‘Gialla’, but a slight shift towards red was observed for the red cultivar ‘Rossa’ after pasteurisation. Unexpectedly, even after repeated thermal treatment neither non-enzymatic browning nor HMF formation was observed in juices from both cultivars. Industrial relevance Cactus pear represents a viable alternative to red beet for food colouring purposes: it neither exhibits negative sensorial impact nor high nitrate levels, but offers a broad colour range. However, no attempt has yet been made to benefit from this potential. The process developed is considered suitable for being scaled up to industrial-scale production thus opening an avenue for large-scale cactus pear fruit processing.

Journal ArticleDOI
TL;DR: An optimum drying procedure for producing non-sulphited mango slices has been developed in this paper, where the interaction of essential drying parameters (air temperature, air velocity, dew point, slice thickness and drying time) on water activity and browning was determined.
Abstract: An optimum drying routine for producing non-sulphited mango slices has been developed The interaction of essential drying parameters (air temperature, air velocity, dew point, slice thickness and drying time) on water activity ( a W ) and browning was determined Microbiological stability of the dried product was achieved at a moisture content of 17% wet base (wb) corresponding to a W = 06 Browning was monitored by the red colour shade of the product (CIE-Lab chromaticity coordinate a *) Drying air temperature and drying time were shown to be the primary factors influencing product colour and a W In contrast to common practice, drying for about 6 h at elevated air temperature (80 °C), instead of 50 or 60 °C for a longer time, was optimal, since significant colour changes of the mango slices were not observed even without the use of any chemical or thermal pre-treatment Moreover, at increased temperature, drying time was considerably shortened from about 9 h to 6 h, resulting in significant extension of the drying capacity Industrial Relevance The suggested process concept for dried mango slices based on high-temperature drying is of utmost significance for the international marketing of dried fruit products Chemical pre-treatments such as sulphitation often used to minimise quality deficiencies could be avoided Sulphitation has been recently under critical consideration with respect to allergen labelling of foodstuffs implemented by EU-Member States in November 2004 (Directive 2003/89/EC) [Directive 2003/89/EC Official Journal of the European Union, 25112003, pp L308/15–18 ( http://europaeuint/eur-lex/pri/en/oj/dat/2003/l_308/l_30820031125en00150018pdf )] Export quality was improved and the drying process simplified, improving the utilisation of drying capacities Particularly referring to an application of the technology in small- and medium-sized enterprises with limited investment possibilities, the suggested novel drying procedure in mango processing aimed at the optimisation of well-established simple drying methods instead of choosing technically more sophisticated technologies

Journal ArticleDOI
TL;DR: Mixtures of phenolic phytochemicals from cranberry and oregano, in synergistic combination with lactic acid, can inhibit V. parahaemolyticus in seafood systems and can be used for enhancing food safety in food industry.
Abstract: Several food additives are used to extend the shelf life of food, and delay or inhibit the growth of pathogenic microorganisms. Extracts of plants, particularly herbs and spices, are rich in essential oils and phenolic secondary metabolites and several possess antimicrobial activity. Some of these plant extracts are used in the aroma and flavor industry, and are classified as “generally regarded as safe” (GRAS). Oregano and cranberry extract mix provide a GRAS-type phytochemical source with the potential to develop a natural and effective antimicrobial strategy against Vibrio parahaemolyticus . Different ratios of extract mixtures were optimized from oregano and cranberry, and evaluated for antimicrobial activity in laboratory medium and seafood products. The results indicated that the antimicrobial activity was enhanced in response to extract mixtures than individual extracts of each species. The efficacy was further improved by combination with lactic acid, which is also considered GRAS. These results show the potential of plant extracts to be antimicrobial and, when combined with lactic acid, they can be used as a more effective multiple-barrier food preservation system. Such a synergistic ingredient approach can have wide implications for improvement of food safety. Industrial relevance Phenolic phytochemicals are excellent sources of antioxidants and antimicrobials in the diet, which contribute positively to the management of oxidation-linked and infectious diseases. Traditionally, individual phenolics have been targeted as antimicrobials with low efficacy. In this manuscript, we have shown how mixtures of phenolic phytochemicals from cranberry and oregano, in synergistic combination with lactic acid, can inhibit V. parahaemolyticus in seafood systems. Such a strategy can be used for enhancing food safety in food industry.

Journal ArticleDOI
TL;DR: In this article, the combined thermal and high pressure inactivation of pectinmethylesterase (PME) from white grapefruit was investigated and the results indicated that a combined high-pressure-(low/mild) heat treatment can eliminate up to 80% of the total PME activity.
Abstract: White grapefruit pectin methylesterase (PME) was successfully purified by affinity chromatography using a kiwi PME inhibitor as ligand. Electrophoretic analysis combined with isothermal and isobaric-isothermal inactivation treatments suggested the presence of a labile PME fraction and a stable PME fraction with molecular weights of 31.5 kDa and 23.7 kDa, respectively. Both isothermal and isobaric-isothermal PME inactivation could be described by fractional conversion models with about 20% of the initial activity corresponding to the stable fraction. Optimum pH-ionic strength conditions for grapefruit PME thermostability were determined. Purified heat-labile PME (in 20 mM Tris Buffer (pH 7.0)) was submitted to combined thermal and high-pressure inactivation experiments in the ranges 10–62 °C and 0.1–800 MPa. The combined pressure–temperature dependence of the inactivation rate constants could be accurately described by a third degree polynomial model, showing a clear antagonistic effect of pressure and temperature on PME inactivation at temperature ≥ 58 °C in a pressure range of 0.1–300 MPa. In the context of fruit-juice processing, the results obtained suggest that a combined high-pressure-(low/mild) heat treatment can eliminate up to 80% of the total PME activity therefore significantly limiting the cloud-loss defect in juices. Industrial relevance The present works describes the combined thermal and high pressure inactivation of pectinmethylesterase (PME) from white grapefruit. White grapefruit contains two PME fractions with different process stability (both towards temperature and pressure), the stable fraction contributing to about 20% of the total PME activity. The results demonstrate that combined mild heat and high-pressure processing cannot be used to fully inactivate PME in grapefruit juice. However, by eliminating up to 80% of the PME activity (labile fraction), such treatment can probably contribute to a significant decay of the cloud loss defect observed in grapefruit juices, while allowing pasteurisation and good quality retention of the latter. Combining high pressure mild temperature processing with other non-thermal approaches (e.g. use of PME-inhibitor) could be of interest in creating juices with extended shelf-life.

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TL;DR: In this paper, the residual activities of lipoxygenase (LOX), peroxidase (POD), and polyphenoloxidases (PPO) were determined in paprika and chili powder after immediate thermal treatment of the fresh plant material.
Abstract: Residual activities of lipoxygenase (LOX), peroxidase (POD), and polyphenoloxidase (PPO) were determined in paprika and chili powder after immediate thermal treatment of the fresh plant material. Heat treatments comprised water and steam blanching of the integral fruits and pasteurization of the comminuted tissues, respectively. PPO showed the lowest heat stability and was completely inactivated by heating at 80 °C for 10 min. Inactivation of LOX was also largely accomplished by heating at 90 °C for 5 min and at 100 °C for 5 min, whereas up to 3.5% (paprika) and 3.3% (chili) of the initial POD activities were retained even when applying rigorous time–temperature regimes. The results demonstrate that substantial inactivation of deteriorative enzymes was ensured by the recently suggested process, thus facilitating the production of high quality spice powders.