Showing papers in "Innovative Food Science and Emerging Technologies in 2009"

Impact of high pressure processing on total antioxidant activity, phenolic, ascorbic acid, anthocyanin content and colour of strawberry and blackberry purées.

Abstract: The present study was undertaken to assess the effect of high pressure treatments and conventional thermal processing on antioxidant activity, levels of key antioxidant groups (polyphenols, ascorbic acid and anthocyanins) and the colour of strawberry and blackberry purees. Bioactive compounds (cyanidin-3-glycoside, pelargonidin-3-glucoside, ascorbic acid) and antioxidant activity were measured in strawberry and blackberry purees subjected to high pressure treatment (400, 500, 600 MPa/15 min/10–30 °C) and thermal treatments (70 °C/2 min). Samples were assessed immediately after processing. Different pressure treatments did not cause any significant change in ascorbic acid (p > 0.05). In contrast, following thermal processing (P70 ≥ 2 min) ascorbic acid degradation was 21% (p 0.05), whereas conventional thermal treatments significantly reduced the levels (p Industrial relevance This research paper provides scientific evidence of the potential benefits of high pressure processing in comparison to thermal treatments in retaining important bioactive compounds. Antioxidant activity (ARP), ascorbic acid, and anthocyanins after exposure to high pressure treatments (400–600 MPa) were well retained. Our results also show that redness and colour intensity of strawberry and blackberry purees were better preserved by high pressure processing than conventional thermal treatment. From a nutritional perspective, high pressure processing is an attractive food preservation technology and offers opportunities for horticultural and food processing industries to meet the growing demand from consumers for healthier food products. Therefore high pressure processed foods could be sold at a premium than their thermally processed counterparts as they will have retained their fresh-like properties.

Effect of thermal and high pressure processing on antioxidant activity and instrumental colour of tomato and carrot purées

Abstract: article i nfo Article history: Received 19 May 2008 Accepted 27 September 2008 Total antioxidant activity, levels of bio-active compound groups and instrumental colour of tomato and carrot pureesubjectedtohighpressuretreatment(400-600MPa/15min/20°C)andthermaltreatments(70°C/2min) were measured. Antioxidant activity in tomato and carrot puree was significantly higher (pb0.05) than in untreated or thermally processed samples. High pressure treatments at 600 MPa retained more than 90% of ascorbic acid as compared to thermal processing in tomato purees. Heat treatments caused a rapid decrease in ascorbic acid (pb0.05). Phenolic contents were in general un-affected by thermal or high pressure treatments. Colour parameters were significantly affected (pb0.05) by thermal and high pressure processing. Principal component analysis (PCA) revealed that the first two components represented 97% and 92% of the total variability in instrumental colour parameters with respect to processing for tomatoes and carrots respectively. Industrial relevance: This research paper provides scientific evidence of the potential benefits of high pressure processing in comparison to thermal treatments in retaining important bioactive compounds. Antioxidant activity (ARP), ascorbic acid, and carotenoids after exposure to high pressure treatments (400-600 MPa) were well retained. Our results also show that redness and colour intensity of purees were better preserved by high pressure processingthan conventionalthermal treatment. Itwouldappear fromanutritional prospective,high pressure processing is an excellent food processing technology which has the potential to retain compounds with health properties in foods. Therefore high pressureprocessed foods could be sold at a premium over their thermally processed counterparts as they will have retained their fresh-like properties.

Extraction of essential oils from five cinnamon leaves and identification of their volatile compound compositions

Abstract: Five cinnamon species, viz. Cinnamomum cassia, Cinnamomum zeylanicum, Cinnamomum tamala, Cinnamomum burmannii, Cinnamomum pauciflorum, were chosen to prepare essential oils by hydrodistillation and to identify and quantify their volatile compound compositions. C. cassia was determined to have the highest yield (1.54%) of essential oil, followed by C. zeylanicum, C. pauciflorum, C. burmannii and C. tamala. Gas chromatography/mass spectrometry (GC/MS) was used to identify and quantify the volatile compound composition. The results indicated the apparent difference in the volatile compound compositions of essential oils between species. The total numbers of volatile compounds identified from C. cassia, C. zeylanicum, C. tamala, C. burmannii and C. pauciflorum leaves were 22, 22, 13, 6 and 21, respectively. trans-Cinnamaldehyde was found in the essential oil of each species, which was also the major volatile component of C. cassia and C. burmannii leaves. Besides trans-cinnamaldehyde, 3-methoxy-1,2-propanediol was the main volatile compound of C. cassia leaf, while eugenol of C. zeylanicumand, C. pauciflorum and C. burmannii leaves, and 5-(2-propenyl)-1,3-benzodioxole of C. tamala leaf were also the main substances. Industrial relevance The essential oil of cinnamon is an important bioactive substance which has many disease prevention effects. In this work, five species of cinnamon leaves were chosen as materials to prepare the essential oils. The yield of essential oil was determined. The volatile compounds of essential oil were identified by GC/MS analysis. The results showed the significant difference of volatile compound composition between species. trans-Cinnamaldehyde was detected to exist in all the species tested as an important volatile component. This work is helpful for extensive development of this medicinal herb.

Effect of degree of hydrolysis on the antioxidant activity of loach (Misgurnus anguillicaudatus) protein hydrolysates.

Abstract: Loach ( Misgurnus anguillicaudatus ) proteins were hydrolysed by papain and Protamex, the antioxidant activity of loach protein hydrolysates (LPH) was investigated. The results demonstrated that extensive hydrolysis by papain and Protamex led to the browning of the hydrolysates. When the degree of hydrolysis (DH) was 23%, hydrolysates prepared by papain (HA) exhibited the strongest antioxidant activity. The maximum values of the hydroxyl, 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activities and the reducing power were 56.1%, 95.5%, 2.80 mM and 1.46, respectively. The hydrolysates prepared by Protamex (HB) showed the strongest hydroxyl radical scavenging activity (55.0%) at DH 28%, DPPH radical scavenging activity (92.2%) and ABTS radical scavenging activity (2.81 mM) at DH 23%, and the reducing power (1.17) at DH 33%. At the same DH value, there were significant ( p Industrial relevance Loach has long been employed as a traditional Chinese medicine for the treatment of many kinds of diseases. From our previous work, loach was determined to be a good source of protein (accounts for approximately 17% (w/w) of the body weight). In this work, loach proteins were hydrolyzed by papain and Protamex to specific extent. The effect of DH on the antioxidant activities of hydrolysates was investigated. The results indicated that loach protein hydrolysates were potent antioxidants which were significantly affected by DH. This research is helpful for extensive development of loach product.

Flavonoid contents and antioxidant activities from Cinnamomum species

Abstract: Cinnamomum has long been regarded as a food or medicinal plant. Leaves of five species of Cinnamomum, namely C. burmanni, C. cassia, C. pauciflorum, C. tamala and C. zeylanica, were chosen to investigate their antioxidant activities in this study. C. zeylanica exhibited the highest total phenolic content while C. burmanni had the highest flavonoid content among the five species. These five species were then screened for their antioxidant potentials using various in-vitro models such as total antioxidant capability, 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, reducing power and superoxide anion scavenging activity at various concentrations. C. zeylanica showed the highest DPPH radical scavenging activity, total antioxidant activity and reducing power, while C. tamala exhibited the highest superoxide anion scavenging activity. By the analysis of the high performance liquid chromatography coupled to diode array detector (HPLC-DAD), three flavonoid compounds namely quercetin, kaempferol and quercetrin were identified and quantified. This study suggested that Cinnamomum leaf can be used potentially as a readily accessible source of natural antioxidants. Industrial relevance This study was focused to evaluate the antioxidant activities of five species of Cinnamomum leaf which is normally used in medicine and also used in food preparation. This study provided an alternative of utilizing Cinnamomum leaf as a readily accessible source of natural antioxidants in food and pharmaceutical industry.

In-vitro antioxidant activities of an ethanolic extract of the oyster mushroom, Pleurotus ostreatus

Abstract: The antioxidant potential of an ethanolic extract of the oyster mushroom, Pleurotus ostreatus , was investigated. The extract exhibited the most potent radical-scavenging activity at a maximum concentration of 10 mg/ml, and the scavenging effects were 56.20% and 60.02% on hydroxyl and superoxide radicals, respectively. The IC 50 values of the extract were found to be 8 mg/ml for hydroxyl and superoxide radicals. Ascorbic acid used as a standard was highly effective in inhibiting hydroxyl and superoxide radicals, showing IC 50 values of 6 mg/ml and 4 mg/ml respectively. At a maximum concentration of 10 mg/ml, the extract effected 56.12% inhibition of lipid peroxidation and 60.68% chelation of ferrous ions; also, at a maximum concentration 10 mg/ml, the extract manifested significant ( p P. ostreatus , has potent antioxidant activity. Industrial relevance The present study suggests that an ethanolic extract of the mushroom, Pleurotus ostreatus , could serve as an easily accessible item of food rich in natural antioxidants, as a possible food supplement or even as a pharmaceutical agent. Hence this study is considerable relevant to the food and pharmaceutical industries.

UV radiation-induced changes of antioxidant capacity of fresh-cut tropical fruits.

Abstract: The effect of ultraviolet (UV-C) treatment on total phenol, flavonoid, and vitamin C content of fresh-cut honey pineapple, banana “pisang mas”, and guava was investigated. The antioxidant capacity of the fruit also was evaluated by measuring its ferric reducing/antioxidant power (FRAP) and DPPH free radical-scavenging activity. The fresh-cut fruits were exposed to UV-C for 0, 10, 20, and 30 min. Total phenol and flavonoid contents of guava and banana increased significantly with the increase in treatment time. In pineapple, the increase in total phenol content was insignificant, but the flavonoid content increased significantly after 10 min of treatment. UV-C treatment decreased the vitamin C content of all three fruits. In fresh-cut banana, longer treatment time resulted in higher FRAP and DPPH values; these values remained stable throughout the experiment for fresh-cut pineapple. For fresh-cut guava, FRAP and DPPH values were stable until 30 min, after which a significant increase in FRAP values occurred. Industrial relevance UV irradiation processing of fresh-cut fruits leads to increase in antioxidants, polyphenols, and flavonoids. Hence, apart from the application of UV for microbial safety at industrial levels, this novel technology can also be exploited for enhancement of health promoting compounds for benefit of consumers.

Effects of high pressure extraction on the extraction yield, total phenolic content and antioxidant activity of longan fruit pericarp

Abstract: High pressure extraction (HPE) was carried out to extract phenolic compounds from longan fruit pericarp. The influence of different solvents, solvent concentration (25−100%, v/v), solid to liquid ratio (1:25−1:100, w/v) were individually determined using these optimum extraction conditions. HPE was carried out at various pressures (200−500 MPa), durations (2.5−30 min) and temperatures (30−70 °C). The extraction yield, total phenolic contents and scavenging activities of superoxide anion radical and 1,1-dipheny l-2-picrylhydrazyl (DPPH) radical of HPE extract were examined and then compared with those of the conventional extraction (CE). The application of HPE obtained a higher extraction yield and required a less extraction time when compared to CE. Furthermore, the total phenolic contents and the antioxidant activities of HPE extract were higher than CE extract. This study indicated that this new technology can benefit the food and pharmaceutical industries. Industrial relevance This study focused on the evaluations of the extraction yield, total phenolic content and antioxidant activity of longan fruit pericarp by high pressure treatment. The high pressure extraction technology provided a better way of utilizing longan fruit pericarp as a readily accessible source of natural antioxidants in food and pharmaceutical industries.

Use of high pressure to reduce cook loss and improve texture of low-salt beef sausage batters

Abstract: Methods were investigated to reduce the salt content of beef-containing smallgoods as high-salt intake has been identified as a public health risk for most individuals. Raw meat batters were manufactured from retail beef mince (4–7% fat) using various NaCl concentrations (0–2%), and were packed into casings and subjected to high pressure processing (up to 400 MPa for 2 min at 10 °C). Following pressure treatment, samples were cooked to an internal temperature of 72 °C and cooled. Cooked products were assessed for cooking loss, colour and physical consistency by texture profile analysis. Flavour and overall acceptability were assessed by sensory panels. High pressure processing (HPP) was found to produce a dramatic improvement in the moisture retention of the cooked products. Control (unpressurised) sausages containing 2% NaCl had a similar cook loss (9.3%) to pressure-treated sausages containing just 1% NaCl, whereas unpressurised samples with 1% NaCl had a cook loss of 24.9%. The hardness and gumminess of pressure-treated samples was higher compared to untreated samples, at all salt concentrations. The greatest differences in texture with pressure treatment were seen in the 1% NaCl samples. Pressure treatment generally caused no changes in the colour of either the raw or cooked product; however there was a slight increase in “whiteness” with pressure treatment. Sensory panels reported a greater acceptability in both appearance and texture of pressure-treated sausages of lower salt content compared with non-pressure-treated samples. Examination of extracted proteins using SDS-PAGE and of muscle proteins by thermal analysis indicated that pressure contributed to enhanced binding through protein solubilisation and gelation through partial protein unfolding. The application of high pressure to beef sausages with low-salt content resulted in reduced cooking losses and improved texture. Industrial relevance Enhanced meat binding through extraction of salt-soluble proteins is an essential step in the formulation of meat products such as sausages and emulsion-type products. The ability to reduce salt and achieve high binding and water retention through use of HPP is important in being able to produce healthier foods.

Controlled release of thymol from zein based film.

Abstract: Active packaging materials, able to release antimicrobial compounds into foodstuffs, can be used in order to inhibit or slow down bacterial growth during storage. Zein-based mono and multilayer films were loaded with spelt bran and thymol (35% w/w) to obtain edible composite polymeric materials. Various composite systems were developed to control the release of thymol. In particular, the thickness of the layers and the biodegradable fibres amount were varied. Results highlight that thymol release rate decreased with the increase of the film thickness for both mono and multilayer films, without spelt bran addition. Conversely, a significant increase of thymol release rate with the increase of the bran concentration is recorded for both mono and multilayer films. Industrial relevance In recent years, food safety is an important area of concern to the food industry. This fact 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. The present work is focused on the development of controlled release systems based on zein incorporated with an active compound, thymol and natural fibres. Release rate of thymol from the developed mono and multilayer films, as affected by layers thickness and fibres amount, was evaluated.

Inactivation kinetics of pectin methylesterase and cloud retention in sonicated orange juice

Abstract: The effect of sonication on pectin methylesterase (PME) activity and cloud stability of orange juice was studied. Ultrasonic acoustic energy density (AED) levels of 0.42, 0.47, 0.61, 0.79 and 1.05 W/mL and treatment times of 0 (Control), 2, 4, 6, 8 and 10 min were investigated. The highest PME inactivation level observed was 62% for sonication at the highest AED level and treatment time. A fraction conversion model adequately described the PME inactivation compared to first order or polynomial models. A significant change in particle size distribution was observed in sonicated samples due to cavitational effects. These results indicate that the cloud stability of sonicated orange juice depends not only on PME inactivation but also on particle size reduction. Industrial relevance Power ultrasound is a non thermal pasteurisation method that has been identified to meet the US FDA requirement for a 5 log reduction in E. coli pertinent to fruit juices. Apart from microbial inactivation, cloud stability is a critical orange juice quality parameter influencing product shelf life and consumer acceptance. This work demonstrates that sonication at low AED levels and temperatures can be employed to achieve the desired cloud stability.

Inactivation kinetics of apple polyphenol oxidase in different pressure-temperature domains.

Abstract: The impact of high hydrostatic pressure and temperature on the stability of polyphenol oxidase (PPO) was studied in cloudy apple juice Application of 200–500 MPa near room temperature or heat treatment at 45–55 °C at ambient pressure caused an increase of PPO activity of up to 65% in freshly squeezed apple juice Combined pressure–temperature inactivation experiments with fully activated PPO (5 min treatment at 400 MPa and 20 °C) were carried out in the range of 01–700 MPa and 20–80 °C Enzyme inactivation kinetics followed a 22 order reaction scheme at all pressure–temperature conditions tested A polynomial model was successfully applied to describe the rate of PPO inactivation as a function of pressure and temperature and was used to construct a pressure–temperature isokinetic diagram This diagram clearly showed synergistic effects of pressure and temperature on the inactivation of apple PPO at pressures above 300 MPa and antagonistic effects at lower pressures Compared to ambient pressure conditions, temperatures required to inactivate PPO in apple juice were increased 10–15 °C at 100–300 MPa Industrial relevance High pressure processing of fresh fruits is gaining popularity in the food industry because of its ability to inactivate microorganisms and some enzymes near room temperature with little impact on flavour or nutritional attributes of the food However, quantitative data regarding the impact of process parameters on the target reaction are required to economically utilise this technology This paper provides a mathematical model describing the combined effect of pressure, temperature and treatment time on the inactivation of PPO in cloudy apple juice

Impact of cinnamon oil-enrichment on microbial spoilage of fresh produce.

Abstract: Cinnamon (Cinnamomum zeylanicum L.) oil (ranging between 25 and 500 ppm) was tested for antifungal activity against Colletotrichum coccodes, Botrytis cinerea, Cladosporium herbarum, Rhizopus stolonifer and Aspergillus niger in vitro. Oil-enrichment resulted in significant (P Industrial relevance The data presented in this work suggest that the use of pure cinnamon essential oil is an innovative and useful tool as alternative to the use of synthetic fungicides or other sanitation techniques in storage/packaging. Oil enrichment may reduce disease development with a major contribution to limiting the spread of the pathogen by lowering the spore load (spore production) in the storage/transit atmospheres as well as the use of essential oil as an alternative food preservative. The effectiveness (oil concentration) of the oil depends on the target pathogen. The effects of natural compounds on individual microorganisms (fungi and bacteria), both responsible for spoilage and food-borne pathogens, as well as the minimum concentration to gain effectiveness without affecting fresh produce quality and storage deserve further research.

Effect of high pressure carbon dioxide on the quality of carrot juice

Abstract: The effect of high pressure carbon dioxide (HPCD) on the quality of carrot juice was investigated. The L-value of HPCD-treated juices increased significantly (P Industrial relevance Carrot juice is one of the most popular vegetable juices, but it requires severe heat treatment for protection from spoilage due to a higher pH, its heat-sensitive quality is inevitably destructed. In this study, HPCD can avoid the drawbacks of the heat treatment as a novel non-thermal pasteurization, available data are provided for the application and evaluation of HPCD in the juice industry.

High-pressure homogenization of orange juice to inactivate pectinmethylesterase.

Abstract: A homogenizer was used to treat orange juice at five pressures (0–250 MPa) and three initial temperatures (22, 35 and 45 °C). A maximum of five passes for the selected conditions were used to process orange juice. Pectinmethylesterase (PME) activity, microbial load, cloudy appearance, and vitamin C were evaluated in just squeezed and homogenized orange juices. A reduction of 50.4, 49.4 and 37.8% of PME activity was observed in juice homogenized by one pass at 250 MPa at the initial temperatures of 22, 35, and 45 °C, respectively. Pectinmethylesterase activity in orange juice was reduced as passes number was increased. The final temperature of the five times homogenized orange juice was not beyond 28 and 37 °C after being treated at 100 and 250 MPa, respectively. More than 30 and 80% of enzyme activity was reduced after five passes at 100 and 250 MPa, respectively. Less that 8.7 × 102 and 1.85 × 103 CFU/mL of mesophiles and yeasts plus molds, respectively, were counted in orange juice treated five times at 100 MPa. The cloudy appearance of the homogenized orange juice was maintained for 12 days under low temperature conditions. Industrial relevance “Cold pasteurization” of orange juice, using a homogenizer as a high-pressure procedure, could be an alternative to thermal processing to avoid sensory, nutritional and physiochemical changes in juice. This process may deliver a pasteurized orange juice with characteristics similar to just squeezed orange juice. In addition to reduce the microbial load, homogenization may reduce pectinmethylesterase enzyme, which may cause phase-separation in juice and consequently give an unwanted appearance that consumers dislike. Additionally, homogenized orange juice appearance could be stable during several days before being brought to the consumers' daily eating table.

Modeling the inactivation of Listeria innocua in raw whole milk treated under thermo-sonication

Abstract: Ultrasound was used to study the inactivation of Listeria innocua and mesophilic bacteria in raw whole milk. Five systems were evaluated in an ultrasonic processor (24 kHz, 120 µm, 400 W). Tested amplitudes of ultrasonic waves were 0, 40, 72, 108 and 120 µm, with a constant temperature of 63 °C and treatment time of 30 min. The pH, acidity and color were measured. After 10 min of treatment, thermal pasteurization achieved a 0.69 log and a 5.3 log-reduction after 30 min. However, after using ultrasound at 60, 90 or 100% in combination with temperature, a 5 log-reduction was obtained after 10 min. Inactivation of mesophilic bacteria was similar to those for Listeria . The heat and the strongest thermo-sonication survival curves were best fitted using a Weibullian model, while an alternative four-parameter model was selected for the mildest thermo-sonication treatment (30%). As intensity of thermo-sonication increased, pH was slightly lower (6.64), acidity was increased (0.141%), and color of samples was whiter (92.37). Industrial relevance Thermo-sonication is an emerging technology that has shown positive effects in bacterial inactivation, reducing treatment times considerably. In the dairy industry, pathogenic microorganisms such as Listeria monocytogenes can be inactivated in milk using ultrasound, although inactivation patterns do not follow traditional first order kinetics. Thermo-sonicated milk has better color and similar physicochemical characteristics compared to conventional pasteurized milk, but the processing time is shorter. Industrially, thermo-sonication seems to be a viable option for pasteurization of milk; however, there are advantages to using conventional pasteurization in combination with ultrasound, as the results in this manuscript show. The possibility of using HTST processing in addition to ultrasound is also feasible, which could reduce treatment times even more.

Extraction optimization of bioactive compounds (crocin, geniposide and total phenolic compounds) from Gardenia (Gardenia jasminoides Ellis) fruits with response surface methodology

Abstract: Response surface methodology (RSM) was employed to optimize the extraction parameters of crocin, geniposide and total phenolic compounds from gardenia fruits. The effects of three independent variables, namely ethanol concentration (EtOH, %), extraction temperature (°C) and time (min) on the yield of crocin, geniposide and total phenolic compounds were investigated. Results indicated that the data were adequately fitted into three second-order polynomial models. The independent variables, the linearity of extraction temperature and time, the quadratics of ethanol concentration and extraction time, the interactions between ethanol concentration and temperature, ethanol concentration and extraction time, as well as extraction temperature and time had a significant effect on the yield of crocin, geniposide or total phenolic compounds. The optimal extraction parameters were the EtOH of 51.3%, extraction temperature of 70.4 °C and time of 28.6 min according to the response surface analysis. Under this condition, the yield of crocin, geniposide and total phenolic compounds was 8.41 mg/g, 109.0 mg/g and 24.97 mg CAE/g dry powder of gardenia fruits, respectively. Industrial relevance There is a strong interest in the food industry in studying the extraction optimization of natural plants to produce higher quality products. Response surface methodology (RSM) is an effective technique for analyzing interactions among factors and optimizing the processes or products where multiple variables may influence the outputs. This work explores the extraction conditions for a natural pigment-gardenia yellow pigment by the RSM method and optimizes the extraction parameters to improve extraction yields of same main components of the natural pigment at the same time. The mathematical methods and models which can describe and predicate experimental data of the extraction would be extremely helpful in the extraction process of the natural products.

Effects of pulsed electric fields (PEF) treatment on physicochemical properties of potato starch.

Abstract: Potato starch–water suspensions (8.0%, w/w) were subjected to pulsed electric fields (PEF) treatment at 30 kV·cm − 1 , 40 kV·cm − 1 and 50 kV·cm − 1 , respectively. The physicochemical properties of PEF-treated potato starch samples were investigated using scanning electron microscopy (SEM), laser scattering technique, X-ray diffractometry (XRD), differential scanning calorimetry (DSC), and the Brabender rheological method, with native potato starch as reference. It has been concluded from SEM analysis that dissociation and damage of PEF-treated potato starch granules appeared. Some granules aggregated with each other and showed gel-like structures. It was revealed from particle size analysis that there was an obvious increase of the granule size after PEF treatment. This has been attributed to the aggregation among granules. It was also demonstrated from other analysis that relative crystallinity, gelatinization temperatures, gelatinization enthalpy, peak viscosity as well as breakdown viscosity of modified samples all decreased with increasing electric field strength. Industrial relevance In this study, the effect of PEF treatment (up to 50 kV·cm − 1 ) on physicochemical properties of potato starch has been investigated. The results from SEM images showed that dissociation, denaturation and damage of potato starch granules had been induced by the PEF treatments. Some of granule fragments showed gel-like structures, and congregated with each other or with other starch granules. Laser scattering measurements of particle size revealed that an obvious increase of granule size under electric field strength of 50 kV·cm − 1 , which was attributed to the aggregation of the starch granules. The X-ray diffraction pattern showed an obvious loss of crystalline structure after the PEF treatment at 50 kV·cm − 1 , which induced a trend of transformation from crystal to non-crystal in potato starch granules. DSC analysis showed a decrease in gelatinization temperatures ( T o and T p ) and gelatinization enthalpy (Δ H gel ) with increasing electric field strength. Brabender rheological method has been used to show that the peak viscosity and breakdown viscosity decrease with increasing electric field strength of PEF treatment. All the results reveal that the PEF treatment can lead to an intragranular molecular rearrangement of potato starch granules, which induces changes of various physicochemical properties of the treated starch thus may endow it some new characteristics and functions. This phenomena may warrant further more detailed study.

Combined high pressure-mild temperature processing for optimal retention of physical and nutritional quality of strawberries (Fragaria × ananassa)

Abstract: Response surface methodology was used to determine the optimal high pressure-temperature condition for the processing of strawberries for maximal inactivation of oxidative enzymes as well as best retention of nutritional and physicochemical quality following processing and during storage. High pressure treatment at 20–40 °C resulted in visual quality closest to the fresh product. High pressure combined with mild temperature caused substantial inactivation of peroxidase in strawberries with a maximum of 58% inactivation after 10 min treatment at 600 MPa and 60 °C. No significant inactivation of polyphenol oxidase was observed in strawberries under the studied condition. Combined high pressure-mild temperature processing did not have significant effect on the total polyphenol and total anthocyanin content of strawberries. However, an average of 22 ± 13% loss of total polyphenol content and 27 ± 10% loss of total anthocyanin contents was observed after 3 months of refrigerated storage. Industrial relevance The work described in this research is relevant to the high pressure processing of strawberries and other berry fruits. The results of the study have shown that best quality retention of strawberry products is obtained when high pressure processing is combined with vacuum packaging in high barrier packaging material and refrigerated storage since strawberry polyphenol oxidase is highly resistant to high pressure inactivation.

Effect of pressure and holding time on colour, protein and lipid oxidation of sliced dry-cured Iberian ham and loin during refrigerated storage

Abstract: The effect of high pressure (HP) treatments (200 MPa 15 min, 200 MPa 30 min, 300 MPa 15 min, 300 MPa 30 min) on colour, lipid and protein oxidation in sliced vacuum-packed dry-cured Iberian ham and loin during refrigerated storage (90 days, + 4 °C) was evaluated. Pressure level and holding time increased the extent of lipid oxidation in both products. Dry-cured ham showed a higher susceptibility to lipid oxidation than dry-cured loin since HP treatment increased TBA-RS values in dry-cured ham samples while HP treatment decreased TBA-RS values in dry-cured loin samples. However, HP treatment did not affect protein oxidation in both meat products. On the other hand, HP treatment affected instrumental colour since non-pressurized dry-cured meat products showed higher redness than pressurized ones. Regarding changes under storage, after 90 days of refrigerated storage lipid and protein oxidation increased while redness decreased in both HP treated and non-treated dry-cured meat products. Changes induced by HP were only noticeable after HP treatment, as storage reduced the initial differences between HP treated and non-treated samples. Therefore, the lack of differences in long stored dry-cured ham and loin HP treated and non-treated indicates that the application of HP (200–300 MPa/15–30 min) could not affect the quality of dry-cured meat products. Industrial relevance Dry-cured meat products are the meat-based products with the highest sensory quality in Spain and have a high projection in exterior markets. High pressure processing is effective in controlling pathogen and spoilage microorganisms in meat and meat products although it can promote color and oxidation changes that modify sensory characteristics. The study aimed the evaluation of pressure and holding time on color changes and protein and lipid oxidation at vacuum packed slices of Iberian dry-cured ham and loin during subsequent extended chilled storage. High pressure treatment of dry-cured Iberian ham and loin induce changes after treatment although initial differences are not maintained along refrigerated storage.

Ultrasonic-assisted extraction of epimedin C from fresh leaves of Epimedium and extraction mechanism

Abstract: Epimedin C is an important component of Epimedium with many beneficial functions to human health. In this study, the feasibility of the extraction of epimedin C from fresh leaves of Epimedium using ultrasonic probe system was demonstrated. The high extraction yield of epimedin C was obtained under an optimum extraction condition: extraction temperature of 50 °C, methanol concentration 60% (v/v), ratio of liquor to solid 30 mL g − 1 , and ultrasonication time 15 min. Scanning electron micrographs and transmission electron micrographs revealed that ultrasound could result in the disruptions of leaf tissues and cell walls, which enhanced the mass transfer of the solvents into the leaf materials and the soluble constituents into the solvents. Compared with traditional Soxhlet extraction method, ultrasonic-assisted extraction reduced extraction time, extraction temperature and solvent consumption, as well as achieved the similar recovery of epimedin C. Industrial relevance Epimedin C is considered one of the most important flavonoids with significant bioactivities in the famous medicinal plant, Epimedium. It shows great potential for becoming a nutraceutical in functional foods or a phytopharmaceutical for preventing and treating some serious and fatal illnesses. In this study, ultrasonic-assisted extraction of epimedin C directly from fresh Epimedium leaves was optimized for further large-scale industrial processing for the first time, and the extraction mechanism was discussed.

Polyphenoloxidase inactivation by light exposure in model systems and apple derivatives

Abstract: The effect of UV-C and visible light on the enzyme polyphenoloxidase was studied in model systems and food. Enzyme inactivation under non thermal conditions was achieved following both UV-C and visible light exposure. UV-C light promoted enzyme inactivation in the entire range of irradiance and exposure time tested whilst visible light was effective only at high doses since lower intensity treatments were associated to enzyme activation. Polyphenoloxidase inactivation upon UV-C light exposure occurred as a consequence of protein aggregations other than those derived from thermal denaturation. The possibility to apply UV-C light exposure to achieve enzymatic stability of clear apple juice and fresh-cut apple slices was studied. Polyphenoloxidase inactivation in apple juice occurred to the detriment of natural occurring phenols which independently underwent photo oxidation. However, UV-C light exposure for few min prevented enzymatic browning during storage of refrigerated apple slices. The latter resulted comparable to the untreated apple slices from the sensory point of view. Industrial relevance Light irradiation is very effective in promoting polyphenoloxidase inactivation. UV-C light treatment has a good potential of successful application to achieve enzymatic stability in fresh-cut vegetables under non thermal conditions.

Inactivation of Escherichia coli in orange juice using ozone

Abstract: This research investigated the efficacy of gaseous ozone for the inactivation of Escherichia coli ATCC 25922 and NCTC 12900 strains in orange juice. Orange juice inoculated with E. coli (10 6 CFU mL − 1 ) as a challenge microorganism was treated with ozone at 75–78 µg mL − 1 for different time periods (0–18 min). The efficacy of ozone for inactivation of both strains of E. coli was evaluated as a function of different juice types: model orange juice, fresh unfiltered juice, juice without pulp, and juice filtered through 500 µm or 1 mm sieves. Fast inactivation rates for total reduction of E. coli were achieved in model orange juice (60 s) and in juice with low pulp content (6 min). However, in unfiltered juice inactivation was achieved after 15–18 min. This indicated that juice organic matter interferes with antibacterial activity of gaseous ozone. The effect of prior acid (pH 5.0) exposure of E. coli strains on the inactivation efficacy of ozone treatment was also investigated. There was a strain effect observed, where prior acid exposure resulted in higher inactivation times in some cases by comparison with the control cells. However, the overarching influence on inactivation efficacy of ozone was related to the pulp content. Generally, the applied gaseous ozone treatment of orange juice resulted in a population reduction of 5 log cycles. Industrial relevance To facilitate the preservation of unstable nutrients many juice processors have investigated alternatives to thermal pasteurisation, including un-pasteurised short shelf life juices with high retail value. This trend has continued within the European Union. However within the US recent regulations by the FDA have required processors to achieve a 5-log reduction in the numbers of the most resistant pathogens in their finished products. Pathogenic E. coli may survive in acid environments such as fruit juices for long periods. This study demonstrates that the use of ozone as a non-thermal technology is effective for inactivation of E. coli and acid exposed E. coli in orange juice. Information on the design of the ozone treatment for inactivation of E. coli which results into safe juice products is also among the main outputs of this work. Ozone auto-decomposition makes this technology safe for fruit juice processing.

Preparation of water-soluble chitosan from shrimp shell and its antibacterial activity

Abstract: Crude chitosan was prepared from shrimp shell by HCl, NaOH and ethanol solution successively. Hydrogen peroxide was used to degrade the crude chitosan into water-soluble chitosan. A mathematical model between degradation conditions (H2O2 level, time and temperature) and the recovery of water-soluble chitosan was constructed using response surface methodology. Each factor showed a significant effect on the recovery. The model was confirmed to have a good fitness by analysis of variance. The optimal conditions to obtain the highest recovery of water-soluble chitosan were 5.5% of H2O2 level, 3.5 h of time and 42.8 °C of temperature. The predicted recovery was 93.5%. Through testing the number of colony, both crude and water-soluble chitosan showed good inhibition activities against B. subtilis. By determination of inhibition zone diameter, water-soluble chitosan showed significantly (P Industrial relevance Chitin is the second abundant polymer next to cellulose over the world. Its deacetylated product, chitosan, is an important ingredient in medicine and food. However, the low solubility in water limits the application of chitosan. In this work, the chitosan was degraded by H2O2 to produce water-soluble chitosan. Response surface methodology was taken to construct a model between degradation conditions and the recovery of water-soluble chitosan. By determination of the antibacterial activity, water-soluble chitosan showed better antibacterial activity than crude chitosan without degradation treatment. The results indicated the high potential of water-soluble chitosan as an antibacterial agent. This work was helpful for applying this product in industry.

Anthocyanin and colour degradation in ozone treated blackberry juice.

Abstract: Response surface methodology (RSM) was used to investigate the effects of ozone concentration (%w/w) and treatment time (min) on the anthocyanin content and colour of fresh blackberry juice. RSM methodology based on a two factor five level central composite design was employed with control variables of ozone concentration (0 to 7.8%w/w) and treatment time (0 to 10 min) at a constant gas flow rate. Predicted models were found to be significant ( p R 2 ) of 0.89, 0.82, 0.95, 0.86 and 0.97 for L , a , b , TCD and anthocyanin content respectively. Ozone concentration and treatment time were found to be critical factors influencing both anthocyanin and colour degradation. This study demonstrated that response surface methodology can be employed to model colour and anthocyanin degradation of ozonated blackberry juice while minimising the number of experiments required. Industrial relevance In the United States (US) legislation requires fruit juice processors to achieve a 5-log reduction in the numbers of the most resistant pathogens in their finished products. Consequently a number of commercial fruit juice processors in the US started to employ ozone for fruit juice pasteurisation. Ozonation was approved by the FDA in 2001 as a direct additive to food. The FDA issued industry guidelines for fruit juice processing with ozone [FDA, (2004). FDA Guidance to Industry, 2004: Recommendations to Processors of Apple Juice or Cider on the Use of Ozone for Pathogen Reduction Purposes. Available online http://www.cfsan.fda.gov/~dms/juicgu13.html .], however this report concludes that these guidelines are based upon limited scientific data. This paper investigates the effect of ozone processing on the anthocyanin content and colour of blackberry juice. The results presented demonstrate that the effect of ozonation on the nutritional properties of blackberry juice or juice products containing blackberry should be considered by processors prior to its adoption as a preservation technique.

Activation and conformational changes of mushroom polyphenoloxidase by high pressure microfluidization treatment.

Abstract: Activation and conformational changes of mushroom polyphenoloxidase (PPO) after high pressure microfluidization treatment were observed by means of UV spectrophotometer, far-UV circular dichroism, fluorescence emission spectra, UV absorption spectra and sulphydryl groups detection. The results indicated that, treated under pressures of 90 MPa, 110 MPa, 130 MPa and 150 MPa one pass, and 150 MPa 1, 2 and 3 passes, respectively, mushroom PPO exhibited an increase in activity. The circular dichroism (CD) analysis demonstrated that some of secondary structures such as α-helix were destroyed. There were some indices that the increase of relative activity was accompanied by a decrease in α-helix content. The fluorescence emission spectra analysis indicated that Trp and Tyr residues in mushroom PPO were more or less exposed to solvent, and the result was in good agreement with that of UV absorption spectra analysis. The sulphydryl groups detection showed that the sulphydryl groups content on the surface of mushroom PPO was increased. Industrial relevance Results of the present study show that high pressure microfluidization can not be used to inactivate mushroom PPO. However, it provides a new way for enzyme preparation, such as enzyme modification, with higher activity. High pressure microfluidization can be easily operated, with shorter treatment time and higher food safety compared with chemical methods.

Impact of PEF treatment inhomogeneity such as electric field distribution, flow characteristics and temperature effects on the inactivation of E. coli and milk alkaline phosphatase

Abstract: High intensity pulsed electric field (PEF) treatment was investigated focusing on the alteration of electric field distribution, flow characteristics and temperature distribution due to the modification of the treatment chamber. The aim was the improvement of the effectiveness of microbial inactivation of E. coli and to reduce the PEF impact on alkaline phosphatase (ALP) activity in raw milk. Mathematical simulation of the PEF process conditions considering different treatment chamber setups was performed prior to experimental verification. Finally the impact of the treatment chamber modifications on microbial inactivation and enzyme activity was determined experimentally. Using a continuous flow-through PEF system and a co-linear treatment chamber configuration the insertion of stainless steel and polypropylene grids was performed to alter the field strength distribution, increase the turbulence kinetic energy and improve the temperature homogeneity. The Finite Element Method (FEM) analysis showed an improved electric field strength distribution with increased average electric field strength and a reduced standard deviation along the center line of the treatment zone indicating a more homogenous electric field. The velocity profile was improved resulting in an increase of turbulence kinetic energy due to the insertion of the grids. As revealed by mathematical modeling, the temperature of the liquid was decreased, and formation of temperature peaks was avoided. Measured inactivation of heat sensitive alkaline phosphatase (ALP) was reduced from 78% residual activity to 92% after PEF treatment and it could be shown that thermal effects and temperature peaks have been the main reason for enzyme inactivation due to PEF. At the same time, an increase of microbial inactivation of 0.6 log–cycles could be determined experimentally due to the modification of the treatment chamber design. Industrial relevance The application of pulsed electric field as a non-thermal pasteurization technology requires an accurately defined treatment intensity followed by a predictable microbial inactivation. Unavoidable thermal effects occurring during PEF treatment due to ohmic heating have to be minimized to assure the retention of heat-sensitive nutrients and bioactive compounds. The presented investigations contribute to the fulfilment of these requirements for further successful industrial implementation of the PEF technology such as the selective inactivation or retention of enzyme activity in liquid food systems.

Growth and survival of Lactobacillus reuteri RC-14 and Lactobacillus rhamnosus GR-1 in yogurt for use as a functional food

Abstract: Both Lactobacillus reuteri RC-14 and Lactobacillus rhamnosus GR-1 are considered probiotic agents with therapeutic properties. To prepare mother cultures for these organism bacteria, four formulations were made with milk (1% fat) with 0.33% yeast extract (T1); 0.4% inulin (T2); 0.33% yeast extract and 0.4% inulin (T3); and one with no additives (T4). The media were inoculated with 1% probiotic cultures and incubated anaerobically at 37 °C overnight. Low-fat (1%) probiotic yogurts were made. Survival of L. reuteri RC-14 and L. rhamnosus GR-1 was monitored after 1, 7, 14, 21, and 28 days of storage at 4 °C. In all treatments, L. rhamnosus GR-1 survived significantly better (P Industrial relevance This study is of relevance to food industry because it deals with the effectiveness of dairy products as a good-vehicle for delivering probiotic microorganisms to consumers. The fermentation of milk into yogurt has gained widespread consumer acceptance in North America and its consumption has increased significantly over the past few years. The normal yogurt cultures, Lactobacillus delbreukii sub-species bulgaricus and Streptococcus thermophilus, are not bile resistant or acid tolerant and thus cannot survive in the intestinal tract, although they may help to lessen the symptoms of lactose intolerance. Various strains of lactic acid bacteria are considered probiotics. Two of the most documented probiotic strains, Lactobacillus reuteri (formerly fermentum) RC-14 and Lactobacillus rhamnosus GR-1 can colonize the intestine and vagina and reduce recurrences of bacterial vaginosis, yeast vaginitis and urinary tract infections. They are bile resistant and survive passage through the human gastrointestinal tract without induction of systemic immune or inflammatory responses. There is no published information on the growth and survival of L. rhamnosus GR-1 and L. reuteri RC-14 in yogurt. The incorporation of L. rhamnosus GR-1 and L. reuteri RC-14 in yogurt is an innovative idea. This research developed a new probiotic yogurt with sufficient viable counts of L. rhamnosus GR-1 accompanied by L. reuteri RC-14. The use of probiotic bacteria, especially those with proven therapeutic effects, in dairy products has attracted a lot of attention from dairy industry and health/wellness industry, and this type of product can provide a bridge between the two industries.

Changes in bioactive compounds and antioxidant activity during homogenization and thermal processing of tomato puree

Abstract: The effect of homogenization and thermal processing on a number of bioactive compounds (carotenoids, total phenolics, ascorbic acid and folates) in both raw tomato puree (RTP) and “hot break” tomato puree (HTP) was investigated. RTP and HTP were homogenized in either one or two-steps, followed by pasteurization at 98 °C for 40 s. Additionally, HTP was pasteurized in parallel at 98 °C, 108 °C and 128 °C. In general, homogenization had no effect, but changes were observed after pasteurization (98 °C for 40 s). Carotenoids were relatively resistant to thermal degradation, whereas total phenolic content and ascorbic acid significantly decreased. However, a higher content of folates was determined in the homogenized and pasteurized samples due to their higher extraction from the subcellular compartment. The increase in pasteurization temperatures of the HTP up to 128 °C led to a decrease of ascorbic acid, total phenolic compounds and folates. In conclusion, homogenization and pasteurization at 98 °C for 40 s improves the nutritional value of tomato puree, increasing the extractability of the folates and maintaining the carotenoid content. Industrial relevance Unlike other vegetables, the tomato is a staple food that is not frequently homogenized by the processing industry, although homogenization could improve product quality. This is why we explored this technique, using one-step and two-step homogenization. The tomato and vegetable processing industry frequently pasteurizes at a constant flow rate, meaning constant heating time. In this study, we employed three different temperatures, using the same time of exposure, to cover different situations in the food industry. Depending on the product’s thickness, an increase in the temperature might be needed to reduce any microbiological hazard in the final product. Homogenization followed by pasteurization at 98 °C for 40 s resulted in a greater improvement of the nutritional value of tomato puree in all situations tested.

Effects of high pressure and temperature on the structural and rheological properties of sorghum starch

Abstract: Pressure-induced gelatinisation of sorghum starch was studied and compared to heat-induced gelatinisation. Starch suspensions were treated at increasing pressure (200–600 MPa) or temperature (60–95 °C) for 10 min. The degree of gelatinisation was determined using differential scanning calorimetry, changes in birefringence and damaged starch measurements. Furthermore, the pasting behaviour and structural changes during gelatinisation were investigated using rheology and microscopy. The pressure-induced as well as the temperature-induced gelatinisation curves were sigmoid-shaped. Gelatinisation occurred between 300 MPa and 600 MPa or between 62 °C and 72 °C. No significant differences were found between the rheological properties and the microstructure of the pressure-treated samples and the temperature-treated samples within the gelatinisation intervals. Granules lost their birefringence, but granular structure was maintained; however, when heated beyond the endpoint of gelatinisation, the formation of a “sponge-like” structure was observed. This change in structure at very high temperatures was reflected by a decrease in complex viscosity. Industrial relevance In order to apply high pressure as an alternative to temperature in the structural engineering of starch-based systems, a full understanding of the pressure-induced gelatinisation process is necessary. No rheological and ultra-structural differences were observed between pressure- and temperature-induced gelatinisation of sorghum starch. These results indicate that pressure treatment can be utilised as a replacement technology for temperature during processing of complex starch-containing products.