Showing papers in "Innovative Food Science and Emerging Technologies in 2011"

Recent developments in the application of seaweeds or seaweed extracts as a means for enhancing the safety and quality attributes of foods

Abstract: The production of rancid flavors and odors due to oxidative stress in foods can lead to a reduction in the sensory attributes, nutritional quality and food safety. Due to consumer demands, interest has been generated in searching plant products for natural “green” additives. Extracts from macroalgae or seaweeds are rich in polyphenolic compounds which have well documented antioxidant properties. They also have antimicrobial activities against major food spoilage and food pathogenic micro-organisms. Thus, possibility of seaweeds being added to foods as a source of antioxidant and antimicrobial is the main focus of this communication. In addition, seaweeds are also rich in dietary minerals specially sodium, potassium, iodine and fibers. Another potential area where the use of seaweed is gaining importance is regarding their addition for improving the textural properties of food products which is also extensively reviewed in this paper. Industrial relevance The trend towards the use of “natural green” plant extracts in various food and beverages in the food industry is gaining momentum. Seaweed, being a rich source of structurally diverse bioactive compounds with valuable nutraceutical properties, can be used as an ingredient to supplement food with functional compounds. Interest in the application of such compounds as natural antioxidants, antimicrobials or texturing agents in different food products is greater than ever. The addition of seaweeds or their extracts to food products will reduce the utilization of chemical preservatives, which will fulfill the industry as well as consumer demands for “green” products. In addition, the current status and the future projections in the functional effects of seaweeds as a means to improve the fiber content and reduce the salt content of food products, which will be of significant importance to the meat industry, is also discussed.

The antimicrobial activity of hydrophobic essential oil constituents acting alone or in combined processes of food preservation

Abstract: This work evaluates the antimicrobial activity of widespread hydrophobic essential oil (EO) constituents, 3 hydrocarbon monoterpenes (α-pinene, β-pinene, and p-cymene) and 8 oxygenated monoterpenes (thymol, carvacrol, borneol, linalool, terpineol-4-ol, 1,8-cineole, α-terpinyl acetate, and camphor), as a function of the treatment medium pH, and possible synergistic effects in combination with mild heat or pulsed electric fields (PEF) treatments. Results obtained using the disk diffusion technique highlight phenols and alcohols as the best growth inhibitors and discount hydrocarbons due to their poorer activity. However, the evaluation of the bactericidal effect at pH 4.0 shows that most compounds assayed, including some hydrocarbons, were very effective against Escherichia coli and Listeria monocytogenes. Most EO constituents caused membrane permeabilization and sublethal injuries within survivors. Outstanding synergistic lethal effects were shown using mild heat (54 °C/10 min) or PEF (30 kV/cm/25 pulses) combined with 0.2 μl/ml of some antimicrobials, achieving 5 log10 cycles of cell inactivation as a function of the treatment conditions. In most cases, combined treatments were more effective in apple than in orange juice. Industrial relevance The efficacy of EO constituents improves when combining with mild heat or PEF treatments, which allows us to propose very low doses of antimicrobials. The valuable synergistic effects observed offer the potential to improve traditional heat treatments by reducing treatment intensity and consequently adverse effects on food quality, and to enhance novel PEF treatments by achieving a higher degree of microbial inactivation.

Optimized ultrasonic-assisted extraction of flavonoids from Prunella vulgaris L. and evaluation of antioxidant activities in vitro

Abstract: The Box–Behnken design combined with response surface methodology was used to optimize ultrasonic-assisted extraction of total flavonoids from Prunella vulgaris L. The results indicated that the highest extraction yield of flavonoids by ultrasonic-assisted extraction could obtain to be 3.62% using ethanol concentration of 41% (v/v) as solvent and liquid to solid ratio of 30:1 (mL/g) for 30.5 min at the temperature of 79 °C. The crude extract was then purified by AB-8 macroporous adsorption resin, the flavonoids content in the purified extract increased to 81.58%. The antioxidant activities of the purified flavonoids were evaluated in vitro by scavenging capability of DPPH free radical and hydroxyl free radical, reducing power, total antioxidant capability and β-carotene bleaching test. The results showed that the flavonoids have significant antioxidant activities, which can be used as a source of potential antioxidant. Industrial Relevance The effective exploitation and application of the natural plant resources have very important significance for the industrial and economic development. Prunella vulgaris L. is a perennial plant commonly found in China and Europe, which was proved to be rich in flavonoids, triterpenes and phenolic acid. It has long been used as a folk medicine for alleviating sore throat, reducing fever and accelerating wound healing. Recent studies have demonstrated that the methanol or water extract of this herb exhibits many of the activities including antihyperglycemic activity, systemic anaphylaxis inhibition, antioxidative antiviral and antibacterial effects. However, attempts have not been made so far to investigate the ultrasonic-assistant extraction of flavonoids from P. vulgaris L. and evaluate their antioxidant activities in vitro. In this work, a four-variable, three-level experiment Box–Behnken design based on response surface methodology was used to optimize ultrasonic-assistant extraction of flavonoids from P. vulgaris L. The optimized results showed that the highest extraction yield of flavonoids by ultrasonic-assisted extraction could arrive 3.62%, using 41% (v/v) ethanol as solvent and 30:1 (mL/g) liquid to solid ratio for 30.5 min at the temperature of 79 °C. The suitability of the model equation for predicting the optimum response values was tested using the selected optimal conditions. The predicted extraction yield of flavonoids was 3.63%, which was consistent with the practical extraction yield of flavonoids of 3.62%. The crude extract was then purified by AB-8 macroporous adsorption resin, the flavonoids content in the purified extract increased to 81.58%. The antioxidant activities of the purified flavonoids were evaluated in vitro by scavenging capability of DPPH free radical and hydroxyl free radical, reducing power, total antioxidant capability and β-carotene bleaching test. The results indicated that the flavonoids have significant antioxidant activities, which can be used as a source of potential antioxidant or functional food material. We believe that the knowledge gained from this study should be helpful to further exploit and apply this resource .

The effect of ball milling treatment on structure and porosity of maize starch granule

Abstract: Maize starch was mechanically treated by a planetary ball mill at 500 rpm for 1, 2 and 3 h. The effect of ball-milling treatment on structure and porosity of maize starch granule was studied. The SEM and TEM analyses indicated that starch granule surfaces were significantly changed and cavities in the central region of distorted granules were observed in the company with disappearance of alternate growth rings. The FT-IR analysis showed that ball milling treatment significantly increased the intensity of band 3382 cm−1 and decreased the ratio of 1047/1018 cm−1 and 995/1018 cm−1 corresponding to the crystalline/amorphous part of starch structure. Special surface area (SBET), cumulative volume (VBJH), average diameter pores (DBJH), span and median diameter (Dv, 0.5) increased rapidly and then decreased gradually. The XRD patterns, FT-IR and 13C CP/MAS NMR spectra showed that the crystallinity of starches and content of double helices of starch chains were decreased, respectively. Industrial relevance Ball milling is one kind of physical modified method in polymer industry. It can be used in a variety of applications, including nanomatrix composites, dispersed alloy materials, metallic refinery, ore treatment, waste disposal, and synthesis of organic materials. Starch is a natural carbohydrate polymer, it contributes greatly to the textural properties of many foods and is widely used in food and industrial applications as a thickener, colloidal stabilizer, gelling agent, bulking agent and water retention agent. However, limitations such as low solubility, high viscosity, shear resistance, thermal resistance, thermal decomposition and high tendency toward retrogradation limit its use in some food and non-food systems. After ball milling treatment, the reactivity of starch is increased. Furthermore, milled starches exhibit the adsorptive capacity which can offer new opportunity for starch application, for example as sorbent in food or pharmaceutical.

Comparing equivalent thermal, high pressure and pulsed electric field processes for mild pasteurization of orange juice. Part II: Impact on specific chemical and biochemical quality parameters

Abstract: The impact of thermal, high pressure (HP) and pulsed electric field (PEF) processing for mild pasteurization of orange juice was compared on a fair basis, using processing conditions leading to an equivalent degree of microbial inactivation. Examining the effect on specific chemical and biochemical quality parameters directly after treatment and during storage at 4 °C revealed only significant differences in residual enzyme activities. For pectin methylesterase inactivation, none of the treatments was able to cause a complete inactivation, although heat and HP pasteurization were the most effective in limiting the residual activity. Peroxidase was completely inactivated by heat pasteurization and was much less susceptible to HP and PEF. All other quality parameters investigated, including the sugar profile, the organic acid profile, bitter compounds, vitamin C (ascorbic acid and dehydroascorbic acid), the carotenoid profile, furfural and 5-hydroxymethylfurfural, experienced no significantly different impact from the three pasteurization techniques.

Extending shelf-life of Fresh-cut ‘Fuji’ apples with chitosan-coatings

Abstract: The effect of coatings in combination with anti-browning agents (1%chitosan; 2%ascorbic acid + 0.5%CaCl2 and 2% ascorbic acid + 0.5%CaCl2 + 1% chitosan) on minimally processed apple slices was studied during storage. Chitosan-coating treatments effectively retarded enzymatic browning on minimally processed apples during storage and they effectively retarded or avoided tissue softening, apple slices underwent a little loss of firmness. Chitosan-coating did not perform very well as water vapor barriers in apple slices. To control initial respiration rate of apple slices, edible coatings were applied to cut apples as semi-permeable barriers against air. Initial respiration rate showed a decrease in 2% ascorbic acid + 0.5%CaCl2 + 1% chitosan apple slices at 5 °C. Industrial relevance Recently, there has been an increasing market demand for minimally processed fruits and vegetables due to their fresh-like character, convenience, and human heath benefits. Minimal processing includes grading, washing, sorting, peeling, slicing, chopping, and then packaging. Since minimal processing results in quality deterioration associated with water loss, softening, microbial contamination, increased respiration and ethylene, and cut-surface browning, minimally processed products become more perishable. Edible coating was used for cut apples to reduced respiration and control physiological changes. The color of products, such as apple slices, is an important quality index. Brown apple slices are aesthetically unattractive. Chitosan has been reported to maintain the quality of fruit and vegetables (EI Ghaouth et al.,1991). The objective of this study was to develop procedures for the use of edible coatings in combination with anti-browning agent and to extend the shelf-life of minimally processed apple slices.

Comparing equivalent thermal, high pressure and pulsed electric field processes for mild pasteurization of orange juice. Part I: Impact on overall quality attributes

Abstract: Mild heat pasteurization, high pressure processing (HP) and pulsed electric field (PEF) processing of freshly squeezed orange juice were comparatively evaluated examining their impact on microbial load and quality parameters immediately after processing and during two months of storage. Microbial counts for treated juices were reduced beyond detectable levels immediately after processing and up to 2 months of refrigerated storage. Quality parameters such as pH, dry matter content and brix were not significantly different when comparing juices immediately after treatment and were, for all treatments, constant during storage time. Quality parameters related to pectinmethylesterase (PME) inactivation, like cloud stability and viscosity, were dependent on the specific treatments that were applied. Mild heat pasteurization was found to result in the most stable orange juice. Results for HP are nearly comparable to PEF except on cloud degradation, where a lower degradation rate was found for HP. For PEF, residual enzyme activity was clearly responsible for changes in viscosity and cloud stability during storage. Industrial relevance Development of mild processing technologies with a minimal impact on fruit juice can be considered as a true alternative of fresh fruit. The present work presents a fair comparison of mild heat treated, high pressure (HP) and pulsed electric field (PEF) processed orange juice as an alternative for thermal pasteurization. Orange juices were monitored during two months of storage.

Stability of anthocyanins and ascorbic acid of high pressure processed blood orange juice during storage

Abstract: The stability of anthocyanins (Cy3Gl) and ascorbic acid (AA) of high pressure processed blood orange juice during storage was investigated. Blood orange juice was processed at pressure levels of 400, 500, 600 MPa for a constant treatment time of 15 min. During processing > 99% and 94.5% retention of Cy3Gl and AA content was observed for all pressure treated samples. The degradation kinetics of processed samples followed first order kinetics during storage. Cy3Gl and AA losses were significantly higher at a storage temperature of 20 °C compared to 4 °C for both high pressure processed and untreated control samples. During storage at 4 °C for 10 days, retention rates for Cy3Gl and AA of 93.4 and 85.0% were observed at 600 MPa and treatment time of 15 min. A strong correlation was observed between AA content and Cy3Gl content with r = 0.79 and r = 0.90 ( p 0.0001) during storage at 4 and 20 °C respectively, indicating a strong influence of AA content on Cy3Gl stability during storage. Predicted shelf-life, based upon nutritional requirements, during storage at 20 °C of high pressure processed juice samples were found to be higher compared to control samples. Industrial relevance This study shows the potential benefits of high pressure processing in retaining ascorbic acid and anthocyanins in blood orange juice. High pressure processed samples showed improved shelf life compared to fresh juice. Results presented in this study revealed that high pressure processing helps preserve the nutritional value of blood orange juice during storage.

Impact of UV-C light on safety and quality of fresh-cut melon

Abstract: The effectiveness of UV-C light exposure on safety and quality of fresh-cut fruit was investigated with reference to melon cubes. UV-C light was applied during cutting operations and before packaging. Melon cubes were then analysed for microbial counts, colour, firmness, juice leakage, sensory properties and preference during storage at 6 °C for up to 14 days. Fruit exposure to UV-C light leaded to 2 log reductions for both total viable count and Enterobacteriaceae , whose counts remained 2 log units lower than that of the untreated sample during storage. No significant effect of UV-C light treatment on product colour and firmness was detected during storage. By contrast, the exposure to UV-C light decreased melon leakage, probably due to the formation of a thin dried film on the product surface. UV-C treated samples were also associated to a better flavour which made them significantly preferred to the untreated ones. UV-C light treatment was demonstrated to be a high potential novel technology for surface decontamination of ready-to-eat food surface. Industrial Relevance UV-C light treatment represents a high potential novel technology allowing to achieve surface decontamination of ready-to-eat fruit products while improving their sensory properties.

Natural antioxidant active packaging film and its effect on lipid damage in frozen blue shark (Prionace glauca)

Abstract: The capacity of a natural antioxidant derived from barley husks to retard oxidation of PUFA in blue shark muscle was investigated. Blue shark slices were packaged in low density polyethylene (LDPE) film containing the natural antioxidant (sample C1 = 7 mg/dm 2 film, and sample C2 = 24 mg/dm 2 film) or in LDPE film without the antioxidant (control sample) and frozen for 12 months. Peroxide value was significantly higher in control samples during the first six months than in samples C1 and C2. The free fatty acids content was significantly higher in the control samples than in samples C1 and C2 during the 12 months of the study. Up to the sixth month of storage, the concentrations of thiobarbituric acid reactive substances in C1 and C2 were significantly lower than in the control sample. The results demonstrate that hydrolytic activity and lipid oxidation are sensitive to antioxidant content and storage time. The results confirm the efficacy of active packaging with a natural antioxidant derived from barley husks to slow the progress of lipid hydrolysis and increase oxidative stability in blue shark muscle. Industrial relevance: The use of barley husks, which is a residue the brewing process unwieldy and unhelpful, is optimized to obtain a crude extract antioxidant. Natural extracts of phenolic compounds with high antioxidant activity was obtained after prehydrolysis and delignification of barley husks. The raw extracts show more than twice higher antioxidant capacity than BHT in terms of EC50. The crude extract antioxidant has as important feature his high content of p-coumaric and ferulic acid. The results demonstrated the efficacy of an active packaging with a natural antioxidant derived from barley husks. The extract dosed on the surface of the film shows and maintains an excellent antioxidant capacity and is not separated of film in aqueous or oily media, so these can be used in a wide type of food.

Optimized microwave-assisted extraction of total phenolics (TP) from Ipomoea batatas leaves and its antioxidant activity

Abstract: An efficient microwave-assisted extraction (MAE) technique was employed to extract total phenolics (TP) from sweetpotato [Ipomoea batatas (L.) Lam.] leaves (TPSL). The optimal conditions for microwave-assisted extraction of TPSL were determined by response surface methodology. A face-centered cubic design (FCD) was applied to evaluate the effects of three independent variables (microwave power, extraction time and ethanol proportion) on the recovery of TPSL. The correlation analysis of the mathematical-regression model indicated that quadratic polynomial model could be employed to optimize the microwave extraction of TPSL. From response surface plots, microwave power, extraction time and ethanol proportion exhibited independent and interactive effects on the extraction of TPSL. The optimal conditions to obtain the highest recovery of TPSL were as follows: microwave power, 302 W; extraction time, 123 s; ethanol proportion, 53% (v/v). Under these optimal conditions, the experimental values agreed with the predicted ones by analysis of variance. It indicated high fitness of the model used and the success of response surface methodology for optimizing TPSL extraction. After method development, the antioxidant activity of the MAE extract was preliminarily evaluated. MAE showed obvious advantages in terms of high extraction efficiency and antioxidant activity of extract with in shortest extraction time. Industrial Relevance: Sweet potato leaves have been neglected except for a partial use as livestock feed in China. This study describes the response surface optimization of microwave-assisted extraction (MAE) process for the enhanced recovery of total phenolics from sweetpotato leaves (TPSL). MAE showed obvious advantages in terms of high extraction efficiency and antioxidant activity of extract within shortest extraction time. TPSL obtained using MAE showed potential for use in health-care food and pharmaceutical industry.

Study of starch-lipid complexes in model system and real food produced using extrusion-cooking technology

Abstract: The formation of starch-lipid complexes during extrusion of model system (rice starch added with oleic acid) and real food (rice starch added with pistachio nut flour) was evaluated. Both formulas were extruded at the same processing conditions (temperature profiles, screw speed and water feed content). The formation of starch-lipid complexes in real food, is strongly dependent on water feed content. In fact, at barrel temperature of 128 °C, the highest melting enthalpy of real food (6.7 J/g) was obtained only at 21% of water feed content whereas in the model system it was obtained both at 16 and 21%. These results point out the importance to consider all components present in the extruded food in order to study biopolymers modifications that occur during processing. Industrial relevance Additions of lipids alter the physical and chemical properties of starchy foods. The changes brought about by them in starchy foods have been attributed to the formation of complexes between amylose and lipids. These changes in the functionality of starch are of interest to the food industry and for human nutrition. Lipid complexation with starch is a very important reaction in extrusion cooking that affects structure formation and texture of the extruded products. Most studies on the starch-lipid complex formation during extrusion of model systems like starch and free fatty acids have been carried out, instead very little is known about starch-lipid complex formation during extrusion of flour blends containing fatty meal. This paper points out the importance to consider all components present in the food extruded in order to study biopolymers modifications that occur during processing. For this reason it is very important to use model systems that are not very different to real food and anyhow it would be advisable to verify the obtained results on real food, above all when a relation between macromolecular modifications and quality characteristics of extruded products would be studied.

Valorization of citrus by-products using Microwave Steam Distillation (MSD)

Abstract: A microwave steam distillation (MSD) of essential oils from fresh citrus by-products (orange peels) was studied. The effectiveness of this innovative method in extraction of citrus essential oils have been evaluated and compared to conventional steam distillation. MSD offers important advantages like shorter extraction time (6 min), cleaner features and provides an essential oil with better sensory properties (better reproduction of natural fresh fruit aroma of the citrus essential oil) at optimized power (500 W). Results from chemical and cytological approaches confirm the effectiveness of this new technique, that allows substantial savings in terms of time and energy. Industrial relevance The treatment of by-products represents a strong demand for industrial fruits processing, which produces tonnages of waste material such as peels, seeds and fibers. The disposal of these materials usually represents an industrial legal restriction problem. Moreover, the waste treatment represents significant costs and is often misjudged by companies. Transformation of waste products with high value-added allows companies to reduce the global treatment costs, sometimes even to take some profits and thus improve their competitiveness. Moreover, the recovery process of by-products is part of the current existing sustainable development and environmental protection.

Influence of high pressure application on the nutritional, sensory and microbiological characteristics of sliced skin vacuum packed dry-cured ham. Effects along the storage period

Abstract: The effect of high pressure processing at 600 MPa on sliced and vacuum packaged commercial dry-cured ham was determined by analyzing the induced color changes, the physicochemical characteristics, the microbiological count and the changes in sensory attributes and also its effect on lipid oxidation measured through TBARS (thiobarbituric reactive substances), antioxidant enzyme activities and the content of fatty acid from total, free and phospholipid fractions. This effect was also studied during 50 days refrigerated storage with different light conditions. The high pressure processing at 600 MPa modified the color of dry-cured ham producing an increase in lightness L*-parameter. Many sensory attributes were also modified resulting in an increase in hardness, chewiness, brightness, odor intensity and saltiness, while reducing color intensity. High pressure produced a reduction in the aerobic count. The oxidative stability of the pressurized dry-cured ham was not altered as observed from the absence of differences in fatty acid contents and antioxidant enzyme activities. Initially pressurization produced a decrease in TBARS levels, however this effect was not found after 50 days of refrigerated storage. Industrial relevance The application of high hydrostatic pressure (HHP) in food technology is a useful tool to combine a minimal processing that increases the shelf-life of the food products, maintaining their safety and nutritional properties and with minimal changes in flavor or taste. This processing technology is very important to increase the safety of the sliced foods which are prone to the microbiological deterioration, as cured meat products and cooked ham. Pressurization of sliced dry-cured ham at 600 MPa has been shown effective reducing spoilage associated microorganisms. The present study was carried out to evaluate the oxidative stability, nutritional quality, safety and sensory attributes of dry-cured ham pressurized at 600 MPa. This is very important because the hypothesis that HHP does not affect to sensorial characteristics needs to be confirmed in different kind of foods. Also, the possible causes of the observed effects should be explained by the study of physic–chemical parameters. In this way the oxidative stability is an important issue because some authors claimed that HHP can increase oxidation in food containing lipids.

Dealcoholizing wine by membrane separation processes

Abstract: The present work studies the use of membrane separation processes for producing wine with low alcohol content. Several membranes of reverse osmosis (CA995PE from Alfa Laval) and nanofiltration (NF99 HF, NF99, NF97 from Alfa Laval and YMHLSP1905 from Osmonics) were used for removing ethanol from a 12 vol.% red wine, in diafiltration mode, whereas pervaporation membranes of polyoctylmethylsiloxane supported in polyetherimide (POMS/PEI) from GKSS were used to recover the aroma compounds before the dealcoholization step, and adding them back to the dealcoholized wine. YMHLSP1905, NF99 and NF99 HF nanofiltration membranes showed higher effectiveness in alcohol removal from wine, due to their good permeability to ethanol and high aroma compounds' rejection, resulting in dealcoholized wine samples with promising organoleptic properties. The addition of pervaporated aroma compounds to the dealcoholized wine samples increased the flavour sensations during the wine tasting, making this combined process the one that originates the best dealcoholized wine samples. Industrial relevance The alcohol removal from wines has a great importance in the beverages industry due to the increasing demand on the non-alcoholic drinks market and also due to the increase of ethanol content of wine. This fact results namely from global warming or oenological practices and some winemakers have to pay taxes if ethanol content overcomes 14.5 vol.%. Membrane processes can be used for removing the ethanol from a regular wine. The results of this study indicate that nanofiltration and pervaporation are effective for dealcoholizing wine and preserving its original characteristics.

UV-C inactivation of Escherichia coli at different temperatures

Abstract: The influence of treatment parameters (dose and temperature), treatment medium characteristics (absorption coefficient, pH and water activity) and microbiological factors (strain, growth phase and UV damage and repair capacity) on Escherichia coli UV-C resistance has been investigated. UV-C doses to inactivate at 25 °C 99.99% of the initial population (4D) of five strains of E. coli in McIlvaine buffer of pH 7.0 with tartrazine added (absorption coefficient of 10.77 cm−1) were 16.60, 14.36, 14.36, 13.22, 11.18 J/mL for strains E. coli STCC 4201, STCC 471, STCC 27325, O157:H7 and ATCC 25922, respectively. The entrance in the stationary growth phase increased the 4D value of the most resistant strain, E. coli STCC 4201, from 13.09 to 17.23 J/mL. Survivors to UV treatments showed neither oxidative damages nor injuries in cell envelopes. On the contrary, the photoreactivation by the incubation of plates for 60 min below visible light (11.15 klx) increased the dose to 18.97 J/mL. The pH and the water activity of the treatment medium did not affect the UV tolerance of E. coli STCC 4201, but the lethal effect of the treatments decreased exponentially (Log10 4D = − 0.0628α + 0.624) by increasing the absorption coefficient (α). A treatment of 16.94 J/mL reached 6.35, 4.35, 2.64, 1.93, 1.63, 1.20, 1.02 and 0.74 Log10 cycles of inactivation with absorption coefficients of 8.56, 10.77, 12.88, 14.80, 17.12, 18.51, 20.81 and 22.28 cm−1. The temperature barely changed the UV resistance up to 50.0 °C. Above this threshold, inactivation rates due to the combined process synergistically increased with the temperature. The magnitude of the synergism decreased over 57.5 °C. An UV treatment of 16.94 J/mL in media with an absorption coefficient of 22.28 cm−1 reached 1.23, 1.64, 2.36, 4.01 and 6.22 Log10 cycles of inactivation of E. coli STCC 4201 at 50.0, 52.5, 55.5, 57.5 and 60.0 °C, respectively. Industrial relevance Results obtained in this investigation show that UV light applied at mild temperatures (57.5 to 60 °C) could be an alternative to heat treatments for 5-Log10 reductions of E. coli in liquid foods. Since microbial resistance to UV-C light did not depend on the pH and water activity (aw) of the treatment media, eventual advantages of UV light for pasteurization purposes will be higher in low aw foods. E. coli STCC 4201 could be considered as a target when UV light processing of foods.

Fresh cut ‘Tommy Atkins’ mango pre-treated with citric acid and coated with cassava (Manihot esculenta Crantz) starch or sodium alginate

Abstract: This work aimed to evaluate quality parameters of ‘Tommy Atkins’ mango slices pre-treated with citric acid and cassava starch or sodium alginate edible coatings, with or without glycerol. Samples only treated with citric acid were also evaluated. Mango slices dipped in sanitising solution were used as control. Colour parameters, mechanical properties, weight loss and respiration rate were analysed during 15 days at 5 °C. Cassava starch coating, with or without glycerol, provided higher stress at failure and lightness values than control sample throughout storage (p ≤ 0.05). The citric acid promoted colour preservation, but increased significantly samples weight loss during storage. Sodium alginate coatings did not maintain quality characteristics, showing stress at failure and lightness values lower than control after 15 days. All coatings reduced respiration rate, but citric acid dipping and cassava starch coating without glycerol treatments were more effective, reaching values around 41% lower, when compared to control sample. Industrial Relevance Fresh-cut mangoes are appreciated world-wide for its exotic flavour and nutritional composition. However, their shelf life is limited by changes in colour, texture, appearance and microbial growth. The edible coatings act as gas and water vapour barrier, extending the storage time of fresh-cut fruit and vegetables. Thus, cassava starch and alginate are alternatives to preserve minimally processed mangoes, maintaining the quality parameters of fresh fruit. This work is useful for the minimal processing industry in order to increase shelf life of fresh-cut mangoes, which can be considered an alternative to fast food and other ready-to-eat products, attending the demand for healthy and convenient foodstuffs.

Combination of salicylic acid and ultrasound to control postharvest blue mold caused by Penicillium expansum in peach fruit

Abstract: The effect of ultrasound (40 kHz, 10 min) and salicylic acid (SA, 0.05 mM) either separately, or combined on blue mold caused by Penicillium expansum in peach fruit was investigated. The results showed that the application of SA alone could reduce blue mold, while the use of ultrasound had no effect. Our results also revealed that SA combined with ultrasound treatment was more effective in inhibiting fungal decay during storage than the SA treatment alone. The combined treatment increased the activities of defense enzymes such as chitinase, β-1,3-glucanase, phenylalanine ammonia-lyase, polyphenol oxidase and peroxidase, which were associated with higher disease resistance induced by the combined treatment. Furthermore, the combined treatment did not impair the quality parameters of peach fruit after 6 days of storage at 20 °C. These results suggested that the combination of ultrasound and SA treatment may be a useful technique to reduce blue mold in peach fruit. Industrial relevance This paper investigates the effect of ultrasound combined with SA on decay incidence of peach fruit. The results presented demonstrate that the effect of the combined treatment on the disease resistance and fruit quality should be considered by processors prior to its adoption as a preservation technique.

Changes in flavonoid content of grapefruit juice caused by thermal treatment and storage

Abstract: The effect of conventional and microwave pasteurization on the main flavonoids present in grapefruit juice and their stability throughout 2 months of refrigerated and frozen storage was evaluated. Individual flavonoids were analyzed by HPLC. The results showed that naringin, narirutin, quercetin and naringenin were the most abundant flavonoids in grapefruit juice. In general, although every pasteurization treatment caused a significant reduction in the content of all the studied flavonoids, the treated samples were more stable during storage. While fresh squeezed juice (FS) and conventional pasteurized juice (CP) were better preserved under refrigeration conditions, microwave pasteurized juice (MP) conserved better when frozen stored. In fact, after 2 months, frozen MP samples showed the greatest flavonoid retention. From this point of view, microwave treatment can be considered a good alternative to conventional pasteurization. Industrial relevance Flavonoids are polyphenolic compounds present in fruits and vegetables relevant not only in terms of quality, as they influence the visual appearance and taste, but also from a therapeutical point of view, as they appear to be associated with the prevention of degenerative diseases. The consumption of grapefruit juice is fairly widespread among the population. Traditionally, juices have been pasteurized by heat treatment to prolong their shelf life. However, this process may cause irreversible losses of nutritional quality and antioxidant activity and, in consequence, may affect their health-related properties. In this sense, the use of microwaves can be considered an alternative to conventional thermal pasteurization. Microwave energy was applied as alternative to conventional heating for grapefruit juice pasteurization. The results obtained in this study showed that when the effect of pasteurization process and storage is considered together, the use of microwave energy led to a greater retention of all the analyzed flavonoids, thereby representing a good alternative to conventional pasteurization. In this case, frozen storage of processed product would be recommended to better preserve these compounds.

Freshness measurement of eggs using near infrared (NIR) spectroscopy and multivariate data analysis

Abstract: Near infrared (NIR) spectroscopy combined with multivariate analysis were attempted to determine freshness of eggs. Independent component analysis (ICA) and principle component analysis (PCA) algorithms were performed comparatively to extract effective features from the original data. Artificial neural network combined with genetic algorithms (GA–ANN) were employed to calibrate regression model. Some parameters of GA–ANN model were optimized by cross-validation in building models. The performance of the final optimized model was evaluated according to the root mean square error of prediction (RMSEP) and the correlation coefficient (R) in the prediction set. The optimal performance was obtained when 7 ICs from ICA were used in GA–ANN model. It was achieved with RMSEP = 2.443 and R = 0.879. This work shows that NIR spectroscopy combined with multivariate calibration has significant potential in the analysis of freshness of eggs. Industrial relevance Freshness makes a major contribution to the quality of egg and egg products, because consumers may perceive variability in freshness as lack of quality. Egg freshness grading was mostly relied on storage time. However, based on individual differences of eggs, freshness of them fluctuated. Consumers might buy un-fresh eggs from the market. This work presents a non-destructive method for the measurement of egg freshness, and builds a robust calibration model to improve the prediction ability. The research data presents a potential way for fast, non-destructive and automatic measurement of freshness in egg industry.

Application of high pressure processing to improve the functional properties of pale, soft, and exudative (PSE)-like turkey meat

Abstract: Improvement of functional and rheological properties of turkey breast meat proteins with different ultimate pHs at 24 h post-mortem (pH24) was attempted using high pressure processing (up to 200 MPa for 5 min at 4 °C). Pressures of 50 and 100 MPa were found to increase the water holding capacity of low pH meat. At these pressures, higher protein surface hydrophobicity and greater exposure of sulfhydryl groups were evident. These elements may have contributed to improved water retention properties of the treated protein. The formation of a better gel network was also evident at 50 and 100 MPa as revealed by the dynamic viscoelastic behavior. Application of high pressure significantly (P Industrial relevance A major concern in the poultry industry is reduced meat functionality, such as low water holding capacity (WHC) in low pH poultry meat leading to reduced yield causing economic loss in the production of further processed products. An alternative technology to reduce salt and improve water retention properties is by the application of high pressure processing (HPP) to produce healthier food products.

Comparative assessment of antioxidant activity in three edible species of green seaweed, Enteromorpha from Okha, Northwest coast of India

Abstract: Three edible species of green seaweed Enteromorpha (E. compressa, E. linza and E. tubulosa) were studied for their antioxidant activity. The maximum total phenol content (%) was observed in the extract of acetone (11.63 ± 0.39), methanol (3.45 ± 0.18) and acetone (6.30 ± 0.06) for E.compressa, E.linza and E.tubulosa respectively. The excellent DPPH radical scavenging was observed in methanolic extract of E. compressa (IC50 1.89 mg/ml). The acetone extract of E. tubulosa showed good reducing power as compared to the extract of E. compressa and E. linza at 0.1 mg/ml. Methanol and propanol extracts of E. compressa showed good ferrous ion chelation activity. The extract of these three seaweeds exhibited high antioxidant activity in linoleic acid system during the incubation time. The potential of these extracts of Enteromorpha was evident, as it possessed various antioxidant activities. Hence, these extracts could be used as either natural antioxidants or ingredients in pharmaceutical industries. Industrial Relevance The results showed that different solvent extracts obtained from edible species of Enteromorpha exhibited good antioxidant activities. Bioactive compounds found in Enteromorpha species anticipate a major breakthrough for a variety of food/medical applications as they have the potential for application of such compounds as natural antioxidants in different food/pharmaceutical products.

Efficacy of pulsed light for shelf-life extension and inactivation of Listeria monocytogenes on ready-to-eat cooked meat products

Abstract: Pulsed light (PL) was tested for its utility to improve the microbial quality and safety of ready-to-eat cooked meat products. Vacuum-packaged ham and bologna slices were superficially inoculated with Listeria monocytogenes and treated with 0.7, 2.1, 4.2 and 8.4 J/cm2. PL treatment at 8.4 J/cm2 reduced L. monocytogenes by 1.78 cfu/cm2 in cooked ham and by 1.11 cfu/cm2 in bologna. The effect of PL on lipid oxidation and sensory properties was also investigated. The 2-thiobarbituric acid values were very low and chromaticity parameters were within the normal values reported for cooked meat products. PL at 8.4 J/cm2 did not affect the sensory quality of cooked ham, while treatments above 2.1 J/cm2 negatively influenced the sensory properties of bologna. The combination of PL and vacuum packaging provided ham with an additional shelf-life extension of 30 days compared with only vacuum packaging. The shelf-life of bologna was not extended by PL. Industrial relevance The efficacy of pulsed light for the decontamination of surfaces offers excellent possibilities to ensure food safety and to extend shelf-life of ready-to-eat (RTE) products. The results of this study indicate that Listeria monocytogenes can be reduced by approximately 2 log cfu/cm2 in RTE cooked ham and 1 log cfu/cm2 in bologna using a fluence of 8.4 J/cm2. This dose does not affect the sensory properties of ham and triples its shelf-life when compared with conventional RTE products. On the contrary, fluences above 2.1 J/cm2 are not suitable for the treatment of bologna since sensory quality is modified.

High pressure carbon dioxide treatment for fresh-cut carrot slices

Abstract: The effects of high pressure carbon dioxide (HPCD) treatment on natural microorganisms, indigenous enzyme activity, damage to cell membranes and hardness in fresh-cut carrot slices were investigated. 1.86 log 10 cycle reduction for aerobic bacteria (AB) and 1.25 for yeasts and molds (Y&M) were achieved at 5 MPa and 20 °C for 20 min. The residual activity ( RA ) of peroxidase (POD), polyphenol oxidase (PPO), and pectinmethylesterase (PME) exhibited initially increase and secondly decrease with treatment time and their minimum activity was 75.8%, 90.9% and 52.8% at 5 MPa and 20 C for 15 min, respectively. Membrane damage was evaluated by relative electrolyte leakage (REL) and malondialdehyde (MDA) content. HPCD caused a significant increase of REL in carrot slices and the REL of carrot slices treated at 5 MPa and 20 °C for 15 min was 5.7 times as much as that of the untreated, however, HPCD showed no effect on MDA content. The hardness was well retained after HPCD treatment and the largest loss was 7.9% at 5 MPa and 20 °C for 15 min. Industrial relevance Fresh-cut carrot slices are one of the most widely used products in prepared salads, and it required strict treatment conditions to protect its quality, especially to prevent microbial spoilage and enzymatic discoloration. HPCD is one promising novel non-thermal technique without compromising the flavor, taste and nutrition aspect of food. This study analyzed the effectiveness of HPCD as a method of preserving fresh-cut carrot slices, including inactivating natural microorganisms and enzymes which are crucial to quality control. Available data provided in this study will benefit the fresh-cut fruits and vegetables industry.

Effect of water activity (aw) and irradiation on the shelf-life of fresh noodles

Abstract: In this work, the effect of water activity (a w ), irradiation and their combination on the preservation of fresh noodles was studied. Microbial growth, pH and sensory characteristics were investigated during 16 days' storage time under 37 °C. The combination of glycerol (3%), propylene glycol (2%), compound phosphate (0.4%) and salt (3%) was proved to be the most effective group which could reduce a w from 0.979 (control) to 0.900. Under this condition, the shelf-life of fresh noodles could be extended for more than 7 times. Moreover, a synergism between humectants and irradiation treatment was observed in relation to microorganism inhibition and shelf-life extension. For all the irradiated noodles, TPC (total plate count) did never exceed the selected deterioration threshold limit (10 6 CFU/g) during the entire observation period. When the irradiation dose was 4 kGy or higher, scarcely any bacteria proliferation was observed. Noodle samples irradiated at 4 kGy showed the best pH and sensory stability as the storage time increased. Industrial relevance This paper presents an effective and low-cost method to prolong the shelf-life of fresh noodles, which can largely extend the store time of fresh noodles at room temperature, and does not produce any negative changes in sensory attributes. This method will be a new system for food preservation with lots of possible industrial applications. The results of this research also have implications for dumpling skins and other noodle types.

The effect of pulsed electric fields (PEF) in combination with high intensity light pulses (HILP) on Escherichia coli inactivation and quality attributes in apple juice

Abstract: Treatments involving pulsed electric fields (PEF) in combination with high intensity light pulses (HILP) were applied to reconstituted apple juice in a continuous system using a 2 × 4 factorial design, with sequence and energy levels as main factors. Two PEF field strengths (24 kV/cm or 34 kV/cm) were selected (treatment time 89 μs each) corresponding to “high” (H) and a “low” (L) energy inputs (261.9 and 130.5 J/ml, respectively). Juice was also pumped through a HILP system (pulse length 360 μs, frequency 3 Hz) and exposed to energy dosages of 5.1 J/cm2 (H) or 4.0 J/cm2 (L) corresponding to 65.4 and 51.5 J/ml, respectively. Microbiological analysis was performed by inoculating juice with Escherichia coli K12 and counting microbial populations pre- and post-processing. Selected physical and chemical quality attributes were compared with those of unprocessed controls. A sensory evaluation was conducted using 31 untrained panellists and the products compared to thermally processed juice (94 °C for 26 s). With the exception of HILP (H) and PEF (L), all combinations achieved the minimum microbial reduction of 5 log units required by the FDA. The results obtained for PEF (L) followed by either HILP (L or H) suggest a synergistic effect on microbial inactivation. In general, the quality attributes were not affected by the chosen treatments and sensory evaluation revealed that the HILP(L)/PEF(L) combination was the most acceptable of the selected non-thermal treatments. Industrial Relevance Heat remains the dominant microbial/enzyme inactivation technique though its impact on food quality is often at odds with increased consumer demand for minimally processed (MP) products. The reduction in intrinsic preservation in MP products raises new safety and stability risks and a major trend is the combination of inhibitory techniques to effectively preserve without the extreme use of a single technique (i.e. hurdle technology). PEF and HILP are emerging nonthermal/mild-heat technologies which have antimicrobial capabilities when applied alone or in combination with other physicochemical hurdles. Only a limited amount of work has focused on combinations of emerging technologies. As consumers have less reservations about physical (vs. chemical) preservation treatments, the objective of this paper is to assess if novel combinations of these emerging physical hurdles achieves the twin goals of food safety and quality in apple juice. This will involve assessing whether these combinations are effective vs. selected microorganisms un-/mildly heated products. In addition the nutritional/sensory quality of these MP products will be compared to untreated products.

Effects of combined high-pressure homogenization and enzymatic treatment on extraction yield, hydrolysis and function properties of peanut proteins

Abstract: Peanut protein isolate (PPI) was extracted by high-pressure homogenization (HPH) under 0.1 MPa (atmospheric pressure) and 40 or 80 MPa (high pressure). Effects of Alcalase (a proteolytic enzyme) on the enzymatic hydrolysis of PPI and the antioxidant activity of the PPI hydrolysates were investigated. The molecular weight distributions of the PPI hydrolysates were analyzed using Sephadex G-25 gel filtration chromatography while the antioxidant activities, including reducing power, 1,1-dipheny-2-picrylhydrazyl (DPPH) radical-scavenging activity and hydroxyl free radical-scavenging activity of the PPI hydrolysates were evaluated. The extraction yields of PPI by HPH under 0.1, 40 and 80 MPa were 16.84, 30.65 and 39.86%, respectively, which showed that HPH treatment improved the PPI extraction. The HPH treatment increased the degree of hydrolysis of PPI and significantly increased the reducing power and hydroxyl radical­scavenging activity. Furthermore, the molecular weight distributions of the PPI hydrolysates appeared principally over the range of 1000–5000 Da, while the HPH treatment enhanced the production of small peptides, which was in agreement with the high PPI hydrolysis degree. These results suggest that HPH treatment in combination with enzymatic hydrolysis could modify PPI properties and increase the antioxidant activities of the PPI hydrolysates. Industrial relevance This study was focused to evaluate the effects of high-pressure homogenization (HPH) in combination with enzymatic hydrolysis on extraction yield and enzymatic hydrolysis of PPI and antioxidant activity of the PPI hydrolysates. This study indicated the possibility of improving the availability of PPI by HPH treatment via increasing extraction yield and enzymatic hydrolysis of the PPI, which can provide a better utilization of the peanut by-product.

Shelf-life extension of cooked ham model product by high hydrostatic pressure and natural preservatives

Abstract: The inactivation of different spoilage organisms and surrogate pathogens in a cooked ham model product by high pressure (HP) treatment (100–700 MPa, 5–40 °C, 10 min) was investigated. A 5 log reduction could be achieved at ≥ 600 MPa at ≥ 25 °C. Subsequently, the shelf-life of packaged sliced product was studied during storage (7 °C) after treatment at 600 MPa (10 °C, 10 min) in combination with caprylic acid and Purasal ® . Without HP treatment, a plate count of 6 log CFU/g was reached after 40 days, both in presence and absence of antimicrobials. HP treatment delayed this initiation of spoilage to 59 days in absence of antimicrobials. However, microbial growth was completely suppressed during at least 84 days in the HP treated products containing caprylic acid or Purasal ® . HP treatment increased drip loss but had no or little effect on colour and sensorial evaluation by a taste panel. However, the antimicrobials had a negative influence on the flavour and aroma at the concentrations used. Industrial relevance With a steadily increasing number of commercial applications being introduced on the market, HP pasteurization is growing out of its infancy. To further support this development, there is a need of integrated studies that translate fundamental scientific findings from simplified laboratory model systems to the complexity and scale of real food products. In this work, we determined HP processing conditions to control spoilage and pathogenic bacteria in a cooked ham model product, and subsequently conducted a large pilot scale experiment comprising a total of 432 individual packages of sliced cooked ham product, in which the microbiological, physicochemical and sensorial quality was evaluated during refrigerated storage after HP treatment. In addition, the usefulness of the natural preservatives caprylic acid and lactate-diacetate as an additional hurdle was also studied. This study is one of the most comprehensive available in the literature to document the shelf-life extension that can be achieved with HP treatment of cooked ham.

Athermal concentration by osmotic evaporation of roselle extract, apple and grape juices and impact on quality

Abstract: Osmotic evaporation (or osmotic distillation) was carried out on roselle extract, apple and grape juices. The industrial pilot plant used had a hydrophobic, polypropylene, hollow-fiber membrane with an area of 10.2 m2 and an average pore diameter of 0.2 ?m. It was suitable for concentrating vegetable extracts and fruit juices, and controlled various parameters such as temperature, flow velocity, and brine concentration. The final total soluble solids (TSS) contents achieved were 660, 570, and 610 g kg?1 for grape juice, apple juice, and roselle extract, respectively. Temperature and concentration of solutions significantly influenced evaporation flux, which, for roselle extract, was 1.5 kg h?1 m?2 at 610 g TSS kg?1 and 45 °C. The physico-chemical, biochemical, and aromatic qualities of concentrates obtained by osmotic evaporation were much higher than those of thermal concentrates, and close to those of the initial products. Industrial relevance: Membrane processes are increasingly used to concentrate thermo-sensitive fruit juices and plant extracts. Their capacity to operate at moderate temperatures and pressures means that their energy consumption is low, while they produce good quality concentrates. Nonetheless, the main disadvantage of baromembrane processes is their inability to reach the concentration levels standard for products of thermal evaporation because of limitations resulting from high osmotic pressure. Actually, reverse osmosis membranes and equipment limit the final concentration of fruit juices to about 25-35°Brix. Osmotic evaporation has attracted considerable interest, as it can concentrate juices to as much as 65°Brix. This process, when applied to various juices, better preserves the quality of raw materials. However, because of the geometrical limitations of commercially available membranes and modules, juices must first be clarified. To our knowledge, only a few studies on osmotic evaporation have so far been conducted at a semi-industrial scale and never with roselle extracts. (Resume d'auteur)

Physical–chemical and sensory properties of pulsed electric field and high hydrostatic pressure treated citrus juices

Abstract: The consumers have increasing desire towards fresh, long shelf-life and healthy products by consisting favourable sensory properties. As an ambivalent fact appears that the product should meet all these requirements and should be consumable long time. All these demands lead to the importance of the minimal processing methods. The properties of widely common citrus juices (100% orange, – grapefruit, – and tangerine juice) were analyzed by measuring the possible changes in the physical–chemical parameters (pH, Brix°, electric conductivity, colour) respectively the aroma and acid content. The applied technology was pulsed electric field (in furthers: PEF) treatment with the parameters of 28 kV/cm with 50 pulses; respectively high hydrostatic pressure (HHP) technology with the parameter of 600 MPa pressure for 10 min treatment time. The sensory properties of the juices were analyzed with electronic-nose and -tongue to measure the possible changes of the treated juices compared to the untreated (control) samples with the help of these electronic tools, which can serve as a potential detection system for the differentiation of the treatments mentioned above. Industrial relevance Fruit juices are preserved mainly by heat treatment which can change many prosperous flavour- , acid and sensory properties. The present work shows in case of citrus juices the application of pulsed electric field treatment and high hydrostatic pressure techniques as non-thermal preservation possibilities and the use of electronic tongue and – nose as a new method for sensory testing.