Search

Edible films including active ingredients can be used as an alternative to preserve food products. Essential oils (EOs) exhibit antimicrobial activity against pathogenic microorganisms but their low water solubility limits the application in foods. To improve water dispersion and protect EOs from degradation, nano-sized emulsions emerge as a viable alternative. Nanoemulsions containing EOs and polysaccharides could be used to form edible films with functional properties. This study was focused on the evaluation of physical, mechanical and antimicrobial properties of alginate-based edible films formed from nanoemulsions of EOs. Nanoemulsions containing thyme (TH-EO), lemongrass (LG-EO) or sage (SG-EO) oil as dispersed phase and sodium alginate solution as continuous phase were prepared. The average droplet size of nanoemulsions was reduced after the microfluidization treatment exhibiting multimodal size distributions. The zeta-potentials of nanoemulsions were between 41 mV and 70 mV depending on the type of EO used. The lowest whiteness index was found in SG-EO nanoemulsions, whereas those containing TH-EO showed the highest value. Films formed from SG-EO nanoemulsions exhibited higher transparency, water vapor resistance and flexibility than films formed from TH-EO or LG-EO. Edible films containing TH-EO were those with the strongest antimicrobial effect against inoculated Escherichia coli, achieving up to 4.71 Log reductions after 12 h. Results obtained in the present work evidence the suitability of using nanoemulsions with active ingredients for the formation of edible films, with different physical and functional properties. (C) 2015 Elsevier Ltd. All rights reserved This research was supported by the Ministerio de Ciencia e Innovación (Spain) throughout projects ALG2009-11475 and ALG2012-35635. Author Acevedo-Fani also thanks to the University of Lleida for the pre-doctoral grant. Author Martín-Belloso acknowledges to the Institució Catalana de Recerca I Estudis Avançats (ICREA) for the Academia 2008 Award.

The aim of this research was to evaluate changes in the phenolic compounds, isoflavones and antioxidant activity of soymilk following in vitro gastrointestinal digestion (including dialysis). Gastric digestion significantly influenced the release of bioactive substances from the soymilk matrix, increasing the concentration of total phenolic components (35% as the sum of individuals and 14% by Folin-Ciocalteu [F-C] method), total isoflavone content (22%) and total antioxidant activity (76%). The concentration of all those compounds was reduced significantly in the duodenal fraction in comparison to gastric digestion and their lowest concentration was observed in the dialysed fraction, where phenolic acids were not detected. The bioaccessibility of soymilk phenolic compounds was 15% as the sum of individuals and 20% by F-C assay; isoflavones 36% and constituents with antioxidant activity 27%. Results suggest that most of these compounds were sufficiently available to be absorbed and could contribute health benefits.

The effect of alginate-based edible coating as carrier of antibrowning agents (ascorbic and citric acid) on color, bioactive compounds content and antioxidant activity of fresh-cut mangoes ‘Kent’ stored at 4 °C were evaluated. The application of alginate edible coating in conjunction with antibrowning agents (ascorbic and citric acid) to mango cubes maintained higher color values (L* and °Hue) and increased vitamin C content compared to mango cubes treated only with alginate coating or control. Total phenols content, measured throughout the Folin–Ciocalteu method, was increased 2-fold in cubes coated with alginate plus antibrowning agent. This behavior was attributed to vitamin C addition and not to a real increase in phenolic compounds. However, mangoes coated with alginate plus antioxidant presented higher concentration of ρ-hydroxybenzoic and ellagic acid than those samples coated just only with alginate or control. Mango cubes with antibrowning agents had the highest antioxidant activity due the ascorbic acid addition. The combination of alginate and antibrowning agent preserved the color of fresh-cut mangoes and increased the antioxidant potential of cubes.

This paper aims to evaluate the effects of high intensity pulsed electric fields (HIPEF) (35 kV/cm with 4 μs bipolar pulses at 200 Hz for 800 and 1400 μs) or thermal pasteurization (90 °C for 60 s), on the free amino acid (AA) profile of a fruit juice–soymilk (FJ–SM) beverage stored at 4 °C. The free AA profile of the FJ–SM beverage was constituted by Arg, Pro, Glu, Asp and Ala, as the most abundant AAs, and Ser, Phe, Leu, Lys, Thr, Tyr, Met, Val, Gly, Hys and Ile in lower concentrations. Immediately after HIPEF-800 μs process no significant changes on individual free AA content of the FJ–SM beverage were observed, except for Val concentration which increased. Conversely, when HIPEF-1400 μs or heat treatments were applied, Glu, Gly, Tyr, Val, Leu, Phe, Lys and Ile content was significantly reduced, while the concentration of Arg, Ala and Met slightly increased. Hence, total free AA content of HIPEF-800 μs treated FJ–SM beverage was similar to that of the untreated one (64.5–64.79 mg/100 mL), whereas those HIPEF-1400 μs or heat treated beverages presented lower values (60.25–61.82 mg/100 mL). Regardless of the treatment applied, the concentration of most individual free AAs, as well as total content, significantly increased along the storage; although, Pro content diminished with time. Additionally, His, Tyr, Met and Leu content of thermally treated beverages decreased as storage time increased. Overall, HIPEF treated FJ–SM beverages had higher free AA content than those thermally processed. Hence, free AA composition of mixed beverages could be well retained after applying HIPEF processes. Industrial relevance HIPEF process is a potential technology in order to obtain mixed beverages with similar content of health-related compounds than fresh products. The FJ-SM beverage evaluated in this study represents a good source of almost essential AA recommended for good health. Food industry could apply this novel process to preserve liquid foods with high content of bioactive compounds and fresh-like characteristics, avoiding the detrimental effects caused by heat.

Effects of high intensity pulsed electric field (HIPEF) (35 kV/cm with 4 μs bipolar pulses at 200 Hz for 800 and 1400 μs) or thermal (90 °C for 60 s) treatments on fatty acid and mineral profiles of a fruit juice-soymilk (FJ–SM) beverage during storage (56 days) at 4 °C were evaluated, having the just prepared beverage as a reference. Linoleic, oleic, linolenic, palmitic and stearic acids were found at highest concentration in the FJ–SM beverages; whereas, Ca and Mg were identified as the most abundant minerals, irrespectively of the treatment applied. Initial concentration of most fatty acids and minerals was not affected by HIPEF or thermal processes; only elaidic and linoleic acid concentration decreased after HIPEF or heat treatments, and Fe and Zn content was significantly enhanced in HIPEF beverages. Along the storage, total fatty acid content showed a significant increase in untreated and treated beverages; whereas minerals remained highly stable. Nevertheless, HIPEF beverages always showed higher concentration of fatty acids and minerals than those heat processed. Hence, HIPEF could be a potential alternative to obtain FJ–SM beverages with a long shelf-life and elevated amounts of health related compounds.

A fruit juice-soymilk (FJ-SM) beverage was treated by high intensity pulsed electric fields (HIPEF) (35 kV/cm with 4 μs bipolar pulses at 200 Hz for 800 or 1400 μs) or heated (90 °C, 60 s) in order to evaluate and compare the effects of both technologies on the isoflavone profile along the storage at 4 °C. Total isoflavone content was determined by quantification of aglycone and glucoside forms analyzed with HPLC. Immediately after treatments, all the evaluated samples showed a higher concentration of glucosides than aglycones, genistin being the most abundant glucoside. Heat treated samples showed higher initial concentration of glucosidic forms as compared to the untreated or HIPEF treated beverages. No significant changes were observed in total isoflavone content after the increasing HIPEF treatment time from 800 to 1400 μs. During the storage, genistein, daidzein and daidzin content increased; while genistin showed a slight decrease, irrespective of the treatment applied. In this way, total isoflavone content tend to increase throughout the time in all the evaluated samples. After 56 days of storage, there was no significant difference in HIPEF treated and fresh FJ-SM beverages, the latter being slightly higher in those thermally treated. As a result, HIPEF could be a good technology in order to obtain FJ-SM beverages with a high content of isoflavones and fresh-like characteristics. Considering the great concentration of isoflavones in untreated and treated FJ-SM beverages, their consumption could be a good way to increase the isoflavone daily intake of the population. Industrial relevance HIPEF processing could be a competent technology in order to obtain FJ-SM beverages with fresh-like appearance and similar isoflavone content than just made products. The fruit juice-soymilk beverage evaluated in the present research has a great isoflavone content regarding to commercial soy based beverages. Its consumption could increase the current isoflavone intake of the population. Industry could apply this non-thermal technology in order to meet current consumers' claims for quality foods with high nutritional values.

The effects of high-intensity pulsed electric fields (HIPEF) treatment (35 kV/cm, 4 μs bipolar pulses at 200 Hz for 800 or 1400 μs) on the microbial stability, quality parameters and antioxidant properties of a fruit juice–soymilk (FJ–SM) beverage along the storage time at 4 °C were compared to those obtained by thermal pasteurization (90 °C, 60 s). HIPEF processing for 800 μs ensured the microbial stability of the beverage during 31 days; however, longer microbial shelf-life (56 days) was achieved by increasing the treatment time to 1400 μs or by applying a thermal treatment. Peroxidase and lipoxygenase of HIPEF treated beverages were inactivated by 17.5–29% and 34–39%, respectively; whereas thermal treatment achieved 100% and 51%. During the storage, vitamin C content and antioxidant capacity depleted with time, and they were higher in FJ–SM beverages processed by HIPEF than in those thermally treated. Instead, total phenolic content of beverages did not present significant changes over the time, and it was higher in the 1400 μs-HIPEF treated beverages. In general, color, soluble solids, pH, and acidity values were not significantly affected by the processing treatments. Beverage viscosity increased over time, regardless of the treatment applied. Hence, application of HIPEF may be a good alternative treatment to thermal processing in order to ensure microbiological stability, high nutritional values and fresh-like characteristics of FJ–SM beverages.

Edible films and coatings are applied on many products to control moisture transfer, gas exchange or oxidation processes. One major advantage of using edible films and coatings is that several active ingredients can be incorporated into the polymer matrix and consumed with the food, thus enhancing safety or even nutritional and sensory attributes. This review discusses the use of edible coatings as carriers of functional ingredients on fresh-cut fruits, including the recent advances in the incorporation of antimicrobials, antibrownings, texture enhancers and nutraceuticals to improve quality and functionality of fresh-cut fruits. Sensory implications, regulatory status and future trends are also reviewed.

The influence of dipping in ascorbic acid, citric acid and calcium chloride (AA + CA + CaCl 2 ) solution and storage time on color, bioactive compounds content and antioxidant activity of fresh-cut mango ‘Kent’ stored at 5 °C was evaluated. The treated mangoes showed better color retention during storage than control mangoes. The dipping treatments with AA + CA + CaCl 2 significantly increased the vitamin C values compared with untreated mango cubes. β-Carotene was not affected by dipping treatments and vitamin E showed a significant decline over storage time for both treated and untreated mango cubes. However, higher vitamin E values were found in treated mangoes. Dipped cubes had higher antioxidant activity measured as TEAC and %RSA than controls. In general, addition of ascorbic acid as an anti-browning agent not only retarded quality loss of fresh-cut mango cubes but also promoted significant increases in antioxidant activity in comparison with control samples.

The use of alginate- (2% w/v) or gellan-based (0.5% w/v) coating formulations on fresh-cut papaya pieces was investigated in order to determine their ability to improve water vapor resistance (WVR), to affect gas exchange and to carry agents that help to maintain the overall quality of the minimally processed fruit. Formulations containing 2% (w/v) glycerol+1% ascorbic acid or 1% glycerol+1% ascorbic acid exhibited slightly improved water barrier properties for both types of coatings, as compared to the uncoated samples. The incorporation of 0.025% (w/w) sunflower oil into the alginate or the gellan-based formulations resulted in a 16% and 66% increase in the WVR of the coated samples, respectively. In general, coatings improved firmness of the fresh-cut product during the period studied. Furthermore, the addition of ascorbic acid as antioxidant in the coatings aided to preserve the natural ascorbic acid content of the fresh-cut papaya, helping to maintain its nutritional quality throughout storage. The gas barrier properties of the formulated coatings were not modified to allow substantial changes on respiratory rate and ethylene production of the coated papayas.

Influence of packaging conditions on fresh-cut ‘Gold’ pineapple shelf-life were studied during 20 d of storage at 5 °C. Fresh-cut fruit pieces were packed in polypropylene trays (PP) and wrapped with 64 μm polypropylene film under active (high 40% or low oxygen, 11.4%) or passive modified atmospheres (air or cut fruit coated with 1%, w/v alginate). Changes in headspace composition, titratable acidity, pH, soluble solids content, juice leakage, color, texture, and microbial growth were evaluated over time. For all packaging conditions, oxygen concentration continuously decreased below its initial concentration over 20 d storage, but never reached levels below 2% O 2 . Meanwhile, CO 2 concentration inside all packages continuously increased over time up to 10.6–11.7% from the initial conditions. Ethylene concentrations were always less than 0.4 μl L −1 while ethanol was detected only after 13 d of storage. Color parameters L * and b * significantly decreased over time in all packaging conditions and were directly attributed to the translucency phenomenon in the fruit flesh. When alginate coating was used, juice leakage was significantly reduced in contrast with the substantial juice accumulation observed in the rest of the packaging conditions. Texture profile analysis (TPA) parameters, did not significantly change over time, suggesting that structural characteristics of fresh-cut pineapple pieces were preserved throughout storage. From the microbial point of view, the shelf-life of ‘Gold’ fresh-cut pineapple was limited to 14 d by mesophilic bacterial growth. Further studies are needed to evaluate the sensory aspects, as well as to characterize the flesh translucency phenomenon and reduce juice leakage of fresh-cut pineapple.

Mechanical, barrier and antimicrobial properties of 0.1–0.5% suspensions of the following essential oils (EOs)/oil compounds (OCs) were evaluated against the foodborne pathogen Escherichia coli O157:H7 in alginate–apple puree edible film (AAPEF): oregano oil/carvacrol; cinnamon oil/cinnamaldehyde; and lemongrass oil/citral. The presence of plant essential oils did not significantly affect water vapor and oxygen permeabilities of the films, but did significantly modify tensile properties. Antimicrobial activities of solutions used to prepare edible films (AAPFFS) were also determined. The results obtained demonstrate that carvacrol exhibited the strongest antimicrobial activity against E. coli O157:H7. The data show that the antimicrobial activities were in the following order: carvacrol > oregano oil > citral > lemongrass oil > cinnamaldehyde > cinnamon oil. This study showed that plant-derived essential oils and their constituents could be used to prepare apple-based antimicrobial edible films for food applications.

Edible coatings with antimicrobial agents can extend the shelf-life of fresh-cut fruit. The effect of lemongrass, oregano oil and vanillin incorporated in apple puree-alginate edible coatings, on the shelf-life of fresh-cut ‘Fuji’ apples, was investigated. Coated apples were packed in air filled polypropylene trays and wrapped with polypropylene film. Changes in headspace atmosphere, color, firmness, sensory quality and microbial growth were measured during 21 days storage at 4 °C. A significant reduction in the rates of O 2 depletion and CO 2 production was observed in samples containing high concentrations of essential oils. Ethylene production in the coated apples remained below 50 μL L −1 , while production of this gas increased continuously in uncoated apples and those coated without essential oils during storage. Apples coated with apple puree-alginate exhibited ethanol and acetaldehyde formation in the first week. Coatings with calcium chloride and N -acetylcysteine helped to maintain firmness and color, while lemongrass containing coatings induced severe texture softening. Vanillin containing coatings (0.3% w/w) were the most effective in terms of sensory quality after 2 weeks storage. All antimicrobial coatings significantly inhibited the growth of psychrophilic aerobes, yeasts and molds. The antimicrobial effect of essential oils against L. innocua inoculated into apple pieces before coating was also examined. Lemongrass (1.0 and 1.5% w/w) and oregano oil containing coatings (0.5% w/w) exhibited the strongest antimicrobial activity against L. innocua (4 log reduction).

Alginate (2% w/v) and gellan (0.5% w/v)-based edible coatings were formulated to study the effect of glycerol (G) and antibrowning agents (N-acetylcysteine and glutathione) on water vapor resistance (WVR). The ability of the coatings to carry antibrowning agents was investigated following color changes of coated fresh-cut Fuji apples. Selected formulations obtained by a response surface analysis were 1.5% G, 1% N-acetylcysteine and 0.63% G, 1% N-acetylcysteine for alginate and gellan, respectively. The addition of sunflower oil with essential fatty acids (ω3 and ω6) at 0.025%, 0.05%, and 0.125% w/v concentrations was also investigated in an attempt to improve the barrier properties of the alginate and gellan coatings for fresh-cut apples. The WVR increased significantly from 15.70 and 14.60 s/cm to 19.2 and 27.6 s/cm for alginate and gellan coatings with sunflower oil, respectively, in comparison with oil free coatings. The addition of sunflower oil in gellan was more effective than in alginate to increase the WVR of coated apples. Alginate and gellan-based coatings proved to be good carriers for antibrowning agents.