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Atmospheric cold plasma is a green and emerging technology, highly interesting to the food industry for its application. Dielectric Barrier Discharges (DBD) can generate atmospheric cold plasma inside sealed packages filled with air through the use of high voltages. This study investigated the use of a large gap DBD design to generate a plasma discharge within the headspace of packaged herring fillets, and its effects on microbiological and quality markers of the fish stored for 11 days at 4 °C. DBD plasma treatment conditions were 70 kV or 80 kV for 5 min treatment time. Results showed that the microbial load (total aerobic mesophilic, total aerobic psychrotrophics, Pseudomonas , lactic acid bacteria and Enterobacteriaceae ) were significantly (p 1 H LF NMR). The results indicate that in-package plasma treatment could be employed as an effective treatment for reducing spoilage bacteria in fish. Industrial relevance Dielectric Barrier Discharge (DBD) was evaluated as a treatment for highly perishable fish products. DBD's is a safety and lower costs alternative for processing industry. DBD has been scarcely tested on fish; this work showed results on quality and shelf-life of a highly perishable fish species, which might serve as reference for processing optimisation of fish products minimally processed by DBD.

The objective of this study was to characterise herring brine and assess its use as natural antioxidant in herring preservation. Herring brines from different marinated products (brine from fillet-ripened spice-cured herring SC, traditional barrel-salted spice-cured herring TSp and brine from traditional barrel-salted herring TSa) were used without any pre-treatment or with a previous pH adjustment, and tested either as coating agents (glazing) for frozen herring or additives in fresh mince herring, in order to prevent oxidation. TSa and TSp were the most effective glazing agents, retarding lipid oxidation. Brines tested as additive retarded lipid and protein oxidation in a similar trend than herring mince containing salt and/or protein. SC brine was more efficient against lipid and protein oxidation when compared to the other tested brines. Using protein fractions isolated from herring marinating brines as glazing or additive seems feasible for preventing oxidation of both frozen and fresh herring.

The effect of vacuum frying processing on proximate composition, fatty acid profile, oxidative status and sensorial properties of fish patties, was evaluated as compared with conventional (atmospheric) frying. Vacuum frying procedure was carried out at 80 mmHg (water boiling point: 42 °C) and oil temperature (107 °C) determined to obtain an equivalent thermal driving force (Δ65 °C) of that of the atmospheric frying conditions used (165 °C). Frying times of 2, 4, 6, 8 and 10 min were investigated. Vacuum frying significantly prevented degradation of EPA (Eicosapentaenoic acid) and DHA (Docosahexaenoic acid), reducing the polyene index and maintaining a lower ω6/ω3 fatty acid ratio in samples, while no significant differences with conventional frying in total oil content were observed. The use of vacuum also reduced formation of peroxides and carbonyl derivatives. Tocopherol levels decreased in all samples regardless of the frying conditions used, although vacuum-fried samples maintained higher tocopherol levels after processing. These samples also showed higher lightness and lower a* and b* values, which can be associated to lower non-enzymatic browning levels. These results support the applicability of vacuum frying technology for fish patties, since it prevents colour changes, improves juiciness and reduces oxidation when compared to conventionally (atmospheric) fried counterparts. Industrial relevance Consumers are increasingly aware of the link between food and health, maintaining a high demand for healthy products. In this regard, consumption of fatty fish, with healthy properties widely known, is lower than recommended by health authorities, especially in children. Novel processing technologies focused on increasing the appealing of products based on fatty fish can help in ameliorating this deficient consumption. Vacuum frying is a promising way of obtaining attractive products, due to some product modification after the deep-fat frying process, and yet retaining natural colour, juiciness and healthy properties to a high extent. Vacuum frying allows reducing ω3 fatty acids and tocopherol degradation, differentiating fish products so obtained, which can be launched into the market and benefit from this technology. Compared to conventional frying, the results are better nutritional and sensory properties in a final product.

Green tea extract (GT) was evaluated as a preservative treatment for fresh-cut lettuce. Different quality markers, e.g. respiration, browning, ascorbic acid and carotenoid content were evaluated. GT concentration (0.25, 0.5 and 1 g 100 mL − 1 ) and temperature (20 °C and 50 °C) were tested. Optimal GT treatment (0.25 g 100 mL − 1 at 20 °C) was compared with chlorine (120 ppm at 20 °C). High GT concentrations (0.5 g 100 mL − 1 and 1.0 g 100 mL − 1 ) maintained better prevent ascorbic acid and carotenoid loss than 0.25 g 100 mL − 1 GT and chlorine. GT increased browning of samples, probably due to the content of polyphenols of the treatment; the use of heat-shock reduced this negative effect. GT and heat-shock combined also showed negative effects, reducing the antioxidant content (ascorbic acid and carotenoids). No significant differences were observed between chlorine and optimal GT (0.25 g 100 mL − 1 at 20 °C) in browning appearance and sensory properties. GT better kept the antioxidant activity of the samples than chlorine. Industrial relevance An alternative treatment for minimally processed Iceberg lettuce is tested, based on its antioxidant capacity. Minimally processed industry is constantly looking for new treatments to avoid the use of chlorine which is a standard at the moment.

Experiments were conducted to determine the effectiveness of different treatments based on the use of neutral electrolysed water (EW) on fresh-cut lettuce. EW was diluted to obtain different free chlorine concentrations (120, 60 and 12 ppm) and to compare with standard washing treatment of 120 ppm chlorine solution. Shelf-life quality and safety markers were studied at the beginning and at the end of the 7-day-storage at 4 °C. The use of EW decreased the respiration rate of the samples which might be related with the observed reduction in microbial spoilage. The use of EW also increased the activity of a browning-related enzyme (polyphenoloxydase) although sensory results showed all samples as acceptable at the end of the 7 day-storage. Perhaps longer storage time might increase the risk to browning development in the samples treated with EW. The highest EW concentration (120 ppm free chlorine) was the most effective treatment in reducing sample microbial load; however this treatment also affected the final produce with effects such as loss of turgor, plasmolysis and a reduction in mineral content. Results suggest an intermediate EW concentration with 60 ppm free chlorine could be an alternative to 120 ppm chlorine (from sodium hypochlorite) for sanitizing fresh-cut vegetables, reducing to half the amount of chlorine used and maintaining the antimicrobial effectiveness and without differences affecting the quality. However further studies will be necessary in order to observe the effect of the oxidising capacity of EW on other quality and safety markers as pathogens and nutritional content. Industrial relevance Chlorine solutions have been widely used to sanitise fruit and vegetables in the fresh-cut industry. However, the association of chlorine with the possible formation of carcinogenic chlorinated compounds in water has called into question the use of chlorine in food processing. The efficacy in controlling the microbial load and browning of samples treated with electrolysed water shows it as a promising decontaminant agent for fresh-cut lettuce. Due to the high oxidising potential of the EW quality requirements must be balanced to obtain the optimal treatment conditions keeping satisfying safety levels. The use of EW-60 showed similar safety and quality (browning) results as the use of chlorine or double EW concentration (EW-120). However the treatment EW-120 affected negatively the textural properties. The study suggests the use of EW-60 as an alternative to sodium hypochlorite solution with 120 ppm available chlorine, obtaining similar safety and quality results and reducing the amount of chlorine needed. Further investigations in the effect of EW on lettuce, such as those on pathogens or nutritional markers (e.g. carotenoids and vitamin C) are recommended in order to explore this alternative that might reduce the increasingly concerning use of chlorine to decontaminate this type of product.

Whey permeate at different concentrations (0.5%, 1.5% and 3%) was used as natural sanitizing agent in the washing treatment of fresh-cut lettuce and carrots. These treatments were compared with a chlorine 120 ppm widely used in the industry. Microbiological, quality (colour changes, browning-related enzymes, headspace gas composition, textural changes and sensory analysis) and nutritional (ascorbic acid and carotenoids) markers were monitored over 10 days in fresh-cut lettuce and carrot packages stored at 4 °C. Whey permeate at 3% resulted in equivalent or better microbial load reduction than chlorine. Although lower concentration of whey permeate produced minor initial reduction, microbial counts at the end of the storage were below the recommended levels (10 8 CFU/g) for safety of fresh-cut vegetables. Sensory analysis panel considered all the samples of fresh-cut lettuce acceptable. However, in the sensory results the sliced carrots treated with 3% whey permeate and chlorine scored lower acceptability due to higher surface whiteness, although these samples had lower microbial loads. Three percent WP controlled the browning-related enzymes better than 0.5%, 1.5% WP and chlorine and consequently the browning. However, this reduction in browning-related enzymes did not result in a lower browning appearance to visual observation during the 10 storage days. The use of high concentrations of WP accelerated the loss of ascorbic acid and carotenoids. These results suggest that whey permeate could be a promising alternative to chlorine for sanitizing fresh-cut vegetables. Industrial relevance Many attempts have been made to increase the use of whey, a valuable by-product of cheese processing, and many attempts have been made to increase shelf life of fresh-cut fruits and vegetables. This paper takes an interesting approach by attempting to use whey permeate as antimicrobial agent. Whey permeate solution proved successful in controlling total counts via a washing step of fresh cut vegetables. Although this does not reduce the amount of whey released, it could provide use as antimicrobial prior to discarding.