Modelling microbial load reduction in foods due to ozone impact

Ozone is a strong sanitizer that can be applied as a convenient washing-treatment to foods. The main objective was to study the ozone impact on Listeria innocua in red bell peppers, total mesophiles in strawberries and total coliforms in watercress. Modelling microbial load reduction throughout treatment time and due to ozone effect were also targets. The microbiological reductions observed for ozonated samples were higher than the ones obtained for water dipping. However, total coliforms/watercress were less sensitive to both deionized-water and ozonated-water washings. A Weibull-based model was adequate in describing microbiological reductions and may contribute to design more effective sanitizing processes

Bioactive compounds, pigments, antioxidant activity and antimicrobial activity of yellow prickly pear peels

The main goal of this research was to study the effects of pressure, extraction time and ethanol concentration on antioxidant activity, total phenolics, flavonoids, anthocyanins, carotenoids and betalains compounds extraction from yellow prickly pear peels. A Box-Behnken design and Response Surface Methodology were used to evaluate the effects and estimate the optimum extraction conditions. Antimicrobial activity was evaluated against Escherichia coli and Listeria innocua. Ethanol concentration was the variable that showed the highest effect on extraction yields but high-pressure increased extraction yields between 6% and 17%. Models showed good fitting and adequacy to the experimental data and the high correlation of models indicated that it can be employed to optimise extraction conditions. The experimental and predicted values differed <10% and the extracts inhibited the growth of both bacteria. High-pressure could be a promising extraction process to improve extraction of bioactives from prickly pear peels.info:eu-repo/semantics/publishedVersio

Effect of high pressure processing on a functional acorn beverage

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Study on thermosonication and ultraviolet radiation processes as an alternative to blanching for some fruits and vegetables

The impacts of ultraviolet-C radiation, blanching by heat, and combination of heat/ultrasounds (thermosonication) were studied for Listeria innocua (inoculated) in red bell peppers, total mesophiles in strawberries and total coliforms in watercress, in the temperature range 50–65 °C. Quality attributes such as colour and firmness were studied for all products, and total anthocyanins content was additionally determined for strawberries. Results showed that ultraviolet- C radiation was the least effective treatment in terms of microbial load reduction and was equivalent to a simple water washing. Log reductions were 1.05±0.52 for L. innocua, 0.53±0.25 for total coliforms and 0.26±0.18 for total mesophiles. This treatment had the lowest impact on the quality parameters analysed. Thermosonication treatment was similar to heat blanching for all microorganism/product tested, excepted for total coliforms in watercress at 65 °C, in which thermosonication had a higher effect (p<0.05). Heat blanching at 65 °C allowed 7.43±0.12 log-cycles reduction, while loads were diminished by 8.24±0.13 log-cycles if thermosonication at the same temperature was applied. Thermosonication also allowed better quality retention, when compared to heat blanching at the same temperatures. The impact of thermosonication on microbial load reductions was statistically significant and thermosonicated samples retained quality attributes better than heat blanched ones at the same temperatures (p<0.05). Hence, it can be concluded that thermosonication is a promising process and may be a favourable alternative to the conventional thermal treatments

Influence of aqueous ozone, blanching and combined treatments on microbial load of red bell peppers, strawberries and watercress

The effectiveness of ozone in aqueous solution treatment on microbial inactivation was studied for three combinations microorganism/food: Listeria innocua/red bell peppers (artificially inoculated), total mesophiles/strawberries, and total coliforms/watercress, with two concentrations (0.3 and 2.0 ppm). Blanching treatments (50-60 degrees C) were also individually applied and in combination with ozone, for studying possible synergistic effects. In relation to ozone treatments, the highest microbial reductions were obtained for the highest concentration with the highest treatment time (3 min). Under those conditions. L. innocua/peppers, total mesophiles/strawberries and total coliforms/watercress were reduced respectively 2.8 +/- 0.5, 2.3 +/- 0.4 and 1.7 +/- 0.4 log-cycles. However, a substantial portion of the microbial populations were reduced by water washing alone, and the presence of ozone generally added an additional reduction of 0.5-1.0 log-cycles. If ozone at the highest concentration is used, the treatment impacts on L. innocua/peppers and total mesophiles/strawberries load reductions were equivalent to a blanching at 50 degrees C (for the same treatment times). Combining blanching and ozone did not generate synergistic effects, and in some situations microbial reductions were lower than the ones observed when treatments were applied independently.info:eu-repo/semantics/acceptedVersio