Dipping fresh-cut apples in citric acid before plasma-integrated low-pressure cooling improves Salmonella and polyphenol oxidase inactivation.

BACKGROUND: Ready-to-eat fruit and vegetable products have gained tremendous popularity in recent years. The main challenges associated with these minimally processed products are their short shelf life and high food safety concerns. In this study, our goal was to develop an integrated process to both reduce the Salmonella population by >5 log CFU g-1 ) and to reduce polyphenol oxidase activity, followed by quickly cooling the product. We compared the effect of a sequential treatment of dipping in citric acid (CA) followed by cold plasma (CP) treatment on the inactivation of Salmonella Typhimurium, polyphenol oxidase (PPO) activity, browning, total phenolic content and the moisture loss of cut apples during the plasma-integrated low-pressure cooling (PiLPC) process. RESULTS: The greatest inactivation of Salmonella (5.68 log CFU g-1 ) and the highest PPO inactivation (78%) were observed after dipping cut apples in 5% CA, followed by 3 min of CP treatment. The color of cut apples remained relatively unchanged, with a fresh-like appearance during 7 days of storage at 4 °C after this combined treatment. Although the low-pressure cooling time was increased when samples were pre-dipped in CA, related to those undipped, the moisture loss was reduced by more than 50% during the PiLPC process. No significant reduction in phenolic content was observed during the PiLPC when the samples were pre-dipped in 5% CA. CONCLUSION: These results indicate the potential of this integrated process for the inactivation of endogenous food enzymes and bacterial pathogens in fresh-cut apples. © 2021 Society of Chemical Industry.

Salmonella inactivation and rapid cooling of fresh cut apples by plasma integrated low-pressure cooling.

Fresh food products, including fruits, vegetables, raw meat, and poultry, have been associated with safety concerns and quality issues, owing to their susceptibility to rapid deterioration and microbial contamination. This research aimed to develop an integrated process to simultaneously cool and decontaminate high moisture food products. Cold plasma (CP), a novel decontamination technology, was integrated with vacuum cooling to develop a plasma integrated low-pressure cooling (PiLPC) process. To evaluate the rapid cooling and microbial inactivation efficacies of the PiLPC process, fresh cut Granny Smith apples andSalmonella entericaserovarTyphimurium ATCC 13311 were used as the model food and microorganism, respectively. The influence of process parameters including treatment time, pressure, and post-treatment storage, on the inactivation ofSalmonellaon fresh-cut apples was investigated.Inactivation ofSalmonellaincreased with treatment time, with a maximum reduction of 3.21 log CFU/g after 5 min of CP treatment at atmospheric pressure. Inactivationof Salmonellaafter CP treatment at 200 mbar was not significantly different from that at atmospheric pressure for the same treatment time. CP treatment of 3 min at 200 mbar followed by a post-treatment storage of 3 days at 4 °C reduced the totalSalmonellapopulation on cut apple slices by > 6 log CFU/g. The temperature of the cut apples was reduced from room temperature to 2 °Cin 3 to 9 min depending on the sample surface area to volume ratio, when the pressure was reducedto 7 mbar. However, this PiLPC process resulted in moisture loss in cut apples. The results of this study indicate the potential of the PiLPC process for rapid cooling and microbial inactivation of fresh food products in a single process.

Review of the beneficial and anti-nutritional qualities of phytic acid, and procedures for removing it from food products.

Phytic acid (PA) is the primary phosphorus reserve in cereals and legumes which serves the biosynthesis needs of growing tissues during germination. It is generally considered to be an anti-nutritional factor found in grains because it can bind to minerals, proteins, and starch, limiting their bioavailability. However, this same mineral binding property can also confer a number of health benefits such as reducing the risk of certain cancers, supporting heart health, and managing renal stones. In addition, the ability of PA to bind minerals allows it to be used in certain food quality applications such as stabilizing the green color of vegetables, preventing lipid peroxidation, and reducing enzymatic browning in fruits/vegetables. These beneficial properties create a potential for added-value applications in the utilization of PA in many new areas. Many possible processing techniques for the preparation of raw materials in the food industry can be used to reduce the concentration of PA in foods to mitigate its anti-nutritional effects. In turn, the recovered PA by-products could be available for novel uses. In this review, a general overview of the beneficial and anti-nutritional effects of PA will be discussed and then dephytinization methods will be explained.

Inactivation of Salmonella spp. in wheat flour by 395 nm pulsed light emitting diode (LED) treatment and the related functional and structural changes of gluten.

Salmonella spp. is one of the top foodborne pathogens associated with low-moisture foods and they exhibit significant resistance to conventional thermal treatments. UV light pulses emitted from light emitting diode (LED) has shown antimicrobial potential in high-moisture foods and water. However, limited information is available about the antimicrobial potential of UV light with different wavelengths, including 395 nm in low-moisture foods. The objectives of this study were to investigate the antimicrobial potential of 395 nm pulsed LED light in wheat flour and the resulting quality changes. This study demonstrated a maximum 2.91 log reduction of Salmonella cocktail in wheat flour treated with 395 nm pulsed LED for 60 min in a semi-closed system. Oxidation occurred in wheat flour after 30 and 60 min exposure to the 395 nm LED, which subsequently led to bleaching, and polymerization of gluten components through disulphide linkage. The water holding capacity of gluten was reduced by oxidation, and the contents of secondary structures were altered significantly after pulsed LED treatment, but the rheological properties were not deteriorated. The disulfide bond formation naturally happens during dough formation and the oxidation triggered by pulsed LED treatment may play a role on accelerating this process. The 395 nm pulsed LED treatment could be a promising decontamination technology for wheat flour with an additional benefit of bleaching of the flour without chemicals. INDUSTRIAL RELEVANCE: A number of foodborne outbreaks and recalls have been related to low-moisture foods in these decades and recently several outbreaks were reported due to the occurrence of Salmonella in wheat flour. However, it is difficult to solve this problem through conventional thermal approaches because of the increased thermal resistance of Salmonella at low water activity environment. The emerging LED light source can produce light with monochromatic wavelengths without the use of mercury vapor lamps. It also has high durability, low heat generation, and is relatively easy to be adapted in an existing production line. Therefore, there is a great potential of using certain UV wavelengths emitted from LED to disinfect the low-moisture foods in food industries. To the best of our knowledge, no research was conducted on decontamination of wheat flour by using LEDs and only limited studies are available on the influence of pulsed LED treatment on food quality. The aim of this study was to explore the possibility of using 395 nm pulsed LED treatment as a novel tool for decontamination of Salmonella in a low-moisture food product (wheat flour) with industrial feasibility, and investigate the influence of the pulsed LED treatment on quality changes in the product.