A review on plasma-activated water and its application in the meat industry.

Meat is a nutritious food with a short shelf life, making it challenging to ensure safety, quality, and nutritional value. Foodborne pathogens and oxidation are the main concerns that lead to health risks and economic losses. Conventional approaches like hot water, steam pasteurization, and chemical washes for meat decontamination improve safety but cause nutritional and quality issues. Plasma-activated water (PAW) is a potential alternative to thermal treatment that can reduce oxidation and microbial growth, an essential factor in ensuring safety, quality, and nutritional value. This review explores the different types of PAW and their physiochemical properties. It also outlines the reaction pathways involved in the generation of short-lived and long-lived reactive nitrogen and oxygen species (RONS) in PAW, which contribute to its antimicrobial abilities. The review also highlights current studies on PAW inactivation against various planktonic bacteria, as well as critical processing parameters that can improve PAW inactivation efficacy. Promising applications of PAW for meat curing, thawing, and decontamination are discussed, with emphasis on the need to understand how RONS in PAW affect meat quality. Recent reports on combining PAW with ultrasound, mild heating, and non-thermal plasma to improve inactivation efficacy are also presented. Finally, the need to develop energy-efficient systems for the production and scalability of PAW is discussed for its use as a potential meat disinfectant without compromising meat quality.

The antimicrobial effects of mist spraying and immersion on beef samples with plasma-activated water.

The use of plasma-activated water (PAW) as an antimicrobial agent to inactivate Salmonella Typhimurium on chilled beef during meat washing was evaluated. Two meat washing methods, spraying and immersion, were evaluated at contact times of 15, 30 and 60 s and meat storage times of 0, 1 and 7 days. The temperature of PAW was elevated to 55 °C for washing as it increased the microbial inactivation compared to ambient temperature. At the contact time of 60 s and meat storage time of 7 days, PAW spraying and immersion achieved 0.737-log10 and 0.710-log10 reductions against Salmonella Typhimurium, respectively; there were no significant differences between both washing methods, with spraying being preferred for commercial implementation. Compared to untreated and water-treated samples, meat washing with PAW alone improved the S. Typhimurium inactivation and did not cause negative impacts on the lightness and hue angle values, TBARS value, water holding capacity and pH. However, PAW reduced the redness, yellowness and chroma values with the decreased oxymyoglobin values of 44.1% at the storage time of 1 day. PAW spraying at 55 °C followed by additional water washing at 25 °C for 60 s achieved 0.696-log10 reduction and mitigated a reduction in (i) the redness value, from 11.3 to 18.2, (ii) the yellowness value, from 9.19 to 11.1, and (iii) the chroma value, from 14.5 to 21.3, without displaying colour differences (∆E), as detected by human eyes, compared to water-treated samples. Moreover, the content of myoglobin forms was maintained by additional water washing.

Fabrication of novel casein gel with controlled release property via acidification, spray drying and tableting approach.

In this work, casein has been acidified at a pH of 1.0, forming a shampoo/lotion-like gel. It has been further processed by spray drying and tableting for controlled-release applications. The engineered casein gel shows higher moisture contents and lower Tg/dehydration temperatures compared with the non-gelled casein, based on the DSC and FTIR analysis. Casein is sensitive to thermal exposure (DSC), and no significant change in the casein was observed during acidification (FTIR). The particle size of the spray-dried casein gel increased as the spray-drying temperature decreased. The particles that were spray-dried at high temperatures were more likely to have wrinkled surfaces (raisin-like). For the microencapsulation of ascorbic acid (vitamin C), the spray-dried powders had lower moisture contents and higher Tg/dehydration temperatures as the spray-drying temperature was increased. By increasing the inlet temperature (100-190 °C), the retention of ascorbic acid decreased (80-60%) while the yield increased (0-70%). The DMA analysis showed that the casein gel tablet was elastic, and its stiffness was measured to be 0.8 N/mm. For controlled release, the casein gel tablet gave a slow release of ascorbic acid for 24 h at pH of 2 or 12 h at pH of 7.4. High compression pressure (320 MPa) resulted in slightly slower release than a compression pressure of 80 MPa.