Investigating the effect of combined radiofrequency cold plasma (RF-CP) treatment on techno-functional attributes of Cashewnut

Abstract

In the realm of food safety, dried foods often find themselves on the favourable side of the risk spectrum, enjoying the reputation of being relatively safer. However, dried food products are reportedly contaminated by microorganism beyond permissible limits, thus, depleting their quality, shelf-life, etc. and pose a threat to the consumers. This study aims to explore the effect of radiofrequency low-pressure cold plasma (RF-CP) processing on cashew nuts, using four gas combinations: Nitrogen (N₂), Argon (Ar), N₂+O₂, and Ar + O_2. Dried cashew nut kernels underwent RF-CP treatment at six different power options (60, 90, 120, 150, 180, and 210 W), at four distinct time (5, 10, 15, and 20 min). Following the treatment, the samples underwent proximate analysis, microbial load reduction, sensory analysis, peroxide value, and texture analysis. The findings exhibited a direct relationship between plasma power and treatment duration, indicating that an escalation in both parameters induced proportional enhancement in the reduction rate of microbes, with a maximum reduction of over 99% in total plate count, yeast and mould count at 120 W for 20 min and 150 W for 15 min for N₂+O₂ and Ar + O₂ gas combinations, respectively. No statistically significant difference was observed in the sensory, nutritional, and peroxide value between the treated and untreated samples (p > 0.05). However, the moisture content of treated sample decreased, and firmness increased with an increase of power and RF-CP exposure time. This research demonstrates the feasibility of using RF-CP to decontaminate cashews by inactivating microbes, extending shelf life, and altering surface properties, which may enhance texture and appearance. However, it may also induce oxidative changes in lipids and proteins, potentially affecting flavor, nutritional quality, and allergenicity. It is an emerging and alternative to high-temperature processing for disinfecting products like nuts, spices, aromatic plants, and other delicate and luxurious foods.