The Effect of High Power Ultrasound and Cold Gas-Phase Plasma Treatments on Selected Yeast in Pure Culture

Abstract

High power ultrasound (US) and cold gas-phase plasma (CP) are non-thermal processing technologies that maybe used in food processing industry. The main objective of this research was to study the effect of both treatments on selected yeasts (Rhodotorula spp. 74 and Candida spp. 86) in pure culture. Samples were treated by ultrasound with 57.50-, 86.25-or 115-μm amplitude, for 3, 6 or 9 min at 20°C, and 40 or 60°C in the case of thermosonication. For cold gas-phase plasma treatments, samples were treated at a gas flow of 0.75, 1 or 1.25 L min −1 , treatment time of 3, 4 or 5 min, and sample volume of 2, 3 or 4 mL. Each technology has its own advantages and is able to give the best effect on the desired target product. The experiment was designed using central composite design (CCD), and results were analysed and presented using response surface methodology (RSM). The greatest reduction of yeasts was observed after ultrasound treatments at 60°C (thermosonication) and after plasma treatments, after the longest treatment time (5 min) and the lowest sample volume (2 mL). For high power ultrasound treatment, reduction in the number of yeast cells (N) can be attributed to elevated temperature (60°C), cavitation and free radical formation. For plasma treatment, the inactivation can be attributed to UV radiation and plasma reactive oxygen species (ROS).

Effects of cold atmospheric gas phase plasma on anthocyanins and color in pomegranate juice

“…Recently, our results showed influence of cold plasma on food decontamination (Herceg, Režek Jambrak, Vukušić, Stulić, Stanzer, & Milošević, 2015;Režek Jambrak, Vukušić, Stulić, Mrvčić, Milošević, & Herceg, 2014), and other authors confirmed suitability for use with fruit juices (Shi, Zhang, Wu, Li, Ma, & Shao, 2011;Surowsky, Frohling, Gottschalk, Schluter, & Knorr, 2014). Furthermore, our research group proposed that non-thermal plasma can be used for pasteurization in fruit juice production (Elez Garofulić, Režek Jambrak, Milošević, Dragović-Uzelac, Zorić, & Herceg, 2015).…”

Free radical detection in water after processing by means of high voltage electrical discharges and high power ultrasound

“…However, there is a need to observe formation of free radicals upon nonthermal processing of food products to observe current production of free radical that can have influence on oxidation of nutritive compound. There are some researches and review papers that are mentioning formation of free radicals upon nonthermal food processing (Barba et al., 2020; Misra et al., 2018; Nutrizio et al., 2020; Tresp et al., 2013), and that formation is connected to inactivation of microorganisms (Jambrak et al., 2015). However, extended processing can lead to increased formation of free radicals that will rapidly interact with organic compound and lead to deterioration of food (Režek Jambrak et al., 2019).…”

Gas phase plasma impact on phenolic compounds in pomegranate juice

“…Cold atmospheric plasma has been already shown to be highly efficient at microbial inactivation Režek Jambrak et al, 2014). The concept of applying cold-plasma to enhance the shelf-life of fresh/freshly-prepared food is new and there is scarce information about the interactions of energetically highly reactive plasma species with phytochemical compounds (Grzegorzewski, Ehlbeck, Schlüter, Kroh, & Rohn, 2011).…”