Investigation of a Non-Thermal Effect of Microwave Treatment

Abstract

The aim of our experiments was to demonstrate the non-thermal effect of microwave treatment on Saccharomyces cerevisiae fermentation activity. A method was developed for studying the effects of various treatments in the course of must fermentation. The raw material (must) was treated in different ways: (i) heat transfer; (ii) microwave treatment; (iii) inoculation with yeast, and (iv) their combinations. The results of the treatments were compared with respect to alcohol concentration, sugar content, and acidity. The results proved that sugar content of the treated samples rapidly decreased compared to the control sample, and fermentation time was 40% shorter in the fastest case. These results can be explained by the yeast inoculation and microwave treatment. Due to non-thermal effects, fermentation capacity increased by about 30%, while the energy consumption decreased.

Impact assessment of microwave treatment of raw cow's milk on its microbiological properties

“…The data indicate that microwave irradiation has a smaller impact on yeast at lower power levels, however, a sharp increase can be identified when a power level of 600 W is applied, reaching a rate of 96%. This corresponds to the experiments of Kapcsándi [13] where Saccharomyces cerevisiae suspensions were examined at similar power levels and treatment times. In their case, the survival rate of yeast presented a higher value, but the extent of destruction followed the same trend.…”

“…Nevertheless, the period of treatment in the above experiments has been defined as a short time range of only several minutes, and longer exposure might lead to a different outcome. Kapcsándi [13] proved that low-power (50 W) microwave treatment makes a positive impact on the life activity of Saccharomyces cerevisiae (30 °C), therefore the influence on microbes strongly depends on the power level applied. This effect has been proven by the increase of the glucose utilization capacity of yeast during fermentation processes.…”

Effect of non-thermal effects in microwave heating on the rheology and chemical properties of petroleum asphalt

“…The thermal effect of microwaves is characterized by high efficiency and energy savings, which make microwaves widely used in the civil and industrial fields. Thus, the thermal effect of microwaves has long attracted the attention of researchers [1][2][3][4][5]. However, the non-thermal effects of microwaves are still being explored in research.…”

Comparing microwave and convective heat treatment methods by applying colour parameters of wine

“…It has also been proven that mould reduction (species Aspergillus) is more substantial using microwave-based heat treatment (Valderrama & Sanches, 2008). Kapcs andi et al (2013Kapcs andi et al ( , 2016, seeking to demonstrate the effects of microwave treatment on grape must fermentation, finds that sugar content of the treated samples rapidly decreases compared to the control sample and that fermentation time is 40% shorter.…”