“…Despite several reports suggesting that the improvement in the digestion process after microwave pretreatment is mainly attributable to the heating effect of microwaves, recent studies have shown that may not necessarily be the case (Coelho et al, 2011, Shazman et al, 2007. Changes in physiological characteristics of microorganisms after exposure to microwaves (Rai et al, 1995;Singh et al, 1994), increases in the inactivation rate of microorganisms in comparison with conventionally treated samples (Dreyfuss and Chipley, 1980;Hong et al, 2004), and increases in microbial biological activity such as biogas production or growth rate (Banik et al, 2006;Grundler et al, 1992;Grundler and Keilmann, 1983), were reported as examples of non-heat-related effects. These phenomena are frequently justified by the existence of an athermal effect, because they occur independently of temperature rise in media irradiated with microwaves.…”