Effects of tempering with plasma-activated water on total plate count and quality properties of wheat flour

Abstract

Nonthermal plasma-activated water (PAW) was prepared and used as wheat tempering water. The effects of tempering with PAW on total plate count and quality properties of wheat flour streams were studied. With the extension of plasma activation time, the content of NO3−, NO2− and H2O2 in PAW significantly increased, and pH decreased dramatically (p < 0.05). After tempering with PAW activated for 40 min, total plate counts in bran, low-grade and patent flour were significantly decreased by 68.85%, 60.91% and 27.27%, respectively (p < 0.05). The polyphenol oxidase, lipase and lipoxygenase activities in low-grade flour markedly decreased by 41.27%, 18.07% and 31.42%, respectively, with the treatment of PAW (p < 0.05). Rapid Visco Analyzer results showed a decrease in peak, trough and final viscosity of straight-grade flour. The free sulfhydryl content in straight- and low-grade flour also decreased. Mixolab test showed there was no significant change in dough rheological characteristics of straight-grade flour. Overall, tempering with PAW could be a promising nonthermal technique to decrease the microbial loads of flour without obvious detrimental effects on its processing quality.