Effect of Nonthermal Plasma-Activated Water on Quality and Antioxidant Activity of Fresh-Cut Kiwifruit

Abstract

Recently, plasma-activated water (PAW) has received extensive attention in food safety field due to its advantages of eco-friendly and high sterilization efficiency. In this paper, the effects of PAW on microbe loads and quality of fresh-cut kiwifruit (FCK) were studied, and the preservation mechanism of PAW on FCK was explored. A 1 mL of PAW and 1 mL of sterile water as control sample were separately sprayed on FCK and stored at 4 °C for 8 days. Compared to the control sample, the microbial population of FCK was reduced by approximately 1.8 log CFU/g after the PAW treatment. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in PAW-treated FCK samples were improved. Further test results showed that H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−</sup> accumulation rates of PAW-treated FCK were slower than that of the control sample. Finally, by analyzing the effect of pH and H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> on the activity of antioxidant enzymes in FCK, it was found that either pH or H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> treatment could enhance the activities of antioxidant enzymes in FCK. Concerning the fruit quality, our measurement shows that the PAW treatment had no significant effect on the firmness and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$b^\ast $ </tex-math></inline-formula> value of FCK.