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Food Chemistry 124 (2011) 444–449

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Inhibition of polyphenol oxidase and peroxidase activities on fresh-cut apple by simultaneous treatment of ultrasound and ascorbic acid
Ji-Hyun Jang, Kwang-Deog Moon *
Department of Food Science and Technology, Kyungpook National University, 1370 Sankyuk-dong, Buk-gu, Daegu 702-701, Republic of Korea

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The effects of ultrasound and ascorbic acid on activity changes of polyphenol oxidase and peroxidase, of fresh-cut apple during storage, were investigated. The combined treatment of ultrasound and ascorbic acid inactivated monophenolase, diphenolase, and peroxidase, whilst the individual treatment of ultrasound or ascorbic acid had inverse and limited inhibitory effect on the enzymes. The main protein bands had a molecular weight of approximately 63 kDa. A diffuse band, lacking the electrophoretic mobility of proteins, was observed after combined treatment. This investigation revealed that simultaneous treatment with ultrasound and ascorbic acid had synergistic inhibitory effects on several enzymes related to enzymatic browning. Ó 2010 Elsevier Ltd. All rights reserved.

Article history: Received 11 February 2010 Received in revised form 29 March 2010 Accepted 14 June 2010

Keywords: Ultrasound Ascorbic acid Polyphenol oxidase Peroxidase Fresh-cut apple

1. Introduction In recent years, a rapid market growth for fresh-cut fruits and vegetables has been observed due to the consumers’ increased demand for convenience, fresh-like quality, and high nutritive value (Rico, Martín-Diana, Barat, & Barry-Ryan, 2007). Fresh-cut apples, in particular, are desired as a convenient snack for catering services to salad-bars, schools, and company cafeterias (Saftner, Abbott, Bhagwat, & Vinyard, 2005). Surface colour is one of the most important quality attributes because consumers