Comparative study of enzymes, phenolics, carotenoids and color of apricot nectars treated by high hydrostatic pressure and high temperature short time

Effects of high hydrostatic pressure (HHP) at 300-500 MPa for 5-20 min and high temperature short time (HTST) at 110 degrees C for 8.6 s on enzymes, phenolics, carotenoids and color of apricot nectars were investigated. Polyphenol oxidase (PPO) and peroxidase (POD) in apricot nectar were significantly activated (p<0.05) and the activity of pectinmethylesterase (PME) was not changed by HHP treatments, but HTST induced a complete inactivation of these enzymes. Compared to the untreated apricot nectar, HTST resulted in a significant increase in total phenolics, and exhibited no effect on total carotenoids and individual carotenes except a-carotene. The effects of HHP treatments on total and individual phenolics, total carotenoids and individual carotenes and color were closely related to the pressure levels and treatment times. Mostly, HHP treatments increased total and individual phenolics in apricot nectars, which were significantly lower than those in HTST-treated apricot nectars. HHP treatments also showed no effect on total carotenoids and individual carotenes in apricot nectars except that the treatment at 500 MPa/20 min increased total carotenoids and beta-carotene. Moreover, total color difference (221) in the HTST-treated apricot nectars with increased lightness and more intensity was higher than that (<= 1.34) in the HHP-treated apricot nectars, indicating that the color of HPP-treated apricot nectars was closer to the untreated apricot nectar than after HTST. Compared with HHP treatment (500 MPa/20 min), HTST led to complete inactivation of enzymes, higher total phenolics, (-)-epicatechin, ferulic acid and p-coumaric acid and lighter and more intensity color, since HTST treatment gave better impact on the quality of apricot nectar. Industrial relevance: Effects of high hydrostatic pressure (HHP) treatment and high temperature short time (HTST) treatment on enzymes, phenolics, carotenoids and color of apricot nectar were investigated. Our results show that micronutrients and phytochemicals of nectar were well preserved by both HHP and HTST. Compared with HHP treatment (500 MPa/20 min), HTST led to complete inactivation of enzymes, higher total phenolics, (-)-epicatechin, ferulic acid and p-coumaric acid, and lighter and more intensity color than those of HHP treatment, since HTST treatment gave better impact on the quality of apricot nectar. And polyphenol oxidase, peroxidase and pectinmethylesterase in apricot nectar were found to be highly resistant to high pressure inactivation, thus in order to maintain the quality of apricot nectar, high pressure processing should be accompanied by additional measures. (C) 2013 Elsevier Ltd. All rights reserved.