title: Effect of high-pressure processing and thermal pasteurization on overall quality parameters of white grape juice.
abstract: BACKGROUND
  The aim of this study was to investigate the microbial levels, physicochemical and antioxidant properties and polyphenol oxidase (PPO) and peroxidase (POD) activities as well as to conduct a sensory analysis of white grape juice treated with high-pressure processing (HPP) and thermal pasteurization (TP), over a period of 20 days of refrigerated storage.
  
  
  RESULTS
  HPP treatment of 600 MPa and TP significantly reduced aerobic bacteria, coliform and yeast/mold counts. At day 20 of storage, HPP-600 juice displayed no significant differences compared with fresh juice in terms of physicochemical properties such as titratable acidity, pH and soluble solids, and retained less than 50% PPO and POD activities. Although significant differences were observed in the color, antioxidant contents and antioxidant capacity of HPP-treated juice, the extent of these differences was substantially lower than that in TP-treated juice, indicating that HPP treatment can better retain the quality of grape juice. Sensory testing showed no significant difference between HPP-treated juice and fresh juice, while TP reduced the acceptance of grape juice.
  
  
  CONCLUSIONS
  This study shows that HPP treatment maintained the overall quality parameters of white grape juice, thus effectively extending the shelf life during refrigerated storage. © 2016 Society of Chemical Industry.
authors.affiliation: Food Industry Research and Development Institute, Tainan, Taiwan.
authors.forename: Yin-Hsuan
authors.initials: YH
authors.lastname: Chang
authors.affiliation: Department of Horticulture and Landscape Architecture, National Taiwan University, Taipei, Taiwan.
authors.forename: Sz-Jie
authors.initials: SJ
authors.lastname: Wu
authors.affiliation: Department of Food Science, Fu Jen Catholic University, Taipei, Taiwan.
authors.forename: Bang-Yuan
authors.initials: BY
authors.lastname: Chen
authors.affiliation: Department of Horticulture and Landscape Architecture, National Taiwan University, Taipei, Taiwan.
authors.forename: Hsiao-Wen
authors.initials: HW
authors.lastname: Huang
authors.affiliation: Experimental Forest, National Taiwan University, Nantou, Taiwan.
authors.forename: Chung-Yi
authors.initials: CY
authors.lastname: Wang
mesh_terms: D000975:Antioxidants / Q000032:analysis; D005511:Food Handling / Q000295:instrumentation / Q000379:methods*; D005638:Fruit / Q000737:chemistry; D000067030:Fruit and Vegetable Juices / Q000032:analysis*; D006358:Hot Temperature; D061352:Pasteurization; D059808:Polyphenols / Q000032:analysis; D027843:Vitis / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D059808:Polyphenols
keywords: POD; PPO; grape juice; high pressure; pasteurization; sensory