Theses and Dissertations
Issuing Body
Mississippi State University
Advisor
Silva, Juan L.
Committee Member
Ma, Din-Pow
Committee Member
Schilling, M. Wes
Committee Member
Matta, Frank B.
Committee Member
White, Charles H.
Date of Degree
8-9-2008
Document Type
Dissertation - Open Access
Major
Food Science and Technology
Degree Name
Doctor of Philosophy (Ph.D)
College
College of Agriculture and Life Sciences
Department
Department of Food Science, Nutrition and Health Promotion
Abstract
Inhibition of blueberry PPO activity by sodium benzoate, potassium sorbate and potassium metabisulfite and their influence on degradation of individual anthocyanins in an extract was studied. Maceration of blueberries was carried out at 55ºC for 1h with the addition of 0.1% sodium benzoate or with blanching pretreatment at 90ºC for 1min. After maceration pretreatments the extracted juice was processed with traditional hot fill pasteurization, high hydrostatic pressure (HHP) and pulsed electric field (PEF). Sodium benzoate and potassium metabisulfite were very effective PPO inhibitors in concentrations of 0.1% and 10ppm, respectively. Potassium sorbate was the weakest inhibitor, with 50% PPO remaining. Degradation of anthocyanins by PPO was dependent on their structure. Tri-phenolic anthocyanins experienced the most degradation, followed by diphenolic and monophenolic compounds, respectively. Sodium benzoate was the most effective at preventing anthocyanin degradation; potassium metabisulfite did not have any protective effect, while potassium sorbate increased anthocyanin degradation Blanching of blueberries inactivated native PPO, but also increased the degradation of anthocyanins, especially malvidin glycosides. Addition of 0.1% sodium benzoate decreased PPO activity when compared to frozen blueberries but not in respect to control maceration. Only 12% of anthocyanins and 33-41% of phenolics were extracted into juice from the frozen fruit. Hot fill pasteurization, high hydrostatic pressure and pulsed electric field did not significantly influence anthocyanins, phenolics and antioxidant activity in blueberry juice.
URI
https://hdl.handle.net/11668/19380
Recommended Citation
Stojanovic, Jelena, "Determination of Polyphenol Oxidase (PPO) Activity, Anthocyanin Contents and the Phytonutrient Changes in Blueberry Juice as Influenced by Different Processing Methods" (2008). Theses and Dissertations. 1348.
https://scholarsjunction.msstate.edu/td/1348