Role of pectin characteristics in orange juice stabilization: Effect of high-pressure processing in combination with centrifugation pretreatments.

"High-pressure processing (HPP) plus" combined technologies are applied to overcome the limitation of single HPP and to produce juices with more stable quality during storage. This research explored the potential of HPP in combination with centrifugation to produce cloud stable orange juice during refrigerated storage. The results indicated that HPP combined processing technology significantly improved the cloud stability of orange juice, which was related to removed large particles, reduced viscosity, decreased protein contents, and inactivated pectin methylesterase activity induced by centrifugation (P < 0.05). Besides, chelator solubilized pectin (CSP) decreased but water solubilized pectin (WSP) maintained in the juice after centrifugation. During storage, the conversion of pectin fraction from WSP to CSP, resulting in sedimentation appeared in centrifugation treated orange juice when stored for 28 days. In general, pectin characteristics changes and pectin fractions conversion were the main driving forces affecting cloud stability of orange juice pasteurized by HPP in combination with centrifugation and during chilled storage.

Effect of centrifugal pre-treatment on flavor change of cloudy orange juice: Interaction between pectin and aroma release.

Cloud loss of orange juice could be effectively inhibited by centrifugal treatment, but it can induce flavor changes, which become a new challenge for the industry. This work aims to investigate the effect of centrifugation on flavor changes in orange juice and explore its possible mechanism. Taste- and aroma-related attributes were analyzed, and pectin was characterized. Results indicated that pH (4.00), total soluble solid (9.67 °Brix), titratable acidity (0.42%), sucrose (44%), fructose (29%), and glucose (27%) were less affected by centrifugation (P > 0.05). However, aroma compounds significantly changed (P < 0.05), where terpenes and alcohols tended to be distributed in pulp and serum after centrifugation, respectively. Pearson correlation analysis showed that aroma compound distribution induced by centrifugation was highly related to chelator-solubilized pectin fraction and sodium carbonate-solubilized pectin fraction (|R| > 0.9). In general, centrifugation clearly changed aroma of orange juice, which was mainly affected by pectin characteristics.

Evaluation of quality changes of differently formulated cloudy mixed juices during refrigerated storage after high pressure processing.

Cloudy fruit and vegetable mixed juice (MJ) pasteurized by high pressure processing (HPP) showed an increasing market demand. However, browning, sedimentation, and flavor changes of HPP juice during storage have been a great challenge for the beverage industry. The aim of this work was to investigate quality changes of HPP MJs during storage and to explore the potential to create the shelf-stable MJs with fresh-like organoleptic quality through HPP. In the work, commercial MJ1 (orange, mango, and kiwifruit) and MJ2 (carrot and pineapple) were formulated and their quality changes during storage were investigated. The results indicated no visible color changes and sedimentation were observed in MJ1 and MJ2 during refrigerated storage (90 days). However, sucrose decreased as glucose and fructose increased; a large number of aldehydes and alcohols decreased but some terpenoids increased during storage. In general, blending proper fruit and vegetable to produce MJs combing with HPP could maintain high cloud and color stability, but sugars and volatiles clearly changed during storage.