Effect of high hydrostatic pressure and high temperature short time on quality of cloudy and clear sugarcane juice

Effects of high hydrostatic pressure(HHP,500 MPa/4 min) and high temperature short time(HTST,95 ℃ /15 s) on the p H,titrable acidity(TA),total soluble solid(TSS),total phenols,color,browning degree,clarity,turbidity and microorganism in cloudy and clear sugarcane juices were investigated. During 15 days storage at 4 ℃,quality variation of the sugarcane juices were analyzed. As the results shown,both HHP and HTST treatments could be effectively used for the pasteurization of the sugarcane juices. The p H of HHP-treated and HTST-treated clear sugarcane juices declined significantly,while the titrable acidity(TA) of HTSTtreated clear sugarcane juices increased. Both treatments had no influence on the total soluble solid(TSS) and total phenols in clear and cloudy juices. Compared with HTST treatment, color parameters did not change significantly under HHP treatment. However,after HPP treatment,the clarity of clear juice rises and turbidity of cloudy juice decreased. The sensory quality in the HHP-treated sugarcane exhibited superior advantages against the HTST-treated one. After 15 days storage at 4 ℃,the total bacterial count in cloudy sugarcane juices went up,but both clear and cloudy juices maintained a stable level of the molds and yeasts count. During the storage,p H in clear juices and HTST-treated cloudy juices declined while the polyphenol content went up. The clarity in the clear juice and the turbidity in the cloudy juice dropped. The browning degree and b* in HHP-treated clear juices increased but HTST-treated juices remained a similar color. It concluded that HHP benefited the quality of the sugarcane juice and was a good processing technology for sugarcane juice.