Evaluation of microbiological safety, physicochemical and aromatic qualities of shiikuwasha (Citrus depressa Hayata) juice after high pressure processing

This study evaluated high pressure processing (HPP) for achieving greater than 5-log reduction of Escherichia coli O157:H7 in shiikuwasha (Citrus depressa Hayata) juices and compare quality parameters, including microbiological safety, total phenolic content (TPC), total flavanones (TFC), and polymethoxylated flavones, browning, volatile aromatic, and physicochemical properties of HPP-treated juice with those of high-temperature short-time pasteurized juice. A HPP of 600 MPa for 150 s was identified capable of achieving greater than 5.15-log reductions of E. coli O157:H7 in shiikuwasha juice. The microbiological shelf life of the juices were at least 28 days when processed at HPP for 600 MPa/150 s or HTST for 90 degrees C/60 s. The color, aromatic, and antioxidant contents (TPC, TFC, Tangeletin, Nobiletin) were well preserved after HPP, however, HTST resulted in a significant (p < 0.05) loss of antioxidant content (TPC (8.8%), Tangeletin (6.8%)), and negatively impacted the juice color. By the end of storage, the amount of these aroma relevant volatiles appears to still be higher in HPP pasteurized juices compared to their conventional counterparts. This study demonstrated that under optimal conditions of HPP can attain the same level of microbiological safety as thermal pasteurization and preserved the acceptable quality of shiikuwasha juice.