Effect of Ultrafiltration Combined with High-Pressure Processing on Safety and Quality Features of Fresh Apple Juice

Ultrafiltration (UF, 0.05 mu m) with a ceramic membrane was combined with high-pressure processing (HPP) at 500 MPa/6 min and high-temperature short time (HTST) at 110 degrees C/8.6 s to process fresh apple juice. The aim of this study was to compare the effect of UF + HPP and UF + HTST on quality features of fresh apple juice and analyze the quality changes of the juice treated by UF + HPP and stored during 60 days at 4 degrees C. Applying UF, total plate count (TPC) and yeasts and molds (Y&M) significantly decreased by 0.29 and 0.28 log cycle, total phenols and ascorbic acid decreased by 33.50 and 26.52 %, and antioxidant capacity, using the DPPH and FRAP assay, significantly decreased by 26.40 and 25.37 %. Meanwhile, the juice clarity was 99.75 +/- 0.07 % and seven aroma compounds were changed. TPC and Y&M in juices treated by UF + HPP and UF + HTST were <1 log cycle. When compared to the juice treated by UF + HTST, the juice treated by UF + HPP showed lower browning degree and higher total phenols and clarity, and retained seven main volatile aroma compounds. Fresh apple juice processed by UF + HPP was microbiologically safe (TPC <1.8 log cycles and Y&M <1 log cycle) during 60 days of storage at 4 degrees C. The first-order model was a suitable model for all quality parameters of refrigerated fresh apple juice; however, rate constant k of first-order model was between -0.0157 and 0.0350, showing the quality features of the refrigerated juice was stable.