Use of ultra-high-pressure homogenization to preserve apple juice without heat damage

Ultra-high-pressure homogenization (UHPH) is a technology for continuous treatment of fluid food products and can be applied to avoid thermal treatment of fruit juices. Treatment of fresh apple juice at homogenization pressures from 100 to 300MPa and inlet temperatures of 4C or 20C caused important decreases in microbial counts when treatment pressure reached at least 200MPa. After the treatment, counts were1logcfu/ml when homogenization pressure reached at least 200MPa, and remained stable for more than 2months at 4C. Hydroxymethylfurfural for thermal-treated juice reached values 100-fold higher than for its UHPH-treated or raw counterparts. Browning index was higher in non-thermal-treated juice, and it had an inverse correlation with the severity of UHPH treatment. Part of this browning occurred during Pilot Plant processing, but it kept on browning during preservation in juices in which PPO was not fully inactivated. UHPH treatment of apple juice may be an alternative to conventional thermal processing.