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

Abstract

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 300 MPa and inlet temperatures of 4 °C or 20 °C caused important decreases in microbial counts when treatment pressure reached at least 200 MPa. After the treatment, counts were<1 log cfu/ml when homogenization pressure reached at least 200 MPa, and remained stable for more than 2 months at 4 °C. 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.

Keywords:

• apple juice
• high pressure homogenization
• sensory characteristics
• color
• browning index
• HMF