Effect of high pressure processing and thermal treatment on physicochemical parameters, antioxidant activity and volatile compounds of green asparagus juice

This study was conducted to investigate the effect of high pressure processing (HPP) at different pressures (200, 400 and 600 MPa) and treatment times (10 and 20 min) on microbial population, physicochemical parameters, bioactive compounds, total antioxidant activity and volatile compounds in green asparagus juice, in comparison with thermal processing (121 degrees C/3 min) and control (no treatment). The results indicated that HPP at 400 and 600 MPa for both treatment times decreased the total mesophilic bacteria to undetectable level as the thermal treatment did, thus ensuring the safety of asparagus juice. The pH value and soluble solids content of asparagus juice were not significantly affected by HPP treatments as compared to thermal processing and control. However, all HPP treatments retained significantly more ascorbic acid, rutin and total phenolic contents and higher total antioxidant activity than thermal treatment. The main volatile compounds in asparagus juice were aldehydes, alcohols and ketones. HPP treatments maintained significantly higher concentrations of aldehydes, alcohols and ketones than thermal treatment. These results suggest that HPP could be an effective alternative to conventional thermal processing for production of high quality green asparagus juice. (C) 2014 Elsevier Ltd. All rights reserved.