Effect of high hydrostatic pressure on qualities of prepared green asparagus spears

Green asparagus( Asparagus officinalis L.) spears is one of tender shoot vegetables with high water content and strong respiration metabolism during storage. High hydrostatic pressure( HPP) is an immerging minimal processing technology which might be used as a potential approach for extending the storage time of raw asparagus spears.Effect of HHP on inactivation of aerobic bacteria,mould and yeast at various pressure levels( 300~600 MPa) for 1~20 min treatments were studied.In addition,three treatment conditions were selected to study the effect of HHP on the quality of prepared green asparagus during storage. The results showed that the effects of microorganism inactivation were improved with increasing of pressure and / or the holding time.The mold and yeast were more sensitive to HHP than the aerobic bacteria,which were inactivated completely at treatment of 300 MPa for 3 min.The aerobic bacteria of the 400 MPa processing 10 min,500 MPa treatment 5 min,600 MPa 3 min were less than 100 cfu / g.The Weibull model was used to analyze the survival curves. The coefficients of determination( R²) were all higher than 0.97,indicating that the Weibull model fitted the microbial inactivation kinetics curve well.During the storage,the asparagus treated at 500 MPa for 5 minutes can be stored for 21 days and obtained better qualities,such as color and texture,than that of the products treated at 400 and 600 MPa.