PILOT PLANT EVALUATION OF INDIVIDUAL QUICK BLANCHING (IQB) FOR VEGETABLES

A pilot plant IQB blancher was field tested at a California freezing plant. The system included: a warming and drying preconditioning unit, a steam chamber for single layer belt heating, a deep moving-bed holding chamber for temperature equilibration and enzyme inactivation and an air-water spray cooling unit. IQB with and without preconditioning were compared to conventional, steam blanching at equivalent levels of enzyme inactivation in green beans, lima beans, Brussels sprouts and green peas. Effluent volume and total-solids concentration were measured. Product yields were determined by measuring residual peroxidase activity, chlorophyll conversion and ascorbic acid content as well as by sensory panel testing for color and flavor. Results showed that vegetables blanched with IQB and IQB with preconditioning were essentially the same in quality as those blanched at commercial conditions. Solids loss in the effluent was substantially less with IQB and preconditioning than with conventional steam blanching