Microwave Blanching Of Vegetables For Frozen Storage

Abstract

The quality of five vegetables, blanched using either microwave or hot water methods currently recommended to the American consumer, was examined after one, two, four, and six months of frozen storage. The vegetables were analyzed for residual peroxidase activity immediately after blanching. Storage stability of cooked and uncooked vegeta bles was determined by examining various quality factors after each period of frozen storage. Quality factors included color, texture, flavor, and overall acceptability of the vegetables as measured using objective methodology and sensory evaluation. Broccoli and zucchini retained high levels of peroxidase activity after microwave blanching. Broccoli and green beans blanched with microwave energy retained less chlorophyll (p 0.05), had higher shear force values (p 0.05), and received lower sensory eval uation scores than the water blanched vegetables (p 0.05) for quality factors common ly used by consumers. The texture of zucchini blanched with microwave energy was limp as measured by shear force and by sensory evaluation. No significant differences (p 0.05) were found in the quality of carrots or cauliflower blanched by the two meth ods. Instructions currently available for microwave blanching of vegetables for home freezing do not result in a quality product for all vegetables.