USE OF VACUUM IMPREGNATION TO DEVELOP HIGH QUALITY AND NUTRITIONALLY FORTIFIED FROZEN STRAWBERRIES

Strawberries (Totem) were vacuum impregnated (VI) before freezing with cryoprotectants of high fructose corn syrup (HFCS) or high methoxyl pectin (HMP) to improve quality, and with calcium and zinc salts to enhance the nutritional value of the product. The VI process consisted of a 15 min vacuum at 50 mm Hg and 30 min restoration at atmospheric pressure. VI pretreatment significantly increased the calcium and zinc content of frozen strawberries. VI with cryoprotectant improved the textural quality and reduced drip loss of frozen-thawed strawberries in comparison with untreated strawberries. Calcium in the VI solutions further increased the firmness of frozen-thawed strawberries, and zinc improved the color stability of the strawberries during the impregnation and freeze-thawing process.