Effect of Several Heat Treatments on Quality and Shelf life of a Frozen Guava Nectar Base

Abstract

Studies were conducted concerning the effect of several heat treatments on the quality and shelf-life of a frozen guava nectar base prepared from wild fruit. Heating nectar bases to 150°, 185° and 210° to 215° F., followed by rapid cooling and chilling, had no apparent effect on quality and shelflife. No appreciable changes were observed in acidity and reducing-sugars over a storage period of 400 days at —10° F. Insignificant changes in color occurred in plain tin and fully-enameled containers, even when F. D. C. Red No. 2 colorant was added to improve the color. Vitamin C retention during storage ranged from 89.0 to 97.8 percent. Vitamin C retention was observed higher than 100 percent in the samples canned in plain tin containers, attributed to formation of reducing interfering substances. Addition of vitamin C in levels ranging from 94 to 623 mg. per 100 g. of base had no effect on vitamin C retention. Heat treatments reduced bacterial and yeast counts. Because the several heat treatments tested had no appreciable effect on quality and shelf-life, the product may be packed without heat treatment in commercial practice or may be pasteurized by heating above 185° F. to reduce microorganism counts.