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Utilization and Storage Stability of Mechanically Harvested Strawberries

出版	University of Arkansas, Fayetteville, 1980
URL	http://books.google.com.hk/books?id=9trjNAAACAAJ&hl=&source=gbs_api

註釋The influence of immature fruits on strawberry puree and jam quality was evaluated using two cultivars, 'Cardinal' and Arkansas breeding-line 5344, which were suited to once-over machine harvest. Analyses of the fruit maturities found in a once-over strawberry harvest showed the immature and mature green fruits to have poorer color, due to the presence of chlorophyll and absence of anthocyanins, than the ripe fruits. Green berries were higher in acidity, total phenols, puree viscosity, cellulose, protopectin and peroxidase and polyphenol oxidase activity, and lower in soluble solids, total ascorbic acid, and water soluble pectins than the riper fruits. When puree from ripe fruits was combined with puree from immature fruits, puree color decreased as the percentage of ripe fruit puree decreased from 100 to 25%. During holding at 10(DEGREES), 30(DEGREES) and 50(DEGREES)C for up to 36 hours, puree from immature fruits did not affect anthocyanin loss, but it increased discoloration as measured by the ratio of absorbances (520/430 nm). This increase in discoloration was probably due to degraded chlorophyll and phenolic compounds. The influence of immature fruits was a dilution effect rather than an acceleration of color loss since the two maturities could be combined after holding to create the same color differences found when the purees were held as a combination. The principal pigment in the purees was found to be pelargonidin-3-monoglucoside, and it was less stable than cyanidin-3-monoglucoside during holding. The jam that was made from a combination of small mostly green fruit and large ripe fruit decreased as the percentage of ripe fruits decreased from 100 to 25%. Initially, and after 6 and 12 months storage at 2(DEGREES)C, jam of all maturity mixtures of both cultivars were rated acceptable by the sensory panel. The acceptability of the jam containing only 25 and 50% ripe fruits was due to moderate to high anthocyanin levels of ripe fruits of the two cultivars. After storage at 25(DEGREES) for 6 and 12 months the loss of color increased, and jam prepared from 25 and 50% ripe fruits of A-5344 was approaching unacceptable levels of color. During storage immature fruits did not influence anthocyanin loss. Although the addition of immature fruits reduced color of jam, the anthocyanin content was more important than percent ripe fruit in determining sensory color acceptability. A total anthocyanin content of 2.9 O.D. units/g or more and a discoloration index value of 0.93 or higher were associated with acceptable jam color.