BEHAVIOR OF PECTIC SUBSTANCES AND NARINGIN IN GRAPEFRUIT IN THE FIELD AND IN STORAGE

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Abstract
A relationship is noted between (1) the susceptibility of grapefruit (Citrus grandis) to storage pitting and (2) the amt. of pectic substances and naringin in the albedo, the temp. prevailing in the grove during the 5 days preceding the picking of the fruit, and the length of time during which the fruit maintained a negative pressure when enclosed in air-tight chambers. All these factors tended to increase or decrease together. The length of time during which a grapefruit maintained a negative pressure in an air-tight container after the fruit was removed from storage depended on the temp. and duration of the storage. Lowering the temp. or length-ening the storage period reduced the duration of negative pressure. The storage effect became noticeable within 2 days after the fruit was placed in storage. Total pectic substances and naringin showed a small apparent increase after storage for 6 weeks at 68[degree], 56[degree], 46[degree], and 38[degree] F, the increase in the albedo varying directly with the temp. of the storage. The changes in pectic substances and naringin content are not claimed to cause changes in the susceptibility to pitting but they show that compositional changes take place in unpicked mature fruit which affect the readiness with which the fruit will develop pitting while in cold storage.