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Abstract
Preharvest treatment with 400 ppm aminoethoxyvinylglycine (AVG) delayed the ripening of ‘Bartlett’ pears kept at 20°C. The effect was not uniform, with the delay in ripening ranging from a few to 112 days. Prolonged storage at 20° was accompanied by a relatively steady, low level of respiration, gradual degreening, and partial suppression of the eventual climacteric. The combined effect of AVG treatment and prolonged ‘nonripening’ storage at 20° led to a marked attentuation of the production of 4 readily measurable volatiles including methyl-, ethyl-, and hexylacetate as identified by cochromatography and combined gas chromatography–mass spectrometry. Surprisingly, prolonged storage resulted in a much increased production of 2 other volatile fractions when AVG inhibition was reversed by C2H4 treatment. The emanation of all measured volatiles was closely coincident with the climacteric peak. These observations confirm prior reports of disuniform effects of preharvest AVG treatment and reveal that metabolic transitions during prolonged, nonripening storage may have adverse effects on fruit quality.
Abstract
As the pistachio (Pistacia vera L. cv. Kerman) nut matured, kernel moisture, respiration rate, and total protein content decreased, while kernel dry weight increased. At optimum maturity, ether-extractable fat and total sugar contents reached a peak. Either or both of these constituents may be useful as a maturity index, in addition to ease of hull separation, to determine optimum harvest date for pistachio nuts. Nut quality was acceptable for harvest during a 2- to 3-week period bracketing the time when the hull separates easily from the shell. Compositional analyses of hulls indicated some limitations on their potential use as animal feed.
Abstract
The chemical composition and sensory attributes of pistachio nuts (Pistacia vera L.) were studied in relation to genotype, production area, maturity, moisture content, degree of shell staining, and storage conditions. ‘Kerman’ kernals were rated higher in firmness and sweetness, and lower in crispness, bitterness, and rancidity than those of the ‘Red Aleppo’, ‘Trabonella’, and ‘Bronte’ cultivars. Differences in composition and flavor of ‘Kerman’ pistachios harvested from 3 production areas were small. Nuts harvested at near optimum maturity were superior in quality to those harvested earlier or later. Drying nuts to 4–6% moisture levels resulted in the best quality. Shell staining did not influence eating quality of kernels but detrimentally affected shell appearance. Dried pistachio nuts can be kept for 12 months at 20°C. Moisture content influenced crispness and firmness while total sugars content was related to sweetness and overall flavor intensity.