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Abstract
Exposure of sweet peppers (Capsicum annuum L.) to 30% CO2 for 6 days at 13°C immediately after harvest retarded wall softening and ripening in air at 13° but caused the subsequent development of severe calyx injury and decay at 20°. Slight to moderate calyx injury was induced by a 6-day exposure to 20% CO2. Severity of the injury was greater when the CO2 was used with 3% O2 as compared to 21% O2. Injury was not induced by a 6-day treatment with 10% CO2. When stored at 13°, quality of peppers with this treatment was superior after 10 days, but inferior after 20 days to that of peppers kept continuously in an atmosphere of 5% CO2 and 3% O2. Benefits obtained from the 3-day elevated CO2 treatment (10 to 30%) were nullified after 10 days’ storage at 13°. Ethylene production was greatly inhibited in high CO2 atmospheres but rose immediately after transfer to air. Red color development, chlorophyll degradation, and ascorbic acid accumulation were retarded only in the presence of high CO2.
Abstract
Rates of ethylene production, respiration, and yellowing of broccoli (Brassica oleracea L. Italica group) at 20°C were reduced by an aminoethoxy analog of rhizobitoxine (AAR) [L-2-arnino-4-(2-arnino-ethoxy)-trans-3-butenoic acid] and by sodium benzoate (SB). Loss of chlorophyll and ethylene production were retarded by concn of 5 × 10-3M of AAR; at concn of 10-3M or 5 × 10-4M, the retardation was less pronounced. Yellowing and ethylene production were markedly reduced by SB at concentrations of 0.01M, 0.05M, or 0.1M. However, the latter two concentrations caused chemical injury and off-odor which resulted in unsalable quality. The data suggest that senescence of broccoli is related to ethylene production and that senescence can be retarded by inhibiting ethylene production.
Mature leaves of kale (Brassica oleracea L., Alboglabra group) and collard (Brassica oleracea L., Acephala group), and Brussels sprouts (Brassica oleracea L., Gemmifera group) were heated by moist air at 40, 45, 50, or 55 °C for durations of 0, 30, 60, or 90 minutes. Heating of kale at 45 °C for 30 minutes was effective in maintaining better postharvest quality, delaying yellowing, and reducing losses of sugars and organic acids during subsequent storage at 15 °C. Exposure of collard at 40 °C for 60 minutes also delayed yellowing and maintained turgidity of the leaves. Other treatments were either less beneficial, not effective, or caused injury. Heat injury occurred when temperature and duration exceeded the tolerance levels. In some cases, heat-injured tissues remained green but developed fungal infection. Heat treatments had no measurable effects on the rate of senescence or storage quality of Brussels sprouts.
Mature leaves of kale (Brassica oleracea L., Alboglabra group) and collard (Brassica oleracea L., Acephala group), and Brussels sprouts (Brassica oleracea L., Gemmifera group) were heated by moist air at 40, 45, 50, or 55 °C for durations of 0, 30, 60, or 90 minutes. Heating of kale at 45 °C for 30 minutes was effective in maintaining better postharvest quality, delaying yellowing, and reducing losses of sugars and organic acids during subsequent storage at 15 °C. Exposure of collard at 40 °C for 60 minutes also delayed yellowing and maintained turgidity of the leaves. Other treatments were either less beneficial, not effective, or caused injury. Heat injury occurred when temperature and duration exceeded the tolerance levels. In some cases, heat-injured tissues remained green but developed fungal infection. Heat treatments had no measurable effects on the rate of senescence or storage quality of Brussels sprouts.
Abstract
Pollen tube growth in styles of ‘d’Anjou’ pear (Pyrus communis L.) is largely dependent on prevailing temp. At 21°C the process was completed within 24 hr, while at 15.5° and 10° growth was completed by 72 and 120 hr respectively. The initial fruit development 14 days following pollination was greatly influenced by day temp (ranging from 13° to 23.4°) during an thesis.
Fruit of the cultivated strawberry (Fragaria ×ananassa Duchesne ex Rozier) are a good source of natural antioxidants, which play an important role in protecting human health. Antioxidant levels vary considerably among strawberry genotypes. The cultivated strawberry is a hybrid of two very different wild progenitor species: F. virginiana Mill. and F. chiloensis (L.) Mill. The progenitor species are valued by strawberry breeders as sources of novel traits, but have not been evaluated for antioxidant capacity or levels of antioxidant compounds. The objectives of this study are 1) to evaluate the antioxidant contents and antioxidant activities in representatives of F. virginiana and F. chiloensis in comparison with representatives of the cultivated strawberry species (F. ×ananassa), 2) to determine which strawberry compounds are most closely correlated with antioxidant capacity among these three species, and 3) to identify wild strawberry genotypes with high antioxidant activity and bioactive compounds for use in cultivar development. Fruit of 19 accessions from each of the three species, cultivated strawberry plus the two progenitor species (F. ×ananassa, F. virginiana, and F. chiloensis), were evaluated for levels of antioxidant capacity (oxygen radical absorbance capacity), total phenolics, total anthocyanins, ellagic acid, quercetin 3-glucoside plus quercetin 3-glucuronide, kaempferol 3-glucoside, kaempferol 3-rutinoside, p-coumaryl–glucose, pelargonidin 3-glucoside, pelargonidin 3-glucoside–succinate, cyanidin 3-glucoside, and cyanidin 3-glucoside–succinate. Fruit of the 13 accessions tested from the wild progenitor species F. virginiana had significantly higher antioxidant capacity, total phenolics, and total anthocyanins than did the fruit of three accessions tested from the cultivated strawberry F. ×ananassa, or the three accessions tested from the other wild progenitor species (F. chiloensis), and will be valuable as a source of parent material for developing more nutritious strawberry cultivars. The high correlation with antioxidant capacity, relative efficiency, and lack of genotype-by-year interaction in this study suggests that the measurement of total phenolics may be the better assay to use for the later selection stages in a strawberry cultivar development program. Of the evaluated F. virginiana accessions, NC 95-19-1, JP 95-1-1, CFRA 0982, NC 96-5-3, and RH 30 fruit were highest in antioxidant capacity and should prove useful toward development of strawberry cultivars with high antioxidant capacities.
Abstract
Continuous exposure of pears to 7.2°C (night) - 21.1°C (day) for 2 days or 10°C - 21.1°C for 9 days or 7.2°C - 26.7°C for 21 days induced the physiological disorder, premature ripening, during the month immediately preceding normal harvest. During the same period, premature ripening did not develop with temp exposures of 12.8°C - 21.1°C or with 7.2°C - 32.2°C. Cool temp 6 to 9 weeks prior to harvest may also cause premature ripening to occur but the fruit will recover to normal behavior if subsequent temp are above the threshold level.
Abstract
Treatment with 500 ppm ethylene for 24 hr or with 4000 ppm Ethrel (2-chloro-ethanephosphonic acid) dip for 30 sec resulted in ‘Anjou’ pears attaining full ripeness without a concomitant change in respiratory activity. A decrease in flesh firmness and increases in protein nitrogen and soluble pectin occurred, even though the fruit remained in the preclimacteric condition. This was shown by a positive response in rate of respiration to ethylene at the fully ripe stage. Continuous, 48- and 24-hr treatments resulted in comparable rates of ripening. However, while the continuous and 48-hr treatments induced the climacteric rise in respiration, the 24-hr exposure failed to do so. The effect of ethylene on respiration is independent from its effect on the initiation of ripening; a respiratory response probably requires a higher concentration or longer exposure to ethylene than does a ripening response.
Abstract
Difference in optical density (∆OD) of intact ‘Bartlett’ pears (Pyrus communis L.) between wavelengths 690 and 740 nm was measured at harvest and during ripening with a single-beam multiwavelength spectrophotometer. The ∆OD indicated the status of ripeness and detected core breakdown of ‘Bartlett’ pears nondestructively. The ∆OD decreased consistently with ripening and was associated with softening, climacteric rise in respiration, and ethylene production. The ∆OD increased in pears with core breakdown even before external symptoms were visible.
Abstract
Quality and ripening capacity of ‘d’Anjou’ pears (Pyrus communis L.) after long-term storage were influenced by the daily-hourly average (DHA) temperatures during 6-week prior to harvest. Fruits of 17.2° and 13.9°C DHA temperatures ripened with high acid and sugar contents while samples of 20.0° and 11.7°C DHA temperature treatments failed to ripen properly and had lower quality. Failure to ripen after prolonged storage was associated with high protein nitrogen levels in the fruits. Samples of lower DHA temperature were more susceptible to friction discoloration, while fruits of higher DHA temperature had a higher percentage of superficial scald. Temperatures during this period did not appear to affect harvest maturity, size or soluble pectin content of the fruit.