Search Results
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.
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.
The severity of chilling injury in zucchini squash stored at 5C than transferred to 20C was reduced with the prestorage treatment of 42C hot water for 30 min. The chilling injury was further reduced when squash were preconditioned at 15C for 2 days after hot water treatment but before the 5C storage. Squash stored at 15C did not develop any symptoms of chilling injury. However, weight loss was most severe in squash stored at 15C. Squash kept at 5C had the least weight loss during the 2-week storage. Weight losses were comparable in squash treated or not treated with hot water. Analysis of polyamines in squash preconditioned with high and low temperatures is in progress. The effect of hot water treatment on the changes of putrescine, spermidine, and spermine and its implication in reducing chilling injury will be discussed.
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.
Abstract
High storage humidities, wax, and polyethylene film as bin-liners were compared for minimizing loss in storage life and preventing fruit shrivel during storage prior to packaging for market of pear (Pyrus communis L. cv. d’Anjou). Lining the sides and covering the top of bins with 1.25-mil polyethylene film was the most beneficial in preventing fruit shrivel without adversely delaying cooling. Enclosing pears in film bin bags also controlled moisture loss but was detrimental to rapid removal of field heat. Waxing the fruit or covering only the top of bins with film did not reduce the cooling rate but were ineffective in preventing excessive moisture loss. Introduction of water vapor to maintain high humidity markedly reduced moisture loss but caused ice formation on the fruit and storage room floor.
Abstract
Addition of rhizbitoxin analogs to holding solutions extended vase life of bulbous iris flowers (Iris xiphium L), daffodils (Narcissus pseudo-narcissus L.) and chrysanthemums (Chrysanthemum morifolium Ramat). Sodium benzoate also increased vase life of daffodils butnot of irises and chrysanthemums. Isopentenyl adenosine delayed senesence of irises but not of chrysanthemums. None of the chemicals tested extended the vase life of roses (Rosa hybrida L). Ethylene production in rose petal tissue was reduced by rhizobitoxine analogs indicating that roses do not have a rhizobitoxine-resistant ethylene producing system. Results suggested that either roses are sensitive to low levels of ethylene or their senescence is triggered by factors other than ethylene.
Fruit and leaves from different cultivars of thornless blackberry (Rubus sp.), red raspberry (Rubus idaeus L.), black raspberry (Rubus occidentalis L.), and strawberry (Fragaria × ananassa D.) plants were analyzed for total antioxidant capacity (oxygen radical absorbance capacity, ORAC) and total phenolic content. In addition, fruit were analyzed for total anthocyanin content. Compared to fruit, leaves were found to have higher ORAC values. In fruit, ORAC values ranged from 7.8 to 33.7 μmol Trolox equivalents (TE)/g of fresh berries, while in leaves, ORAC values ranged from 20.8 to 45.6 μmol TE/g of fresh leaves. Fruit harvested at different stages of maturity were analyzed in blackberries, raspberries, and strawberries. Blackberries and strawberries had their highest ORAC values during the green stages, while raspberries generally had the highest ORAC activity at the ripe stage (with exception of cv. Jewel, a black raspberry). Total anthocyanin content increased with maturity for all three fruit. There was a linear correlation existed between total phenolic content and ORAC activity for fruit and leaves. For ripe berries, there was also a linear relationship between ORAC values and anthocyanin content. Of the ripe fruit and leaves tested, raspberry plants appeared to be the richest source for antioxidants.
The effect of blackberries (Rubus sp.) genotypes on antioxidant activities against superoxide radicals (O2 –), hydrogen peroxide (H2O2), hydroxyl radicals (OH), and singlet oxygen (O,), was evaluated. The results were expressed as percent inhibition of active oxygen species production in the presence of fruit juice. The active oxygen radical absorbance capacity (ORAC) value referred to the net protection in the presence of fruit juice, and was expressed as micromoles of α-tocopherol, ascorbate, α-tocopherol, and β-carotene equivalents per 10 g of fresh weight for O2 –, H2O2, OH, and O2, respectively. Among the different cultivars, juice of Hull' blackberry had the highest oxygen species, superoxide radicals (O2 –), hydrogen peroxide (H2O2), hydroxyl radicals (OH), and singlet oxygen (O2,) scavenging capacity. Different antioxidants have their functional scavenging capacity against active oxygen species. There were interesting and marked differences among the different antioxidants in their abilities to inhibit the different active oxygen species. β-carotene had by far the highest scavenging activity against O2 – but had absolutely no effect on H2O2. Ascorbic acid was the best at inhibiting H2O2 free radical activity. For OH, there was a wide range of scavenging capacities with α-tocopherol the highest and ascorbic acid the lowest. Glutathione had higher O2 – scavenging capacity compared to the other antioxidants.