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`Golden Delicious' and `Red Rome' apples were pressure infiltrated (69 kPa for 2 or 4 min) at harvest with 0, 1, 2, 3 or 4%, and 0, 2, 4, 6 or 8% CaCl2 solutions (w/v), respectively, and placed in 0°C storage. Juice was extracted from the apples after 0, 2, 4 or 6 months in storage. Sensory evaluation of the juice was conducted to determine if CaCl2 concentration affected color, off-flavors, suspended particles or overall acceptability of the juice. Juice color was judged lighter with increased CaCl2 in both cultivars. Detection of off-flavors decreased as CaCl2 was increased in juice from `Red Rome'; whereas, off-flavors increased as CaCl2 was increased in `Golden Delicious' juice. CaCl2 treatments decreased suspended particles in both cultivars. As CaCl2 was increased overall acceptability of juice from `Red Rome' increased, while acceptability of juice from `Golden Delicious' decreased.
The effects of organosilicone and more conventional hydrocarbon surfactants on postharvest radiolabeled calcium (Ca) and on Ca solution infiltration into `Golden Delicious' apples were examined to provide a direct and more efficient pressure infiltration technique to increase fruit Ca concentration. Both radiolabeled Ca infiltration and the proportional increase in fruit Ca estimated by fruit weight gain from Ca solutions of known concentration were significantly enhanced by a range of surfactants having differing chemical structures. Two organosilicone surfactants, Silwet L-77 and Silwet L-7604, known for their greater capacity to lower the surface tension of solutions than conventional hydrocarbon surfactants, were the best among the surfactants tested at augmenting Ca infiltration. Applications of surfactants to fruit were as effective or more effective when used as a pretreatment rather than by mixing with Ca solutions. The applied atmospheric pressure necessary to infiltrate Ca to levels considered sufficient to maintain fruit firmness and resist decay during storage could be lowered in fruit treated with organosilicone surfactants. Postharvest surfactant and Ca treatments may offer a practical means of increasing the Ca concentration of apple fruit.
High glucosinolate content in brassica meal is a limiting factor in consumption of rapeseed. In recent years canola cultivars of rapeseed with decreased glucosinolate content have been developed. However, environmental and nutritional factors are also believed to influence glucosinolate content. This study was conducted to determine the relationships among water stress, B nutrition, and glucosinolate content in canola. Two canola cultivars (`Cyclone' and `American A112') were grown in a continuously recirculating hydroponic system with modified Hoagland solution (0.6 ppm B). Water stress was induced gradually (2% per day using polyethylene glycol 8000) starting when plants were 4 weeks old. Osmotic potential was maintained at –0.1 MPa (high stress level), –0.085 MPa (medium stress), or 0.05 MPa (control). Treatments were arranged in a randomized incomplete-block design, with three blocks, four replications, two cultivars, and three treatments. Upper leaves (no. 15 and higher) were collected and analyzed by inductively coupled plasma emission spectrometry for B content. Total and indole glucosinolate content of seeds were measured colorimetrically and by HPLC. The leaf B content of stressed plants decreased by 55% in `Cyclone' and 29% in `American A112'. Total glucosinolate content increased 28% and 12%, respectively, in stressed plants of `Cyclone' and `American A112'. Indole glucosinolate content was 44% and 13% higher in the same plants. The interaction between cultivar and water stress was not significant for glucosinolate content but was significant for B content of the leaves.
Dietary sources of selenium (Se) are associated with human health benefits, and Brassica species are good sources of Se in human diets. Selenium and S compete for absorption and accumulation in plant tissues; therefore, the ratios of Se to S in the growing environment determine the accumulation of selenium in plants. To determine responses for Brassica oleracea L., two levels of Na2SeO4 (96 mg·L−1 SeO4 2– and 0.384 mg·L−1 SeO4 2–) were added to nutrient solutions with or without MgSO4·7H2O (96 mg·L−1 SO4 2–). The highest plant fresh weight and S and SO4 2– accumulation were found when plants were grown in the medium with a SeO4 2– to SO4 2– ratio of 1 : 250 (0.384 mg·L−1 SeO4 2– and 96 mg·L−1 SO4 2–). However, the highest accumulation of Se was found when a low level of selenate (0.384 mg·L−1 SeO4 2–) was added to nutrient solutions without S. The activity of glutathione peroxidase (GPx) was regulated by Se status; the highest GPx activity was measured when a high level of SeO4 2– (96 mg·L−1) was supplied to nutrient solutions without S supplementation. The lowest concentration of total glucosinolates was found when adding SeO4 2– to nutrient solutions without S. We saw no difference in plant growth and mineral accumulation when plants were grown with K2SeO4 versus Na2SeO4, suggesting that the growth-inhibiting effect of Na2SeO4 was the result of the SeO4 2– rather than potentially toxic effects of Na+.
`Golden Delicious' (`GD') and `Red Rome' (`RR') apples were pressure infiltrated at harvest with 0, 1, 2, 3 or 4% and 0, 2, 4, 6 or 8% CaCl2 solutions (w/v), respectively. Sauce was prepared after 0, 2, 4 and 6 months in 0°C storage. Sensory evaluation was conducted to determine the effects of CaCl2 concentration on color, off-flavors, consistency, uniformity of particles, and overall acceptability of the sauce. Sauce from `RR' was lighter while sauce from `GD' was darker with increased CaCl2. Calcium chloride increased the consistency of `RR' and `GD' sauce but the highest concentrations decreased the consistency of `GD' sauce. The uniformity of sauce particles from both cultivars decreased with increased CaCl2. The presence of off-flavors increased in `GD' sauce with the highest concentrations but decreased in `RR' sauce as CaCl2 was increased. Overall acceptability of sauce made from `RR' and `GD' increased as CaCl2 increased, however, acceptability of sauce made from `GD' decreased at the highest concentrations of CaCl2.
`Golden Delicious' apples (Malus domestics Borkh.) were treated with heat or CaCl2 solutions or a combination thereof to determine the effects of these treatments on decay and quality of fruit in storage. Heat treatment at 38C for 4 days, pressure infiltration with 2% or 4% solutions of CaCl2, or a combination of both, with heat following CaCl2 treatment affected decay and firmness during 6 months of storage at 0C. The heat treatment alone reduced decay caused by Botrytis cinerea (Pers.:Fr.) by ≈30%, while heat in combination with a 2% CaC12 solution reduced decay by ≈60 %. Calcium chloride solutions of 2% or 4% alone reduced decay by 40 % and 60 %, respectively. Heat treatments, either alone or in combination with CaC12 treatments, maintained firmness (80 N) best, followed by fruit infiltrated with 2% or 4% solutions of CaCl2 alone (70 N) and the nontreated controls (66 N). Instron Magness-Taylor and Instron compression test curves show that heat-treated fruit differed qualitatively and quantitatively from nonheated fruit. Heat treatment did not increase the amount of infiltrated Ca bound to the cell wall significantly, and a combination of heat treatment after CaCl2 infiltration increased surface injury over those fruit heated or infiltrated with CaCl2 solutions alone.
`Golden Delicious' and `Red Rome' apples were pressure infiltrated (69 kPa for 2 or 4 min) at harvest with 0, 1, 2, 3 or 4%, and 0, 2, 4, 6 or 8% CaCl2 solutions (w/v), respectively, and placed in 0°C storage. Juice was extracted from the apples after 0, 2, 4 or 6 months in storage. Sensory evaluation of the juice was conducted to determine if CaCl2 concentration affected color, off-flavors, suspended particles or overall acceptability of the juice. Juice color was judged lighter with increased CaCl2 in both cultivars. Detection of off-flavors decreased as CaCl2 was increased in juice from `Red Rome'; whereas, off-flavors increased as CaCl2 was increased in `Golden Delicious' juice. CaCl2 treatments decreased suspended particles in both cultivars. As CaCl2 was increased overall acceptability of juice from `Red Rome' increased, while acceptability of juice from `Golden Delicious' decreased.
`Golden Delicious' apples (Malus domestica Borkh.) were treated postharvest with heat (38C/4 d or 42C/24 h) or 2% CaCl2 (applied as a dip or pressure-infiltrated) or a combination thereof and then stored. Decay caused by Botrytis cinerea was virtually eliminated in fruit heated at 38C after inoculation prior to storage, regardless of Ca treatment. Apples inoculated upon removal from storage were almost completely protected from decay if they had been previously pressure-infiltrated with Ca, regardless of heat regime. Heating at 42C or Ca dips were only partially effective in preventing decay. Pressure infiltration of Ca (regardless of heat regime) or heating at 38C (regardless of Ca treatment) resulted in firmer fruit (68 N) than Ca dips or heating at 42C (56 N), which were firmer than nontreated fruit (52 N).
Prestorage infiltration of `Golden Delicious' apples (Malus domestica Borkh.) with calcium (Ca) retarded texture changes during storage at 0C and inhibited ethylene production of the fruit at 20C. Infiltration of the fruit with the polyamines (PA) putrescine (PUT) or spermidine (SPD) also altered texture changes, but did not inhibit ethylene production. When the fruit were treated with Ca first and then with PA, cell wall-hound Ca concentrations increased 4-fold, but PA levels in the cell wall increased only slightly. When the fruit were treated with PA first and then with Ca, PA levels in the cell wall increased 3-fold, but Ca concentration increased only 2-fold. These results indicate that Ca and PA may he competing for the same binding sites in the cell wall and that the improvement of fruit quality during storage by these cations could involve strengthening of the cell wall.
A study was conducted to quantify volatiles generated from Indian mustard (Brassica juncea L. Czerniak) tissue incorporated into soils under controlled conditions. Mustard residues were incorporated into noncovered and covered soils that varied by texture, temperature, moisture, pH, or sterility (autoclaved or nonautoclaved). Sandy loam soil had 38% more allyl isothiocyanate (AITC) than clay loam soil. AITC concentration in 45 °C soil was 81% higher than in soil at 15 °C, and 56% higher in covered compared to noncovered treatments. The microbial catabolism of AITC was suggested by the result that AITC concentration in autoclaved soils was over three times that measured in nonautoclaved soils. The highest AITC level detected (1.71 μmol·L–1) occurred in the autoclaved covered soil. Several factors also influenced CO2 evolution. At 30 or 45 °C, CO2 concentration was at least 64% higher than at 15°C. The covered soil had over twice the CO2 found in the noncovered soil, and the nonautoclaved soil treatment yielded twice the CO2 measured in the autoclaved soil. There were no main effect differences among soil moisture, soil pH, and soil texture treatments for CO2 concentrations. This information could be helpful in defining ideal soil conditions for field scale experiments. Additionally, this study demonstrates a sampling technique for testing fumigation potential of biofumigation and solarization systems that may have the potential to replace methyl bromide.