Search Results
Abstract
A 4-year study was conducted on ‘Niagara’ grapes (Vitis labrusca L.) to examine the effects of 3 pruning severities (based on nodes retained), 3 levels of nodes/bearing unit (3, 6, and 9), 2 training systems [Geneva Double Curtain (GDC) and Bilateral Cordon (BC)], and 2 canopy management treatments (shoots positioned and shoots not positioned) on yield and fruit quality. Leaving heavy fruit loads suppressed yields in the 4th and final year of this study as a result of reduced node fruitfulness. The 3 node spurs were not as productive as the 6 and 9 node canes. GDC training produced higher yields than BC training in the 3 high yielding years of the study while maintaining vine vigor. Shoot positioning was more beneficial in increasing yields on the BC training system than on the GDC training system, because of the crowded conditions of the canes on the BC system. The effects of these variables on fruit quality were small, but the heavy fruit loads did result in fruit with a reduced percentage of soluble solids and pH, increased acidity and light color (increased CDM ‘L’ values). Shoot positioning reduced fruit pH, slightly in-creased acidity, and produced darker color (decreased CDM ‘L’ values). Under Arkansas growing conditions, if harvest is delayed beyond 14% soluble solids, it is possible that unacceptable fruit pH and acidity levels will exist.
Abstract
The incidence of brown stain on crisphead type lettuce (Lactuca sativa L. cv. Calmar) was highly dependent on postharvest temperature. Following exposure to 2% O2 + 5% CO2 for 5 days at constant temperatures from 0° to 20°C, brown stain decreased as simulated transit temperature increased and was negligible at 10°C and above. Simulated market temperatures following exposure to 2% O2 + 5% CO2 at 0°C markedly influenced brown stain expression with near maximum expression present after a 3-day period in air at 10°C. Low O2 (2%) was more effective in reducing respiration (CO2 production) of lettuce at temperatures above 5°C than at 5°C, or lower.
Abstract
Mechanically harvested fruits of A-5344 and ‘Earlibelle’ strawberry (Fragaria × ananassa Duch.) were stored at 24°C for 72 and 120 hours in atmospheres containing acetaldehyde (Aa) with and without prior dipping in 0 to 1.5% acetaldehyde solutions. Aa atmospheres and a combination of atmospheres and dips were most effective in maintaining visual color, freedom from browning, and product acceptability of machine harvested strawberries for processing. Fruit stored in atmospheres containing Aa vapor increased in acidity by 72 hours.
Abstract
The severity of brown stain on crisphead lettuce (Lactuca sativa L., cvs. Calmar and Great Lakes 118) held at 0° or 2.5°C for 10 days increased with increasing CO2 (1 to 5%) and decreasing O2 (21 to 1%) levels. Very slight or no brown stain developed on lettuce subjected to 0, 1, or 2% CO2 in combination with 10 or 21% O2 for 10 days or on that held in 2.5 or 5% CO2 + 2% O2 for 4 days at 2.5°C. In 2.5 or 5% CO2 + 2% O2, brown stain intensified with duration of exposure (2 to 30 days) at 0° or 2.5°C.
Abstract
Brown stain on crisphead lettuce (Lactuca sativa L. cv. Calmar) was increased by exposure to carbon monoxide (CO) combined with elevated CO2 (1, 2 or 5%) regardless of the O2 level (2, 5, 10, or 21%). Carbon monoxide at 1, 3, or 5% added to air without added CO2 did not induce brown stain. Holding under 5 or 10% O2 in combination with 1% CO2 and with or without 1% CO for 20 days followed by a 4-day period in air at 10°C resulted in better overall visual quality compared with air or 2% O2 controls. Carbon monoxide in combination with air or 2% O2 reduced the respiration rate of lettuce during a 10-day period at 2.5°C. Lettuce previously subjected to CO had higher respiration rates, relative to controls, during the subsequent 4-day period in air at 10°C.
Abstract
Multiple preharvest applications of CaCl2 at 1000, 2000, or 4000 ppm (actual Ca) had little effect on fruit firmness of blackberry (Rubus sp.) at harvest. After a 24 hour holding, fruit from the first harvest was firmer if treated with Ca. Preharvest Ca treatments reduced soluble solids accumulation in fruit and 4000 ppm caused foliar damage. Ca had little effect on acidity or color at harvest, but reduced the rate of ripening during postharvest holding.
Abstract
Succinic acid-2,2-dimethylhydrazide (daminozide) applied to ‘Raven’ blackberries at 4000 ppm and to ‘Raven’ and ‘Brazos’ at 2000 ppm between full bloom and first color development and at 2000 ppm in a multiple application applied at full bloom, 2 weeks, and 3 weeks after full bloom resulted in reduced berry size and yield with no beneficial effects on fruit quality. (2-Chloroethyl) phosphonic acid (ethephon) applied to the same cultivare at 1000 ppm 4 days prior to the first harvest increased the amount of fruit mechanically harvested on the first harvest. Ethephon treatment improved color but resulted in mechanically harvested fruit having lower soluble solids and acidity.
Abstract
Four amino acids (glutamic, γ-aminobutyric, glutamine, and aspartic) make up about 80% of the total free amino acids in fruits of tomato (Lycopersicon esculentum Mill., cv. Cal Ace). Fruits harvested at the table-ripe stage contained more alanine and less glutamic acid than those picked green or at the breaker (incipient red color) stage and ripened at 20°C to table-ripe. The higher glutamic acid concentrations in fruit picked at the breaker or earlier stages were paralled to higher scores for “off-flavor,” as described by a taste panel, relative to fruits picked table-ripe. However, when monopotassium glutamate (60, 120, or 180 mg/l00g) was added to diced table-ripe fruits, the panelists were not able to detect flavor differences due to increased glutamic acid concn. Differences in amino acid composition associated with fruit ripeness when picked do not appear to be directly related to flavor differences.
Abstract
Composition and sensory characteristics were investigated to determine the effect of ripeness at picking on fresh market flavor of ‘Cal Ace’ (1974, 1975, 1976) and ‘Cherry’, ‘Calmart’, and ‘Early Pak 7’ (1976) tomato (Lycopersicon esculentum Mill.). Tomatoes picked at earlier stages of ripeness and ripened at 20°C were evaluated by panelists as being less sweet, more sour, less “tomato-like” and having more “off-flavor” than those picked at the table-ripe stage. Objective tests showed these fruits had less sugars and reduced ascorbic acid, and varied significantly in volatile composition. The magnitude of these differences varied greatly among the cultivars. In ‘Cal Ace’ the “off-flavor” characteristic was largely correlated with a volatile compound (peak 43) but in other cultivars seven other volatile compounds also appeared to play a role.
Abstract
Sensory evaluations and chemical analyses were used to investigate the effects of various postharvest handling procedures on composition and flavor quality of ‘Cal Ace’ tomatoes (Lycopersicon esculentum Mill.) harvested at the mature-green and light-pink stages. Ethylene treatment to speed ripening of green tomatoes at 20°C resulted in a higher reduced ascorbic acid content at the table-ripe stage and did not influence flavor when compared with fruits ripened without added ethylene. Using a low-O2 atmosphere to retard ripening had less of an effect on flavor than stage of ripeness at harvest. No differences were found between fruits where ripening was delayed by using 4% O2-atmosphere at 20° or by using low temperature (12.5°). Exposing fruits to 5° for 7 days before ripening at 20° affected flavor; i.e., chilled fruits were more acid. Above the chilling range (0-12.5°); duration of holding after harvest was more important than storage temperature. Lower holding periods resulted in loss of characteristic “tomato-like” flavor and development of “off-flavors.” Mature-green fruits, ripened at 20° under restricted air flow, had increased “off-flavors” when compared to those ripened under accelerated air exchange. Light-pink fruits subjected to impact bruising before ripening had more “off-flavor” and less “tomatolike” flavor than those without physical damage. Quantitative differences in a few volatile components were found with certain treatments, but no qualitative differences were detected and there was no significant difference in total volatile content among any of the treatments tested.