No 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.

California's mild climate has led to handling and storage practices with sweet potatoes that do not necessarily provide optimum conditions for wound healing. Experiments were conducted during a four-year period with three varieties on San Joaquin Valley farms to determine whether a curing period in a warm house, such as is customary in other areas, would favor wound healing and reduce storage losses and quality changes. A two-week curing period in a warm house, with a temperature of around 85°F and high relative humidity, was compared with a similar period in a field pile, the method commonly used in California, and with direct placement in an unheated storage house. The experiments indicated that where storage of sweet potatoes for several months is economically sound, a warm-house curing period will usually reduce rot (except block rot), improve the appearance of roots, and decrease handling and sorting at the end of storage. The improvement was more consistent in the Porto Rico and Hawaiian varieties than in Yellow Jersey, which was more heavily infected with block rot. The treatments had little effect on sugar percentage, or, except toward the end of the storage period, on loss of dry weight. Anatomical studies and photomicrographs were mode of changes in the natural uninjured periderm and in wound tissue on broken ends and cut sides of roots under the three methods of treatment. The natural periderm increased during the curing period in the Hawaiian and Porto Rico varieties but not in the Yellow Jersey. In all varieties the cork layer of wound tissue in roots cured in the warm house was thicker, more regular, and lighter in color than under the other treatments. Healing was similar in the two types of wounds. In the wound area on the broken ends of roots, sieve tubes and faticifers were compressed and pinched off, and vessel elements became filled with tyloses, which sometimes divided to produce across the vessel lumen a cork layer continuous with that in surrounding tissue.

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.

Developing fruits of Momordica chamntia, known as bitter melon, bitter gourd or balsam pear, were harvested at horticultural maturity and stored up to 14 days in humidified air at different temperatures. Respiration rates of fruits at 20 and 10°C were approximately 40 and 15 ~1 CO2 g-l h-l, respectively. Ethylene production rates at these temperatures were O.l-0.3 nl g-l h-l. Fruits stored for >8 days at 7.5"C showed severe chilling symptoms (decay, pitting and discoloration) and typical chill-induced respiratory and ethylene production increases after transfer to 15°C. Fruit quality was best maintained if bitter melon were stored at 10 and 12S"C. Fruits at 15°C continued to develop, showing undesirable changes including seed development, loss of green color, and fruit splitting. Immature fruit maintained postharvest quality better than fruit harvested at the fully developed green stage. Bitter melon stored at 15°C in controlled atmospheres (21, 5 or 2.5% 02 in combination with 0, 2.5, 5 or 10% COZ) were not different in quality from air-stored fruits at 2 weeks. Fruits stored 3 weeks in 2.5 or 5% CO* in combination with 2.5% 02 showed greater retention of green color and had less decay and splitting than air-stored fruit.

CO (5 and 10%) + 4% O2 atmospheres retarded growth of Botrytis cinerea Pers. ex Fr. (in vitro) and reduced decay incidence and severity on inoculated tomatoes (Lycopersicon escuientum Mill.) harvested at the mature-green (MG) or pink (P) stage and held at 12.5°C for up to 14 days (MG) or 10 days (P). This reduction was still evident after holding for an additional 2 to 3 days (P) or 7 days (MG) at 20° in air. CO + 4% O2 atmosphere was more effective than CO + air atmosphere in all experiments. CO + air treatments increased CO2 and C2H4 production rates and hastened ripening of MG fruits, while CO + 4% O2 atmosphere had no or very small effect on these physiological responses relative to 4% O2 atmosphere at 12.5°. After transfer to air at 20°, fruits previously exposed to CO exhibited slightly higher CO2 and C2H2 production and faster ripening than control fruits. CO added to air or 4% O2 did not affect ripening rate of fruits picked at the breaker, turning, or pink stages. CO + air or 4% O2 atmosphere slowed down softening of pink fruits during a 7- or 14-day storage period at 12.5°. Fruits subjected to CO + 4% O2 for 7 days maintained their sugar and acid content better than control fruits.

No 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.