Orville Osmicote, Charles F. Forney, Jeffrey Richards, and Chiam Liew
Charles F. Forney, Stephanie Bishop, Michele Elliot, and Vivian Agar
Extending the storage life of fresh cranberries (Vaccinium macrocarpon Ait.) requires an optimum storage environment to minimize decay and physiological breakdown (PB). To assess the effects of relative humidity (RH) and temperature on storage life, cranberry fruit from four bogs were stored over calcium nitrate, sodium chloride, or potassium nitrate salts, which maintained RH at 75%, 88%, and 98%, respectively. Containers at each RH were held at 0, 3, 5, 7, or 10 °C and fruit quality was evaluated monthly for 6 months. Both decay and PB increased with increasing RH in storage. After 6 months, 32%, 38%, and 54% of fruit were decayed and 28%, 31%, and 36% developed PB when stored in 75%, 88%, and 98% RH, respectively. The effects of RH continued to be apparent after fruit were removed from storage, graded, and held for 7 days at 20 °C. The decay of graded fruit after 4 months of storage in 75%, 88%, or 98% RH was 10%, 13%, and 31%, respectively, while PB was 12%, 12%, and 17%, respectively. Fresh weight loss decreased as RH increased averaging 1.9%, 1.4%, and 0.7% per month for storage in 75%, 88%, and 98% RH, respectively. Fruit firmness was not affected by RH. Storage temperature had little effect on decay. However, PB was greatest in fruit stored at 10 °C, encompassing 55% of fruit after 5 months of storage. When graded fruit were held an additional 7 days at 20 °C, decay and PB were greater in fruit previously stored at 0 or 3 °C than at 5, 7, or 10 °C. Fresh weight loss increased as storage temperature increased, averaging 0.8%, 1.0%, 1.3%, 1.7%, and 1.9% per month at 0, 3, 5, 7, and 10 °C, respectively. Fruit firmness decreased during storage, but was not affected by storage temperature. To maximize storage and shelf life, cranberry fruit should be stored in a RH of about 75% at 5 °C.
Artur Miszczak, Charles F. Forney, and Robert K. Prange
`Kent' strawberries were harvested at red, pink, and white stages of development, and stored at 15C in the light. Fruit were sampled over a 10-day period and evaluated for volatile production and surface color. Volatile production by red and pink fruit peaked after 4 days of storage. Maximum volatile production by red fruit was 8- and 25-fold greater than maximum production by pink and white fruit, respectively. Aroma volatiles were not detected in the headspace over white berries until 4 days following harvest after which volatile production increased through the tenth day of storage. Changes in the surface color of white berries during postharvest ripening coincided with the production of volatiles. In another experiment, red, pink, and white `Kent' strawberries were stored for 3 days at 10 or 20C in the dark or light. Fruit were then evaluated for volatile production, weight loss, anthocyanin content, and surface color changes. White berries produced volatile esters after 3 days of storage at 20C in the light. Both light and temperature influenced the relative production of the volatiles produced by pink fruit. Fresh weight loss, color change, and anthocyanin content were temperature and light dependent.
Charles F. Forney, James P. Mattheis, and Rodney K. Austin
Broccoli (Brassica oleracea L., ltalica Group) produces severe off-odors when it is stored under anaerobic conditions which can develop in modified atmosphere packages. The compounds responsible for these off-odors, which render the broccoli unmarketable, were produced after sealing 50 g of fresh broccoli florets in glass pint jars held at 15C. Twenty-four hours after sealing oxygen concentration dropped to around 0.5% and remained at this concentration for 6 days. Volatile compounds found in the head space of the jars were identified using gas chromatography with flame photometric and mass spectroscopic detection. Volatile compounds produced were identified as methanethiol, hydrogen sulfide, dimethyl disulfide, acetaldehyde, acetone, ethanol, and ethyl acetate. Methanethiol was detected 48 hours after sealing and appears through olfactory evaluation to be the primary compound responsible for the objectionable odor.
Charles F. Forney, Willy Kalt, and Michael A. Jordan
Wilhelmina Kalt, Agnes M. Rimando, Michele Elliot, and Charles F. Forney
Recent interest in the human health-promoting properties of fruit phenolics, and especially fruit flavonoids, has stimulated research on how these secondary metabolites may be affected by pre- and postharvest horticultural factors. Resveratrol, although a minor phenolic in many fruit, possesses potent bioactivities, and is therefore of particular interest. To study the effects of postharvest storage and UV-C irradiation on selected phenolic components and antioxidant capacity of cranberry (Vaccinium macrocarpon), fruit of cv. Pilgrim, Stevens, and Bergman, were irradiated with UV-C at levels between 0 and 2.0 KJ·m-2, followed by storage at 9 °C for 7 and 17 d. Total phenolic content did not change during storage. However, resveratrol content was higher and antioxidant capacity (ORAC) was lower at 7 days of storage compared to 17 days. There was no main effect of UV-C on total phenolics, anthocyanins, resveratrol, or ORAC. However, there was an interaction between storage time and UV-C irradiation. Anthocyanin content was lower at 7 days, and higher at 17 days, at UV dosages of 1.0 or 2.0 KJ·m-2. Resveratrol content was higher in UV-C irradiated fruit at 7 days, while at 17 days there was no difference between UV-treated and untreated fruit.
Charles F. Forney, Leonard J. Eaton, and Leigh Gao
Increasing the size of containers used to transport wild lowbush blueberry (Vaccinium angustifolium) fruit from the field to the processing facility has the potential to increase handling efficiency. Currently the wild blueberry industry uses a standard 18-inch-long × 15-inch-wide × 5-inch-deep plastic container that holds about 20 lb of fruit. This study examined the development of a new, pallet-sized high-capacity blueberry container and determined its effects on fruit quality following harvesting, transport, and processing. Laboratory studies on the effects of packing depth of berries on fruit quality demonstrated that container depths of 14.2 inches were damaging to fruit 24 hours following harvest, transport, and holding under ambient conditions, while depths of 7.1 inches were not. In commercial trials with larger pallet-sized prototype containers, fruit depths of up to 10 inches were not damaging to fruit under otherwise typical commercial handling conditions. Dumping fruit from the 10-inch-deep pallet-sized containers onto conveyer belts at the processing facility caused minimal damage to the fruit. In addition, fruit crushing that occurred in the large pallet-sized containers was similar to that occurring in the standard 20-lb plastic containers currently used by the industry. Results of these studies indicate that large pallet-size blueberry containers with a depth of 10 inches could be used without causing significant damage to fresh fruit during harvest, transport, and processing. Thus as a whole, the adoption of this type of container would improve handling efficiency and potentially the quality of the fruit.
Charles F. Forney, Sharon J. Peterson, and Preston Hartsell
Callus tissue grown from `Marsh' grapefruit (Citrus paradisi Macf.) albedo tissue was grown at 30C for ≈ 40 days. Calli were preconditioned in normal air for 5 days at 10 or 30C before being fumigated for 2 hr with 0, 32, or 48 g of methyl bromide (MB)/m 3. Calli were then held at 10C and K+ leakage was measured after 1, 10, 20, and 30 days. The amount of K+ leaked from MB-fumigated calli was greater than that for nonfumigated calli and increased with higher MB dose. Leakage also increased with time following fumigation. Leakage of calli preconditioned at 30C and fumigated with 48 g MB/m3 was 140%, 196%, and 260% greater than leakage from nonfumigated calli 10, 20, and 30 days after fumigation, respectively. Leakage from calli preconditioned at 10C for 5 days before MB fumigation was less than that from calli held at 30C. MB doses of 32 and 48 g·m-3 increased leakage of calli preconditioned at 10C by 6% and 43% and for those preconditioned at 30C by 99% and 140%, respectively, 10 days after fumigation. In addition to K+ leakage, MB induced the development of a tan to orangish-brown discoloration.
D. Mark Hodges, Charles F. Forney, and Wendy Wismer
The degree of damage that may occur through harvesting and packing represents one of the major factors that can affect quality of fresh-cut produce. The purpose of this study was to examine the effects of different steps in a representative fresh-cut processing line on storage quality of spinach (Spinacia oleracea L.). To this end, spinach leaves were removed at successive points on the line: 1) before entry into the line (control); 2) after a shaking procedure but before initial rinsing with 10 °C water + 5 mg·L-1 chlorine dioxide; 3) after centrifugal drying; and 4) after commercial packaging. After removal from the different points in the line, the spinach samples were stored at 10 °C for 16 days, during which time malondialdehyde (MDA) concentration (lipid peroxidation assay), electrolyte leakage (membrane leakiness), chlorophyll content (a, b, and total), and color attributes (L, saturation, hue angle) were measured. Both lipid peroxidation and electrolyte leakage increased with time of storage and with stage of procesing. Electrolyte leakage increased most in material removed after the shaking procedure, but prior to hydrocooling. Overall total chlorophyll loss during storage did not change with time of removal from the processing line, although overall chlorophyll b content decreased in stored material 8 days following centrifugal drying and packaging. A more rapid loss in chlorophyll a relative to chlorophyll b over the first 8 days of storage was reflected in hue angle measurements regardless of the point of removal. The processing line under study, thus had both beneficial and detrimental effects on storage quality of spinach. Detrimental effects associated with centrifugal drying and packaging procedures could be modified to improve quality.
Jun Song, Lihua Fan, Paul D. Hildebrand, and Charles F. Forney
The biological effect of corona discharge on onions (Allium cepa L.) in a commercial storage was investigated. Surface discoloration and mold were modestly but significantly reduced by the corona discharge when onions were stored for 2 or 4 weeks with or without an additional 2 weeks of shelf life under high humidity. Corona discharge treatment also reduced airborne mold spores in the storage room. No significant changes in internal decay, firmness, sprouting, or rooting, in treated onions were found.