Journal of Horticulture and Postharvest Research

Abstract Purpose: Increasing demand for pre-packaged fresh-cut cowpea based on nutritional content, convenience and ready-to–use attributes is limited due to its highly perishable nature. Research method: Two experiments were conducted to investigate the shelf life and storability of fresh-cut cowpea. Fresh-cut cowpea (cv. Local Green) subjected to hydro-cooling with or without sodium hypochlorite was sealed-packaged in LDPE bags and stored at 4-5°C and 20-22°C up to 12 days. The second experiment focused on the occurrence and alleviation of chilling injury (CI) on fresh-cut cowpea (cv. Local Green and cv. Local Pink), stored at 4-5°C and 20-22°C in sealed LDPE bags after 3 and 6 days and upon transfer after 6 days at 4-5°C plus 1, 2 and 3 days at 20-22°C. Findings: Fresh-cut cowpea (Local Green cv.) was 100% marketable after 6 days in sealed LDPE bags at 4-5°C, then decreased to 70% after 12 days. At 20-22°C marketable quality ratings were 87.3% after 3 days, declined to 30% after 6 days and eventually to 100% after 12 days. Absence of chilling injury for both fresh-cut cowpea cultivars, were obtained within the initial 6 days of storage at both temperatures. After 6 days at 4-5°C plus 1, 2 and 3 days at 20-22°C, resulted in progressive increases in CI development which was higher for the Local Pink versus Local Green cultivar. Limitations: Wider range of postharvest dips required. Originality/Value: Temperature control combined with MAP prolonged shelf-life of fresh-cut cowpea and reduced incidence of chilling injury.

Abstract Purpose: Comparison and determination of ZEN production capacity of F. oxysporum, F. graminearum, and F. solani. The influence of low temperature stress and incubation time on the production of ZEN was also investigated. Research Method: Production of ZEN was evaluated by incubating media cultures at a constant temperature of 25°C for a period of 14 days before being incubated at 8°C for 14 days (Low-temperature stress/ LTS). The second set of the samples was incubated at constant 25°C for 4 weeks’ time (constant- temperature/ CT). HPLC and a fluorescence detector were employed to measure the concentration of ZEN. The species-specific pair of primers was used to perform a PCR assay on the fungal DNA. Findings: The higher levels of ZEN were seen at LTS compared with CT in three Fusarium species. The highest ZEN was produced in F. oxysporum media cultures. The significant production of ZEN was seen when F. oxysporum incubated at LTS compared with CT (P≤0.05). The highest and the lowest levels of ZEN were seen in F. oxysporum and F. solani and the difference of ZEN production by them were significant in CT and LTS, respectively (P≤0.05). ZEN production for the F. graminearum was in the intermediate level. Presence of PKS4 gene was confirmed by PCR in these Fusarium species. Limitations: Higher cost of ZEN detection by HPLC was a limitation. Originality/Value: Production of ZEN in LTS and CT by the Fusarium evaluated species was confirmed. However, LTS stimulate ZEN production in Fusarium media cultures, especially for F. oxysporum.

Abstract Purpose: Physiologically matured fruits of Haden, Kent, Palmer, and Keitt mango varieties were used for experiment. The fruits were held at ambient (29-31 ^oC) and simulated-transit temperature (10-13 ^oC) conditions. Quality which includes fruit firmness, weight, and spoilage, were assessed and used to determine shelf life of stored fruits. Research Method: A Completely Randomized Design with four replications was used. For each of the four varieties, five mango trees were sampled at random in each of the four replications of a mango plantation when fruits were physiologically matured.  Findings: For the ambient and simulated-transit temperature conditions, Kent (4.09 days and 3.85 days, respectively) and Keitt (4.08 days and 3.92 days, respectively) fruits stored longer. Haden fruits ripened significantly earlier (9.50 days and 3.5 days, respectively) than Keitt fruits (11.01 days and 5 days, respectively). Ripening time was statistically not different among Haden, Kent, and Palmer fruits. Softness, colour, and decay were limiting quality factors for all mango fruits stored at both conditions. Higher shriveling rates were observed in Haden and Palmer fruits with a slight preponderance of the former, for both conditions. Average weight loss was highest (6.50 % and 3.31 %, respectively) for Haden and lowest (4.09 % and 2.34 %, respectively) for Keitt, but generally lower in fruits stored under transit conditions. Research limitations: No limitations to report. Originality/Value: A single quality attribute cannot be used to express loss of quality of mango fruit over the normal physiological range of mango fruit growth and development.