Submitted to: Journal of Food Quality
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/28/2008
Publication Date: 4/12/2010
Citation: Wall, M.M., K.A. Nishijima, M.M. Fitch, and W.T. Nishijima. 2010. Physicochemical, nutritional and microbial quality of fresh-cut and frozen papaya prepared from cultivars with varying resistance to internal yellowing disease. Journal Food Quality. 33: 131-149. Interpretive Summary: Fresh-cut and frozen papaya cubes have potential as value-added products for Hawaii’s papaya industry, but have been limited by high coliform bacterial counts and deterioration in edible quality. The bacterium, Enterobacter cloacae, is one source of the high coliform counts and the causal agent of internal yellowing disease of papaya. The nutritional and microbial quality of fresh-cut and frozen papaya prepared from cultivars with varying resistance to internal yellowing disease were determined. Visual and textural changes limited shelf-life, but the papaya products retained nutritional and microbial quality. Preparing value-added products from cultivars resistant to internal yellowing disease appears to be a viable option for diversifying the papaya industry while conforming to food safety guidelines.
Technical Abstract: Quality, nutritional, and microbial analyses were completed for fresh-cut and frozen papaya cubes prepared from cultivars with varying resistance to internal yellowing disease, caused by the bacterium Enterobacter cloacae. In general, fresh-cut and frozen papaya retained nutritional and microbial quality, but visual and textural quality declined. Pretreatment with 1% calcium lactate improved the firmness of fresh-cut fruit, but translucency limited the shelf-life of cubes dipped in either water or calcium lactate. Translucency was not a symptom of chilling injury, but rather a result of water intrusion into the fruit. Vitamin C content did not differ among cultivars when prepared as fresh-cut or frozen products. The average vitamin C content was 61.5 mg/100 g and 52.2 mg/100 g for fresh-cut and frozen fruit, respectively. Vitamin A content was greatest in fresh-cut ‘Laie Gold’ and ‘Rainbow’ fruit, and averaged 35.1 µg RAE/100 g for all cultivars. For frozen cubes, the yellow-orange flesh cultivars (‘Kapoho’, ‘Laie Gold’, Rainbow) had more vitamin A than the orange-red flesh cultivars (‘Sunrise’ and ‘SunUp’) that contained lycopene. Total sugar concentrations (10-11 g/100 g) were highest in papaya cubes prepared from the yellow-orange fleshed cultivars, but sucrose was hydrolyzed to glucose and fructose in frozen samples. Microbial counts were very low or not detectable for most samples. Among the IY-resistant cultivars, ‘Rainbow’ had the highest vitamin A and sugar contents, and did not develop translucency. The selection of IY-resistant papaya cultivars will allow processors to produce nutritious value-added products that conform to food safety guidelines.