Effects of Modified Atmospheres Packaging, Oxygen Permeable Films and Storage Temperatures on the Quality of Minimally Processed Jicama (Pachyrhizus erosus)

The effects of modified atmosphere packaging (MAP), O₂-permeable films and storage temperature on the quality of minimally processed jicama roots were studied. Fresh-cut jicama was prepared by manual peeling and automatic slicing, packed in regular air and modified atmosphere (~4% CO₂ in Air). The products were packed in four types films with different oxygen transmission rate (OTR). Microbiological, physicochemical and sensory analyses were performed for jicama packed during 12 and 16 days stored at 10 and 5 ºC respectively. Storage temperature significantly influenced the fresh-cut jicama quality, those samples stored at 5 ºC had better appearance than those stored at 10 ºC. However mesophilic aerobic bacteria (MAB) and lactic acid bacteria (LAB) growth were observed in all treatments; fresh-cut jicama stored at 5 ºC for 8 days reached a microbial growth population by 6 to 7 log ufc g^-1 and 7 to 8 log ufc g^-1 for MAB and LAB respectively. In headspace, CO₂ concentration increased and O₂ decreased faster at 10 than 5 ºC. Carbon dioxide increased rapidly after 4 day of storage at 5 ºC. After 12 days at 5 ºC, the CO₂ concentration in the MAP and regular air packages averaged 33, 21, 36 and 11 % and the O₂ concentration decreased from ~21% to 1, 2, 3 and 4 %, for 381, 3875, 5100 and >5000 cc/m²-day OTR package respectively. The texture measurements decreased in both atmospheres, showing a significant softening. Minimal processed jicama stored at 5 ºC and under MAP condition, the membrane integrity was maintained to a greater extent than under regular air. Hue value tended to increase during storage in all applications. In conclusions, fresh-cut pieces packed and stored at 10 ºC had lower visual quality, crispiness and higher CO₂ levels accumulation during 12 days of storage than those stored at 5 ºC, and according to sensory results its acceptability is limited to less than 8 days mainly for normal air atmosphere application. OTR packaging film of 381 cc/m²-day could be suggested for better preservation of minimally processed jicama for 8 days stored at 5 ºC.