Shelf-life extension of fresh-cut "Fuji" apples at different ripeness stages using natural substances

Shelf-life extension of fresh-cut "Fuji" apple at two stages of ripeness (partially ripe and ripe) using natural substances was evaluated. Cylinders of fresh-cut "Fuji" apples were immersed for 1 min in: (a) an aqueous solution of N-acetyl-L-Cysteine at 1% (w/v), glutathione at 1% (w/v) and calcium lactate at 1% (w/v) (CGLW), (b) CGLW and D-L-malic acid at 2.5% (w/v) (CGLW+MA) or (c) sterile distilled water (W). Gas production, firmness, color and behavior of native flora (mesophilic bacteria, psychrophilic bacteria, yeasts and mould) were studied weekly over 30 days. Sensory evaluation of fresh-cut apples was carried out at 0 and 15 days during storage. Statistically significant differences (P < 0.05) were found in ethylene and ethanol production between fresh-cut partially ripe and ripe apples, respectively, reaching values of ethylene of 8.92 and 134.11 mu L L-1 and ethanol of 28.73 and 59.39 mu L L-1 at 30 days of storage. The firmness of fresh-cut apples was significantly different (p < 0.05) between partially ripe (initial values of 12.4 +/- 0.8 N) and ripe apples (initial values of 8.3 +/- 1.0 N), but did not differ throughout the storage time, nor among dipping conditions. An important reduction in lightness (p < 0.05) was observed throughout storage in the fresh-cut apples with all dipping conditions. However, an influence of the ripeness stage on microbiological stability was not detected. A reduction in growth rate and an increase in the lag phase of mesophilic and psychrophilic bacteria, yeasts and moulds were found in fresh-cut apples dipped in CGLW+MA, which gave as a result an extension of 13 days over the microbiological stability of fresh-cut apples immersed in W (10.1 days). Thus, the use of a combination of CGLW + MA might be a good low cost alternative for the fresh-cut industry since it can offer better maintenance of the physicochemical characteristics and microbiological stability of fresh-cut apples, ensuring a shelf-life of, at least, 14 days. (c) 2007 Elsevier B.V. All rights reserved.