Degradation patterns for external and nutritional quality parameters of fresh-cut 'cantaloupe' melons

Nutritional quality of fresh-cut produce is very important for the consumer. Its evaluation may be expensive and time-consuming for the industry, which conversely can easily determine changes in external appearance including color. The aim of this work was to find possible relationships between degradation of appearance attributes and the retained nutritional content of fresh-cut 'Cantaloupe' melons. Melon pieces were stored for 8 days in air at 5°C and 99% RH. Initially and after 1, 2, 3, 7 and 8 days of storage external (color, appearance score) and internal (acidity, soluble solids, fructose content, vitamin C, phenolic, antioxidant activity) quality parameters were monitored. For each parameter a degradation curve over time was obtained, which was fitted to zero and first order kinetics. For most of the quality parameters degradation patterns followed a kinetic of the first order, antioxidant activity and soluble solids could not be described by any significant kinetic. The appearance score showed the highest kinetic rate (0.17 day-1), followed by titratable acidity (0.09 day-1) and vitamin C (0.06 day-1). Score 3 and 2, which were defined as the limits of marketability and edibility, respectively, were used as reference for comparing the percentage of quality changes over time. When melon pieces reached score 3 that corresponded to 40% of initial variation, acidity increased of 39% and vitamin C decreased by 20%. When score reached a value of 2 (60% of variation), acidity increased by 73% and vitamin C decreased by 30%. Further research about different storage conditions and melon cultivars is needed in order to confirm the relationship between simple quality indicators linked to appearance degradation and nutritional quality of fresh-cut melon.