DEGRADATION PATTERNS FOR EXTERNAL AND INTERNAL QUALITY ATTRIBUTES OF FRESH-CUT APPLES

Abstract

The aim of this work was to find possible relationships between degradation of appearance attributes and the retained nutritional and organoleptic value of fresh-cut apples (‘Stark red delicious’), and the influence of temperature on quality degradation. Apple pieces were stored for 9 days in air at 5 and 10°C and 99% RH. Initially and after 1, 2, 5, 7 and 9 days of storage external (color, appearance score) and internal (acidity, soluble solids, phenol content, antioxidant activity) quality parameters were monitored. For each parameter a degradation over time curve was obtained, which was fitted in kinetics of zero and first order. For apple pieces stored at 5°C, appearance score, color attributes L*, a*, and b* showed significant kinetics, together with sensorial evaluation of taste, texture and aroma. At 10°C, appearance score, color attributes, sensorial evaluations, phenol content, and antioxidant activity, showed significant kinetics. Sensorial evaluations were fit in an order 0 kinetic, together with a* values, while L* and b*, and phenols and antioxidant activity at 10°C were fit in an order 1 kinetic. Appearance score degradation over time at 10°C showed a kinetic slope that was doubled than at 5°C, while taste and aroma kinetic rates increased almost 10 times when temperature varied from 5 to 10°C. According to the highest kinetic rate, shelf-life of fresh-cut apples was limited by the appearance degradation at 5°C and by aroma and taste degradation at 10°C. Using appearance score 3 and 2, which were respectively defined as the limits of marketability and edibility, as reference for comparing the percentage of quality changes over time, the following relation can be found. A variation of 34% of appearance score at 5°C, corresponded to 19% variation of aroma, 17% of taste and 10% for texture. At 10°C all sensorial (taste, texture, aroma) decreased about 40%, while phenols increased by 29% and antioxidant activity decreased by 28%. When the score reached the value of 2 (i.e., 56% of initial variation) at 5°C, aroma decreased by 32%, taste by 28% and texture by 18%. At 10°C, all sensorial decreased by about 70%, phenols increased by 75% and antioxidant activity decreased by about 41%.