Cold-Storage Affects Antioxidant Properties of Apples in Caco-2 Cells

Abstract

Data on the composition of phenolic antioxidant compounds present in food plants and assessment of their activity are essential for epidemiological explanation of the health benefits of fruit and vegetables. Various factors such as cultivation methods, industrial processing, and storage may affect the final concentrations of phytochemicals in food plants and their eventual bioactivity. This study investigated the influence of commercial cold-storage periods on the antioxidant properties of apples grown either by organic or integrated systems. In both cases, total phenolics and total antioxidant activity decreased only in the first 3 mo and only in apples with skin (P < 0.05), suggesting that cold storage rapidly impoverishes these properties in skin but not in pulp. Assessment of antioxidant bioactivity in vitro, measured in terms of intracellular antioxidant, cytoprotective, and antiproliferative activity in human colon carcinoma (Caco-2) cells (differentiated to normal intestinal epithelia for intracellular antioxidant and cytoprotective effects), showed strong, time-related decreases over 6 mo of cold storage for all 3 parameters (P < 0.01), irrespective of the cultivation system. These findings with integrated and organic apples further support the concept that organic systems of cultivation do not generally provide real health benefits. Moreover, the data from the present study clearly show that factors such as cold storage may affect the antioxidant properties of apples. Epidemiological studies on the cancer-preventive benefits of fruits and vegetables should take into account the cold-storage bias for apples, and possibly for other products.