DISTAM, Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, Universita degli Studi di Milano, 20133 Milano, Italy.
J Agric Food Chem. 2009 Dec 23;57(24):11491-7. doi: 10.1021/jf901865r.
Phytochemical contents, color, and inhibition efficacy toward oxidative and glycoxidative reactions were studied in dehydrated apples following storage in the water activity range from 0.1 to 0.7 at 20, 30, and 40 degrees C, which can be considered as room conditions. Hunter colorimetric parameters were analyzed at different temperatures and time intervals, and nonenzymatic browning was modeled according to pseudo-zero-order kinetics. The effect of temperature on the browning rate followed the Arrhenius equation, with an activation energy of 64000 J/mol, which was not affected by the water activity level. The phytochemical contents, inhibition efficacy of protein glycation, and antioxidant properties were then analyzed in the products stored under selected "equivalent" conditions in terms of browning effects, namely, 120 days/20 degrees C, 50 days/30 degrees C, and 22 days/40 degrees C. After storage for 120 days/20 degrees C, the retention percentages of hydroxycinnamic acids, phloridzin, and epicatechin were >86%, but ascorbic acid, catechin, and procyanidins were less stable; concurrently dehydrated apples retained about 80% of the radical scavenging activity and 70% of the ability to inhibit protein glycation. Following storage at higher temperatures the expected browning effect occurred in a shorter time scale; however, the patterns of product degradation were different. A sharp increase in the degradation rates of all antioxidants, relative to browning rate, was observed at temperatures >or=30 degrees C, and this trend was accelerated with concurrent increase in water activity at >0.3 levels. The application of low-temperature/long-time conditions for storage of dehydrated apples corresponded to maximum retention of their efficacy to counteract oxidative and glycoxidative reactions, which have been linked to human chronic diseases.
脱水苹果在 20、30 和 40°C 的水活度范围内（可视为室温条件）储存时，研究了其脱水后在 0.1 到 0.7 范围内的化学成分、颜色和对氧化及糖基化反应的抑制效果。在不同的温度和时间间隔下分析亨特比色参数，并根据拟零级动力学模型模拟非酶褐变。温度对褐变速率的影响遵循阿仑尼乌斯方程，其活化能为 64000 J/mol，不受水活度水平的影响。然后，根据褐变效果，在选定的“等效”条件下（即 20°C/120 天、30°C/50 天和 40°C/22 天）分析储存产品的植物化学成分含量、蛋白质糖基化抑制效果和抗氧化性能。在 20°C/120 天的储存期后，羟基肉桂酸、根皮苷和表儿茶素的保留率>86%，但抗坏血酸、儿茶素和原花青素的稳定性较差；同时脱水苹果保留了约 80%的自由基清除活性和 70%的抑制蛋白质糖基化的能力。在较高温度下储存时，预计的褐变效果在较短的时间尺度内发生；然而，产品降解的模式是不同的。在温度>or=30°C 时，所有抗氧化剂的降解速率相对于褐变速率急剧增加，并且随着水活度>0.3 水平的增加，这种趋势加速。低温/长时间储存条件的应用对应于脱水苹果功效的最大保留，以对抗氧化和糖基化反应，这些反应与人类慢性疾病有关。
