Department of Food Science, University of Massachusetts Amherst, 240 Chenoweth Laboratory, 102 Holdsworth Way, Amherst, MA, United States.
Food Res Int. 2020 Apr;130:108844. doi: 10.1016/j.foodres.2019.108844. Epub 2019 Dec 9.
Understanding lipid oxidation mechanisms in low moisture foods is necessary to develop antioxidant strategies to increase shelf life and/or to improve nutritional quality by increasing polyunsaturated fatty acid concentrations. In this study, we examined the influence of water activity (a), sugars (glucose, maltose, maltodextrin, and cyclodextrin), and proteins (casein and gluten) on the lipid hydroperoxide and hexanal lag phases of model crackers. Oxidative stability of crackers was in an order: a 0.7 > a 0.4 > a 0.2 > a 0.05. Higher water activities resulted in bigger differences between hydroperoxide lag phases and hexanal lag phases. Compared to non-reducing cyclodextrin and no added sugar controls, reducing sugars including glucose, maltose, and maltodextrin at the same dextrose equivalence increased both hydroperoxide and hexanal lag phases. At the same dextrose equivalence, oxidative stability was in the order of maltose > maltodextrin > glucose > control (no sugar added). The antioxidant effectiveness of maltose, a low sweetness profile sugar, increased with increasing concentrations from 1.1 to 13.8%. Increasing a increased the antioxidant activity of maltose. For example, 1.1% maltose increased both hydroperoxides and hexanal lag phases by 9 days at an a of 0.2, but increased hydroperoxide lag phase by 24 days and hexanal lag phase by 15 days at an a of 0.7. Gluten was able to inhibit lipid oxidation with activity increasing with increasing a while casein showed minimal antioxidant impact. Antioxidant activity of gluten decreased when its sulfhydryl groups were blocked by N-ethylmaleimide suggesting that cysteine was an important antioxidant component of gluten. Adjusting water activity and addition of reducing sugars and gluten could be strategies to increase oxidative stability of low moisture crackers.
了解低水分食品中脂质氧化的机制对于开发抗氧化策略以延长货架期和/或通过增加多不饱和脂肪酸的浓度来提高营养质量是必要的。在这项研究中，我们研究了水活度 (a)、糖（葡萄糖、麦芽糖、麦芽糊精和环糊精）和蛋白质（酪蛋白和谷蛋白）对模型饼干脂质氢过氧化物和己醛滞后期的影响。饼干的氧化稳定性顺序为：a 0.7>a 0.4>a 0.2>a 0.05。较高的水活度导致氢过氧化物滞后期和己醛滞后期之间的差异更大。与非还原环糊精和未添加糖对照相比，包括葡萄糖、麦芽糖和麦芽糊精在内的还原糖在相同的葡萄糖当量下均增加了氢过氧化物和己醛的滞后期。在相同的葡萄糖当量下，氧化稳定性的顺序为麦芽糖>麦芽糊精>葡萄糖>对照（未添加糖）。低甜度的麦芽糖的抗氧化效果随着浓度从 1.1 增加到 13.8%而增加。增加 a 增加了麦芽糖的抗氧化活性。例如，在 a 为 0.2 时，1.1%的麦芽糖将氢过氧化物和己醛的滞后期分别增加了 9 天，但在 a 为 0.7 时，将氢过氧化物的滞后期增加了 24 天，将己醛的滞后期增加了 15 天。谷蛋白能够抑制脂质氧化，其活性随 a 的增加而增加，而酪蛋白的抗氧化作用最小。当谷蛋白的巯基被 N-乙基马来酰亚胺封闭时，其抗氧化活性降低，这表明半胱氨酸是谷蛋白的一个重要抗氧化成分。调节水活度和添加还原糖和谷蛋白可能是提高低水分饼干氧化稳定性的策略。
