Department of Dairy Technology, University of Veterinary and Animal Sciences, Lahore, Punjab, Pakistan.
Institute of Home and Food Sciences, Faculty of Science and Technology, Government College University, Faisalabad, Punjab, Pakistan.
Lipids Health Dis. 2017 Aug 24;16(1):163. doi: 10.1186/s12944-017-0553-z.
Antioxidant capacity of milk is largely due to vitamins A, E, carotenoids, zinc, selenium, superoxide dismutase, catalase, glutathione peroxidase and enzyme systems. Cow milk has antioxidant capacity while the antioxidant capacity of buffalo milk has been studied in a limited way. The information regarding the effect of pasteurization and boiling on antioxidant capacity of cow and buffalo milk is also scared.
Cow and buffalo milk was exposed to two different heat treatments i.e. 65 °C for 30 min and boiling for 1 min. After heat treatments, milk samples were cooled down to 4 °C packaged in transparent 250 ml polyethylene PET bottles and stored at 4 °C for 6 days. Milk composition, total flavonoid content, total antioxidant capacity, reducing power, DPPH free radical scavenging activity, antioxidant activity in linoleic acid, vitamin C, A, E, selenium, Zinc, fatty acid profile, peroxide value and sensory characteristics were studied in raw, pasteurized and boiled cow and buffalo milk at 0, 3 and 6 days of storage period.
Total antioxidant capacity (TAC) of raw, pasteurized and boiled milk for cow (42.1, 41.3 and 40.7%) and buffalo (58.4, 57.6 and 56.5%) samples was found, respectively. Reducing power (RP) of raw cow and buffalo milk was 6.74 and 13.7 while pasteurization and boiling did not showed significant effect on RP of both cow and buffalo milk. DPPH activity of raw, pasteurized and boiled milk for cow (24.3, 23.8 and 23.6%) and buffalo (31.8, 31.5 and 30.4%) samples was noted, respectively. Storage period up to 3 days was non-significant while DPPH assay after 6 days of storage period indicated significant decline in antioxidant activity of milk samples. Antioxidant activity in linoleic acid (AALA) of buffalo and cow milk were recorded 11.7 and 17.4%, respectively. Pasteurization and boiling did not showed any impact on antioxidant capacity of cow and buffalo milk. The Loss of vitamin C in pasteurization (40 and 42%) and boiling (82 and 61%) of cow and buffalo milk was recorded, respectively. Concentration of vitamin A and E in pasteurized cow and buffalo milk was not significantly different from raw milk samples of cow and buffalo. Concentration of selenium and zinc was not influenced by the heat treatment in both cow and buffalo milk samples. After 3 days of refrigerated storage, antioxidant capacity of both cow and buffalo milk decreased. Concentrations of short-chain and medium-chain fatty acids increased in pasteurized and boiled cow and buffalo milk, while long-chain fatty acids decreased in pasteurized and boiled cow and buffalo milk, with no effect on colour and flavor score. Peroxide value of pasteurized and boiled cow and buffalo milk was not influenced by the storage up to 3 days.
These results suggest that buffalo milk had a higher antioxidant capacity than cow milk and pasteurized milk should be consumed within 3 days of refrigerated storage for better antioxidant perspectives.
牛奶的抗氧化能力主要归因于维生素 A、E、类胡萝卜素、锌、硒、超氧化物歧化酶、过氧化氢酶、谷胱甘肽过氧化物酶和酶系统。牛奶具有抗氧化能力，而水牛奶的抗氧化能力研究有限。关于巴氏杀菌和煮沸对牛奶抗氧化能力影响的信息也很少。
将牛奶暴露于两种不同的热处理，即 65°C 30 分钟和煮沸 1 分钟。热处理后，将牛奶样品冷却至 4°C，装在透明的 250 毫升聚乙烯 PET 瓶中，并在 4°C 下储存 6 天。在生奶、巴氏杀菌奶和煮沸奶中研究了牛和水牛奶的成分、总类黄酮含量、总抗氧化能力、还原能力、DPPH 自由基清除活性、亚油酸抗氧化活性、维生素 C、A、E、硒、锌、脂肪酸谱、过氧化物值和感官特性，在 0、3 和 6 天的储存期内。
生奶、巴氏杀菌奶和煮沸奶的总抗氧化能力（TAC）分别为 42.1%、41.3%和 40.7%（牛）和 58.4%、57.6%和 56.5%（水牛）。生奶和巴氏杀菌奶的还原能力（RP）分别为 6.74 和 13.7，而巴氏杀菌对牛和水牛奶的 RP 没有显著影响。生奶、巴氏杀菌奶和煮沸奶的 DPPH 活性分别为 24.3%、23.8%和 23.6%（牛）和 31.8%、31.5%和 30.4%（水牛）。在 3 天的储存期内没有显著差异，而在 6 天的储存期后 DPPH 测定表明，牛奶样品的抗氧化活性显著下降。水牛奶和牛奶的亚油酸抗氧化活性（AALA）分别为 11.7%和 17.4%。巴氏杀菌和煮沸对牛奶的抗氧化能力没有影响。牛和水牛奶在巴氏杀菌中的维生素 C 损失（40%和 42%）和煮沸（82%和 61%）分别记录。巴氏杀菌牛奶和水牛奶中的维生素 A 和 E 浓度与生奶样本无显著差异。牛和水牛奶样品中的硒和锌浓度不受热处理的影响。在冷藏储存 3 天后，牛和水牛奶的抗氧化能力下降。巴氏杀菌和煮沸的牛和水牛奶中的短链和中链脂肪酸浓度增加，而长链脂肪酸减少，但对颜色和风味评分没有影响。巴氏杀菌和煮沸的牛和水牛奶的过氧化物值在 3 天的储存期内不受影响。
这些结果表明，水牛奶的抗氧化能力高于牛奶，巴氏杀菌奶应在冷藏储存 3 天内饮用，以获得更好的抗氧化效果。
