Antioxidant potential of milks, yoghurts, fermented milks and cheeses
2018
Fardet, Anthony
The antioxidant potential (AP) is an important nutritional property of foods, as increased oxidative stress is involved in most diet-related chronic diseases. In dairy products, the protein fraction contains antioxidant activity, especially casein. Other antioxidants include antioxidant enzymes; lactoferrin; conjugated linoleic acid; coenzyme Q10; vitamins C, E, A and D3; equol; uric acid; carotenoids; and mineral activators of antioxidant enzymes. The AP of dairy has been extensively studied in vitro, with few studies in animals and humans. Available in vivo studies greatly differ in their design and objectives. Overall, on a 100 g fresh weight-basis AP of dairy is close to that of grain-based foods and vegetable or fruit juices. Among dairy, cheeses present the highest AP due to their higher protein content. AP of milk increases during digestion by up to 2.5 times because of released antioxidant peptides. AP of casein is linked to specific amino acids, whereas b-lactoglobulin thiol groups play a major role in AP of whey. Thermal treatments such as UHT have no clear effect on AP of milk. Raw fat-rich milks have higher AP than less fat-rich milk, because of lipophilic antioxidants. Probiotic yoghurts and fermented milks have higher AP than conventional yoghurt and milk because proteolysis by probiotics releases antioxidant peptides. Among the probiotics, Lactobacillus casei/acidophilus leads to the highest AP. The data are insufficient for cheese, but fermentation-based changes appears to positively impact AP. In conclusion, AP might participate in the reported dairy product protective effects against some chronic diseases.
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