In vitro and in vivo antioxidant potential of milks, yoghurts, fermented milks and cheeses: a narrative review of evidence.

Anthony Fardet,Edmond Rock

doi:10.1017/s0954422417000191

Abstract

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 products has been extensively studied in vitro, with few studies in animals and human subjects. Available in vivo studies greatly differ in their design and objectives. Overall, on a 100 g fresh weight-basis, AP of dairy products is close to that of grain-based foods and vegetable or fruit juices. Among dairy products, 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 β-lactoglobulin thiol groups play a major role in the AP of whey. Thermal treatments such as ultra-high temperature processing have no clear effect on the 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 appear to make a positive impact on AP. In conclusion, AP might participate in the reported dairy product-protective effects against some chronic diseases.

Highlights

The antioxidant activity of foods is important for both their shelf life and protection from oxidative damage in the human body
Whole milk contains both hydrophilic and lipophilic antioxidants, and its overall total antioxidant activity will notably depend on the fat content and time–temperature combination applied (Table 2)
Among different plain fermented products marketed in Poland, yoghurt and kefir were shown to have the highest antioxidant activity: the mean ferric-reducing ability of plasma (FRAP) values were 1·19, 1·03, 0·66, 0·48 and 0·45 μmol Fe2 + /g(63)

Summary

Introduction

The antioxidant activity of foods is important for both their shelf life and protection from oxidative damage in the human body. Chen et al[30] observed that the total antioxidant capacity (ABTS assay) in commercial cows’ milk (3 % fat) was significantly higher than in cows’ milk with 0·5–1·5 % fat and skimmed milk Such results suggested that interference with lipids and the reactivity of the lipophilic antioxidants and the fat globule membrane proteins may influence the total antioxidant capacity. Severe heat treatments provide recovery and even a possible increase in the antioxidant properties of milk due to the formation of brown melanoidins (Maillard reaction products) These results emphasise the important role played by the time– temperature combination of heat treatments, which could explain the apparent discrepancy with other studies showing no significant effect of temperature on the antioxidant capacity of milk. This reduction in the total antioxidant capacity of milk can be attributed to constant and undefined interactions involving many pro- and antioxidants, but further details were not given

Conclusions

Findings