The effect of Pediococcus pentosaceus on antioxidant characteristics of probiotic yoghurt was studied in cow, goat and camel milk and results evidence that antioxidant of goat milk yoghurt was 93% as compared to 86% in camel milk. These results suggested that antioxidant characteristics of yogurt can be enhanced by probiotic bacteria [70]. Yoghurt is a fermented milk product with distinctive therapeutic value and presented in diversified forms and flavors. Yoghurt was added with carrots, pumpkin, broccoli and red sweet pepper at 10% concentration and ferric reducing antioxidant power (FRAP) and DPPH assays were used for antioxidant activity during the storage period of 14 days. Yoghurt added with broccoli and red sweet pepper revealed higher DPPH free radical scavenging activity and FRAP. However, antioxidant activity decreased during the storage period of 14 days [71]. Similarly, cow, buffalo and goat milk yoghurts were supplemented with aqueous extracts of Zingiber officinale and Beta vulgaris DPPH free radical scavenging activity and FRAP of goat milk yoghurt was greater than other cow and buffalo milk [72]. In another study, antioxidant capacity of yoghurt was increased by supplementing the yoghurt milk 60 mg vitamin C, 12 mg vitamin E and 3 mg beta-carotene. Antioxidant characteristics of supplemented yoghurts were higher than non-supplemented yoghurts with no effects on sensory properties [73]. Yoghurt was supplemented with fruit pulp of papaya and cactus pear using Lactobacillus bulgaricus and Streptococcus thermphillus as starter cultures and total phenolic contents, ascorbic acid and total antioxidant activity were analyzed. Yoghurt added with papaya fruit pulp had higher total phenolic contents, antioxidant activity and vitamin C concentration [74]. Typical yoghurt starter bacteria Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophiles inhibited the lipid peroxidation through the scavenging of reactive oxygen species such as hydrogen perode and hydroxyl radicals [75]. Antioxidant activity of milk fermented with Lactobacillus fermentum ME-3 was significantly increased higher than milk [76]. The antioxidant activity in fermented dairy products is mainly due to the bioactive peptides released from α-lactalbumin, β-lactoglobulin and α-casein [77].

In-vivo studies

In-vivo study was performed to assess the antioxidant capacity of the peptides produced in a fermented dairy product similar to yoghurt by the proteolytic strains of Lb. bulgaricus. Results revealed that reactive oxygen speices decreased in the live yeast cells [78]. In another in-vivo study, therapeutic perspectives of camel milk were established [79]. The effect of fermented dairy products was observed on the antioxidant enzymes in liver of Swiss mice. Feeding fermented dairy product considerably increased the level of Catalase, Superoxide dismutase (SOD), Glutathione peroxidase and superoxide dismutase [80]. The effect of antioxidant peptides of cow and buffalo cheddar cheese was evaluated against tert-butylhydroperoxide-induced colon cancer. Antioxidant peptides of cow and buffalo milk can protect intestinal epithelium from oxidative damage [81].

Therapeutic Perspectives of Milk and Dairy Products

Cultured milk has higher antioxidant properties as compared to the normal milk and intake of two servings of cultured milk on daily basis reduced the risk of bladder cancer up to 38% as compared to the people who do not use cultured milk [82]. Intake of milk fermented with E. faecium RM11 and L. fermentum RM28 had 21 and 29% less chances of colon cancer [83]. In another investigation, it was observed that men and women consuming milk on daily basis had 53% lower risk of bladder cancer while Swedish women containing four servings of high fat milk and dairy products showed 13% less risk of colorectal cancer [84]. Reyes et al. [85] found that milk fermented with Lactobacillus spp. and Bifidobacterium spp. had a protective effect against liver cancer. Consuming more than 500 ml milk/day significantly decreased the risk of colorectal cancer [86]. Individuals consuming lower amount of milk had higher chances of colorectal cancer [87]. Intake of half liter milk and ricotta cheese on daily basis reduced the risk of colon cancer to 12 and 17% [88]. Intake of 25 g white cheese on daily basis decreased the chances of premenopausal cancer up to 50% as compared to the women consuming less than 6 g white cheese on daily basis [89]. Milk proteins and peptides have shown anti-carcinogenic properties [90]. For instance, lactoferrin is well known for anti-cell proliferation, antioxidant and anti-inflammatory activities [91]. Oral administration of lactoferrin derived from bovine milk considerably reduced the risk of several types of cancers [92]. Casein and whey proteins may protect from colon, breast and prostate gland cancer [93]. The anticancer capability of casein and whey protein may be attributed to the presence of higher concentration of glutathione, which is well known for its antioxidant activity [91]. Immunoglobulins such as IgG1, IgM, IgA and IgG2 has antimicrobial and glutathione enhancing activities which is the important antioxidant of the cell [94]. The association between the dietary intake of milk and dairy products was evaluated and no association was found between the intake of dairy products and cardiovascular diseases [95]. An inverse relation was found between the intake of dairy products and non-fatal cardiovascular disease [96]. No significant association was recorded between the intake of cheese and cardiovascular disease [97]. Intake of low fat, medium fat and high fat cheese had no correlation with cardiovascular disease [98]. Intake of 54 g whey protein on daily basis for a period of 12 weeks significantly reduced the systolic and diastolic blood pressure [99]. Xu et al. [100] observed as strong correlation in the concentration of bioactive peptides produced by the activities of microbiota and gastrointestinal enzymes which are abundantly present in fermented dairy products [101]. A study was conducted on 3435 Parisians for the duration of three days, it was found that higher intake of dairy products led to a lower risk of types 2 diabetes up to 14% [102]. Components of milk and dairy products are industrially used to increase the functional value of the foods. For example, phosphopeptides of casein are used as supplement for several dietary and pharmaceutical applications [103].