Effect of Biological A ctivity of Lactic A cid Microorganisms on Antioxidant Profile of Fermented Dairy Products

Antioxidants support human immune system by providing protection against oxidation products caused by free radicals and reactive oxygen species. The human body has a native system of protection against oxidative stress; however, antioxidants may also be acquired with food. Plant foods are rich in direct-acting antioxidants; fermented dairy products also possess a rather high antioxidant potential. Lactic fermentation synthesizes biologically active substances, some of which are known for their antioxidant properties, e.g., group B vitamins. Although they are not direct-acting antioxidants, these vitamins improve the native antioxidant defense system, which means they are to be present in human diet in sufficient quantities. Amino acids provide the synthesis of glutathione, thus maintaining the native defense system and its action against oxidative stress. This review covered scientific and technical publications on the biological activity of various species and strains of lactic acid microorganisms able to improve the antioxidant potential of dairy products, fortifying them with vitamins and amino acids. The authors also compared Lactobacillus acidophilus and Streptococcus thermophilus as means of improving the antioxidant potential of fermented dairy products in situ by increasing the content of vitamins and amino acids.