Antioxidant properties of medicinal plants and their effect on microbial spoilage of semi-finished meat, poultry and fish

Plant extracts rich in polyphenols can be used in the food industry as natural preservatives, extending the shelf life of prepared and semi-finished foods without chemical preservatives. In this paper, we investigate the polyphenolic composition, antioxidant activity and antibacterial properties of herbal extracts as part of food systems. The research objects were knot grass (Polýgonum aviculáre), marjoram (Oríganum), bur beggar-ticks (Bídenstripartíta), thyme (Thymus), whortleberry leaves (Vaccínium ida vítis), calendula (Calendula), sage (Salvia), chamomile flowers (Matricāriachamomīlla), eucalyptus (Eucalýptus) and bearberry (Arctostáphylosúva-úrsi). We determined the total content of phenolic compounds and flavonoids; the antioxidant activity by DPPH and FRAP methods; variations in the bacterial сontamination of animal raw materials over total bacterial count (TBC), coliform bacteria, yeast/fungi, salmonella and staphylococcus. Extracts of sage (1138±57 mg GA/100 g and 537±25 mg C/100 g), eucalyptus (1073±49 mg GA/100 g and 412±20 mg C/100 g), chamomile flowers (1002±36 mg GA/100 g and 493±22 mg C/100 g) and marjoram (1015±42 mg GA/100 g and 458±21 mg C/100 g) contain the largest amount of biologically active substances (phenols and flavonoids, respectively). Sage, eucalyptus and chamomile extracts demonstrate the highest antioxidant activity among the studied samples. Most of the studied extracts exhibit little or no effect on the organoleptic properties of finished products. In addition, chamomile flower, sage and eucalyptus extracts suppress the growth of pathogenic microorganisms in foods under experimental conditions. The microflora growth is significantly reduced when treating animal raw materials with calendula flowers, marjoram and thyme extracts. Extracts of sage, chamomile flowers, calendula flowers, marjoram and thyme can be recommended as components of food raw materials.