| Abstract [eng] |
The research is based on bioconversion of lactose in dairy by-products (cheese whey and lactose molasses) to free fatty acids and obtained metabolite antimicrobial activities estimation. Lactic acid bacterial strains used for fermentations: L. plantarium LUHS135, L. brevis LUHS140, P. pentosaceus LUHS22, L. paracasei LUHS244, L. plantarium LUHS18. At first, ß-galactosidase enzymatic activity changes using different bacterial strains in fermentations (whey, lactose molasses) were studied. Qualitative and quantitative analysis of free fatty acids were estimated using gas chromatography method. Myristic, palmitic, stearic, oleic and linolic fatty acids were identificated in fermented cheese whey. The total concentration of fatty acids raised from 75,8 mg/l to 122,19 mg/l. In fermented lactose mollases myristic fatty acid was missed but identificated another – linolenic acid. The total concentration of fatty acids raised from 73,2 mg/l to 100,75 mg/l. Free fatty acids production volume was related to lactic acid bacterial strains. P. pentosaceus LUHS22 and L. paracasei LUHS244 demonstrated the best free fatty acids (oleic, linolic, linolenic) production capacity. Lower pH (in cheese whey fermentation to 4,45, lactose molasses – 5,34), higher acetate (from 0,48 to 2,32 mM – in whey, from 1,08 to 2,2 mM – in lakcose molasses) and lactic (from 7,188 to 35,433 g/l and from 6,136 g/l to 30,251 g/l respectively) acids concentrations have positive influence for free fatty acid production capacity. After fermentation antifungal activities were studied. Fermented lactose molasses has antifungal activities against Fusarium spp. and it demonstrated better antifungal activities results than using fermented cheese whey. Both of fermented substrates have not antifungal activities against Aspergilus spp. and Penicillium spp. Relations between free fatty acids compositions (quantitative and qualitative) and their antifungal activities were estimated using regresion analysis method. Regresion analysis results demonstrated that antifungal activity is related to linolenic (R2 = 0,995) oleic (R2 = 0,994), stearic (R2 = 0,953) and linolic (R2 =,934) fatty acids while palmitic fatty acid has no antifungal activity (R2 = 0,294). |
