Milk naturally contains components that have antioxidant capacities, such as casein, lactoferrin, vitamins and some flavonoids. Milk casein and lactoferrin are capable of inhibiting lipid peroxidation1. Some flavonoids act as antioxidants that play a role in radical scavenging and metal ion binding2. Milk processing into fermented products provides beneficial nutrients3, increases antioxidant activity, inhibits oxidation and decreases lipid per-oxidation. During fermentation, milk may produce bioactive peptides that possess antioxidant activity4.
Yeast growth in fermented products provides flavor components, as result of the utilization of lactose or metabolites of (LAB) Lactic Acid Bacteria5. Yeast has been used as a co-culture in traditional fermented products in some regions such as; kefir, koumiss, amasi and dadih. However, the composition of natural starters is unknown and it is difficult to obtain the stability of fermentation products. Efforts are underway to utilize yeast as co-starter in the manufacturing of fermented products to obtain more stable product quality6.
In the above mentioned context a new study was carried out investigate the ability of L. plantarum Dad 13 individually or in combination with other lactic acid bacteria or a combination thereof with yeast to produce the most favorable fermented milk characteristics. Lactobacillus plantarum Dad–13 was isolated from “dadih” which is traditional Indonesian fermented milk7.
From the study results it was observed that the starter and starter combinations did not affect the lactic acid bacteria and yeast populations in the production of fermented milk. The starter and starter combinations significantly affected the pH value, the titratable acidity and theβ-caroteneof fermented milk produced.
Overall the results of the study showed a positive interaction between L. plantarum and L. lactis, as well as between lactic acid bacteria and yeast in the production of fermented milk. The lactic acid bacteria population tended to be higher in combination compared to the single starter lactic acid bacteria (L. plantarum or L. lactis only), although there was no significant difference.
Lactobacillus plantarum Dad 13 combined with L. lactis and S. cerevisiae can be used to produce the best product characteristics, particularly antioxidant activity. Saccharomyces cerevisiae in fermentation is essential to promote β-carotene and the use of L. lactis in fermentation increases the production of lactic acid, which can act as a scavenger of free radicals. The presence of L. lactis also played a role in breaking down milk protein into bioactive peptides during fermentation to increase the antioxidant activity of the fermented milk.
At the end of study from the results it was established that the combination of LAB and yeast had no effect on microbiological characteristics, whereas the combination of starter L. plantarum Dad 13, L. lactis and S. cerevisiae improved the chemical quality and antioxidant activity of fermented milk.
- Cervato, G., R. Cazzola and B. Cestaro, 1999. Studies on the antioxidant activity of milk caseins. J. Food Sci. Nutr., 50: 291-296.
- Lindmark-Mansson, H. and B. Akesson, 2000. Antioxidative factors in milk. J. Nutr., 84: 103-110.
- Satir, G. and Z.B. Guzel-Seydim, 2016. How kefir fermentation can affect product composition? Small Rumin. , 134: 1-7.
- Fitzgerald, R.J. and B.A. Murray, 2006. Bioactive peptides and lactic fermentations. J. Dairy Technol., 59: 118-125.
- Fleet, G.H. and M.A. Main, 1987. The occurrence and growth of yeasts in dairy products. J. Food Microbiol., 4: 145-155.
- Jakobsen, M. and J. Narvhus, 1996. Yeasts and their possible beneficial and negative effects on the quality of dairy products. Dairy J., 60: 755-768.
- Dina T.M., Nurliyani, Widodo and Sunarti , 2017. Characterization and Antioxidant Activity of Fermented Milk Produced with a Starter Combination. J. Nutr., 16: 451-456.