Development of fermented milk using food-grade recombinant Lactococcus lactis NZ3900
Yu Hsuan How, Michelle Yee Mun Teo, Lionel Lian Aun In, Siok Koon Yeo, Liew Phing Pui
Abstract
Fermented milk has been associated with the improvement of human health for decades. Food-grade Lactococcus lactis NZ3900 is a potential host for producing and delivering various biologics, including oral vaccines, hence it could enhance the functionality of fermented milk as a starter culture. A cultured fermented milk product was developed in this study using the food-grade recombinant L. lactis NZ3900 harboring plasmid pNZ8149. Response surface methodology was used to optimize the inoculum concentration (5–15% v/v), fermentation temperature (23–37 °C), and fermentation time (18–30 h) to enhance the viability, acidification activity, viscosity, and minimize syneresis of the L. lactis NZ3900-fermented milk using response surface methodology. The optimal inoculum concentration and fermentation conditions for L. lactis NZ3900-fermented milk are 12.5% (v/v) inoculum, 28 °C fermentation temperature, and 30 h of fermentation time, resulting in higher viability (9.64 log10 CFU/mL), acidification activity (pH 4.42, 0.78% titratable acidity), viscosity (11,096.9 mPa·s), and comparable syneresis (63.62%) against commercial fermented milk products. This shows that food-grade L. lactis NZ3900 can be used as a starter culture, and NZ3900-fermented milk could be used as a functional drink for oral vaccine delivery.