Co-Culture Strategy of Lactobacillus kefiranofaciens HL1 for Developing Functional Fermented Milk.

Sheng-Yao Wang,Ming-Ju Chen,Jia-Shian Shiu,Ren-Feng Huang,Yen-Po Chen,Ker-Sin Ng

doi:10.3390/foods10092098

Abstract

Our previous studies indicated that Lactobacillus kefiranofaciens HL1, isolated from kefir grain, has strong antioxidant activities and anti-aging effects. However, this strain is difficult to use in isolation when manufacturing fermented products due to poor viability in milk. Thus, the purpose of this study was to apply a co-culture strategy to develop a novel probiotic fermented milk rich in L. kefiranofaciens HL1. Each of four selected starter cultures was co-cultured with kefir strain HL1 in different media to evaluate their effects on microbial activity and availability of milk fermentation. The results of a colony size test on de Man, Rogosa and Sharpe (MRS) agar agar, microbial viability, and acidification performance in MRS broth and skimmed milk suggested that Lactococcus lactis subsp. cremoris APL15 is a suitable candidate for co-culturing with HL1. We then co-cultured HL1 and APL15 in skimmed milk and report remarkable improvement in fermentation ability and no negative impact on the viability of strain HL1 or textural and rheological properties of the milk. Through a co-culture strategy, we have improved the viability of kefir strain HL1 in fermented skimmed milk products and successfully developed a novel milk product with a unique flavor and sufficient probiotics.

Highlights

To select a suitable bacteria strain for co-culturing with L. kefiranofaciens HL1 to produce probiotic fermented milk, we first evaluated the effects of four lactic acid bacteria (LAB) strains often applied as starter cultures in dairy products on the growth of L. kefiranofaciens HL1 incubated in MRS medium
HL1 solely grown on MRS agar plate were not significantly different from those co-cultured with S. thermophilus BCRC 12268 (ST 12268), S. thermophilus BCRC 13869T
It is worth noting that the HL1+APL15 group showed a significantly lower pH than the HL1 and APL15 counterparts in MRS broth, indicating that the co-culture strategy for Lc. lactis subsp. cremoris APL15 and L. kefiranofaciens HL1 could provide a positive effect to stimulate each other to produce organic acids. These findings indicated that Lc. lactis subsp. cremoris APL15 might have stimulated probiotic L. kefiranofaciens HL1 to produce organic acids during co-incubation in MRS medium

Summary

Introduction

Fermented dairy products have been recognized as healthy foods for thousands of years. It is well-known that the fermentation process can extend the shelf-life of fresh milk and nourish the flavor of the final product with high nutrition value. Bulgaricus, LB) and Streptococcus thermophilus (S. thermophilus, ST), are commonly used to produce fermented milk [1], defined as “yogurt” [2]. Other lactic acid bacteria (LAB), such as Lactobacillus (L. acidophilus, L. johnsonii, L. reuteri, and L. rhamnosus) and Bifidobacterium (Bifidobacterium bifidum, B. breve, B. infantis, and B. longum), are introduced to increase the variety and health benefits of dairy products [3,4]

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Conclusion