A Comprehensive Study of the Impacts of Oat β-Glucan and Bacterial Curdlan on the Activity of Commercial Starter Culture in Yogurt.

Marek Aljewicz,Beata Nalepa,Małgorzata Majcher

doi:10.3390/molecules25225411

Abstract

This study provides important information about the impacts of various levels of oat (OBG) and bacterial (curdlan) β-glucan and fat contents in milk on survivability and metabolism of yogurt starter cultures. The results show that addition of β-glucans in the concentration higher than 0.25% reduced starter bacterial counts during storage and prolonged the milk acidification process. A significant increase in lactose consumption by starter cultures was noted in the yogurt samples with OBG addition up to 0.75%. The highest (by 567% on average) increase in lactic acid content was noted in the control yogurts. Whereas the lowest (by 351%) increase in lactic acid content was noted in yogurts with OBG. After 28-day storage, the acetic aldehyde content was significantly influenced by fat content, type and addition level of polysaccharide. A higher increase in acetoin content was noted in samples with 0.25% than in samples with 1% of polysaccharides. In turn, significantly lower increases in diacetyl and 2,3-pentanedione contents were observed in the yogurt samples with OBG than in these with curdlan, with diacetyl production increase along with the higher concentration of the polysaccharide. The addition of OBG and curdlan to milk contributed to differences in the starter culture metabolism, consequently, in the milk acidification dynamics.

Highlights

Functional foods include products, which, apart from providing specific nutrients to the body, exert a beneficial effect on consumer’s health
The results of the multi-way analysis of variance showed that Lactobacillus bulgaricus (LB) count determined after 28 days of storage was significantly affected by polysaccharide type and addition level (p < 0.01) (Table S7), which is consistent with the findings presented by Lazaridou et al [9]
The present study proved a significant effect of two purified, structurally-different β-glucans isolated from oats (OBG) and bacteria added to milk fermented by Streptococcus thermophilus and Lactobacillus bulgaricus ssp. bulgaricus starter cultures

Summary

Introduction

Functional foods include products, which, apart from providing specific nutrients to the body, exert a beneficial effect on consumer’s health. The best-known examples of functional foods are fermented milk and yogurts [1]. The addition of polysaccharides (commonly known as prebiotics) is used in their production process to maintain a certain number of bacterial cultures, stimulate growth, and increase the survival rate of probiotic cultures [3]. Depending on the source of isolation, structure, or concentration, the polysaccharides serve different technological functions. They can be used as stabilizers, thickeners, or fat substitutes in low-calorie products (the so-called light type products)

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Conclusion