Sensory, Microbiological and Physicochemical Characterisation of Functional Manuka Honey Yogurts Containing Probiotic Lactobacillus reuteri DPC16.

Anand Mohan,Yu Li,Siew-Young Quek,Quan Shu,Joshua Hadi,Noemi Gutierrez-Maddox,Yihuai Gao,Ivanhoe K H Leung

doi:10.3390/foods9010106

Abstract

Consumer acceptance of synbiotics, which are synergistic combinations of probiotics and their prebiotic substrates, continues to expand in the functional food category. This research aimed at evaluating the effect of antibacterial manuka honey on the probiotic growth and sensory characteristics of potentially synbiotic yogurts manufactured with Lactobacillus reuteri DPC16. Probiotic viable count in yogurts with 5% w/v Manuka honey (Blend, UMFTM 18+, AMFTM 15+ and AMFTM 20+) was evaluated by the spread plate method over the refrigerated storage period of three weeks. A panel of 102 consumers preferred the yogurt made with invert syrup over the manuka honey variants, and the unsweetened control was least liked overall. Invert syrup yogurt was also the most effective in promoting the growth of the probiotic lactobacilli. However, the honey-sweetened yogurts had a more favourable fermentation metabolite profile, especially the lactic and propionic acids, as estimated by nuclear magnetic resonance (NMR) analyses. The probiotic counts in AMFTM 15+ manuka honey yogurt (7 log cfu/mL) were significantly higher than the other honey yogurt types (Manuka Blend and UMFTM 18+) and above the recommended threshold levels. The combination thus can be developed as a synbiotic functional food by further improving the sensory and physicochemical properties such as texture, apparent viscosity and water holding capacity.

Highlights

Functional foods with probiotics are often supplemented with co-cultures, such as yogurt starters, to manufacture products with acceptable sensory characteristics and consumer acceptance.Lactic acid bacteria (LAB) includes the yogurt starter cultures (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus), and probiotic species mostly belonging to the Lactobacillus and Bifidobacterium genera
Local purchases were made for invert syrup (IS) and manuka honey with different antibacterial gradings: Drapac Manuka Honey Blend (MB), Comvita Manuka Honey UMFTM 18+ (UMF18), and Drapac DrKiwi AMFTM 15+ (AMF15) and AMF 20+
LAB counts at day 1 of cold storage were above 7 log cfu/mL in all the yogurts samples, with the highest being in MB (7.31 log cfu/mL)

Summary

Introduction

Functional foods with probiotics are often supplemented with co-cultures, such as yogurt starters, to manufacture products with acceptable sensory characteristics and consumer acceptance.Lactic acid bacteria (LAB) includes the yogurt starter cultures (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus), and probiotic species mostly belonging to the Lactobacillus and Bifidobacterium genera. Functional foods with probiotics are often supplemented with co-cultures, such as yogurt starters, to manufacture products with acceptable sensory characteristics and consumer acceptance. Lactic acid bacteria (LAB) includes the yogurt starter cultures Bulgaricus and Streptococcus thermophilus), and probiotic species mostly belonging to the Lactobacillus and Bifidobacterium genera. It is important to note that the probiotic bacterial species are different from the starter cultures commonly used for fermenting milk into yogurts. Foods 2020, 9, 106 large intestine to benefit the health of the host in numerous ways [1,2]. For a beneficial health effect on the host, the recommended minimum dosages of probiotics reported in the literature range from 6 to 7 log colony forming units (cfu) per millilitre (mL) of the sample under consideration [3,4]. Maintaining the viable counts at the efficacious levels during the storage period is one of the major technological challenges for probiotics incorporation in functional foods [2,3]

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