Trans-α-glucosylation of stevioside by the mutant glucansucrase enzyme Gtf180-ΔN-Q1140E improves its taste profile

Koen Quataert,Gerrit J. Gerwig,Evelien M. te Poele,Koen Dewettinck,Wim Soetaert,Davy Van de Walle,Johannis P. Kamerling,Tim Devlamynck,Lubbert Dijkhuizen

doi:10.1016/j.foodchem.2018.08.025

Koen Quataert, Gerrit J. Gerwig + Show 7 more

Open Access

https://doi.org/10.1016/j.foodchem.2018.08.025

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Abstract

The adverse health effects of sucrose overconsumption, typical for diets in developed countries, necessitate use of low-calorie sweeteners. Following approval by the European Commission (2011), steviol glycosides are increasingly used as high-intensity sweeteners in food. Stevioside is the most prevalent steviol glycoside in Stevia rebaudiana plant leaves, but it has found limited applications in food products due to its lingering bitterness. Enzymatic glucosylation is a strategy to reduce stevioside bitterness, but reported glucosylation reactions suffer from low productivities. Here we present the optimized and efficient α-glucosylation of stevioside using the mutant glucansucrase Gtf180-ΔN-Q1140E and sucrose as donor substrate. Structures of novel products were elucidated by NMR spectroscopy, mass spectrometry and methylation analysis; stevioside was mainly glucosylated at the steviol C-19 glucosyl moiety. Sensory analysis of the α-glucosylated stevioside products by a trained panel revealed a significant reduction in bitterness compared to stevioside, resulting in significant improvement of edulcorant/organoleptic properties.

Highlights

Over the past decade, Western society has increasingly been confronted with lifestyle diseases, such as type 2 diabetes, ischaemic heart attacks and various cardiovascular problems
The Lactobacillus reuteri wild-type glucansucrase Gtf180-ΔN and its derived Gtf180-ΔN-Q1140E mutant enzyme both readily catalyzed the trans-α-glucosylation of stevioside (Stev), using sucrose as donor substrate
Stevioside (Stev) is the most abundant of all steviol glycosides extracted from the leaves of the Stevia rebaudiana plant, its lingering bitterness prevents applications as a sweetener in low-calorie foods and beverages

Summary

Introduction

Western society has increasingly been confronted with lifestyle diseases, such as type 2 diabetes, ischaemic heart attacks and various cardiovascular problems. The risk of suffering from lifestyle diseases increases significantly when the BMI is higher than 25 kg/m2 (Field et al, 2001; Gregg et al, 2005). Important causes of overweight are a decrease of physical activity and inappropriate dietary patterns. An excessive sugar intake appears to be directly associated with an increase in body weight (Te Morenga, Mann, & Mallard, 2013). A wider array of sweet food products with less or even no sugar content is a necessity in order to reduce the prevalence of lifestyle diseases

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