Identification of Key Aroma Compounds in Type I Sourdough-Based Chinese Steamed Bread: Application of Untargeted Metabolomics Analysisp.

Bowen Yan,Yijie Cai,Daming Fan,Wei Chen,Faizan Sadiq,Jianxin Zhao,Hao Zhang

doi:10.3390/ijms20040818

Abstract

Untargeted metabolomics is a valuable tool to analyze metabolite profiles or aroma fingerprints of different food products. However, less attention has been paid to determining the aroma characteristics of Chinese steamed breads (CSBs) by using this approach. The aim of this work was to evaluate the key aroma compounds and their potential generation pathway in Chinese steamed bread produced with type I sourdough by a metabolomics approach. Based on the aroma characteristics analysis, CSBs produced with type I sourdough and baker’s yeast were clearly distinguishable by principal component analysis (PCA) scores plot. A total of 13 compounds in sourdough-based steamed breads were given the status of discriminant markers through the untargeted metabolomics analysis. According to the odor activity values (OAVs) of discriminant aroma markers, ethyl acetate (fruity), ethyl lactate (caramel-like), hexyl acetate (fruity), (E)-2-nonenal (fatty) and 2-pentylfuran (fruity) were validated as the key volatile compounds in the breads produced with type I sourdough as compared to the baker’s yeast leavened steamed bread. The metabolite analysis in proofed dough indicated that esters are mainly generated by the reaction between acid and alcohol during steaming, and aldehydes are derived from the oxidation of palmitoleic acid and linoleic acid during proofing and steaming.

Highlights

The aroma of Chinese steamed bread (CSB) is one of the most important sensory attributes that determines the quality of the bread and consumers’ acceptability [1]
Specific aroma compounds with higher concentration or odor activity values (OAVs) have been reported and used to evaluate the aroma feature of bread or CSB, these compounds are limited to overall representation of the CSB aroma property
Radar charts illustrated differences in the aroma profile of different CSBs based on metal-oxide semiconductor (MOS) gas sensor (Figure 1A)

Summary

Introduction

The aroma of Chinese steamed bread (CSB) is one of the most important sensory attributes that determines the quality of the bread and consumers’ acceptability [1]. The role of microbes in conferring aromatic properties to fermented cereal products is well-known, and a strong correlation between representative microbiota of type I sourdough and volatile compounds was previously reported by us and other researchers [1,7]. Due to the importance of aroma characteristics in reaching consumer expectations, high marketability and product development of breads, sensory and instrumental evaluations have been widely used to determine the aroma profile of many types of breads [8,9]. Untargeted metabolomics has frequently been used in clinical research as well as in food systems for the identification of characteristic aroma compounds of a product or to determine discriminant volatiles [12,13,14]. The combination of the untargeted metabolomics analysis and odor threshold techniques could potentially provide a better and comprehensive overview of the key aroma compounds of a CSB produced with different starter cultures

Objectives

Methods

Results

Conclusion