Odour-active compounds in liquid malt extracts for the baking industry

Nadine S Rögner,Veronika Mall,Martin Steinhaus

doi:10.1007/s00217-021-03707-z

Abstract

An odorant screening by gas chromatography–olfactometry (GC–O) and a crude aroma extract dilution analysis (AEDA) applied to the volatiles isolated from a light and a dark liquid malt extract (LME) by solvent extraction and solvent-assisted flavour evaporation (SAFE) identified 28 odorants. Fifteen major odorants were subsequently quantitated and odour activity values (OAVs) were calculated as ratio of the concentration to the respective odour threshold value (OTV). Important odorants in the light LME included 3-(methylsulfanyl)propanal (OAV 1500), (E)-β-damascenone (OAV 430), and 4-ethenyl-2-methoxyphenol (OAV 91). In the dark LME, sotolon (OAV 780), 3-(methylsulfanyl)propanal (OAV 550), (E)-β-damascenone (OAV 410), acetic acid (OAV 160), and maltol (OAV 120) were of particular importance. To get an insight into the changes during malt extract production, the quantitations were extended to the malt used as the starting material for both LMEs. Addition of a minor amount of water to malt before volatile extraction was shown to be effective to cover the free as well as the bound malt odorants. Results showed that some LME odorants originated from the starting material whereas others were formed during processing. Important process-induced LME odorants included (E)-β-damascenone and 4-ethenyl-2-methoxyphenol in the light LME as well as maltol, sotolon, (E)-β-damascenone, and 2-methoxyphenol in the dark LME. In summary, the odorant formation during LME production was shown to be more important than the transfer of odorants from the malt.

Highlights

Malts are germinated and re-dried grains, primarily of barley, and of wheat, rye, and other cereals
The objective of the present study was to elucidate the major odour-active compounds in a light liquid malt extract (LME) and in a dark LME for the baking industry, both produced from the same malt, and relate their concentrations to the concentrations that were initially present in the malt
A light LME and a dark LME, both obtained from the same batch of malt, were orthonasally compared by a trained sensory panel in a quantitative olfactory profile analysis using 12 pre-defined descriptors

Summary

Introduction

Malts are germinated and re-dried grains, primarily of barley, and of wheat, rye, and other cereals. The grains are first treated with water until the moisture content increases from ~ 12% to 43–48%. This initiates germination, during which enzymes start to break down starch to reducing sugars. Malts can be further processed to malt extracts. For this purpose, the malt grains are milled and mashed with warm water. After separation from the solid grain particles (malt draff), the aqueous phase is concentrated to yield a liquid malt extract (LME) with a syrup-like consistency. The LME can be further dried, e.g. by spray drying, to obtain a crystalline material marketed as dried malt extract (DME) [2, 3]

Objectives

Methods

Results