Effects of Protein Components on the Chemical Composition and Sensory Properties of Millet Huangjiu (Chinese Millet Wine)

Abstract

Millet Huangjiu is a national alcoholic beverage in China. The quality of Chinese millet Huangjiu is significantly influenced by the protein components in the raw materials of millet. Therefore, in this study, the impact of different protein components on the quality of millet Huangjiu was investigated by adding exogenous proteins glutelin and albumin either individually or in combination. The study commenced with the determination of the oenological parameters of different millet Huangjiu samples, followed by the assessment of free amino acids and organic acids. In addition, the volatile profiles of millet Huangjiu were characterized by employing HS-SPME-GC/MS. Finally, a sensory evaluation was conducted to evaluate the overall aroma profiles of millet Huangjiu. The results showed that adding glutelin significantly increased the contents of total soluble solids, amino acid nitrogen, and ethanol in millet Huangjiu by 32.2%, 41.5%, and 17.7%, respectively. Furthermore, the fortification of the fermentation substrate with glutelin protein was found to significantly enhance the umami (aspartic and glutamic acids) and sweet-tasting (alanine and proline) amino acids in the final product. Gas chromatography-quadrupole mass spectrometry coupled with multivariate statistical analysis revealed distinct impacts of protein composition on the volatile organic compound (VOC) profiles of millet Huangjiu. Excessive glutelin led to an over-accumulation of alcohol aroma, while the addition of albumin protein proved to be a viable approach for enhancing the ester and fruity fragrances. Sensory analysis suggested that the proper amount of protein fortification using a Glu + Alb combination could enhance the sensory attributes of millet Huangjiu while maintaining its unique flavor characteristics. These findings suggest that reasonable adjustment of the glutelin and albumin contents in millet could effectively regulate the chemical composition and improve the sensory quality of millet Huangjiu.

A quality comparison for Xiecun Huangjiu with different aging stages based on chemical profile, aroma composition and microbial succession

“…Amino acids could serve as essential nitrogen sources for microbial growth and metabolism while also participating in reactions with other compounds, leading to the formation of flavor compounds such as alcohols and esters ( Gambetta, Cozzolino, Bastian, & Jeffery, 2017 ). These compounds primarily originate from the degradation of proteins present in the raw materials, facilitated by proteases derived from both secretory and autolytic microorganisms ( Zhou et al, 2023 , Zhao et al, 2023 ). Nineteen amino acids in XCHJ were identified using UPLC, with their total concentrations falling within the range of 1901.45 to 3764.45 mg/L ( Table 1 ).…”

“…Among these alcohols, isoamylalcohol (ranging from 1039.02 to 3537.02 μg/kg), the most abundant aroma compound, played a pivotal role in shaping the aroma profile across all samples. Additionally, the concentration of phenethylalcohol, a byproduct of phenylalanine degradation ( Zhou et al, 2023 , Zhao et al, 2023 ), reached its highest point at 1220.8 μg/kg after six years of aging for XCHJ. 4-Ethylguaiacol, with its roasted and smoky odors, played a crucial role in the formation of the distinctive smoky aroma found in Huangjiu ( Chen et al, 2018 ).…”

“…Hence, it is imperative to elucidate the intricate interactions between microorganisms and these physicochemical factors to identify potential target parameters for controlling specific microbial growth in aged Huangjiu. The redundancy analysis (RDA), an extension of PCA that provides the advantage of capturing the regression between diverse microorganisms and multiple environmental variables ( Zhao et al, 2023 , Zhou et al, 2023 ), was employed to elucidate the aforementioned relationship ( Fig. 5 C and Fig.…”

Analysis of Starch Structure and Pasting Characteristics of Millet Thick Wine during Fermentation

“…After fermentation, large protein packages gradually became small pieces, and the small pieces became smaller and smaller as the fermentation time was prolonged, which may be attributed to the degradation of proteins. Numerous studies have pointed out that the proteins in raw materials are broken down and form peptides and amino acids by microorganisms from koji during the production of Chinese rice wine [37][38][39]. Figure 3B-M show that the large starch granules and the encapsulation of proteins from millet first expanded and then burst and disappeared, and the pomegranate-like aggregates gradually decomposed and became smaller after cooking and fermentation.…”