Investigation on the key factors associated with flavor quality in northern strong aroma type of Baijiu by flavor matrix

Effects of storage time on flavor characteristics of bran-free fermented Baijiu by using electronic sensory, descriptive sensory analysis, GC × GC-MS, and ICP-MS

By examining and analyzing bran-free fermented Baijiu (BFB) with varying storage periods (0-20 years), it was observed that the overall concentration of volatile compounds initially increases and subsequently decreases over time. Furthermore, BFB exhibited more kinds of long chain esters, higher concentration of acetals, and reduced furfural content. The process of cellaring can enhance the aged, sweet, and fruity aroma of BFB. 16 flavor compounds, including 1,1-diethoxyethane, ethyl dodecanoate, and ethyl hexadecanoate, can be used as markers for vintage BFB, and electronic sensory technology was capable of discerning BFB in different years. The results of redundancy analysis (RDA) showed a positive correlation between metals and aldehydes, esters, and ketones, while indicating a negative correlation with acids and alcohols. Al, Fe, and Ca underwent the most significant changes during storage period, and they were positively correlated with differential substances, such as benzaldehyde, vanillin, ethyl isovalerate, and ethyl palmitate (P < 0.01).

Unraveling the chemosensory characteristics on different types of spirits based on sensory contours and quantitative targeted flavoromics analysis

Due to differences in raw materials and production processes, different spirits exhibit various flavor even if undergo distillation operation. In this study, sensory analysis could clearly distinguish 5 types spirits, and had been validated through quantitative targeted flavoromics analysis. Consequently, 44 potential differential markers between 5 types spirits were screened. Among, 34 definite differential markers were further confirmed to be highly correlated with target sensory attributes and could effectively distinguish types of spirits. Ultimately, 14 key differential markers (including 2-methylbutane, linalool, acetaldehyde, d-limonene, β-myrcene, phenylethyl alcohol, phenethyl acetate, heptyl formate, ethyl octanoate, ethyl decanoate, ethyl pentanoate, ethyl hexanoate, hexanoic acid, and ethyl hexadecanoate) could reveal the chemical sources of spirit sensory and serve as targets for identifying different types of spirits. Overall, the results of flavoromic characterization of 5 types spirits provided a significant step forwards in understanding of differentiation of spirits by sensory coupled with quantitative, and statistical analysis.

Why does distilled liquor (Baijiu) have a yellowish color: A comprehensive analysis

Elucidating the mechanisms underlying Baijiu production is a shared aspiration among academic groups specializing in the field of Baijiu research. This study comprehensively examined the mechanisms underlying the yellowish coloration of Baijiu through a synergistic application of chromatographic, spectroscopic, and physical methodologies. Aging of Baijiu in earthenware pots involves the infiltration of mineral ions such as iron, aluminum, and calcium; however, these ions are detected at extremely low concentrations and are therefore not linked to the development of Baijiu's yellowish color. Instead, the yellowish coloration is attributed to the diverse colorants generated during the high-temperature fermentation of small-molecule sugars derived from the saccharification of grain materials. Although these colorants exist in minimal quantities and exhibit spectral absorption peaks ranging from 300 to 450 nm, their overlapping spectra collectively contribute to the light-absorbing properties of Baijiu across a broad wavelength range, ultimately accounting for its characteristic yellowish color.

Differences and correlations between industrial experts and semi-trained assessors in the sensory evaluation of strong-aroma baijiu using rate-all-that-apply

Baijiu has rich and complex sensory characteristics, and how to make the sensory analysis results given by baijiu industrial experts better understood by consumers has been attracting a lot of attention. In this study, 35 strong-aroma baijiu samples were evaluated by 12 industrial experts and 21 semi-trained assessors, respectively, using rate-all-that-apply (RATA) methods, which involved 2 groups of lexicons generated by the 2 panels. The results showed that the RATA method was suitable for analyzing and distinguishing different baijiu samples by both industrial experts and semi-trained assessors. Although the industrial experts and the semi-trained assessors selected very different lexicons to describe the same strong-aroma baijiu samples, most descriptors from the expert evaluators are either positively or negatively correlated with the semi-trained assessors, such as the attributes "aldehyde," "mud," "multi-grain," and "scorched," and these attributes are effective in distinguishing different strong-aroma baijiu samples. These correlations could enable the marketing promotion and consumer evaluation of baijiu products in the future. PRACTICAL APPLICATION: The result could help baijiu market, in particular the worldwide beverage market, better understand how different baijiu samples are described and evaluated by industrial experts, and further enable the marketing promotion and consumer evaluation of baijiu products in the future.

Analysis of Fungal Diversity, Physicochemical Properties and Volatile Organic Compounds of Strong-Flavor Daqu from Seven Different Areas

Strong-flavor Daqu, as a fermentation agent, plays a significant role in shaping the quality of strong-flavor baijius, and fungal species in Daqu are important factors affecting the quality of Daqu. Therefore, we selected strong-flavor Daqu from seven different origins to study the fungal composition and the effects of the fungal composition on the physicochemical properties and volatile organic compounds (VOCs). It was found that the fungal composition influences the physicochemical properties of Daqu. Specifically, there was a positive link between Rhizomucor, Rhizopus, Thermomyces, and liquefying activity and a positive correlation between Aspergillus and fermenting activity. Furthermore, the relationships between esterifying activity and Thermomyces, Rhizomucor, Aspergillus, Pichia, and Saccharomycopsis were found to be positive. The VOCs in Daqu were affected by Aspergillus, Issatchenkia, Pichia, and Thermoascus. Issatchenkia was significantly positively correlated with benzeneethanol as well as Aspergillus and pentadecanoic acid ethyl ester, ethyl myristate. Pichia and Thermoascus were significantly negatively correlated with benzaldehyde and 2-furaldehyde. This study deepens our understanding of the relationship between VOCs, the physicochemical properties with microbial communities, and reference significance for the production of better-quality strong-flavor Daqu.

Fungal Community Succession and Volatile Compound Changes during Fermentation of Laobaigan Baijiu from Chinese Hengshui Region

To investigate the core fungal community succession and its effects of volatile compound production during different stages (D-1, D-2, D-3, E-4, E-5, and E-6) of Hengshui Laobaigan Baijiu, high-throughput sequencing (HTS) was carried out, accompanied by the identification and quantification of the volatile flavor compounds using headspace solid-phase coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS). HTS results demonstrated that the fungal community of stage D-1 was similar to that of E-4 after adding Daqu, while the richness and diversity of the fungal community were most prominent at stage E-6. Moreover, the addition of Daqu at the beginning of Ercha fermentation resulted in a significant increase in the relative abundances of the fungal community at the genus level, setting the stage for the production of volatile compounds. GC-MS analysis revealed the presence of a total of 45 volatile compounds. Combining the GC-MS result with the heat map and principal component analysis (PCA), the concentrations of volatile compounds were highest in stage E-5. Meanwhile, concentrations of esters, especially ethyl acetate, ethyl lactate, isoamyl acetate and ethyl hexanoate, were high in both stages E-5 and E-6. This indicated that stage E-5 was crucial to the fermentation process of Laobaigan Baijiu. Three fungal genera (Saccharomyces, Candida, and Pichia) were indicated as the core microbiota for the production of the main volatile flavor compounds of Laobaigan Baijiu through partial least square (PLS) analysis. The information provided in this study offered valuable insights into the fermentation mechanism of Laobaigan Baijiu, thereby serving as a theoretical framework for enhancing the quality of Baijiu and realizing cost-effective production.

Integration of Chemometrics and Sensory Metabolomics to Validate Quality Factors of Aged Baijiu (Nianfen Baijiu) with Emphasis on Long-Chain Fatty Acid Ethyl Esters

The storage process of Baijiu is an integral part of its production (the quality undergoes substantial changes during the aging process of Baijiu). As the storage time extends, the flavor compounds in Baijiu tend to undergo coordinated transformation, thereby enhancing the quality of Baijiu. Among them, long-chain fatty acid ethyl esters (LCFAEEs) were widely distributed in Baijiu and have been shown to have potential contributions to the quality of Baijiu. However, the current research on LCFAEEs in Baijiu predominantly focuses on the olfactory sensation aspect, while there is a lack of systematic investigation into their influence on taste and evaluation after drinking Baijiu during the aging process. In light of this, the present study investigates the distribution of LCFAEEs in Baijiu over different years. We have combined modern flavor sensory analysis with multivariate chemometrics to comprehensively and objectively explore the influence of LCFAEEs on Baijiu quality. The results demonstrate a significant positive correlation between the concentration of LCFAEEs and the fruity aroma (p < 0.05, r = 0.755) as well as the aged aroma (p < 0.05, r = 0.833) of Baijiu within a specific range; they can effectively reduce the off-flavors and spicy sensation of Baijiu. Furthermore, additional experiments utilizing a single variable suggest that LCFAEEs were crucial factors influencing the flavor of Baijiu, with Ethyl Palmitate (EP) being the most notable LCFAEE that merits further systematic investigation.