Untargeted foodomics reveals molecular mechanism of magnetic field effect on Feng-flavor Baijiu ageing

Impact of Pulsed Electric Fields Combined with Dissolved Oxygen and Ferrous Ions on the Aroma and Components of Strong-Flavor Baijiu

This research examined the influences of electric field strength and pulse frequency of pulsed electric field (PEF) treatment, along with the combined effects of dissolved oxygen and ferrous iron ions on the aroma and components of strong-flavor baijiu. PEF treatment improved fruity aromas and decreased the pit mud odor. Electric field strength promoted the production of short-chain fatty acid esters, while pulse frequency facilitated the formation of acetal oxidation products. The most notable changes were observed at an electric field strength of 25 kV, and a pulse frequency of 350 Hz. Increasing dissolved oxygen significantly improves fruity and mellow aromas and promotes the generation of 17 compounds including ethyl lactate, ethyl butyrate, hexan-1-ol, octanoic acid, and 3-methylbutanal, while Fe2⁺ treatment reduces the fruity aroma of baijiu and significantly suppresses the production of 15 esters including ethyl hexanoate, hexyl hexanoate, and ethyl lactate. Dissolved oxygen may contribute to the generation of hydroxyl radicals and regulated oxidation reactions partially in baijiu. And, Fe2+ may react with organic acids to promote the hydrolysis of ester compounds. This study aims to offer valuable insights into the practical application of PEF in the flavor regulation of baijiu.

Chemical Isotope Labeling Liquid Chromatograph-Mass Spectrometer: A Powerful Tool for Analyzing Non-Volatile Organic Acids in Baijiu

Non-volatile organic acids (NVOAs) are essential to the flavor profile of Baijiu. However, the low levels and diversity of NVOAs in Baijiu make their isolation, annotation, and quantification challenging. In this study, a well-established pipeline combining chemical derivatization, isotope labeling, and high-resolution mass spectrometry with a three-tier annotation process was used to quantify NVOAs in three typical flavor types of Baijiu with high coverage and confidence. The results revealed the annotation of 56, 145, and 1277 NVOAs in Baijiu at tier 1, tier 2, and tier 3 levels, respectively. Among them, a total of 166 high-confidence NVOAs were first reported in Baijiu. Furthermore, multivariate statistical analyses indicated that abundant NVOAs could potentially be used as biomarkers to distinguish between different flavor types of Baijiu. This study provides a powerful tool for the qualification and quantification of NVOAs in Baijiu. The results will greatly expand the understanding of NVOAs in Baijiu.

Evolution of aroma compounds in round soy sauce aroma type baijiu during aging and the effect of aging markers on the lasting aroma in finished glass

Soy sauce aroma type Baijiu (SSAB) is a complex blend of seven rounds of raw SSAB, each with distinct aroma profiles that evolve during maturation. Tracking the aging of individual rounds is crucial for understanding flavor development. The round 1-4 SSABs were analyzed by gas chromatography-mass spectrometry and an electronic tongue over one-year aging. Results showed that short/medium-chain esters decrease while long-chain esters, acids, aldehydes, pyrazines, ketones, and furans increase. Kinetic analysis showed that short/medium-chain ethyl esters reach equilibrium in the esterification-hydrolysis reactions, whereas long-chain ethyl esters favor esterification, with their reaction quotient (Qc) diverging from the equilibrium point. Linoleic acid ethyl ester, identified as a key aging marker, was found to reduce the volatilization rate of critical aroma compounds in the finished glass, thereby prolonged the duration of lingering aromas. These findings provide a foundation for improving SSAB blending and storage, highlighting aging's key role in enhancing Baijiu quality.

Unraveling the chemosensory characteristics dependence of sauce-flavor baijiu on regionality using descriptive sensory analysis and quantitative targeted flavoromics

Descriptive sensory analysis, headspace solid-phase microextraction-gas chromatography-mass spectrometry, gas chromatography-flame ionization detector and multivariate statistical analysis were used to elucidate the regional dependence of sauce-flavor baijiu (SFB). Although SFB samples from different regions couldn't be clearly classified by sensory profiles, they could be clearly divided into 5 groups in principal component analysis plot based on quantitative targeted flavoromics analysis. And then, the relationship between sensory attributes and volatile compounds were investigated by network analysis. Twenty regional aroma markers were identified by multivariate statistical analysis to distinguish SFB samples from different regions. Furthermore, the influence of manufacturing operation on SFB in Guizhou region was further analyzed. Thirty-eight potential compounds were significant different in Guizhou SFB samples with different manufacturing operations. This study not only provides a better understanding of regional dependence on SFB flavor, but also further clarifies the inheritance importance of manufacturing operation in traditional SFB production.

Effects of irradiation on the aging and sensory quality of navel orange distilled spirits

BACKGROUND

60 Co-γ irradiation can simulate the effects of aging and enhance the flavor of distilled spirits. The present study aimed to investigate the effects of 0, 2, 4, 6, 8 and 10 kGy 60 Co-γ irradiation doses on the key aroma components in newly produced navel orange distilled spirits and thus determine the mechanism of their aging distilled spirits.

RESULTS

The identification of aroma compounds demonstrated that ethyl hexanoate, d-limonene, ethyl octanoate, 3-methyl-1-butanol and linalool are the key aroma compounds in navel orange distilled spirits, which were increased except for linalool with irradiation doses of 2-6 kGy. Irradiation treatment simulated the effects of the aging of navel orange distilled spirits by promoting the content of total acids, total esters and aldehydes. Irradiation doses of 2-6 kGy increased the aroma intensity of navel orange distilled spirits, reaching an optimum at 6 kGy. However, irradiation doses as high as 8 and 10 kGy decreased the content of esters in navel orange distilled spirits, which led to a deterioration of the spirit flavor.

CONCLUSION

Low doses of 60 Co-γ irradiation can simulate the effects of the aging by increasing the content of key aromatic compounds in navel orange distilled spirits. © 2023 Society of Chemical Industry.

Harmless and resourceful utilization of solid waste: Multi physical field regulation in the microbiological treatment process of solid waste treatment

Solid waste (SW) treatment methods mainly include physical, chemical, and biological methods, while physical and chemical methods have advantages such as fast effectiveness and short treatment time, but have high costs and were prone to secondary pollution. Due to the advantages of mild conditions and environmental protection, microbial methods have attracted the attention of numerous researchers. Recently, promotion of biological metabolic activity in biotreatment technology by applying multiple physical conditions, and reducing the biochemical reaction energy base to promote the transfer of protons and electrons, has made significant progress in harmless and resourceful utilization of SW. This paper main summarized the harmless and resourceful treatment methods of common bulk SW. The research of physical field-enhanced microbial treatment of inorganic solid waste (ISW) and organic solid waste (OSW) was discussed. The advantages and mechanisms of microbial treatment compared to traditional SW treatment methods were analyzed. The multi-physical field coupling enhanced microbial treatment technology was proposed to further improving the efficiency of large-scale treatment of bulk SW. The application prospects and potential opportunities of this technology were analyzed. Novel research ideas for the large-scale harmless and resourceful treatment of bulk SW were provided.

Virtual screening, identification, and potential antioxidant mechanism of novel bioactive peptides during aging by a short-chain peptidomics, quantitative structure-activity relationship analysis, and molecular docking

Antioxidant peptides have received a great deal of attention. However, only a few studies have been conducted on the antioxidant peptides originating from Baijiu. A total of 1490 features deemed potential short-chain peptides (the amino acid number between 2 and 4, SCPs) were screened and analyzed by a customized short-chain peptidomics approach in Feng-flavor Baijiu (FFB) during 14 years of aging, with an obvious discrepancy between FFB aged for 3 years and 6 years being observed. Thirty-nine characteristic SCPs in total were identified and accurately quantified by high-throughput parallel reaction monitoring-based synthetic standards, with the contents ranging from 0.16 to 279.33 μg L-1. Combined with the absorption, distribution, metabolism, excretion, and toxicity analysis model, PGRW, WK, SC, and PAW, four novel antioxidant peptides with high ABTS radical scavenging capacity, were obtained using a customized quantitative structure-activity relationship (QSAR) model based on a two terminal position numbering method, with satisfied coefficients of determination (R2), internal cross-validated R2 (Q2), and external R2 (R2pre) of 0.925, 0.808, and 0.665, respectively. Furthermore, these 4 antioxidant peptides could block the Keap-Nrf2 interaction and promote the accumulation of Nrf2 by molecular docking analysis, and the interaction energy between peptide PGRW and Keap1 was higher than that between epigallocatechin gallate and Keap1 based on CHARMm forced field. Overall, this study facilitated the discovery of functional peptides in Baijiu and the understanding of aging mechanisms.

Microbiota structure of traditional starters from around the Tai-hang mountains and their influence on the fermentation properties, aroma profile and quality of Chinese steamed bread

BACKGROUND

Steamed bread is a popular staple food in China, and the significant regional differences of the microbiota in traditional starters make the flavor and quality of steamed bread highly variable along with long preparation times. Therefore, analyzing the microbial flora of traditional starters and their influences on the flavor and quality may help to solve the problems mentioned earlier, and it may also be conducive to potentially meet consumer needs and permit industrialization of this traditional fermented food.

RESULTS

One hundred and thirty-two fungal and 50 bacterial species were identified in five traditional starters, each with a different dominant genus. The fermentation properties of dough showed that total titratable acid, dough volume and gas production increased and the pH decreased with fermentation time. The traditional starters improved the quality of Chinese steamed bread (CSB) including the crumb structure, specific volume and sensory attributes. Thirty-three aroma compounds with a VIP (variable importance for the projection) > 1 were identified as characteristic aroma compounds. The correlations among the microbiota, aroma and qualities of CSB showed a greater contribution from the bacteria, which was consistent with the predictions of metabolic pathways in the sequenced genomes.

CONCLUSION

The quality of CSB fermented with traditional starters was improved induced by their different microbial profiles, and bacteria made a greater contribution than fungus to the aroma and qualities of CSB. © 2023 Society of Chemical Industry.

Machine learning based age-authentication assisted by chemo-kinetics: Case study of strong-flavor Chinese Baijiu

The aged Chinese liquor, Baijiu, is highly valued for its superior organoleptic qualities. However, since age-authentication method and aging-mechanism elucidation of Baijiu is still in the exploratory stage, high-quality aged Baijiu is often replaced by lower-quality, less-aged product with fraudulent mislabeling. Authentic high-quality strong-flavor Baijiu was analyzed by gas chromatography-mass spectrometry. Total esters decreased with aging, while acids, alcohols, aldehydes, ketones, terpenes, pyrazines increased. Although concentrations of partial compounds showed non-monotonic profiling during aging, a close positive linear correlation (R² = 0.7012) of Baijiu Evenness index (0.55-0.59) with aging time was observed, indicating a more balanced composition in aged Baijiu. The reaction quotient (Qc) of each esterification, calculated by the corresponding reactant and product concentration, approached to the corresponding thermodynamic equilibrium constant Kc. This result demonstrated that the spontaneous transformation driven by thermodynamics explained part of the aging compositional profiling. Furthermore, an aging-related feature selection and an age-authentication method were established based on three models combined with five ranking algorithms. Forty-one key features, including thirty-six compound concentrations, four esterification Qc values and the Evenness index were selected out. The age-authentication based on neural network using forty-one input features accurately predicted the age group of Baijiu samples (F1 = 100 %). These findings have deepened understanding of the Baijiu aging mechanism and provided a novel, effective approach for age-authentication of Baijiu and other liquors.

Synergy of physicochemical reactions occurred during aging for harmonizing and improving flavor

Numerous counterfeit vintage Baijiu are widely distributed in the market driven by economic interest which disturb the market economic rules and damage the reputation of particular Baijiu brand. Found on the situation, the Baijiu system variation during aging period, aging mechanisms and discrimination strategies for vintage Baijiu are systematically illuminated. The aging mechanisms of Baijiu cover volatilization, oxidation, association, esterification, hydrolysis, formation of colloid molecules and catalysis by metal elements or other raw materials dissolved from storage vessels. The discrimination of aged Baijiu has been performed by electrochemical method, colorimetric sensor array or component characterization coupled with multivariate analysis. Nevertheless, the characterization of non-volatile compounds in aged Baijiu is deficient. Further research on the aging principles, more easy-operation and low-cost discrimination strategies for aged Baijiu are imperative. The above information is favorable to better understand the aging process and mechanisms of Baijiu, and promote the development of artificial aging techniques.

Molecular mechanism of Mare Nectaris and magnetic field on the formation of ethyl carbamate during 19 years aging of Feng-flavor Baijiu

Ethyl carbamate (EC) is carcinogen occurring naturally in fermented foods, while the EC formation pattern in Feng-flavor Baijiu during Mare Nectaris storage and magnetic field treatment remains controversial. In this work, variation of EC in Mare Nectaris and magnetic field were investigated for the first time through ultra high performance liquid chromatography quadrupole-orbitrap high resolution mass spectrometry (UHPLC-Q-Orbitrap). Quantification results revealed that EC decreased significantly in the stage of 3-9 years and kept at 12.4 μg L-1 after 10 years of aging. Arginine succinate synthase (ASS) and urease were deemed as vital factors for EC decomposition. Degradation effetc of EC in 250 mT is simillar to that of EC in Baijiu stored in Mare Nectaris for 8 years. This is due to that aging process was accelerated by magnetic field and the content of total acid in Baijiu was increased, creating a favorable environment for decomposition of EC and urea.

Hydrogen bonds and hydrophobicity with mucin and α-amylase induced honey aroma in Feng-flavor Baijiu during 16 years aging

Honey aroma is one of the most significant factors of Feng-flavor Baijiu, which is also an essential element to attract consumers. However, the evaluation and chemical basis of honey aroma is unclear. Palmitoleic acid, lagochilin, phomotenone and ethyl behenate were confirmed to be the strongest contributors to honey aroma by time-intensity analysis and UHPLC-Q-Orbitrap-MS. Predictive modeling was developed for processing honey aroma intensity responses in order to obtain significant Feng-flavor Baijiu rankings. In this study, the effects of ex-vivo saliva on Feng-flavor Baijiu were investigated for the first time. Mucin and α-amylase, as major proteins in ex-vivo saliva, were applied to simulate molecular docking of ethyl benzoate. Mucin and α-amylase modified the aroma release, which depended on hydrogen bonds and hydrophobic interactions, respectively. It is blazing a trail in the field in sensory experience of Feng-flavor Baijiu as well as contributes to our understanding of Feng-flavor Baijiu drinking process.

Chinese Baijiu: The Perfect Works of Microorganisms

Chinese Baijiu is one of the famous distilled liquor series with unique flavors in the world. Under the open environment, Chinese Baijiu was produced by two solid-state fermentation processes: jiuqu making and baijiu making. Chinese Baijiu can be divided into different types according to the production area, production process, starter type, and product flavor. Chinese Baijiu contains rich flavor components, such as esters and organic acids. The formation of these flavor substances is inseparable from the metabolism and interaction of different microorganisms, and thus, microorganisms play a leading role in the fermentation process of Chinese Baijiu. Bacteria, yeasts, and molds are the microorganisms involved in the brewing process of Chinese Baijiu, and they originate from various sources, such as the production environment, production workers, and jiuqu. This article reviews the typical flavor substances of different types of Chinese Baijiu, the types of microorganisms involved in the brewing process, and their functions. Methods that use microbial technology to enhance the flavor of baijiu, and for detecting flavor substances in baijiu were also introduced. This review systematically summarizes the role and application of Chinese Baijiu flavor components and microorganisms in baijiu brewing and provides data support for understanding Chinese Baijiu and further improving its quality.

Characterisation of key odorants causing honey aroma in Feng-flavour Baijiu during the 17-year ageing process by multivariate analysis combined with foodomics

Honey aroma is a typical sensory characteristic of Feng-flavour Baijiu, which originates from a unique manufacturing process, the formation mechanism of which is unclear. Multivariate analysis combined with foodomics assisted by sensory evaluation was performed to investigate the molecular mechanism of honey aroma formation in Feng-flavour Baijiu during the 17-year ageing process. A total of 1995 compounds was identified, and 47 variables were screened as significant substances according to variable importance in projection and Spearman's rank correlation coefficient (|ρ| > 0.7), which corroborated that the long-term interaction between Baijiu and storage containers was the dominant origin of honey aroma. Recombination and omission experiments further validated the important contributions of significant substances, including acids, alcohols, aldehydes and ketones. A typical honey aroma dominated by fruity, floral, sweet and nutty notes was successfully simulated, and nutty notes could be enhanced by amides, whereas amines presented masking effects on fruity and floral aromas.