Based on metabolomics, chemometrics, and modern separation omics: Identifying key in-pathway and out-pathway points for pesticide residues during solid-state fermentation of baijiu.

By collecting real samples throughout the entire production process and employing chemometrics, metabolomics, and modern separation omic techniques, it unveiled the patterns of pesticide transfer during solid-state fermentation. The results indicated that 12 types of pesticide residues were prevalent during baijiu production, with organochlorine and carbamate pesticides being the most abundant in raw materials. After fermentation, organochlorine pesticides and pyrethroid pesticides exhibited higher content, while carbamate pesticides dominated in the final product. The pathways for pesticide input and elimination were identified, and the intricate mechanisms underlying these changes were further elucidated. Additionally, key control points were defined to facilitate targeted monitoring. The results indicated that pesticide residue primarily originates from raw materials and Daqu, whereas both solid-state fermentation and distillation processes were effective in reducing pesticide residues. The study offers valuable guidance for establishing pesticide residue standards in the context of baijiu production.

Nanotechnology-based optical sensors for Baijiu quality and safety control.

Baijiu quality and safety have received considerable attention owing to the gradual increase in its consumption. However, owing to the unique and complex process of Baijiu production, issues leading to quality and safety concerns may occur during the manufacturing process. Therefore, establishing appropriate analytical methods is necessary for Baijiu quality assurance and process control. Nanomaterial (NM)-based optical sensing techniques have garnered widespread interest because of their unique advantages. However, comprehensive studies on nano-optical sensing technology for quality and safety control of Baijiu are lacking. In this review, we systematically summarize NM-based optical sensor applications for the accurate detection and quantification of analytes closely related to Baijiu quality and safety. Furthermore, we evaluate the sensing mechanisms for each application. Finally, we discuss the challenges nanotechnology poses for Baijiu analysis and future trends. Overall, nanotechnological approaches provide a potentially useful alternative for simplifying Baijiu analysis and improving final product quality and safety.

Decoding Molecular Mechanism Underlying Human Olfactory Receptor OR8D1 Activation by Sotolone Enantiomers.

Sotolone, a chiral compound, plays an important role in the food industry. Herein, (R)-/(S)-sotolone were separated to determine their odor characteristics and thresholds in air (R-form: smoky, burned, herb, and green aroma, 0.0514 µg/m3; S-form: sweet, milk, acid, and nutty aroma, 0.0048 µg/m3). OR8D1 responses to (R)-/(S)-sotolone were detected in a HEK293 cell-based luminescence assay. (S)-Sotolone was a more potent agonist than (R)-sotolone (EC50 values of 84.98 ± 1.05 and 167.20 ± 0.25 µmol/L, respectively). Molecular dynamics simulations and molecular mechanics Poisson-Boltzmann surface area analyses confirmed that the combination of (S)-sotolone and OR8D1 was more stable than that of (R)-sotolone. Odorant docking, multiple sequence alignments, site-directed mutagenesis, and functional studies with recombinant odorant receptors (ORs) in a cell-based luminescence assay identified 11 amino-acid residues that influence the enantioselectivity of OR8D1 toward sotolone significantly and that N2065.46 was indispensable to the activation of OR8D1 by (S)-sotolone.

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

The strong aroma type of Baijiu is popular with its balanced flavor. However, the flavor characteristics of strong aroma type of Baijiu in different regions have significant diversities. Among them, the key aroma compounds in northern strong aroma type of Baijiu and the factors affecting the aroma profile and flavor quality are still unclear. In this study, a total of 78 aroma compounds were identified by gas chromatography-olfactometry-mass spectrometry (GC-O-MS). The quantitative analysis was completed and ethyl hexanoate (1003.24-4506.04 mg/L) was the highest. Aroma profile was successfully simulated by reconstitution, and omission test was applied to investigate the effects of the important aroma compounds on the aroma profile. Additionally, the relationship between expression of aroma compounds and sensory characteristics of samples was illustrated by flavor matrix. The overall aroma profile of northern strong aroma type of Baijiu was formed by the key aroma compounds with different aroma expression.

Reducing the background interference of liquid-liquid extraction method during Baijiu aroma analysis.

Liquid-liquid extraction coupled with gas chromatography-mass spectrometry (LLE-GC/MS) is a useful methodology for Baijiu aroma analysis. However, the background problems caused by LLE have rarely been investigated. In the present study, synthetic Baijiu was analyzed by traditional LLE-GC/MS to assess background problems, and a series of ghost peaks of some compounds were detected within the retention time of 47.0-60.0 min, including 2,4-di-tert-butylphenol (2,4-DTBP), palmitic acid and oleanitrile. 2,4-DTBP, which has a phenolic odor, is an important component in both strong and light-flavor Baijiu. Single-factor experiments confirmed that 2,4-DTBP is not a constituent of Baijiu but migrates from sodium sulphate and sodium chloride, and, high-temperature baking was an effective approach to eliminate these compounds. A combined strategy using standard cleaning coupled with high-temperature baking was proposed to reduce the background problems during LLE. Furthermore, more trace compounds could be identified through this process in the future.

meso-α,α-5,15-Bis(o-nicotinamido-phen-yl)-10,20-diphen-ylporphyrin n-hexane monosolvate.

The structure of the title solvated porphyrin, C56H38N8O2·C6H14, is reported. Two porphyrin mol-ecules, one ordered and one disordered n-hexane solvate mol-ecules are present in its asymmetric unit. The porphyrin macrocycle shows a characteristic saddle-shaped distortion, and the maximum deviation from the mean plane for non-hydrogen atoms is 0.48 Å. N-H⋯N, N-H⋯O, and C-H⋯O hydrogen bonds, as well as π-π inter-actions, are observed in the crystal structure.

Insights into a new alternative method with graphene oxide/polyacrylamide/Fe3O4 nanocomposite for the extraction of six odor-active esters from Strong-aroma types of Baijiu.

Liquid-liquid extraction (LLE) is the most commonly utilized technique for the extraction of odor-active esters (OAEs) in strong-aroma types of Baijiu (SAB). However, since the contents of different OAEs in SAB vary widely, it is still a puzzle to ensure that all OAEs to be thoroughly extracted by LLE without the problem of saturated adsorption. Herein, a novel approach of magnetic solid phase extraction (MSPE), based on the magnetic graphene oxide nanocomposite modified with polyacrylamide (GO/PAM/Fe3O4), was employed for the efficient extraction of six OAEs from SAB. Compared with LLE, GO/PAM/Fe3O4 exhibited highly selective recognition properties and larger adsorption capacities for OAEs (ranging from 13.68 to 39.06 mg/g), resulting in better extraction performances for OAEs. Coupled with GC-MS, six OAEs in real SAB were successfully determined, with recoveries ranged from 70.1 âˆ¼ 90.0% and LODs at 0.08 âˆ¼ 1.35 µg/L. Overall, the MSPE-GC/MS is a promising alternative for accurate determination of OAEs in SAB.

Quick classification of strong-aroma types of base Baijiu using potentiometric and voltammetric electronic tongue combined with chemometric techniques.

Nowadays, the classification of strong-aroma types of base Baijiu (base SAB) is mainly achieved by human sensory evaluation. However, prolonged tasting brings difficulties for sommeliers in guaranteeing the consistency of results, and may even cause health problems. Herein, an electronic tongue (E-Tongue) combined with a gas chromatography-mass spectrometry (GC-MS) method was successfully developed to grade high-alcoholic base SAB. The E-tongue was capable of identifying base SAB samples into four grades by a discriminant function analysis (DFA) model based on human sensory evaluation results. More importantly, it could effectively and rapidly predict the quality grade of unknown base SAB with an average accuracy up to 95%. The differences of chemical components between base SAB samples were studied by the GC-MS analysis and 52 aroma compounds were identified. The qualitative and quantitative results showed that with the increase of base SAB grade, the varieties and contents of aroma compounds increased. Overall, the comprehensive analysis of E-tongue data and GC-MS results could be in good agreement with human sensory evaluation results, which also proved that the newly developed method has a potential to be a useful alternative to the overall quality grading of base Baijiu.

Succession patterns of aroma components during brewing process of broomcorn millet (Panicum miliaceum L.) Huangjiu.

The flavor of Huangjiu is closely related to its brewing technology. Patterns of aroma component succession during the process of brewing broomcorn millet Huangjiu were investigated by solvent-assisted flavor evaporation combined with gas chromatography-mass spectrometry and chemometrics. During fermentation, esters, alcohols, acids, ketones, acetals, sulfur compounds, furans, and lactones were formed mostly in the chief fermentation stage; nitrogenous and phenolic compounds increased in the primary fermentation stage and then decreased; aldehydes decreased after fermentation started; and terpenes decreased after five days. During aging, acids, alcohols, ketones, lactones, phenols, and nitrogenous and sulfur compounds first decreased and then increased; and esters, acetals, aldehydes, and furans always increased, while terpenes decreased continuously. Key odorants, including acetic acid, 3-methylbutanoic acid, 1,1-diethoxyethane, and 3-methylbutanal, were produced in large quantities in the primary fermentation stage; ethyl lactate, ß-phenylethanol, and 2/3-methyl-1-butanol were generated in large quantities in the chief fermentation stage; and sotolon and methional were generated in the aging stage. This study is of great significance for the quality control of Huangjiu production.

Characterization of Key Aroma Compounds in Tartary Buckwheat (Fagopyrum tataricum Gaertn.) by Means of Sensory-Directed Flavor Analysis.

The key odorants of tartary buckwheat (TB) were researched by a sensory-directed flavor analysis approach for the first time. After the volatiles of TB were isolated by solvent-assisted flavor evaporation (SAFE), 49 aroma-active components with flavor dilution (FD) factors in the range of 1-2187 were identified using gas chromatography-olfactometry-mass spectrometry (GC-O-MS) combined with aroma extract dilution analysis (AEDA). Geranylacetone, phenethyl alcohol, and ß-damascone showed the highest FD factors of 2187. All 49 odorants were further quantitated by the internal standard curve method, and their odor activity values (OAVs) were obtained. The overall aroma of TB was successfully simulated (similarity > 98.16%) by mixing 16 odorants (OAV ≥ 1) with their natural concentrations. The omission tests revealed that geosmin, α-isomethylionone, α-methylionone, ß-ionone, linalool, ß-damascone, geranylacetone, guaiacol, ethyl hexanoate, geraniol, vanillin, tetrahydrolinalool, and 2,5-dimethyl-4-hydroxy-3-(2H)-furanone were the key odorants of TB. Chiral analysis showed that tetrahydrolinalool and linalool existed as racemics in the commercial TB. The relative content of R-enantiomers of α-isomethylionone and α-methylionone was slightly higher than that of their S-enantiomers. The odor thresholds of R- and S-enantiomer of tetrahydrolinalool were first detected as 0.029 and 3.8 µg/L in air, respectively.

Characterization and comparative study of the key odorants in Caoyuanwang mild-flavor style Baijiu using gas chromatography-olfactometry and sensory approaches.

Caoyuanwang Baijiu (CYW), a mild-flavor style Baijiu (MSB), is popular in northern China. However, there is a lack of studies reporting its aroma-active components. The aroma compounds of five CYW samples were analyzed using gas chromatography-olfactory-mass spectrometry coupled with aroma extraction dilution analysis. Fifty-five aroma-active compounds were identified in CYW, of which 27 had odor activity values ≥ 1. Reconstituted models successfully simulated the aroma profiles of CYW. The omission tests elucidated that ß-damascenone, dimethyl trisulfide, ethyl pentanoate, butanoic acid, ethyl acetate, 3-methylbutanal, ethyl lactate, hexanoic acid, γ-nonalactone, 3-hydroxy-2-butanone, ethyl butanoate, 1-propanol, 4-(ethoxymethyl)-2-methoxy-phenol, and vanillin were key odorants in CYW. The addition test confirmed the significant influence of dimethyl trisulfide on Chen-aroma note. Nine key odorants were identified as the differential quality-markers, and 85.71% key odorants were predicted using the partial least square regression (PLSR) analysis, indicating the applicability of PLSR in selecting the target compounds for omission tests.

An efficient phthalate ester-degrading Bacillus subtilis: Degradation kinetics, metabolic pathway, and catalytic mechanism of the key enzyme.

Phthalate ester pollution in the environment and food chain is frequently reported. Microbial treatment is a green and efficient method for solving this problem. The isolation and systematic investigation of microorganisms generally recognized as safe (GRAS) will provide useful resources. A GRAS Bacillus subtilis strain, BJQ0005, was isolated from Baijiu fermentation starter and efficiently degraded phthalate esters (PAEs). The half-lives for di-isobutyl phthalate, di-butyl phthalate and di-(2-ethylhexyl) phthalate were 3.93, 4.28, and 25.49 h, respectively, from the initial amount of 10 mg per 10 mL reaction mixture, which are records using wild-type strains. Genome sequencing and metabolic intermediate analysis generated the whole metabolic pathway. Eighteen enzymes from the α/ß hydrolase family were expressed. Enzymes GTW28_09400 and GTW28_13725 were capable of single ester bond hydrolysis of PAEs, while GTW28_17760 hydrolyzed di-ester bonds of PAEs. Using molecular docking, a possible mechanism affecting enzymatic ester bond hydrolysis of mono-butyl phthalate was proposed of GTW28_17760. The carboxyl group generated by the first hydrolysis step interacted with histidine in the catalytic active center, which negatively affected enzymatic hydrolysis. Isolation and systematic investigation of the PAE degradation characteristics of B. subtilis will promote the green and safe treatment of PAEs in the environment and food industry.

Discovery and development of a novel short-chain fatty acid ester synthetic biocatalyst under aqueous phase from Monascus purpureus isolated from Baijiu.

Short-chain fatty acid esters are important flavor chemicals in Chinese traditional fermented Baijiu. Monascus purpureus was recognized as an important microorganism contributing to ester synthesis. However, the molecular basis for ester synthesis was still lacking. The present work combined genome sequencing, transcriptome sequencing, gene library construction, and enzyme engineering to discover a novel catalyst from M. purpureus (isolated from Baijiu fermentation starter). Enzyme LIP05, belonging to the α/ß hydrolase family, was identified to synthesize short-chain fatty acid esters under aqueous phase. After deleting the lid domain of LIP05, the synthesis of ethyl pentanoate, ethyl hexanoate, ethyl octanoate, or ethyl decanoate was achieved. Ethyl octanoate with the highest conversion ratio of 93.7% was obtained with the assistance of ultrasound. The study reveals the molecular basis for synthesizing short-chain fatty acid esters by M. purpureus and will promote the application of the species or the enzyme in food industry.

A novel wheat germ polysaccharide: Structural characterization, potential antioxidant activities and mechanism.

A wheat germ polysaccharide (WGP-1) was isolated from wheat germ through hot-water (pH = 7.3) extraction and further fractionated by anion-exchange column using DEAE-52 cellulose column and purified by gel-permeation chromatography using Sephacryl S-500 column. WGP-1 was mainly consisted with rhamnose, arabinose, xylose, mannose, galactose and glucose, and linked with 1→, 1 â†’ 2, 1 â†’ 4, 1 â†’ 3 and 1 â†’ 6 glucosidic bands. The present study was designed to evaluate the antioxidant activities of WGP-1 in oleic acid (OA)-induced HepG2 cell model with its related mechanisms. Results showed that WGP-1 remarkably elevated the expression of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and total antioxidant capacity (T-AOC), and decreased the levels of malondialdehyde (MDA) and reactive oxygen species (ROS) in OA-treated cell. WGP-1 was found to promote the expression of PI3K, the phosphorylation of AKT and the translocation of Nrf2, further increased the expression of HO-1 in OA-induced cells. These results demonstrate again that WGP-1 can effectively improve OA-induced oxidative damage, probably by up-regulating of PI3K expression, Nrf2 translocation, and AKT phosphorylation.

Structural characterization and immuno-stimulating activities of a novel polysaccharide from Huangshui, a byproduct of Chinese Baijiu.

Huangshui (HS), a byproduct of Baijiu, has been widely studied for the utilization of aromatic compounds and microorganisms. However, there is little information on the bioactive polysaccharides in HS. In this study, a novel complex polysaccharide (HSP-2) composed of mannose, glucose, galactose, arabinose, xylose, and rhamnose at approximate percentages of 53.0, 29.6, 11.5, 2.7, 2.1, and 1.0, respectively, was successfully extracted and purified from HS. The results of FT-IR, methylation analysis, and NMR showed that the backbone of HSP-2 was â†’ 2)-ß-D-Manp-(1 â†’ 2,6)-ß-D-Manp-(1 â†’ 6)-α-D-Glcp-(1 â†’ 4)-α-L-Rhap-(1 â†’ 3,4)-α-L-Rhap-(1→. In addition, HSP-2 showed significant immuno-stimulating effects via increasing the ROS and NO generation, and enhancing the pinocytic and phagocytic capacities of THP-1 cells in a dose-dependent manner. Meanwhile, HSP-2 treatment increased IFN-γ, TNF-α, IL-6 and IL-1ß secretion through activating the expression of the related mRNAs and proteins. These results will provide a molecular basis for immuno-stimulating effects of HSP-2 and lay a foundation for the potential application of HS in functional foods.

Biodegradation of phthalate esters by Paracoccus kondratievae BJQ0001 isolated from Jiuqu (Baijiu fermentation starter) and identification of the ester bond hydrolysis enzyme.

Phthalate ester (PAE) pollution is an increasing problem globally. Paracoccus kondratievae BJQ0001 was isolated from the fermentation starter of Baijiu and showed an efficient degradation capability toward PAEs. To our poor knowledge, this is the first report of a P. kondratievae strain capable of degrading PAEs. The first complete genome sequence of P. kondratievae was presented without gaps, and composed of two circular chromosomes and one plasmid. The species simultaneously degraded di-methyl phthalate (DMP), di-ethyl phthalate (DEP), di-butyl phthalate (DBP), di-isobutyl phthalate (DIBP) and di-(2-ethylhexyl) phthalate (DEHP), with DMP and DEP as the preferred substrates. The half-life (t1/2) of DMP was only 6.34 h with an initial concentration of 200 mg/L. Combined with gene annotation and metabolic intermediate analysis, a metabolic pathway was proposed for the species. Benzoic acid, the intermediate of anaerobic PAE metabolism, was identified in the aerobic degradation process. Two key enzymes for alkyl ester bond hydrolysis were obtained, and belonged to families IV and VI of hydrolases, respectively. These results will promote the investigation of PAE degradation by P. kondratievae, and provide useful information for improving the quality control of food and environmental PAE treatment.

Polyamine-Modified Magnetic Graphene Oxide Nanocomposites and HPLC-MS/MS Allow the Determination of Two Indolic Derivatives in Strong-Aroma Types of Base Baijiu.

Simultaneous detection of 3-indoleacetic acid (IAA) and 3-indolepropionic acid (IPA) in strong-aroma types of base Baijiu (base SAB) is crucial for elucidating the metabolic pathway of 3-methylindole during the base SAB brewing. Herein, a novel magnetic poly(allylamine)-modified graphene oxide (GO@PAA@Fe3O4) was synthesized as extraction sorbent, followed by high performance liquid chromatography mass spectrometry HPLC-MS/MS. As a surface modifier of GO, the introduction of PAA and Fe3O4 provided more adsorption sites for IAA and IPA, mainly through the generation of H-bonding sites. Moreover, modified by an activation step, the capacity of the activated GO@PAA@Fe3O4 for the adsorption of IAA and IPA was 2.1-3.4 times higher than that of unactivated material. The adsorptions of IAA and IPA on GO@PAA@Fe3O4 were fitted to the pseudo-second-order kinetic model and Langmuir isotherm, respectively. Under the optimal conditions, IAA and IPA were determined in 16-base SAB for the first time, and their concentrations ranged from 0.6 to 11.3 and 0.7 to 18.7 µg/L, respectively.

Evaluation of antioxidant peptides generated from Jiuzao (residue after Baijiu distillation) protein hydrolysates and their effect of enhancing healthy value of Chinese Baijiu.

BACKGROUND: Jiuzao is the residue after Bajiu distillation which is usually used as forage for livestock. However, it is not fully utilized yet considering the content of protein remained. The present study aimed to isolate antioxidant peptides from Jiuzao protein hydrolysates, then add these peptides into Baijiu product to enhance the healthy value of Baiju. Meanwhile environmental pollution caused by massive Jiuzao can be mitigated indirectly. RESULTS: Four peptides Ala-Tyr-Ile(Leu) (AYI(L)) and Asp-Arg-Glu-Ile(Leu) (DREI(L)) were identified from Jiuzao protein hydrolysates, the extraction contents of AYI + AYL and DREI + DREL were 896.10 and 110.51 mg kg-1 Jiuzao, respectively. On the one hand, antioxidant activities of these peptides were investigated. For in vitro antioxidant assays, AYI, AYL and DREI exhibited strong capacities in oxygen radical absorbance capacity (ORAC) assay. Furthermore, three levels of four peptides were assessed by 2,2'-azobis(2-methylpropanimidamidine) (AAPH)-induced HepG2 cells model. The results showed that these peptides exerted a degree of antioxidant activities in cells. Meanwhile, selected peptides concentrations according to cell assays remined at effective doses after in vitro digestion. On the other hand, the influence of these four peptides on the characteristic aroma compounds in Baijiu was studied. Most characteristic aroma compounds releases were increased with the addition of peptides. CONCLUSION: In the study, antioxidant activities of peptides were evaluated, the feasibility of utilizing Jiuzao protein hydrolysates to obtain beneficial peptides was also proved. Healthy effect of Baijiu or other food can be increased by adding these functional substances. The findings might contribute to food application and Baijiu industries. © 2019 Society of Chemical Industry.

Binding of aldehydes to myofibrillar proteins as affected by two-step heat treatments.

BACKGROUND: The present study investigated the effect of two-step heat treatments on the structure of grass carp myofibrillar proteins (MPs) and their binding ability for selected aldehydes (hexanal, heptanal, octanal and nonanal). RESULTS: Within 30 min of the first heating step at 40 °C and 5-10 min of the second heating step at 90 °C, the enhancement of the flavor-binding ability was likely explained by the increases in surface hydrophobicity and total sulfhydryl content due to the unfolding of secondary structures of MPs through exposure of hydrophobic amino acids and sulfhydryl groups. Nevertheless, lengthy heating at 90 °C accelerated the aggregation of unfolded MPs and reduced the hydrophobic bonding sites, thus weakening the hydrophobic interactions and decreasing the resultant binding ability of MPs with aldehydes. CONCLUSION: The binding ability of aldehydes to MPs was found to be strongly influenced by changes in protein structure and surface during the two-step heating process. The results provided insight into improving the flavor characteristics of freshwater fish surimi products. © 2019 Society of Chemical Industry.

Characterization of key odorants causing the roasted and mud-like aromas in strong-aroma types of base Baijiu.

The roasted and mud-like aromas in Chinese strong-aroma types of base Baijiu (base SAB) and the interactions among the corresponding key compounds causing these two characteristic aromas were investigated. A total of 68 and 64 odorants were identified in the base and commercial SAB by comparative aroma extract dilution analysis. Furthermore, the complex matrix of Baijiu always pose a long-term challenge for quantitative accuracy and precision of target aroma compounds; thus, the odorants with flavor dilution (FD) ≥ 9 were further quantified by multiple quantitative techniques, including the direct injection combined with gas chromatography-flame ionization detector, the vortex-assisted surfactant-enhanced emulsification liquid-liquid microextraction (VSLLME) combined with GC-MS, and the derivatization method combined with VSLLME-GC-MS, and 37 and 26 odorants were shown to be important odorants as their OAVs ≥1. Among these components, 5 compounds, hexanoic acid, butyric acid, p-cresol, 3-methylindole, and 3-(methylthio)propanal showed higher OAVs in base than in commercial SAB, and based on aroma recombination and omission analysis, they were confirmed to be the key odorants responsible for the mud-like and roasted odors. The evaluation of the aforementioned five key odorants by the "addition" test showed that the roasted and mud-like aromas of base SAB were related, and the odors were mainly attributed to additive or masking effects among the compounds.