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BACKGROUND: Baijiu brewing adopts the solid‐state fermentation method, using starchy raw materials, Jiuqu as saccharifying fermenting agent, and distilled spirits made by digestion, saccharification, fermentation and distillation. In the late stages of solid‐state fermentation of Baijiu, the reduced activity of glucoamylase leads to higher residual starch content in the Jiupei, which affects the liquor yield. The direct addition of exogenous glucoamylase leads to problems such as the temperature of the fermentation environment rising too quickly, seriously affecting the growth of microorganisms. RESULTS: To solve the problem of reduced activity of glucoamylase in the late stage of solid‐state fermentation of Baijiu, microcapsule beads (M‐B) based on microcapsule emulsion were prepared and the effect of M‐B on solid‐state fermentation of Baijiu was investigated. The results showed that the release of M‐B before and after drying was 53.27% and 25.77% in the liquid state (120 h) and 29.84% and 22.62% in the solid state (15 days), respectively. Adding M‐B improved the alcohol by 0.33 %vol and reducing sugar content by 0.51%, reduced the residual starch content by 1.21% of the Jiupei, and had an insignificant effect on the moisture and acidity of the Jiupei. CONCLUSION: M‐B have excellent sustained‐release properties. The addition of M‐B in solid‐state fermentation significantly increased the alcohol content, reduced the residual starch content of Jiupei, ultimately improving the starch utilization rate and liquor yield of Baijiu brewing. The preparation of M‐B provides methods and approaches for applying other active substances and microorganisms in the brewing of Baijiu. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The glucoamylase@ZIF‐8 was prepared using ZIF‐8 material as the carrier in this study. The preparation process was optimized by response surface methodology, and the stability of glucoamylase@ZIF‐8 was determined. The material was characterized by scanning electron microscopy, X‐ray diffraction, and Fourier transform infrared spectroscopy. The results showed that the optimum preparation process of glucoamylase@ZIF‐8 was 1.65 mol 2‐methylimidazole, 5.85 mL glucoamylase, 33°C stirring temperature, 90 min stirring time, and 84.0230% ± 0.6006% embedding rate. At 100°C, the free glucoamylase completely lost its activity, whereas the glucoamylase@ZIF‐8 still had a retained enzyme activity of 12.0123% ± 0.86158%; at pH 3–6, the highest activity of glucoamylase@ZIF‐8 was 95.9531% ± 0.96181%, and about 80% of glucoamylase activity could be retained under alkaline conditions. When the ethanol concentration was 13%, the retained enzyme activity was 7.9316% ± 0.19805%, significantly higher than free enzymes. The Km of glucoamylase@ZIF‐8 and free enzyme were 1235.6825 and 80.317 mg/mL, respectively. Vmax was 0.2453 and 0.149 mg/(mL min), respectively. The appearance, crystal strength, and thermal stability of glucoamylase@ZIF‐8 were improved after optimization, and they had high reusability. [ABSTRACT FROM AUTHOR]

Glucoamylase was often used in the brewing industry but was unstable to several environmental factors and reacted quickly to produce fermentable sugar, which limited its applications. Microencapsulation could effectively overcome the drawbacks. This study evaluated the feasibility of the preparation of glucoamylase microcapsules (GM) using W/O/W complex coacervation‐freeze‐drying method. The parameters of the microcapsules were optimized by the response surface optimization design: core‐wall ratio at 1:1, wall‐material concentration at 8%, and coagulation time for 20 min. Under current condition, the final microencapsulation efficiency reached 85.64 ± 1.60%. Glucoamylase could be slowly released for more than 96 h in the liquid state, and could react slowly for more than 336 h in the solid state. The optimized GM were incubated for 1 h, and the relative enzyme activity was better than that of free glucoamylase under high temperature conditions. The water capacity, solubility, morphology, differential scanning calorimetry, and Fourier transform infrared spectroscopy were conducted. Glucoamylase exhibited good sustained release characteristics. The microcapsules were more resistant to environmental stimuli and showed stronger robustness after optimization. Practical Application: Saccharification enzymes are often used in the winemaking industry, and direct addition will cause the fermentation process to heat up too quickly, resulting in the inactivation of microorganisms and saccharification enzymes, affecting the efficiency of saccharification enzymes. Therefore, microcapsules are used to encapsulate the saccharification enzyme, and its efficacy is slowly released for a long time during the fermentation process. [ABSTRACT FROM AUTHOR]

To explore the reuse of brewer's grains and develop novel Chinese fermented sausage with healthy characteristics, the influences of the addition of plant protein‐dietary fiber composite gel and Lactiplantibacillus plantarum XC‐3 on Chinese dry fermented sausages were studied. The results showed that the addition of Lactiplantibacillus plantarum XC‐3 reduced the pH, water activity, total volatile base nitrogen, residual nitrite, and thiobarbituric acid of fermented sausages while increasing the hardness, springiness, chewiness, and total volatile flavor substances of the fermented sausages (p < 0.05). In all, 69 volatile flavor substances were identified in the fermented sausages. The addition of plant protein‐dietary fiber composite gel resulted in a significant increase in the acids and esters content of fermented sausages (p < 0.05), but the increase in gel addition resulted in a decrease in the total content of volatile flavor substances in fermented sausages (p < 0.05) (still much higher than in the fermented sausage without gel addition). Novelty impact statement: The addition of plant protein‐dietary fiber gel and inoculation with Lactiplantibacillus plantarum XC‐3 effectively reduced harmful carcinogens in fermented sausages while promoting the production of flavor substances and adding some new ones. The novel fermented sausage developed in this study is delicious and healthy, which provides theoretical support for the development of healthy foods in the meat processing industry. [ABSTRACT FROM AUTHOR]

Changes in the content and morphology of residual starch in Zaopei during strong‐flavor Baijiu fermentation are investigated. The results show that the residual starch content increases through the Baijiu production and that the residual starch content of distiller's grains (DGS) is the highest (76.35%). The crystalline structure of starch changes from A‐type (raw grain starch) to B + V‐type (Zaopei, Hongzao, Mianzao, DGS). The upper Zaopei starch has the typical diffraction peaks of B + V‐type (7.4°, 12.8°, 14.9°, 19.7°, 19.6°, 26.6°) and retains the typical diffraction peaks of A‐type (17.0°, 22.2°). The intermediate and bottom Zaopei starch has the typical diffraction peaks of B + V‐type (7.4°, 12.8°, 16.9°, 19.7°, 20.7°, 26.6°) and loses the typical diffraction peaks of A‐type. With the progression of Baijiu production, the gelatinization temperature and enthalpy of starch increase, while the water‐holding capacity, freeze‐thaw stability, solubility, and swelling power decrease. The above results show that the starch complex is the primary form of residual starch in strong‐flavor Baijiu. [ABSTRACT FROM AUTHOR]

Glucoamylase is one of the most widely used enzymes in industry, but the development background and existing circumstances of industrial glucoamylase were not described by published articles. CiteSpace, a powerful tool for bibliometric, was used to analyze the past, existing circumstances, and trends of a professional field. In this study, 1820 Web‐of‐Science‐indexed articles from 1991 to 2021 were collected and analyzed by CiteSpace. The research hotspots of industrial glucoamylase, like glucoamylase strain directional improvement, Aspergillus niger glucoamylase, glucoamylase immobilization, application of glucoamylase in ethanol production, and "customized production" of porous starch, were found by analyzing countries, institutions, authors, keywords, and references of articles. Practical applications: The research progress of glucoamylase with industrial potential was analyzed by CiteSpace, and a significant research direction of glucoamylase with industrial potential was found. This is helpful for academic and corporate audiences to understand the current situation of glucoamylase with industrial potential and carry out follow‐up works. [ABSTRACT FROM AUTHOR]

The traditional quality testing methods of Baijiu have several challenges including long duration of testing that increases the workload of the laboratory. In this experiment, Raman spectroscopy was used to efficiently control the quality of Baijiu. The spectroscopy were primarily preprocessed using the wavelet domain denoising technique and the principal component analysis (PCA). The rapid identification and classification of 496 samples of Baijiu with various alcohol concentrations (AC), flavor grade (FG), and production year (PY) were achieved using a neural network model constructed based on Raman spectroscopy and genetic algorithm-back propagation (GA-BP). The results indicated that in comparison to the BP neural network, the best GA-BP network model achieved 95.68%, 91.37%, and 93.96% correct recognition rates for the three indicators namely, AC, FG, and PY respectively. Additionally, the average correct recognition rate of the model was enhanced by 3.62%, 9.4%, and 8.45% for AC, FG, and PY respectively. In this study, for the first time, AC, FG, and PY of Baijiu were combined to construct a model that enabled the scientific identification of Baijiu samples in unique circumstances and it also provided a new reference method for the identification, detection, and classification of Baijiu. [Display omitted] ● Prediction of alcohol concentration, flavor grade and production year of Baijiu. ● Spectral preprocessing using wavelet denoising and principal component analysis. ● Baijiu was identified by combining Raman spectroscopy with GA-BP neural network. [ABSTRACT FROM AUTHOR]

Summary: Oxygen is contributing to the deterioration of the beer and shortening the shelf‐life of the packaged product. The effect of dissolved oxygen (DO) on oxidative and structural characteristics of protein in beer during forced ageing was examined. Results showed that increased DO decreased obviously protein content in beer, and further reduced antioxidant activities of beer and lipid transfer protein 1 (LTP1). Meanwhile, the increase of DO decreased significantly the free thiol groups content and enhanced the disulfide bonds level in beer and LTP1. Results from circular dichroism, surface hydrophobicity and zeta‐potential illustrated that the increase of DO dramatically changed the secondary and tertiary structure of LTP1 with the decrease in the surface hydrophobicity, α‐helix and β‐turn contents, and the increase in the random coil and negative zeta potential. These results indicated that increased DO could damage the structure of LTP1 and had a negative impact on oxidative stability of beer. [ABSTRACT FROM AUTHOR]

Abstract Very high-gravity (VHG) worts (24 °P) supplemented with wheat gluten hydrolysates (WGH) and their ultrafiltration fractions (Mw > 1 kDa and <1 kDa fractions) were used to evaluate their effects on physiological activity and ethanol fermentation of brewer's yeast. The results demonstrated that WGH and their ultrafiltration fractions supplementations could obviously improve the biomass and viability of yeast, and further enhance the sugar utilization and ethanol production under VHG fermentation. Supplementation with Mw < 1 kDa fraction exhibited the maximum biomass (6.90 g/L dry cell), sugar utilization (79.79%) and ethanol concentration (11.88%, v/v) during VHG fermentation. Meanwhile, the addition of Mw < 1 kDa fraction significantly decreased the plasma membrane permeability and intracellular reactive oxygen species (ROS) accumulation, and increased the mitochondrial membrane potential in cells during VHG fermentation. Moreover, Mw < 1 kDa fraction supplementation caused the highest accumulations of intracellular trehalose and glycerol, which were 12.10% and 31.22% higher than the control, respectively. These results illustrated that WGH (especially Mw < 1 kDa fraction) addition was an economic and efficient method to improve physiological activity and ethanol fermentation of brewer's yeast in VHG worts. Highlights • WGH and their ultrafiltration fractions were obtained as nitrogen sources of yeast. • WGH supplementation changed nitrogen metabolism of yeast during VHG fermentation. • Biomass and ethanol production were increased by WGH addition under VHG condition. • Physiological activity of yeast was improved by WGH addition under VHG condition. • Trehalose and glycerol in yeast accumulated by WGH addition under VHG condition. [ABSTRACT FROM AUTHOR]

Highlights • WGH supplementation improved the tolerance to osmotic and ethanol stress in yeast. • WGH supplementation improved ethanol production of yeast under VHG fermentation. • WGH addition caused the decrease in ROS and the increase in membrane integrity. • WGH addition increased the levels of intracellular glycerol and trehalose in yeast. • 40% ethanol fraction from WGH showed the best bioactivity for yeast cells. Abstract Wheat gluten hydrolysates (WGH) and their fractions (0%, 20% and 40% ethanol fractions) obtained on XAD-16 were used to examine their effects on multiple stress tolerance and ethanol fermentation performances of yeast during very high-gravity (VHG) fermentation. Results showed that WGH and their fractions supplementations increased significantly osmotic/ethanol stress tolerance, growth and vitality of yeast cells. Supplementation with 40% ethanol fraction resulted in 46.54% and 35.01% of increase in cell membrane integrity, and 42.59% and 21.79% of reduction in intracellular ROS level under osmotic and ethanol stress conditions, respectively. Moreover, WGH and their fractions supplementations also increased physiological activity and ethanol yield of yeast cells under VHG fermentation, and 40% ethanol fraction supplementation caused the maximum biomass and ethanol production during VHG fermentation. These results suggested that WGH supplementation was an efficient and convenient method for improvement of yeast cells with enhanced multiple stress tolerance and ethanol fermentation performances. [ABSTRACT FROM AUTHOR]

Wheat gluten hydrolysates (WGH) were used to examine their adsorption–desorption kinetics and thermodynamics characteristics on six macroporous resins, and their effects on the stress tolerance in brewer’s yeast. Results showed that the pseudo second-order kinetics, Langmuir and Freundlich model could illuminate the adsorption mechanism, and the adsorption process was physical, spontaneous and exothermic. The 40% ethanol fraction separated by XAD-16 resin improved significantly the ethanol tolerance and the viability of brewer’s yeast, while the 0% ethanol fraction separated by XAD-16 resin increased obviously the osmotic stress tolerance and the viability of brewer’s yeast. Results from scanning electron microscopy showed that both these WGH fractions could increase budding rate and maintain normal morphology of yeast cells under various environmental stress. Thus, WGH separated by macroporous resin could be used in high gravity brewing to enhance the ethanol and osmotic stress tolerance in brewer’s yeast. [ABSTRACT FROM AUTHOR]

Summary: Three kinds of beers with different degrees of ageing were used to examine their nonvolatile small molecules by a metabonomics approach based on ultra performance liquid chromatography coupled with quadrupole time‐of‐flight tandem mass spectrometry (UPLC‐Q‐ToF‐MS/MS). Results showed that a total of 2114 compounds were detected in forced‐aged beers with the positive mode of UPLC‐Q‐ToF‐MS/MS. There was a clear separation among three groups of beers with different degrees of ageing in principal component analysis (PCA) model. Sixteen potential metabolite markers related to beer oxidative stability were identified by orthogonal partial least‐squares discriminate analysis (OPLS‐DA). Results from the changes in the spectrum also indicated that some new compounds formed in beer during forced ageing. Thus, the proposed metabonomics approach is a powerful tool to give a fully understanding the ageing process of beer based on the identification of the markers related to oxidative stability. [ABSTRACT FROM AUTHOR]

Abstract: Lys and Leu were generally considered as the key amino acids for brewer's yeast during beer brewing. In the present study, peptide Lys–Leu and a free amino acid (FAA) mixture of Lys and Leu (Lys + Leu) were supplemented in 24 °P wort to examine their effects on physiological activity and fermentation performance of brewer's yeast during very high‐gravity (VHG) wort fermentation. Results showed that although both peptide Lys–Leu and their FAA mixture supplementations could increase the growth and viability, intracellular trehalose and glycerol content, wort fermentability, and ethanol content for brewer's yeast during VHG wort fermentation, and peptide was better than their FAA mixture at promoting growth and fermentation for brewer's yeast when the same dose was kept. Moreover, peptide Lys–Leu supplementation significantly increased the assimilation of Asp, but decreased the assimilation of Gly, Ala, Val, (Cys)2, Ile, Leu, Tyr, Phe, Lys, Arg, and Pro. However, the FAA mixture supplementation only promoted the assimilation of Lys and Leu, while reduced the absorption of total amino acids to a greater extent. Thus, the peptide Lys–Leu was more effective than their FAA mixture on the improvement of physiological activity, fermentation performance, and nitrogen metabolism of brewer's yeast during VHG wort fermentation. [ABSTRACT FROM AUTHOR]

As a promising adjunct material to beer brewing, Qingke (hulless barley) can provide sufficient hydrolyzable starch and rich nutrients for beer brewing. In this study, the effect of Qingke addition on the physicochemical properties, antioxidant capacity and flavor composition of beer was evaluated. The results showed that the addition of Qingke reduced the turbidity (25.03 NTU) and color (19.48 EBC) of the beer. The Qingke adjunct beer was enriched with more bioactive substances, which also made the Qingke adjunct beer exhibit better antioxidant capacity. The addition of Qingke resulted in elevated levels of higher alcohols (68.29 mg/L) and esters (76.71 mg/L). The addition of Qingke decreased the amount of volatile acid in the beer (5.84 mg/L). This study has guiding significance for the application of Qingke in beer industry. [Display omitted] • Proposal of a new adjunct material for beer brewing--Qingke. • Qingke can effectively boost the endogenous antioxidant power of beer. • The effect of Qingke on the composition of beer flavor substances was revealed. [ABSTRACT FROM AUTHOR]

The property changes of sorghum starch during multiple cycles of gelatinization and fermentation were studied. This study simulated the gelatinization and fermentation process of raw starch in strong-flavor Baijiu production (Sorghum as raw material, the distillers' grains as a control). The results showed that the starch content of the same batch of sorghum after five cycles of gelatinization and fermentation was 9.98% (Cannot continue to be used for fermentation), and about 60% of the starch was consumed in the first three cycles of gelatinization and fermentation. The gel properties of sorghum starch gradually decreased during fermentation but slightly increased after gelatinization. After five cycles of gelatinization and fermentation, the sorghum starch has a uniform size and a thin and small fragment structure. At the same time, sorghum starch does not form new groups. The recrystallization of starch caused by multiple cycles of gelatinization and fermentation increased the onset gelatinization temperature (from 61.6 to 114.4 °C), peak gelatinization temperature (from 78.5 to 139.5 °C), and gelatinization enthalpy (from 7.980 to 17.121 J/g) of sorghum starch. The crystalline structure of sorghum starch changed from the initial type A to type A + V, type A + B + V, and finally to type B. Fig The process of multiple gelatinization and fermentation. [Display omitted] • The crystal structure, gel properties and gelatinization properties of raw starch in Baijiu production process were studied. • The effects of five cycles of gelatinization and fermentation on the properties of sorghum starch were studied. • The changes of residual starch content and proportion of amylose in distiller's grains were studied. [ABSTRACT FROM AUTHOR]

In this study, microcapsule beads‐0–3‐layers (M‐0–3 indicates microencapsulated beads with 0, 1, 2, and 3 layers) were prepared, their properties were measured and characterized, and the effects of M‐0–3 on solid‐state fermentation were investigated. The results showed that in a liquid environment, the releasing glucoamylase activities of M‐0–3 were 55.77%, 47.67%, 45.85%, and 42.87% in 360 h, respectively. In the solid environment, the reducing sugar production efficiency of M‐0–3 was 29.84%, 27.72%, 19.16%, and 15.93% in 15 days, respectively. Adding M‐0–3 improved the alcohol and reduced sugar content while decreasing the residual starch content of the Jiupei, indicating that adding M‐0–3 was beneficial to the solid‐state fermentation of Baijiu. Solid‐state fermentation simulation experiments illustrated that microcapsule beads play a positive role in the production of Baijiu, enhancing raw material utilization and yield of Baijiu production. [ABSTRACT FROM AUTHOR]

Highlights • Wheat gluten hydrolysates (WGH) and soy protein hydrolysates (SPH) were prepared. • WGH and SPH exhibited significant yeast growth and fermentation promoting activity. • The bioactivity was not linear with the degree of hydrolysis and addition amount. • Bioactivity of hydrolysates was related to the molecular structure characteristics. • Glu, Leu, Lys and Arg in hydrolysates were responsible for their bioactivity. Abstract Wheat gluten hydrolysates (WGH) and soy protein hydrolysates (SPH) were used to examine their effects on the growth and fermentation performance of yeast during high-gravity fermentation. Results showed that both the kind and the addition amount of hydrolysates had significant impacts on the biomass, viability, fermentability and ethanol yield of yeast cells. Worts supplemented with WGH and SPH (with the hydrolysis time of 24 h and 12 h, and the addition amount of 1.0% and 0.1%, respectively) increased 5.5% and 12.6% of net cell growth, 0.3% and 1.1% of fermentability, and 19.3% (v/v) and 23.7% (v/v) of ethanol yields, respectively. All these results indicated that both hydrolysates were effective and preferential nitrogen sources for yeast growth and fermentation. The moderate molecular weight distribution, the complexity of nitrogen source and the higher hydrophilic and basic amino acids contents in hydrolysates might be responsible for their specific bioactivity. [ABSTRACT FROM AUTHOR]

Summary: Wheat gluten hydrolysates (WGH) were fractionated through ultrafiltration membrane with molecular weight (Mw) cut‐off of 3 kDa and ethanol precipitation, respectively. WGH and their fractions were used to examine their effects on the growth and fermentation performances of brewer's yeast under high gravity fermentation. Results showed that WGH and their fractions exhibited significant differences in biomass accumulation, viability, ethanol yield, free amino nitrogen and sugar consumptions under high gravity fermentation. Compared to WGH, the fractions with Mw < 3 kDa and the supernatant of WGH treated with ethanol precipitation showed better fermentation performance for brewer's yeast. The relatively lower molecular weight and the higher levels of Leu, Lys, His and Arg in these two fractions might be responsible for their bioactivity for brewer's yeast. Thus, both ultrafiltration and ethanol precipitation could be used as efficient methods for enriching peptides with significant growth‐ and fermentation‐promoting activity for brewer's yeast under high gravity fermentation. [ABSTRACT FROM AUTHOR]

By sampling the wort from different stages of mashing and boiling, part of the sample was used for the acquisition of three spectra (NIR, Raman and UV–Vis) and the other part for chemical analysis. The results of chemical analysis and spectra were combined using chemometrics, and three models of PLS((Partial Least Squares), LS-SVM(Least Squares Support Vector Machines), and NN(Neural Networks) were developed to quantify reducing sugar, free amino nitrogen, and total phenols contents in wort. The aim of the study is to investigate the best spectra and models for the quantitative analysis of key wort components during mashing and boiling of Qingke malt, so as to achieve real-time monitoring of the Qingke beer brewing process. [Display omitted] • Qingke malt has the potential to become a raw material for beer brewing. • Quantitative models were developed using three spectra in combination with chemometrics. • The study focuses on the brewing process of beer to make it clearer and more controllable. In order to monitor the Qingke beer brewing process in real time, this paper presents an analytical method for predicting the content of key components in the wort during the mashing and boiling stages using multi-spectroscopy combined with chemometrics. The results showed that the Neural Networks (NN) model based on Raman spectroscopy (RPD = 3.9727) and the NN model based on NIR spectroscopy (RPD = 5.1952) had the best prediction performance for the reducing sugar content in the mashing and boiling stages; The partial least Squares (PLS) model based on Raman spectroscopy (RPD = 2.7301) and the NN model based on Raman spectroscopy (RPD = 4.3892) predicted the content of free amino nitrogen best; The PLS model based on UV–Vis spectroscopy (RPD = 4.0412) and the NN model based on Raman spectroscopy (RPD = 4.0540) are most suitable for the quantitative analysis of total phenols. The results can be used as a guide for real-time control of wort quality in industrial production. [ABSTRACT FROM AUTHOR]

Crushing and enzyme treatment are pivotal factors that cannot be ignored in the mashing stage of qingke (hull-less barley) craft beer brewing. This study aimed to explore the impact of different mashing conditions on physicochemical, fermentation, and antioxidant properties of qingke wort as well as elucidate the mechanisms of mashing conditions affecting the quality of qingke wort. The results showed that wort with a high fermentable sugar content, including maltose and glucose, could be obtained using a crushed size smaller than 0.9 mm. Furthermore, enzyme treatment further led to an increase in fermentable sugar content, enhancing the fermentation capacity of qingke wort. Notably, crushing significantly affected the antioxidant properties of qingke wort, with smaller crushed particle sizes yielded superior antioxidant properties to the wort, mainly due to the increase in the content of phenolic compounds such as chlorogenic acid, caffeic acid, and epicatechin. • Qingke malt with a crushed size of less than 0.9 mm is suitable for beer brewing. • Phenolic compounds are the main antioxidants in qingke wort. • Crushing and enzyme treatment can effectively improve the quality of qingke wort. [ABSTRACT FROM AUTHOR]

Drying is an important process in black tea processing, at the same time, catechin is an important factor in determining the sensory quality of black tea. However, there is a lack of effective real-time detection methods for the detection of catechins in black tea drying process. Therefore, we analyzed the trends of catechins in black tea drying process under different drying conditions and further explored the quantitative prediction model of eight individual catechins in black tea drying process by Least squares support vector machine (LS-SVM) based on near-infrared spectroscopy (NIRS) and chemometrics methods. The results showed that the prediction accuracy of the eight monomeric catechins prediction models established based on the extraction of competitive adaptive reweighted sampling (CARS) and successive projections algorithm (SPA) feature spectra achieved the best results, and the correlation coefficient values of the prediction sets (R p) were all greater than 0.98, and the relative percentage deviation (RPD) values were all greater than 5. The gallocatechin gallate (GCG) with the highest prediction accuracy was 0.9977 and the RPD value was 14.8. This study shows that the method based on near-infrared spectroscopy and chemometrics has strong predictive power for catechins in black tea drying process, which is a guideline for controlling the sensory quality of black tea drying. • Different drying temperatures and times affect the catechin content of black tea. • Catechin during black tea drying was monitored using NIR spectroscopy. • Different quantitative prediction models were compared to accurate detection of catechins. • NIR spectroscopy can be used to monitor the drying process of black tea. [ABSTRACT FROM AUTHOR]

[Display omitted] • Provides a strategy for the rapid analysis of the flavor substances of baijiu. • Comparing of 11 preprocessing methods and 2 modeling methods. • Modeling analysis of 10 main flavor substances in baijiu. Recently, there has been an increasing demand for developing a reliable method to assess the quality of liquor in the baijiu industry quickly and accurately. The present study sought to establish a strategy for rapid quantitative analysis of the primary flavor components in Nongxiangxing baijiu. Under the experimental conditions, 7 of the 10 major flavor components in Nongxiangxing baijiu could be quantified effectively, such as ethyl butyrate (R2p = 0.9942), ethyl lactate (R2p = 0.9438), n -butanol (R2p = 0.9048), isobutanol (R2p = 0.9696), acetic acid (R2p = 0.9600), butyric acid (R2p = 0.8448), caproic acid (R2p = 0.9971). This result indicates that FT-IR combined with quantitative chemometric modeling could be a potential approach for rapid quality assessment of Nongxiangxing baijiu. Overall, this study provides a theoretical basis for subsequent related studies on Nongxiangxing baijiu. [ABSTRACT FROM AUTHOR]