Search

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]

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]

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]

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]