Search

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]

Background and Objectives: Mashing temperature is important during beer brewing processes. Qingke malt was a new material whose application in the beer industry holds significant importance for the beer industry and agriculture development in the Qinghai–Tibet Plateau. The objective of this study was to investigate the effects of mashing temperature on the physicochemical parameters, fermentation capacity, and antioxidant capacity of Qingke wort. Findings: Ethanol production and the real degree of fermentation decreased with increasing the temperature—S, while the real extract increased with increasing the temperature—S. A lower temperature—S proved to be more advantageous for the fermentation capacity of Qingke wort. In addition, a positive correlation between reducing power and the temperature—P and a negative correlation between the 2,2′‐azinobis‐(3‐ethylbenzothiazoline‐6‐sulfonate) free radical scavenging activity and the temperature—S were found. Conclusion: The fermentation capacity of Qingke wort was obtained the best when the temperature—P was 50°C and the temperature—S was 60°C. The antioxidant capacity of Qingke wort was satisfactory; the best was obtained when the temperature—P was 45°C and the temperature—S was 60°C. Significance and Novelty: This is the first study to investigate the mashing characteristics of Qingke wort under different mashing temperatures. The results show that β‐glucan content was abundant in Qingke wort and was positively correlative with the temperature—S. [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]

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]

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]

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]

BACKGROUND RESULTS CONCLUSION Fern root starch has a high percentage of amylose and has great potential for application in the field of slow‐digesting foods. Clarifying the effect of treatment conditions on fern root starch is key to achieving industrialized production of fern root resistant starch. In the present study, fern root starch was treated by the autoclave‐enzymatic method with pullulanase, glucoamylase and mixed enzyme.The content of resistant starch in fern roots treated with mixed enzyme was the highest (24.07 ± 1.11%), which was approximately 320% times that of the native starch, had the best water‐holding capacity (151.08%), vital transparency and freeze–thaw stability. By contrast, the solubility, swelling and viscosity were lower than natural starch. In addition, mixed enzyme shows a denser structure, and the crystal form changes from C‐type to V‐type, with a high relative crystallinity and significantly enhanced thermal stability.After mixed enzyme combined with autoclave treatment, the content of resistant starch in fern root was greatly increased. The modified starch molecules did not produce new functional groups, which made the crystal structure of starch molecules more compact, and resistance to enzymatic hydrolysis and high temperature thermal stability were significantly enhanced. This provides a positive reference for further in‐depth study of fern root starch, improvement of utilization value, development and innovation of new food health products, and diabetes treatment. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]