Journal of The Institute of Brewing最新文献

New value-adding applications of spent grain, a co-product of brewhouse operations, are considered in the context of a sustainable circular economy. Previous studies have focused on the compounds remaining in the solid phase of the spent grain. However, depending on the dewatering process, the separated water also contains relevant fractions of nutritionally and physiologically valuable compounds including proteins, carbohydrates and polyphenols. Accordingly, the work reported here considers the two fractions and presents a detailed view of relevant substances especially those from liquor. The reported mass balance is the result of these investigations, supplemented by values from the literature. The potential value of these compounds for industrial biotechnology is examined in an economic assessment. © 2022 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling.

Commercial koji are increasingly used as the microbial inoculum in the production of rice wine. This study reports on the use of six commercial koji on rice wine brewing and shows that the microbial composition varied significantly among the different koji. Of the koji, AQ (An Qi) and YB (Yi Bin) contained fewer microflora but exhibited higher starch degradation and wine production efficiency. The Two-way Orthogonal PLS model and Pearson correlation analysis suggests that the presence of biogenic amines in rice wine was related to contaminating microorganisms in the koji including Lactobacillus, Kosakonia, Pantoea, Ralstonia, Kosakonia and Pantoea. The formation of higher alcohols is related to Saccharomyces species. Screening of beneficial yeasts with low production of higher alcohols and avoiding contamination by unwanted bacteria are suggested for improving the quality of rice wine. © 2022 The Institute of Brewing & Distilling.

While cysteinylated (Cys-) and glutathionylated (G-) precursors of 3-sulfanylhexanol (3SHol) and 3-sulfanylpentanol (3SPol) appear to be ubiquitous in hop varieties, no data are available on precursors of their seven-carbon analogue 3-sulfanylheptanol (3SHptol), although the free form has been found in both hops and beer. Chemical synthesis of Cys- and G-3SHptol enabled determination of their chromatographic elution times (14.3-14.8 and 16.2-17.1 min, respectively) and ESI(+) mass spectra (main m/z fragments: 219 and 293, for Cys- and G- 3SHptol, respectively). Here, for the first time, we report the occurrence of G-3SHptol in a natural matrix. RP-HPLC-ESI(+) MRM analysis of selective extracts eluted from a cation exchange resin quantified G-3SHptol in green malt (0.10 mg/kg), while no trace was found after kilning. Neither the cysteinylated nor the glutathionylated conjugate was found in hop or grape extracts. G-3SHptol is formed in-situ from trans-2-heptenal and free glutathione, and its synthesis most likely involves aldol condensation between acetaldehyde and pentanal instead of lipid oxidation. © 2022 The Institute of Brewing & Distilling.

The dilution of whiskey with water can lead to the formation of unwanted haze which is exacerbated at lower temperatures. This phenomenon is well known in the whiskey industry, and it is normal practice to use cold filtration to produce a clear product as well as improve product stability. However, to date, there has been no quantitative characterisation or understanding of the size and concentration of the colloidal particles as a function of whiskey dilution, temperature, and maturation. This report utilises light scattering techniques to characterise the formation of colloids in bourbon whiskeys of different aging periods. Higher water dilution decreased the size of the colloidal particulates and increased their stability. Aged samples (> 36 months) were found to be more stable, having a higher concentration of colloids at lower dilutions. This work demonstrates that dynamic light scattering can be useful for quality control in the spirits industry. © 2022 The Institute of Brewing & Distilling.

The xylanase inhibitor from barley (Hordeum vulgare L.) can inhibit diverse microbial endoxylanases, which have been proposed to induce premature yeast flocculation (PYF) during fermentation with microbially contaminated barley malt. To investigate the inhibition of PYF by recombinant Hordeum vulgare L. xylanase inhibitor (rHVXI), it was constitutively and inducibly expressed in Pichia pastoris using the glyceraldehydes-3-phosphate dehydrogenase (GAP) promoter and the methanol-induced alcohol oxidase (AOX1) promoter, resulting in strains GAP/S and AOX1/αS. With the GAP promoter, the transformants exhibited inhibition against xylanase, with the GAP/S-11 strain showing the greatest activity of rHVXI from 20 transformants. The rHVXI inhibitor was purified and added during the mashing process of PYF positive (PYF+) malt to evaluate its inhibitory effect on PYF. The rHVXI inhibitor affected yeast flocculation during fermentation of PYF+ wort, demonstrating its application to mitigate PYF factors. © 2022 The Institute of Brewing & Distilling

The use of high enzyme sprouted sweet potato flour (SSPF) as a saccharification enhancer to improve the brewing properties of pearl millet (Pennisetum glaucum, L.) was investigated. The results show a linear relationship between hot water extract (HWE) and increased substitution levels of SSPF up to a maximum of 363^oL/kg at 40% substitution (40SM). Similarly, diastatic power (DP) increased from 21^oL in 100% millet malt to 24 and 33^oL at 20% (20SM) and 40% substitution (40SM). This can be attributed to the high amylolytic potential of sprouted sweet potato flour. Saccharification time reduced from 40 to 10 minutes for 20SM and 40SM (SSPF/millet malt) mash samples compared to the barley malt control. With increasing levels of SSPF substitution, the free α-amino nitrogen of SSPF/millet malt wort samples declined from 154 mg/L in all millet malt sample to 126 mg/L in 40SM sample. However, all samples had a high rate of apparent attenuation in fermentation. This substitution method offers opportunities to optimise the brewing potential of millet in countries where the cost of importation of barley malt is prohibitive. However, the levels of modification in the composite samples, suggest sweet potato flour could be used in the brewing and distilling industries alone or together with malted millet.

Baijiu is a traditional Chinese distilled beverage. There are twelve types of Chinese baijiu, each requiring different production technologies resulting in varying styles and characteristics. Proteins, peptides and amino acids are both sources of nitrogen for brewing microflora and precursors of flavour compounds. These compounds are the main non-volatile nitrogenous compounds in baijiu fermentation but are also present in the final product. Of the volatile nitrogenous compounds in baijiu, pyrazines dominate. This paper reviews the roles of nitrogenous compounds in baijiu production; systematically summarises the volatile and non-volatile nitrogenous compounds in baijiu and the relationships between production processes and nitrogenous compounds in Strong and Sauce flavour baijiu. Nitrogenous compounds are closely related to the quality of the baijiu. It is suggested that future work should focus on the role of nitrogenous compounds in the flavour and aroma of baijiu with particular regard to different production technologies, materials and regions. © 2022 The Institute of Brewing & Distilling

Higher alcohols and esters are key compounds from fermentation that help define the character of beer. Higher alcohols are mainly produced by yeast via the Ehrlich amino acid degradation pathway of especially leucine, isoleucine, valine, and phenylalanine. Augmenting the concentration of these amino acids can enhance the output of the Ehrlich pathway. Unlike previous studies, the work reported here explores the possibility of combining endo- and exo-proteases to selectively release these amino acids to potentially impact on flavour formation. The wort from enzyme treated mash was fermented by Saccharomyces pastorianus and the green beer was analysed by GC/MS. Treatment with proteases in laboratory scale mashing increased the level of leucine, isoleucine, valine, and phenylalanine by up to twofold. Fermentation of the wort, produced about 10% more isoamyl alcohol and 17% more isoamyl acetate derived from leucine, compared to the control. © 2022 Novozymes AS. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling.