Investigation of mashing regimes for low‐alcohol beer production

Low‐alcohol beer can be obtained by physical and biological methods. The group of biological methods includes modification of the mashing regimes and changes in the fermentation process. The aim of the present work was to study two mashing regimes for low‐alcohol beer production. The increase in the mashing duration at 50 °C led to a linear increase in the extract and the concentration of reducing and fermentable sugars in the wort. It was found that the rate of formation of reducing sugars was higher than that of the formation of fermentable sugars, which can be used for the optimization of the mashing process. The introduction of a pause at 77 °C did not lead to a substantial increase in the concentration of fermentable extract, but did lead to an increase in the total and non‐fermentable extract. The available nitrogen content in the laboratory wort was in the range of 120–150 mg/dm³. As a result of conducting fermentation processes with the top‐fermenting yeast strain Saccharomyces cerevisiae S‐33, it was found that the combination of a small amount of fermentable sugars and a low fermentation temperature led to a beer being obtained that met the requirements for a low‐alcohol beverage. Copyright © 2016 The Institute of Brewing & Distilling     

Review: Pure non‐Saccharomyces starter cultures for beer fermentation with a focus on secondary metabolites and practical applications

Recently there has been increased interest in using non‐Saccharomyces yeasts to ferment beer. The worldwide growth of craft beer and microbreweries has revitalised the use of different yeast strains with a pronounced impact on aroma and flavour. Using non‐conventional yeast gives brewers a unique selling point to differentiate themselves. Belgian brewers have been very successful in using wild yeasts and mixed fermentations that often contain non‐Saccharomyces yeasts. Historically, ancient beers and beers produced before the domestication of commonly used Saccharomyces strains most likely included non‐Saccharomyces species. Given the renewed interest in using non‐Saccharomyces yeasts to brew traditional beers and their potential application to produce low‐alcohol or alcohol‐free beer, the fermentation and flavour characteristics of different species of non‐Saccharomyces pure culture yeast were screened for brewing potential (Brettanomyces anomalus and bruxellensis, Candida tropicalis and shehatae, Saccharomycodes ludwigii, Torulaspora delbrueckii, Pichia kluyveri, Zygosaccharomyces rouxii). Alcohol‐free beer is already industrially produced using S. ludwigii, a maltose‐negative species, which is a good example of the introduction of non‐Saccharomyces yeast to breweries. Overall, non‐Saccharomyces yeasts represent a large resource of biodiversity for the production of new beers and have the potential for wider application to other beverage and industrial applications. Almost all of the trials reviewed were conducted with varying fermentation parameters, which plays an important role in the outcome of the studies. To understand these impacts all trials were described with their major fermentation parameters. Copyright © 2016 The Institute of Brewing & Distilling     

Assessment of quality and production process of a non‐alcoholic stout beer using reverse osmosis

The market for low‐alcohol and non‐alcoholic beer has been increasing owing to factors such as health concerns, calorie content, strict traffic laws and religion, among others. Beer presents some good nutritional characteristics such as B‐complex vitamins, antioxidants, minerals, fibre, protein and carbohydrates. The availability of non‐alcoholic products is still very low in Brazil and worldwide. This study produced four samples of non‐alcoholic dark beer derived from a Foreign Extra Stout beer style with 6.6% v/v alcohol using the process of reverse osmosis. The membrane filtration processes showed that the fouling rate coefficient increases with time and permeate volume while the flow decreases. The values of colour, bitterness, pH, phenolic compounds and antioxidant activity were maintained close to the parameters of the standard beer (counter test) when the reverse osmosis process was conducted with a diluted sample at a temperature of 20 °C. Copyright © 2016 The Institute of Brewing & Distilling     

利用酒精废糟液无蒸煮发酵生产酒精的研究

通过对几种酶制剂的液化、糖化能力以及几种防腐剂的抑菌效果进行了试验选择性比较 ,确定了在原料无蒸煮废液全回用的状态下 ,酶制剂C的适宜浓度是 0 1g酶蛋白 / 10 0g原材料 ,防腐剂B的适宜浓度是 10 0× 10 -6。在以玉米粉为原料的无蒸煮废液全回用发酵试验中 ,发酵 9天后的乙醇浓度达到 9 0 %v/v ,且酒精收得率可达到 46 5mL/kg以上的极好水平。     

High‐pressure homogenization: a non‐thermal process applied for inactivation of spoilage microorganisms in beer

The inactivation of spoilage microorganisms in beer using high‐pressure homogenization (HPH) was studied with the aim of evaluating the possibility of changing the conventional pasteurization process using this particular process. The homogenization pressure required for the inactivation of lactic acid bacteria, acetic bacteria and yeasts was investigated. For the most resistant microorganisms, the pressure inactivation kinetics and the effects of multiple process passes, initial temperature of the beer and the CO₂ concentration were studied. The results indicated that Lactobacillus delbrueckii was the most resistant microorganism tested, requiring 250 MPa to reach a six decimal reduction. Additionally, results showed that L. delbrueckii inactivation followed a second‐order kinetic process. A multi‐pass process and the use of a high initial beer temperature increased inactivation by HPH with L. delbrueckii, allowing the use of 150 MPa to achieve a five log cycle of inactivation. In contrast, a high CO₂ concentration reduced the efficacy of the HPH process. The results that were obtained are useful for high‐pressure homogenization applications in breweries and help to elucidate the effect of this new technology in a beverage that is both alcoholic and carbonated. Copyright © 2013 The Institute of Brewing & Distilling     

Comparative analysis of the fermentation performance of high‐quality milk beer strains (Kluyveromyces marxianus) and optimisation of medium formula for high‐density fermentation

Milk beer is a new type of dairy beverage in China and increasingly popular with consumers. The strain FXJ1 isolated in our laboratory was an excellent strain for the production of milk beer with alcohol content of 0.48%. Our research verified that the strain FXJ1 was superior to the commercial strain MJ for milk beer production and got the optimal medium formula (67.37 g/L sucrose, 29.7 g/L yeast extract, 15.61 g/L corn steep liquor, 4.13 g/L KH₂PO₄ and 0.3 g/L MgSO₄) which allowed the biomass production of strain FXJ1 to achieve 8.88 ± 0.08 g/L and increase 2.94‐fold as compared with yeast extract peptone dextrose base medium.     

Optimization of alcohol‐free beer production by lager and cachaça yeast strains using response surface methodology

Alcohol‐free beers (AFBs) are an attractive segment of the beer market both for the brewing industry and for consumers. While AFBs produced by arrested/limited fermentation often suffer from a lack of volatile compounds, beer flavour can be improved by yeast selection and optimization of fermentation conditions. The yeast selection strategy was demonstrated by comparing traditional lager yeast with selected cachaça yeast strains. Correspondingly, response surface methodology was used to enhance the formation of the flavour‐active volatile compounds by optimization of the fermentation conditions (original wort extract, fermentation temperature, pitching rate). Statistical analysis of the experimental data revealed the relative significance of process variables and their interactions. The developed quadratic model describing the responses of total esters and higher alcohols to changes in process variables was used to predict the ideal fermentation conditions in terms of flavour formation. The predicted conditions were experimentally verified and alternative strategies of AFB production are suggested. Copyright © 2016 The Institute of Brewing & Distilling     

A review of methods of low alcohol and alcohol-free beer production

The increasing interest of consumers in health and alcohol abuse issues motivates breweries to expand the assortment of products with low alcohol content. The goal of producing beers with low alcohol content can be achieved by two main strategies; namely by gentle removal of alcohol from regular beer and by limited ethanol formation during the beer fermentation. Within these two basic strategies, there are a number of techniques that vary in performance, efficiency and usability. This paper presents an overview and comparison of these techniques and provides an evaluation of sensorial properties of low-alcohol and an alcohol-free beer produced as well as suggests possibilities for their additional improvement.     

Contribution of cysteine and glutathione conjugates to the formation of the volatile thiols 3‐mercaptohexan‐1‐ol (3MH) and 3‐mercaptohexyl acetate (3MHA) during fermentation by Saccharomyces cerevisiae

Background and Aims: 3‐Mercaptohexan‐1‐ol (3MH) and its ester 3‐mercaptohexyl acetate (3MHA) are potent aromatic thiols that substantially contribute to varietal wine aroma. During fermentation, non‐volatile 3MH conjugates are converted by yeast to volatile 3MH and 3MHA. Two types of 3MH conjugates have been identified, S‐3‐(hexan‐1‐ol)‐L‐cysteine (Cys‐3MH) and S‐3‐(hexan‐1‐ol)‐glutathione (GSH‐3MH). Yeast‐driven formation of 3MH from these precursors has been previously demonstrated, while the relationship between 3MHA and GSH‐3MH remains to be established. This paper aims to investigate yeast conversion of GSH‐3MH to 3MH and 3MHA, and to assess the relative contribution of each individual conjugate to the 3MH/3MHA pool of finished wines. Methods and Results: Fermentation experiments were carried out in model grape juice containing Cys‐3MH and GSH‐3MH. We found 3MH formation from GSH‐3MH to be significantly less efficient than that of Cys‐3MH. Conversely, esterification of 3MH to 3MHA was higher when 3MH was formed from GSH‐3MH. Additional in vitro assays for measuring enzyme cleavage activity suggest the involvement of a different mechanism in 3MH conversion for the two precursors. Conclusions: These results indicate that although both 3MH conjugates can be converted by yeast, the type of precursor affects the rate of formation of 3MH and 3MHA during fermentation. Significance of the Study: Management of the pool of aromatic thiols during fermentation can depend on relative proportions of different 3MH conjugates.     

Characterization of an extracellular β‐d‐fructofuranosidase produced by Aspergillus niveus during solid‐state fermentation (SSF) of cassava husk

β‐d ‐Fructofuranosidases are biotechnologically important enzymes produced by various organisms. Here, Aspergillus niveus produced an extracellular β‐d ‐fructofuranosidase during SSF of cassava husk. This enzyme was purified 8.5‐fold (recovery of 5.2%). A 37‐kDa protein band was observed after 8% SDS‐PAGE. Native molecular mass is 91.2 kDa. Optimal temperature and pH of activity were 55°C and 4.5, respectively. The enzyme was stable at 50°C for 1 hr, and 80% of its activity was retained after 1 hr at pH 8.0. The enzymatic activity was improved by Mn²⁺, was resistant to most solvents, and was inhibited by Triton X‐100 and Tween 20. K_m and V_max with sucrose were 22.98 mM and 120.48 U/mg of protein, respectively. With Mn²⁺, these values were 16.31 mM and 0.30 U/mg of protein. The enzyme did not hydrolyze inulin and for this reason can be considered a true invertase. Thus, A. niveus β‐d ‐fructofuranosidase holds promise for invert sugar production.

Practical applications

β‐d ‐Fructofuranosidase is an enzyme that can be applied to different industrial sectors, especially food and beverage industries. It is responsible for the hydrolysis of sucrose and yields an equimolar mixture of D‐glucose and D‐fructose, named as inverted sugar syrup, with broad applications in the confectionery industry. The Aspergillus niveus enzyme hydrolyzed only sucrose here and can be considered a true invertase, showing its potential for application to invert sugar production. Besides, the use of cassava husk for enzyme production means an interesting utilization route of this agroindustrial residue. Thus, characterization of this enzyme is an important step for identification of its potential for practical applications.     

The application of near‐infrared spectroscopy in beer fermentation for online monitoring of critical process parameters and their integration into a novel feedforward control strategy

Traditional methods used in the analysis of fermentation media suffer from a number of limitations. The search for more rapid and efficient methods has led to the development and application of near‐infrared spectroscopy. Near‐infrared spectroscopy has been applied successfully in a variety of industrial processes: agricultural, food, chemical and pharmaceutical, generally in the areas of raw material quality control but also including intermediate and finished product testing. The present research explores its potential for online fermentation monitoring of total cell count (TCC), specific gravity (SG), free amino nitrogen (FAN) and percentage alcohol by volume (% v v⁻¹) in a 300 L pilot‐scale validation batch. Models that were generated from three calibration batches for each of these constituents exhibited overall favourable standard error of cross validation (SECV) and fit of predicted vs actual cross validated results (SECV, R ²): SG (0.00072, 0.995), ethanol (0.17% v v⁻¹, 0.990), FAN (16.5 mg L⁻¹, 0.886) and TCC (1.24 × 10⁶ cells mL⁻¹, 0.640). The data that was most relevant to cell metabolism was determined to be sugar consumption rate, ethanol production rate, yield of ethanol and fermentation lag time. These ‘critical performance parameters’ were incorporated into a novel feed‐forward control strategy where yeast pitching rate was modified based on values of the critical performance parameters from the previous batch. Use of this feed‐forward strategy demonstrated how brewers can utilize near‐infrared monitoring for quality assurance through early detection of shifts in fermentation performance. Copyright © 2017 The Institute of Brewing & Distilling     

Enhancement of antioxidant activity of monascal waxy corn by a 2‐step fermentation

A 2‐step fermentation process was developed to enhance antioxidant activity of monascal waxy corn, fermented by Monascus purpureus TISTR 3090, compared with the conventional method. The results showed that, after 8 days of fermentation, monacolin K content and pigment intensity of monascal waxy corn from 2‐step fermentation were 62.89 mg kg^?1 dry weight and 3072.70 unit g^?1 dry weight, respectively, higher than those of the conventional method, while the residual reducing sugars were exhausted, giving the observed highest growth. The IC₅₀ values of DPPH, ferric reducing/antioxidant powder (FRAP) and chelating ability on Fe²⁺ assays of the 2‐step fermentation were about 50% less than those of the conventional method. A significantly positive correlation was found between pigment intensity and monacolin K content, while significantly negative correlations were found among monacolin K content, IC₅₀ of FRAP and chelating ability on Fe²⁺. An ideal negative correlation between pigment intensity and chelating ability on Fe²⁺ was found.     

Potent antioxidative activity of non‐polyphenolic fraction of green tea (Camellia sinensis) – association with pheophytins a and b

The antioxidative activity of green tea‐derived polyphenols known as catechins has been extensively studied. However, the antioxidative activity of the non‐polyphenolic fraction of green tea has been poorly elucidated and is the subject of the present study. The non‐polyphenolic fraction of green tea showed a significant dose‐dependent suppressive effect against the autooxidation of linoleic acid. The chlorophyll‐related compounds pheophytins a and b showed similar antioxidative activities in the same assay, much higher than those of α‐tocopherol and the green tea catechin (−)‐epigallocatechin‐3‐gallate (EGCG). The non‐polyphenolic fraction of green tea and pheophytins a and b exhibited suppressive activities against superoxide anion (${\bf O}_{2}ˆ{‐}$ ) generation in mouse macrophages induced by 12‐O‐tetradecanoylphorbol‐13‐acetate, showing higher activities than that of EGCG. These results suggest that the non‐polyphenolic fraction of green tea leaves has potent antioxidative activity and that this activity is associated with pheophytins a and b. © 2000 Society of Chemical Industry     

Changes in microbial community during fermentation of high‐temperature Daqu used in the production of Chinese ‘Baiyunbian’ liquor

Daqu is a fermentation starter used in the production of Chinese liquor. The present study investigated changes in the microbial community during the fermentation of Baiyunbian high‐temperature Daqu during a cycle time of 140 days. Two methods were used, a culture‐dependent method (viable cell counting) and a culture‐independent method (high‐throughput sequencing of bacterial 16S rRNA gene and fungal internal transcribed spacer region). It was found that thermotolerant microorganisms such as Bacillus , Thermomyces and Actinobacteria were dominant in all stages of Daqu fermentation, especially during the high‐temperature period of days 7–38. In the initial 110 days of fermentation, operational taxonomic units and number of bacteria were higher than those of fungi, but the opposite was observed towards the end of fermentation (day 140). In mature Daqu , the predominant bacterial species were Bacillus and unclassified Thermoactinomycetaceae, followed by Thermoactinomyces , Kroppenstedtia and Saccharopolyspora ; the predominant fungi were Aspergillus , unclassified Trichocomaceae, Thermomyces , Rhizopus , Monascus and Candida , among others. It is possible that the addition of mother Daqu , temperature and storage time played critical roles in the microbial composition of Daqu . Collectively, the above findings provide important information that can be used to optimize conditions for large‐scale production of Daqu . Copyright © 2017 The Institute of Brewing & Distilling     

The effect of inoculation and additives on D(−)‐ and L(+)‐lactic acid production and fermentation quality of guineagrass (Panicum maximum Jacq) silage

Two experiments were carried out to study the influence of storage time, glucose and urea additions ( Experiment 1 ) and lactic acid bacteria inoculation with and without glucose addition ( Experiment 2 ) on the production of lactate isomers and fermentation quality of guineagrass (Panicum maximum Jacq) silage. All silages in both experiments were well preserved, as indicated by lower pH and little or no butyric acid. In Experiment 1 , addition of glucose or urea did not significantly affect the pH of silages (P > 0.05). Urea addition tended to reduce acetic acid content and greatly increased NH₃ − N content. L (+)‐Lactic acid was produced predominantly in the first 3 days of ensiling, but D (−)‐lactic acid increased gradually until 1 month after ensiling. Thereafter all silages became stable. In Experiment 2 , inoculation of Lactobacillus casei or L rhamnosus with or without glucose reduced D (−)‐lactic acid and increased L (+)‐lactic acid of silages. The proportions of L (+)‐lactic acid in these silages were higher than 80% of total lactic acid. L plantarum alone or in combination with glucose promoted D (−)‐lactic acid production and decreased the proportion of L (+)‐lactic acid. Glucose addition alone tended to reduce the proportion of L (+)‐lactic acid in both experiments. © 2000 Society of Chemical Industry     

Simple and Fast Sample Preparation Followed by Gas Chromatography‐Tandem Mass Spectrometry (GC‐MS/MS) for the Analysis of 2‐ and 4‐Methylimidazole in Cola and Dark Beer

We have developed a simple and fast sample preparation technique in combination with a gas chromatography‐tandem mass spectrometry (GC‐MS/MS) for the quantification of 2‐methylimidazole (2‐MeI) and 4‐methylimidazole (4‐MeI) in colas and dark beers. Conventional sample preparation technique for GC‐MS requires laborious and time‐consuming steps consisting of sample concentration, pH adjustment, ion pair extraction, centrifugation, back‐extraction, centrifugation, derivatization, and extraction. Our sample preparation technique consists of only 2 steps (in situ derivation and extraction) which requires less than 3 min. This method provided high linearity, low limit of detection and limit of quantification, high recovery, and high intra‐ and interday repeatability. It was found that internal standard method with diluted stable isotope (4‐MeI‐d₆) and 2‐ethylimidazole (2‐EI) could not correctly compensate the matrix effects. Thus, standard addition technique was used for the quantification of 2‐ and 4‐MeI. The established method was successfully applied to colas and dark beers for the determination of 2‐MeI and 4‐MeI. The 4‐MeI contents in colas and dark beers ranged from 8 to 319 μg/L and from trace to 417 μg/L, respectively. Small quantity (0 to 8 μg/L) of 2‐MeI was found only in dark beers. The contents of 4‐MeI (22 μg/L) in colas obtained from fast food restaurants were significantly lower than those (177 μg/L) in canned or bottled colas.     

Optimising the determination of maize endosperm vitreousness by a rapid non‐destructive image analysis technique

A rapid non‐destructive image analysis technique was developed and optimised for the determination of maize endosperm vitreousness without the need for sample preparation. Maize kernel translucency measurements were optimised for a light system consisting of positioning whole kernels on top of round illuminated areas smaller than the projected areas of the kernels, allowing light to shine through the kernels. A correction factor to allow for constant illumination of kernels was developed to adjust for kernel size variation in relation to constant light area. The intensity of translucency in maize is linearly correlated to the percentage of kernel illumination (r = 0.99, p < 0.001). Significant correlations were found between corrected translucency values and endosperm yields determined by hand dissection. These were: translucency as a percentage of the whole kernel and vitreous endosperm (mass%), r = 0.77; translucency as a percentage of the whole kernel and opaque endosperm (mass%), (r = ?0.72); translucency as a percentage of endosperm and vitreous endosperm (mass%), r = 0.81; and translucency as a percentage of endosperm and opaque endosperm (mass%), r = ?0.77; with n = 245 in all instances. Translucency varied by 29.5% between the lowest and highest values, and vitreous endosperm (mass%) varied by 16.8% between the lowest and highest values. Correlations increased significantly after corrections for kernel thickness. A thickness increase of 1 mm in the maize will cause a decrease of 21.86% in translucency and vice versa. The method allows for large samples (at least 49 kernels min^?1) to be analysed for individual vitreous and opaque endosperm contents with no interferences with kernel structure. With further development of suitable automated sampling techniques, it could become a suitable potential method for in‐line quantification of maize endosperm contents. Copyright © 2004 Society of Chemical Industry