1,720,979 research outputs found
Influence of Selected Technological Conditions on the Flavour Stability of Unpasteurised Top-Fermented Craft Beer
No full textCraft beers are usually unpasteurised and unfiltered, causing a different ageing behaviour compared to pasteurised and filtered beers. In this work, the influence of microfiltration, storage temperature, and fresh yeast addition for refermentation on the flavour stability of a top-fermented beer was studied. The determination of the main quality parameters (e.g. extract, haze, foam, pH) and volatile compounds was performed. Also, a trained panel evaluated the sensory profile of the beers. A statistical data (analysis of variance and PCA) processing approach was used to better understand how different treatments interact with the stability of an unpasteurised beer. The main quality parameters were not influenced by the different storage conditions. Microfiltration at 0.45 μm led to decreased head retention and flavour stability in all beers. In fact, oxidation and stale notes were detected only in the microfiltered beers. About volatile compounds, the aldehydes content decreased during storage for all the samples. Furthermore, there were significant differences between cold-stored and room-stored beer after 6 months in terms of aroma and flavour, especially for the hop character. This study highlighted the interesting flavour stability of unpasteurised beer, where yeast acts as a natural stabiliser during refermentation and storage. The results confirmed that cold storage (4 ± 1 °C) is the best option for beer flavour stability
Influence of yeast strain, priming solution and temperature on beer bottle conditioning
No full textAbstract
BACKGROUND
Recently, there has been a significant increase in the number of microbreweries. Usually, craft beers are bottle conditioned; however, few studies have investigated beer refermentation. One of the objectives of this study was to evaluate the impacts of different experimental conditions, specifically yeast strain, priming solution and temperature, on the standard quality attributes, the volatile compounds and the sensory profile of the bottle-conditioned beer. The other aim was to monitor the evolution of volatile compounds and amino acids consumption throughout the refermentation process to check if it is possible to reduce the time necessary for bottle conditioning.
RESULTS
The results indicate that the volatile profile was mainly influenced by the strain of yeast, and this may have obscured the possible impacts of the other parameters. Our results also confirm that the two yeast strains showed different metabolic activity, particularly with respect to esters production. Moreover, we found the Safbrew S-33® strain when primed with Siromix® and refermented at 30 °C yielded the fastest formation of higher alcohols while maintaining low production of off-flavours.
CONCLUSIONS
These results suggest a formulation that may reduce the time needed for bottle conditioning without affecting the quality of the final beer which may simultaneously improve efficiency and economic profits. © 2016 Society of Chemical Industr
Rice malting optimization for the production of top-fermented gluten-free beer
No full textBACKGROUND: A safe method to obtain gluten-free beer led to the use of naturally gluten-free grains, such as rice, but the specific malting program for rice is long and requires a large amount of water, and the resulting beer showed a flat flavour profile. In this study, an optimization of the malting and brewing procedure is proposed to overcome the aforementioned issues. Different steeping conditions and kilning temperatures are considered, and a top-fermented beverage from rice malt is obtained for the first time. RESULTS: The malting procedure has been optimized by assessing the use of short-time steeping as an alternate to long air rest to obtain sufficient moisture content in the green malt, saving water consumption. The malt obtained allowed a regular fermentation, as confirmed by the sensorial analysis, which did not reveal any off-flavours. The use of a top-fermenting yeast formed high content of higher alcohol and relatively low amount of esters. CONCLUSION: This study confirms the potential of rice for the production of malt and beer. The optimized malting programme allowed water saving. The production of a top-fermented rice malt beer was a successful attempt to introduce a new flavoured product for consumption by individuals affected by coeliac disease
Near Infrared Spectroscopy in the Brewing Industry
No full textThis paper offers an exhaustive description of the use of Near Infrared (NIR) Spectroscopy in the brewing industry. This technique is widely used for quality control testing of raw materials, intermediates and finished products, as well as process monitoring during malting and brewing. In particular, most of the reviewed works focus on the assessment of barley properties, aimed at quickly selecting the best barley varieties in order to produce a high quality malt leading to high quality beer. Various works concerning the use of NIR in the evaluation of raw materials, such as barley malt, hop and yeast, are also summarized here. The implementation of NIR sensors for the control of malting and brewing processes is also highlighted, as well as the use of NIR for quality assessment of the final product
Near-Infrared spectroscopy for proficient quality evaluation of malt and maize in beer industry.
No full textMoisture and total nitrogen content are considered very important factors that influence barley malt quality, as well as moisture and lipid content for maize quality. In the present study, the feasibility of using Near-Infrared (NIR) spectroscopy to measure the moisture, total nitrogen and lipid content of the whole malt grains and maize grits was examined. The NIR spectra of the following samples were examined: 295 malt whole grains for moisture, 281 malt whole grains for total nitrogen, 128 maize grits for moisture and 102 maize grits for total lipids. Validation was carried out both by means of cross-validation and test set validation. Coefficients of determination (R2) were higher than 93% for both malt and maize moisture and higher than 71 and 80 for malt total nitrogen and maize total lipids, respectively. The Root Mean Square Error (RMSE) values (both in Cross Validation (RMSECV) and in Prediction through external validation (RMSEP)) ranged from 0.127 to 0.165% for both malt and maize moisture, whereas they ranged from 0.043 to 0.053% for malt total nitrogen and from 0.065 to 0.079% for maize total lipids. Repeatability (r95) ranged from 0.105 to 0.222% and from 0.012 to 0.155% for malt moisture and total nitrogen content, respectively, and from 0.086 to 0.192% and from 0.020 to 0.171% for maize moisture and total lipid content, respectively. The findings showed that NIR spectroscopy has potential for the rapid prediction of quality of whole malt grains and maize grits for brewing
Pilot Plant Production of Low-Alcohol Beer by Osmotic Distillation
No full textOsmotic distillation (OD) is a membrane technology frequently applied for dissolved gas removal from liquids and for liquid concentration; recently, there has been increasing interest in the use of this technology to dealcoholize beverages. The aim of this work was to ascertain the feasibility of a semi-industrial scale of beer dealcoholization by OD using a pilot plant. The process was optimized by the variation of technological parameters to determine the effect of different operating conditions on the quality and organoleptic properties of the dealcoholized beer. The most important beer quality parameters were determined before and after the dealcoholization, as well as the volatile composition by gas chromatography and the organoleptic characteristics by a trained panel. The findings indicated that OD is an appropriate process for low-alcohol beer production. Some issues, such as the loss of volatile compounds and the high amount of stripping solution required, limit its growth. The report of the panel showed that beer with an organoleptic profile more characterized by malty features than by ester content could be appropriate for this treatment
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