The main quality challenge of beer is the change of its chemical composition during storage. It is known that the typical bitterness of fresh beer declines in the intensity and changes in the quality with an increasing age of the beverage. The bitter tasting compounds trans-iso-α-acids converse into lingering and harsh bitter tasting tri- and tetracyclic degradation products. In order to investigate the evaluation of beer flavour stability, the behaviour of trans-iso-α-acids, the trans/cis ratio of bitter acids, and the formation of tricyclocohumol and tricyclohumol as representatives of acidic-catalyzed degradation products of trans-iso-α-acids were chosen as analytical markers in wort, fresh beer as well as in 2 and 4 months aged beer samples with and without inline pre-isomerization. The characteristics of these analytical parameters were determined using HPLC-DAD and HPLC-MS/MS analysis. Supplementary to quantitative data, fresh beer as well as 2 and 4 months stored beer samples with or rather without the use of pre-isomerization were evaluated for the attributes aroma, taste, and beer ageing by a trained sensory panel.

In this paper, two non standard methods are introduced and described precisely for measuring the vitality of yeast. Both are simple and produce results in a very short time. For the purpose of demonstrating these methods, brewing yeasts were placed under specific types of stress in various situations and compared to yeast not under stress. Their capacity for producing CO₂ was measured, and the condition of their cell walls was determined parallel through potentiometric titration. The results show that both of the methods demonstrated in this paper are effective for determining the physiological condition of yeast. Also, the condition of their cell walls changed, which was made apparent by the volume titrant required in the potentiometric titration..

Holistic concept for water and recyclables recovery for the food industry in breweries – Part 1

Many industries focus on safeguarding specific physical-chemical properties in effluent water treatment and/or processing. In the food and beverage industry, hygiene and psychological aspects also play a role as consumers disapprove of “mixing” effluent water and food. In this article, strategies for water and recyclables recovery suitable for breweries are proposed. In part 1, pollution arising in brewery effluent water is described and various strategies for water recovery are presented. Part 2 discusses end-of-pipe treatment of effluent water using a combination of biological and membrane processes. Together with possibilities of utilising spent grains, a possible holistic concept is presented.

Quality control begins with yeast culturing

Consistency in beer quality is dependent on many factors. In addition to water, malt and hops, brewing yeast is an essential raw material and plays an important role in successfully producing beers of premium quality. The Weihenstephan Research Center for Brewing and Food Quality at Technische Universität München has developed a comprehensive quality control program for the culturing and propagation of brewing yeast, which fulfills the stringent demands placed on their pure yeast cultures by brewers.

Aroma hops and the production of beers with reduced alcohol content

Various opinions continue to prevail regarding the assessment of hops and their use in the brewery. A large portion of the world’s beer production focuses on following the goal of simply providing bitterness to beer in the form of isomerized alpha acids without regard to the additional task of providing the sensory element. Consequently, hop varieties are almost exclusively judged on the basis of their alpha acid yield. But hops are also considered to be a spice and the vast range of available hop varieties and hopping technologies allow them to contribute significantly to the character and flavor of a beer. Alpha acids don’t alone determine hop quality, rather it is the combination of bittering, aroma and tannic substances and their relationship to one another.

The use of hop oils provides significant advantages with regard to achieving a consistent hop aroma in beer. There are three types of hop oils available: Type Dry, Type Noble and Type Noble Plus with the Type Dry product having the added benefit that it can be produced from specific hop varieties.

John I. Haas, Inc., the leading supplier of hop products and services in the US, announces a new research and technology initiative – “Haas Innovations”. Haas Innovations will focus on new product development, customer technical services and all technical matters related to hops.

The influence of unmalted barley on the brewing process and the quality of the resulting beer-like beverages was investigated with the main focus on the oxidative stability by using traditional beer analyses and EPR-Spectroscopy (EAP-, T₄₅₀-value). Although all analytical values of the final beverages were within the normal range according to MEBAK, a slight decrease in total polyphenol and FAN content caused by an increased barley proportion in the grist was measured. In direct correlation an increase of higher molecular proteins and ß-glucan were detectable. The missing heat exposure and oxidative stress by the malting process resulted in lower values of TBI and wort respectively beer colour with increasing barley proportions in the grist..

Visible and intense turbidity is seen as a defining characteristic of German and Belgian wheat beers. To date, no reliable method has been established for predicting the haze stability of wheat beer. It would be very beneficial for breweries to be able to predict haze stability so as to ensure that the beer retained a satisfactory level of haze during its shelf life. To predict wheat beer haze, trials were undertaken, in which light scattering analysis techniques and particle size distribution measurements were made, for the purpose of characterizing the haze stability of wheat beer. The wheat beer samples assessed had substantial differences in haze stability durability, from 19 days up to more than 160 days, as judged by when 90° scatter light intensity drops bellow 30 EBC units..

The properties of reducing sugars are interesting for the shelf life of beverages, particularly beer, and for human nutrition. For the brewing process the different reducing potentials and the mode of action of fermentable sugars are vitally important, especially during wort boiling where the reactions of sugars are accelerated. Additionally, several breweries use non-fermentable sugars in the brewing process to imbue the beer with unique flavour, body and mouthfeel.

The last outstanding official 2011 crop estimate figures for German growing areas, namely those for the Hallertau, were published on August 18th. We are pleased to provide a list comparing the crop results for 2010 with the estimates for 2011 for the world’s main growing areas.