Two black rice varieties, "black non-waxy" and "black waxy", were investigated as possible raw materials for the production of malt. The malting conditions were optimised using response surface methodology. The three process parameters were steeping, germination time and temperature. Each parameter was tested at three levels: adjustment degrees of steeping were 38, 41, and 44%, germination times were 6, 7, and 8 days, and the temperatures were 20, 25 and 30°C. At the end of the germination process, all samples were kilned at 50°C for 24 h, and shoot/rootlets were removed before a detailed quality assessment was performed. Data analysis was performed using the Design Expert Statistic Program. The optimal conditions found for both rice varieties were as follows: germination time of 8 days at 30°C and 44% grain moisture. Although the extract yield, and α-amylase and β-amylase activities of both rice malts were lower than barley malt, the higher activity of limit-dextrinase enzyme and apparent attenuation limit (AAL), which was higher than 80%, suggests that rice malt has potential for use in brewing.

J. Inst. Brew. 116(4), 464-474, 2010Strain specific detection and control of Saccharomyces pastorianus and Saccharomyces cerevisiae starter cultures is of great importance for the fermentation industry. The preconditions of strain specific fermentation characteristics can be ensured by periodic analysis and confirmation of the strain identity. With regard to industrial S. pastorianus and S. cerevisiae strains and a focus on brewing strains, the differentiation methods most available are time-consuming and not very discriminative. In this work PCR-DHPLC analysis was investigated as a novel approach for the differentiation of industrially used S. pastorianus and S. cerevisiae strains. The PCR-DHPLC-system was specific for S. cerevisiae strains and S. pastorianus hybrid strains that contain IGS2 rDNA, which originates from the S. cerevisiae ancestor. For the DNA of 177 strains of 41 non-target species, which are typical for beverage and fermentation surroundings, the absence of PCR-amplificates could be confirmed by DHPLC analysis. It was shown that single strains of S. cerevisiae and S. pastorianus could be differentiated. A strain specific differentiation within the group of top-fermenting Saccharomyces cerevisiae strains could also be performed. For the group of bottom fermenting S. pastorianus brewing strains, strain-to-strain specific differences in the DHPLC chromatograms could be observed which can be used to differentiate and to compare two single strains with each other, although the comparison of chromatograms of an unknown S. pastorianus strain with a set of known S. pastorianus chromatograms could only reveal tendencies towards grouping into types. The differential DHPLC chromatogram characteristics (fluorescence intensities, number of peaks/side-peaks/peak-shoulders) within S. pastorianus are present, but not as distinctive as for S. cerevisiae. Additionally PCR-DHPLC has advantages compared to other differentiation methods, such as species specificity, speed (2.5 h for one sample) and precision with the described limits.

Saccharomyces pastorianus syn. carlsbergensis strain 34/70 is well known to be the most used strain for lager beer production. The difference between this strain and very closely related strain 34/78 is the latter's greater flocculating character. This single physiological trait can cause technical difficulties in beer production. The aim of this study was to determine whether lipid analysis by a combination of thin layer chromatography (TLC) with electrospray ionization mass spectrometry (ESI-MS) could be used as a strain-typing technique in order to distinguish S. pastorianus syn. carlsbergensis strain 34/70 from strain 34/78. Both strains (34/70 and 34/78) were harvested after continuous culture under standard conditions. Polar lipids were then extracted from lyophilized cultures and analysed by TLC in order to separate phospholipid families. Phosphatidylethanolamine (PE) was extracted and investigated using ESI-MS, to gain further information on individual molecular species. Using TLC analysis, lipids were separated corresponding to standards for PE, phosphatidylcholine (PC), phosphatidylglycerol (PG), cardiolipin (CL), phosphatidylserine (PS), phosphatidylinositol (PI), phosphatidic acid (PA) and sphingomyelin (SM). ESI-MS of the PE band, separated by TLC, showed that electrospray mass spectra were highly reproducible for repeat cultures. Novel findings were that both brewing strains displayed major phospholipid peaks with m/z 714, PE (34 : 2) m/z 742, PE (36 : 2) and m/z 758, PE (37 : 1). However, strain 34/78 had additional peaks of m/z 700, PE (33 : 2) and m/z 728, PE (35 : 2). Strain 34/70 had an extra peak with m/z 686 PE (32 : 2). We conclude that combined TLC/ESI-MS can distinguish between S. pastorianus syn. carlsbergensis 34/70 and 34/78 and may be a useful typing technique for differentiation of closely related yeast strains. This novel approach may aid quality assurance and could be suitable for yeast collections and larger industrial companies.

Both traditional and DNA-based methods sometimes fail to differentiate between closely related strains of commercial interest in the brewing industry. The aim of this study was to compare species and sub species of Saccharomyces cerevisiae on the basis of their polar lipid chemistry using chromatographic methods. Six isolates were studied after propagation under batch conditions. Polar lipids were then extracted from lyophilised cultures and analysed by TLC in order to separate phospholipid families. TLC showed that the major phospholipid classes present were PC > PE > PG. Two unidentified phospholipids were found, one only in strain 34 /70. The major peaks detected by GLC were identified as methyl esters of palmitic acid and palmitoleic acid. The fatty acid composition of PC varied between strains and novel data on lecithin acyl constituents were observed. The polar lipid method succeeded in differentiating strain 34 /70 -one of the most commonly used brewer's lager yeast -from strain 34 /78 and other species tested. The presence of unusual polar lipids in Saccharomyces sensu stricto yeasts may be useful in distinguishing between other closely related strains.

Tfte influence of (+)-catechin and ferulic acid on the formation of haze was investigated. Both phenolic compounds were added in different concentrations to beer before ageing through a force test. The removal of these compounds was observed by measuring the difference before and after forcing the beer. (+)-Catechin and ferulic acid shoived haze-decreasing as well as haze-increasing properties. The removal of (+)-catechin and ferulic acid from beer through three types of polyvinylpoUjpyrollidone (PVPP) at several concentrations was investigated. TJte removal of (+)-catechin and ferulic acid by PVPP-filtration was totally different. The removal of (+)-catechin can be used as a basis to calculate the doses for a desired stability, whereas ferulic acid is removed in irregular amounts. On the other hand polyphenols lower the shelf life of In order to secure a necessary shelf life nearly 90% of beer and increase flavour stability by acting as natural breweries stabilize their beers by either using silica gels, antioxidants. Cross-linking reactions between polyphenols polyvinylpolypyrollidone (PVPP) or a combination of both, and proteins lead to chill haze formation. The theory There is still little known about the functionality of these that polyphenols can lead to haze formation after reactants and the removal of haze relevant substances.polymerization is widespread but also in doubt5-1214. L., , ... ,.• i ■ j j There is not necessarily a correction between high These polymerization reactions are primarily induced ' f , . J .. concentrations of polvpnenols and lower colloidal bv oxidation. ■ stability9. Polyphenol-protem interactions contribute to Catechin and its derivates participate in the formation haze formation in beer but so also do carbohydrates and of precipitates with proteins". Some studies indicate that minerals21.the dimers procyanidin-B3 and prodelphinidin-B3 are . .,. ,. , ... ,",., J-.• ,i^Stabilizing beer with PVPP apparently removes many significantly haze sensitive1**-20 Comparing these two°, , , Influence of(+)-Catechin and Fcnilic Achi Another study confirmed that ferulic acid and the catechins have antioxidant action in the deoxyribose assay, which assesses the ability of molecules to react with OH-radicals17.In this study we investigated the influence of (+)-catechin and ferulic acid on haze formation. The study also assesses the effects of increasing concentrations of PVPP on removal of phenolic acids and determines if there are significant differences between regenerable or non-regenerable PVPP. insufficient purity. For quantification a two point calibration was used. The retention time and the resulting absorption spectra were compared with standards to identify the polyphenols in beer. MATERIALS AND METHODS Analytical ExperimentsLager beer (12°Plato and 4,5% Vol. Ale), stabilized with 25g PVPP/hL, was taken after the PVPP filter with a capacity of 400 hL/h and then kegged. The keg was then used as the beer source and after bottling, the indicated amounts of (+)-catechin and ferulic acid we...