Standardization of a small-scale hot water extract method for application in barley breeding programs

Hot water extract (HWE) is one of the key quality attributes considered when determining the malting performance of barley. The international malting and brewing industries utilise standard procedures for measuring HWE, including European Brewery Convention (Analytica - EBC 1998), Institute of Brewing (IOB - Methods of Analysis 1997), and American Society of Brewing Chemists (ASBC - Methods of Analysis 1992). EBC and ASBC procedures are similar and use a multi-temperature programmed mashing profile, while the IOB procedure uses a constant temperature infusion mashing profile. In Australia, maltsters and brewers generally use the EBC procedure to determine extract levels on commercial samples. Specific quality goals for developing Australian commercial barley varieties include a high extract carbohydrate potential with a desired level in excess of 82% EBC fine grind, dry basis (MBIBTC, 2001). Malting quality testing protocols vary in public Australian barley breeding programs especially in early generation testing where significant quantities of grain may not be available. Different methodologies are used including NIR and small-scale assays developed in-house. A review of the barley quality evaluation laboratories in 1995 by the Grains Research and Development Corporation (GRDC) included a recommendation of implementing standardised methodology for micromalting and quality testing of advanced material (Enright et al., 1995). The Australian Barley Chemists Group (ABCG) incorporating members of barley quality evaluation laboratories in Perth, Adelaide, Horsham, Wagga Wagga and Toowoomba, meet formally on an annual basis to discuss testing protocols and quality issues. The objective of method standardisation is to develop small-scale methods to provide breeding programs and industry groups with MBIBTC equivalent results from within the breeding programs. In 1999, a diastase method was standardised by the ABCG and correlated to the EBC industry method (Fox et al., 1999). Due to sample quantity limitations in some stages of a barley breeding program, a small-scale EBC HWE procedure has been developed and collaboratively evaluated by the participants of the ABCG

Managing quality for quality outcomes

In today’s competitive climate it is increasingly important for an organisation to foster client confidence in the products and or services that they provide. It is no longer adequate for an organisation to rely solely on its past record or reputation. An organisation may demonstrate its commitment to ensuring client confidence through: (a) Implementation of a Quality Assurance Management System (QAMS) (b) Certification of that system to a relevant recognised standard, and (c) Subsequent management and monitoring of the system through formal documented procedures. This paper will briefly discuss the initial steps of a QAMS such as development, documentation and implementation. However, the main emphasis will be directed towards the on-going management of the system to achieve quality outcomes. A combination of formal and informal processes, including planning, auditing, observations and actions are employed to demonstrate compliance of the QAMS to the relevant standard. In addition, these processes verify that the documented procedures and processes are in place to deliver the quality goals desired by both organisation and client. Managing quality for quality outcomes is the essential element for realising optimum benefit to all sectors of the organisation, its business partners and client relationships

Characterisation and assessment of the role of barley malt endoproteases during malting and mashing

Barley malt endoproteases (EC.3.4.21) develop as multiple isoforms mainly during grain germination and pass through kilning almost intact. Thermostability, under simulated mashing conditions, varied from low, to high depending on the substrate used in the assay. This suggests that individual enzymes respond differently to heat exposure and to protein substrates. The optimal pH with haemoglobin was pH 3.5, with hordein pH 4 and with glutelin pH 5. The optimal temperature with hordein was 40degreesC, with glutelin 50degreesC and with haemoglobin 60degreesC, These differences suggest that it is not possible to comprehensively characterise all malt endoproteases under one set of assay, conditions, In brewing, most of the barley protein degradation (> 70 %) occurs during malting. But some proteinases remain active during mashing and contribute to wort soluble proteins and free amino nitrogen. Their contribution to all malt EBC mash total free amino nitrogen was 25 % in Schooner (Australian) and 30 % in Morex (USA). The importance of proteolytic activity during mashing and the possibility that the levels may not be adequate, at high solid adjunct ratios. are acknowledged

Isolation and characterization of a thermostable dextranase

A thermostable dextranase has been isolated from an anaerobic thermophilic bacterium, Rt364, collected from a New Zealand thermal spring. The enzyme was purified by ammonium sulfate precipitation and successive ion exchange, hydrophobic interaction, and size exclusion chromatographies. The enzyme exhibited an apparent molecular weight of ∼140 kDa, a temperature optimum of 80°C, and a pH optimum of ∼5.5. The enzyme was extremely stable. No activity was lost over 12 h at 75°C. It is more thermostable than the dextranase from Chaetomium gracile, the most thermostable dextranase previously characterized; however, the Rt364 dextranase has a much lower specific activity, 10 U mg−1, compared to 2,750 U mg−1 for the fungal enzyme at their respective temperature optima. The enzyme from Rt364 hydrolyzes dextran, starch, amylose, and amylopectin with approximately the same catalytic efficiencies but does not hydrolyze pullulan. It has therefore been designated an amylodextranase which is analogous to the recently characterized amylopullulanas

Thermostable dextranases: Screening, detection and preliminary characterization

Screening methods have been developed for detection of micro-organisms producing thermostable dextranases. They utilize the incorporation of Blue Dextran into agar or liquid culture media for isolation of active dextranase producers growing at temperatures above 55°C. A variety of high temperature environments in sugar factories and naturally occurring thermal water samples were excellent sources of dextranase producers. A number of aerobic and anaerobic thermophilic bacteria, isolated from these sources, were found to produce thermostable dextranases. Dextranases with the greatest thermostability were found in cultures of anaerobic bacteria grown above 65°C. Temperature optima were determined for several crude enzyme preparations, four of which exhibited temperature optima in the range 65–85°C

Mapping and QTL analysis of the barley population Chebec x Harrington

A doubled haploid population of 120 individuals was produced from the parents Chebec, an Australian 2-row barley of feed quality with resistance to the cereal cyst nematode, and Harrington, a 2-rowed, Canadian variety of premium malting quality. This paper describes 18 field and laboratory experiments conducted with the population and summarises the traits mapped and analysed. The genomic location of 25 traits and genes is described and marker–trait associations for 5 traits (malt extract, diastatic power, resistance to cereal cyst nematode, early flowering, resistance to pre-harvest sprouting) important to Australian efforts to improve malting barley varieties have been used in practical breeding programs. Detailed maps for these populations are shown in this paper, while a consensus map incorporating these maps and further experiments on the populations are described elsewhere in this issue