Selection Of Beer Wheat, Optimization Of Malting Processes And Comprehensive Utilization Of Brewer's Grains

Wheat is regarded as a good raw material of beer due to its richness in protein which contributes to the formability and nutrition of beer. Presently, the domestic wheat malt is mainly used to produce the light flavour and bottom fermentative beer. Using wheat as the brewing material can reduce the brewing costs, avoid risk from malting barley-market and promote health and sustainable development of brewing industry. Brewer's spent grain (BSG) is the main by-product of brewing industry; it is also good source of protein and dietary fiber. Therefore, development of high protein and dietary fiber food using BSG will not only turn waste into useful product, enhance additional value, but also increase economic benefit for company and reduce environment pollution. In this research, brewing wheat was systematically selected from 10 different varieties. In the light of the starch content, the protein component, xylan content as well as the change of xylanase activity during malting, we studied the effects of starch and protein component on the qualities of wheat malt and optimized malting craft according to the problems such as higher protein content of wheat, worse protein solubility and lowerα-AN content of wheat malt. Meanwhile, BSG-food with high protein and dietary fiber was researched, and its processing technique was optimized. The main results were as follows:1. The qualities of 10 varieties wheat and wheat malt were determined, and the correlation of their typical properties was analyzed. The results showed that wheat malt made by conventional malting method had lower KolBach Index and lowerα-AN content. Malt extract had significantly negative correlation with total nitrogen and significantly positive correlation with KolBach Index (P<0.01). Appropriate increasing the KolBach Index favored the improvement of extraction ratio. The wheat with higher total nitrogen had bad protein solubility, which lead to lower extraction ratio. Lumai 21 wheat malt was found as the desired brewing variety with saccharification time 10min, extract 80.0%, wort chromaticity 4EBC, filtration time 60min, total nitrogen 2.32%, saccharification power 428WK, recovery 84.5%, and clear wort.2. The contents of amylose, amylopectin and starch in different wheat and wheat malt were determined to study the effects of these contents on malt qualities. The results showed that the amylose differences between different wheat were not significant (P>0.05) except number 2, 4, 5. Amylose differences between different wheat malt were not significant (P> 0.05).The changes of amylose in all kinds wheat were different. Amylopectin and starch content of wheat and wheat malt in number 1⁵ had no significant differences, while significant differences (P<0.05) among 6¹0. Amylopectin and starch content of wheat declined after malting of which Lumai 21 had the smallest starch variation about 1.66%. Wheat amylose was found have no effect on malt qualities. Wheat amylopectin had negative correlation with saccharification time (P < 0.05), while amylopectin and starch had significantly negative correlation with total nitrogen(P<0.01). Malt amylopectin had negative correlation withα-AN (P<0.05); malt amylopectin and starch had significantly negative correlation with saccharification time(P<0.01). Reducing the loss of amylopectin and starch could shorten saccharification time effectively. The malt made from higher amylopectin and starch content wheat had lower total nitrogen.3. The contents of albumins, globulins, gliadins and glutelin of wheat and wheat malt were determined to study the effects of protein components on malt qualifies. The results showed that Albumins and globulins increased after malting expect individual wheat variety, but gliadins and glutelin decreased, protein extraction efficiency also increased. The higher increments of albumins during malting and the lower content of globulins and glutelin in malt, the better for shorten saccharification time. Wheat gliadins had significant negative correlation with extract and KolBach Index(P<0.01); wheat glutelin had positive correlation with wort color andα-AN(P<0.05)and had significant negative correlation with extract (P< 0.05). Malt gliadins had negative correlation with extract(P < 0.05). Choosing the appropriate wheat with lower gliadins and glutelin could enhance the content of extract and promote protein solubility.4. The changes of AX content and xylanase activity were monitored during malting. The results showed that the AX content decreased during germinating stage, while xylanase activity increased, and the maximal increasing was found at the second day in malting floor. The WEAX increased during germinating stage and the more increasing was found at the steeping stage and the second day in malting floor. The effect of temperature on AX was not obvous during drying stage, and the content of WEAX increased fast when the drying temperature was above 65℃. The xylanase activities increased as the raising of drying temperature and reached the maximun (29.91 nkat·g^-1·s^-1) at 55℃, then decreased.5. The effects of germinating time and drying condition on malt qualities were researched to optimize malting craft. The results showed that extending germinating time was not effective for enhancing the protein solubility, but could reduce saccharification power and malt recovery. It was appropriate that germinating time was 5 days. The better malt was made by drying craft C than drying craft A and B withα-AN 143mg/100g, saccharification power 503WK, wort viscosity 1.71μ, turbidity index 3.6EBC, and filtration time 58min,. KolBach Index 33% Drying craft C was benefit for dissolving protein and holding enzymes activityn. Extending the time of optimal temperature of xylanase activities during malt drying could reduce wort viscosity, improve the filtration rate of wort and beer.6. The effects of sieving condition on nutrition constituent of BSG were researched. A new BSG extruded food was developed with corn and BSG as the main materials and cooking extrusion conditions formula were studied by twin-screw extruder. The results showed that the impurities in BSG such as wheat husk could be removed through 60 sieve, and protein 36.0%, dietary fiber 54.7%, fat 4.9%, ash 3.6%, and total nutrition 99.2%. The best extruding conditions were feeding speed 25kg/h, BSG addition 10%, material moisture 17%, screw speed 300r/min, and cooking temperature 130℃. In comparison with corn snack without BSG, the contents of protein and dietary fiber in BSG-corn snack were increased significantly.