The Influence Of Malting Process On Oat Malt Quality

The influence of the malting process on the quality of nutritional malt and brewing maltwere investigated applying single factor and orthogonal experiments. Furthermore, we studiedthe dynamic changes in endogenous (malting) enzyme activities, carbohydrate and phenoliccompounds of oats during malting.The main conclusions of this study were as follows:(1) Compared with the standards of GB/T7416-2008, in addition to the grain weight ofoat was smaller, the other physiochemical indicators basically reached the requirements of GB/T7416-2008. In conclusion, the oats met the requirements of malting, and could be used formalting study.(2) Malting process had a significant effect on the nutritional quality of oats. The overalloptimum conditions were established at15℃germination temperature,4d of germinationtime, and14℃steeping temperature. Under this condition, phytic acid content decreased by36.4%, IVPD increased by86.2%, while beta-glucan content decreased by87.0%. In addition,minerals and polyphenols content increased significantly. This suggested that oat would be agood material to produce whole grain food after malting.(3) Germination temperature and germination time were the main factors affecting theoat malt nutritional quality. Compared with the raw oats, germination could significantlyresult the reduction in β-glucan, phytic acid content and increase in protein digestibility invitro.(4) The optimized malting program of brewing malt was established at15°C steepingtemperature,30h of steeping time,17°C germination temperature and6d of germination time.Under this condition: diastatic power was171.83WK, the Kolbach index of42.72%, maltalpha-amino nitrogen was209.15mg/100g, malt extract of76.6%.(5) The optimum kilning process was wilting and drying period of45°C (6h)-55°C (5h)-65°C (6h), kilning76°C (2h). Under this kilning process, malt enzyme activity was well preserved, and the loss of malt α-amino nitrogen and diastatic power were reduced.(6) Malting of oat grain resulted in the increase in the activity of alpha-amylase,beta-amylase, beta-glucanase, protease, the maximum activities were obtained at144h ofgermination, then declined at different rates during drying and kilning process. Fructose,glucose, sucrose, and maltose content increased during malting. Beta-glucan content declinedsignificantly in the germination process. Total nitrogen content changed little. Both Kolbachindex and soluble nitrogen content slightly decreased during steeping, increased after24h ofgermination, reached the peak at germination of144h, then slightly decreased in the dryingand kilning stage. Total polyphenols, free polyphenols and bound polyphenols content allshowed an upward trend during malting. The content of p-hydroxybenzoic acid, coffeic acid,p-coumaric acid, ferulic acid was increased in varied degrees.