Bhardwaj, Rachana DHeena Rani2023-12-112023-12-112023Heena Rani (2023). Malt quality and thermostability studies in mutants, hulled, hull-less and wild genotypes of barley (Hordeum vulgare L.) (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810202586Despite various attempts to develop malt hydrolytic enzymes, the catalytic activity and thermostability of these enzymes are still far from sufficiency for their use in the malting process. The present study explored diverse barley germplasm to identify the genotypes with high activity and thermostability of enzymes alongwith the proteins responsible for high malt yield. Based on enzymatic assays, we selected BL1714T, DWRB137T and BL2105T with highly activity and thermostability of α and β amylases and limit dextrinase, which are key diastatic power enzymes. The barley proteome of these genotypes was analyzed before and after kilning using label-free quantitative global proteomic approach against the control genotypes; BL1718Ctrl, DWRUB64Ctrl and BL2083Ctrl, respectively. Among various isoforms of hydrolytic enzymes Bamy 1 and Amy1_2 were more abundant in thermostable genotypes indicating their role in controlling the activity of these enzymes at high temperatures. Gene ontology enrichment analysis indicated disulfide reductase, exopeptidase, serine-type peptidase (serpin), cell wall hydrolase and oxidoreductase activities as most common enriched terms in thermostable genotypes. These proteins work to release the bound form of hydrolytic enzymes, resulting in their increased overall activity. These proteins could be employed as biochemical indicators for identifying barley lines with high activity and thermostability. Using GC-MS/MS, we identified maltose, glucose, talose, sucrose, fructose, turanose and other minor sugars in green and kilned malt. Talose and turanose were identified among major sugars for the first time during malting. Further, malt quality analysis suggested that βglucanase and malt β-glucan can be used as additional traits to produce malt with superior quality.EnglishThesis