Browsing by Subject "malt"

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  • Luoto, Sanna (Helsingfors universitet, 2011)
    The literature review dealt with celiac-toxic Triticeae prolamins and their enzymatic degradation. Also the immunochemical methods for prolamin analysis were introduced. The gluten-derived immunogenic peptides are proline-rich and thereby remarkably resistant to proteolytic degradation. Most of the triggering prolamins can, however, be degraded by combining endogenous cereal enzyme activity with acidic incubation. Despite of this residual prolamins still exist and their concentration exceeds the threshold considered to be safe for gluten intolerants. The objective of the experimental work was to further hydrolyse the residual prolamins present in malt autolysates of wheat, barley and rye, with a food grade proline endopeptidase from Aspergillus niger (AN-PEP). Size-exclusion chromatography (SEC), free amino nitrogen (FAN) and SDS-PAGE analysis determined the extent of protein hydrolysis. Actual prolamin degradation was observed with immunological methods. Hydrolysis of residual prolamins was extensive in all malt systems – more than 96% of the prolamins were hydrolysed. The SEC and FAN data revealed that continuation of the hydrolysis overnight converted the polypeptides into smaller hydrolysis products. According to enzyme-linked immunosorbent assay analyses, 22 h incubation decreased the prolamin contents of wheat and rye malt hydrolysates below the level of 100 mg/kg. This level was achieved with AN-PEP concentration of 35 ?L/g in relation to freeze-dried autolysate. According to the Codex Alimentarius, food products containing gluten up to 100 mg/kg can be labelled 'very low gluten' and thus included in coeliac diet. AN-PEP treated rye malt ingredient could especially be a promising low-gluten ingredient to enhance the flavour of often poor-quality gluten-free bread. Before commercial applications can be devised the potential as a flavouring agent as well as the clinical safety of the product must be evaluated.