Thermal, structural and morphological characterization of malt starch during hydrolysis process at protein rest temperature

• Ano de defesa: 2017
• Autor(a) principal: Fregonesi, Fernanda Gabriela
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Positivo; Brasil; Pós-Graduação; Programa de Pós-Graduação em Biotecnologia Industrial; UP
• Palavras-chave em Português: Biotecnologia; Cerveja - indústria; Malte; Hidrólise; CNPQ::CIENCIAS BIOLOGICAS::BIOLOGIA GERAL
• Link de acesso: https://repositorio.cruzeirodosul.edu.br/handle/123456789/2258

Malt is a key ingredient in beer production process. It is obtained through malting barley grains and it provides color and aroma to the final product. During malting process, several endogenous enzymes are made and mobilized. These enzymes later on are responsible for hydrolyzing starch and malt proteins during brewing process. To convert starch onto monosaccharides -main objective of brewing process- it’s used to scarification above gelatinization temperatures, making it more accessible to diastatic enzymes action. Gelatinization causes several changes into starch grains, making hard to comprehend enzymatic alterations on it during hydrolysis. In order to elucidate it, this work simulated a saccharification using temperatures below gelatinization corresponding to protein rest phase of brewing. During this process samples were taken every twenty minutes to observe morphological changes in granules using electronic microscopy (EM), alterations in granules structure using x-ray diffraction (XDR) and variations of thermostability and decomposition using thermal analysis such as thermogravimetry (TG-DTA) and exploratory differential calorimetry (DSC). As hydrolysis takes place it could be observed signs of enzymatic activity in granules surfaces, result that can be corroborate with density of wort raising. Data from thermal analysis have not shown any huge change between samples due to the presence of fibers within starch granules once they could not be isolated in order to simulate brewing process. It was observed a raise in gelatinization temperature in samples, which can be related to hydrolysis of starch amorphous zones. This result can be correlated to XRD results showing a crystallinity change within samples. Therefore, using a hydrolysis temperature below gelatinization we could manage to have a better understanding on how enzymatic activity in starch grains affects its structure and characteristics.