Lactose hydrolyzed milk powder: optimization of the drying process and study of structural and functional properties

• Ano de defesa: 2019
• Autor(a) principal: Fialho, Tatiana Lopes
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Ciência e Tecnologia de Alimentos
• Palavras-chave em Português: Leite em pó; Lactose; Secagem por pulverização; Termodinâmica; Tecnologia de Produtos de Origem Animal
• Link de acesso: https://locus.ufv.br//handle/123456789/30202

The production technology of lactose hydrolyzed milk powder has been developed to meet the needs of lactose intolerant consumers. Although the product is currently marketed in some countries, the industry faces technological issues during the production and storage of the powder such as agglomeration, caking, browning, high hygroscopicity, low production yield and loss of techno-functional properties. In this context, two main objectives were assigned to the work ofthis thesis: (i) to optimize the drying process of lactose hydrolyzed milk powder; (ii) to understand the impact of lactose hydrolysis on the internal structure of lactose hydrolyzed milk powder on a molecular scale. In order to optimize the drying process of lactose hydrolyzed milk powder, powder samples were subjected to various drying conditions: concentrated milk flow rates varying from 0.3 to 1.5 kg.h-¹ and inlet air temperature ranging from 115 to 160 °C, Then, a thermodynamic characterization of the drying process was carried out using the equations of mass and energy balance. To understand the impact of lactose hydrolysis on the internal structure of the powder after drying and during storage, the organization and dynamics of the molecules in lactose hydrolyzed milk powder were analyzed by examining appearance and structure of the powder samples and their techno-functional properties. Throughout the experiments, traditional milk powder was used as a control. In this study, it has been observed that the ideal parameters for lactose hydrolyzed milk powder production were: inletair temperature at 145º C and 1.0 kg . h-¹ flow rate. This finding reinforces the idea that the drying conditions of lactose hydrolyzed milk powder are different from those used to make traditional milk powder. It was also observed that molecules present in milk powder hydrolyzed with lactose presented a more homogeneous molecular organization comparedto traditional milk powder and allowed for greater protein-sugar interaction. Under accelerated aging conditions of the hydrolyzed powder,the protein glycation was the initial process that triggers the main modifications observed in lactose hydrolyzed milk powderduring storage.