Estudo do processamento de soro de leite bovino através da coagulação com quitosana e secagem

• Ano de defesa: 2012
• Autor(a) principal: Amália Luísa Pedrosa Xavier
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Secagem em secador de bandeja; Quitosana; Coagulação; Soro de leite; Soro de leite Processamento; Engenharia quimica
• Link de acesso: http://hdl.handle.net/1843/BUOS-972JR8

Whey is a byproduct of cheese industry. It is a essential amino acids source and their physicochemical properties provide functional properties of great technological interest. Contains about 6% of solids, retaining 55% of milk nutrient. Almost a half of the total worldwide whey produced is being used to feed pigs or discarded, improperly, into rivers and public sewer system. Therefore, it is necessary to develop technologies capable to recycling its nutrients available to small and medium producers. Chitosan, a natural polymer, low cost, renewable and biodegradable, has been widely used in recovery of processing food biomass waste, being used as a coagulating agent. The drying tray dryer is widely used because it is the simplest type of dryer, easy maintenance and low cost, wich make it affordable. In this context, this study aims to evaluate the effectiveness of chitosan as a coagulant, analyzing the effect of its concentration and processing temperature, in whey turbidity removal and subsequent study of the coagulated drying in a convective oven dryer. Characterization analyzes (total solids, ash, lactose, protein, lipid, COD) were performed in order to assess the use of chitosan in the recovery of solids present in whey. Coagulation assays were performed using the factorial design Rotational Center Compound, in conditions of natural whey pH, temperature between 6 and 34°C and concentration between 280 and 420 mg/L. The coagulation assays showed high efficiency of turbidity removal for concentrations of 300, 350 and 400ppm chitosan in 1% solution of acetic acid and at lower temperature (around 10°C). The optimal condition considered for coagulation was 350mg/L of chitosan. From the obtained coagulate, tests in a convective oven dryer were carried out at temperatures of 55, 60, 65°C, kinetic curves and the curve of water activity was determined. The drying studies have shown that the temperature of 55°C maintained for 30 minutes is sufficient to obtain a solid whose humidity is lower than 5% and a water activity of 0.5, as ensuring the microbial contamination. The mathematical model for the sorption isotherm for adjustment of the data was the Langmuir model for water activities greater than 0.5 and BET linearized for water activity below than 0.5. In these processes yielded an average efficiency of turbidity removal, total solids, ash and COD, respectively, 99.21%, 12.49%, 0.22%, 2.67%. The coagulated was characterized with 67% fat, 15% protein, 2.43% lactose and 8.8% chitosan. This product, rich in beneficial lipids and proteins also may have potential for use as a feed additive, improving its nutritional value and sensory properties, such as cosmetics and pharmaceuticals. Thus, we propose a route processing accessible for small and medium producer, adding value into a byproduct, could become a source of income for the producer and giving him a better purpose and facilitating the treatment of the waste generated.