Claudia Regina Vieira

Study of Some Functional Properties of Casein: Effect of pH and Tryptic Hydrolysis

The trypsin was used to hydrolyze commercial casein at varied times and pH range. The functional properties studied were the emulsifying capacity (EC), the emulsifying activity index (EAI), and the emulsion stability (ES). The dispersed phase used was corn oil. The tryptic hydrolysis was beneficial to the solubility and EC of casein in practically all pH values and reaction times. In case of EAI, this same effect was less intense and was observed only in acid region (pH 3.0 to 5.0), while for ES the trypsin action was mainly deleterious in almost all pH range and reaction times.

Extração química e enzimática das proteínas do fubá de milho

Diferentes metodos quimicos e um enzimatico foram testados para extracao das proteinas do fuba de milho. A avaliacao do rendimento da extracao proteica foi feita pela determinacao do teor de proteina e de solidos totais dos residuos obtidos. Para a extracao quimica das proteinas, uma solucao alcalina, isoladamente ou em associacao com etanol, foi empregada como solvente. O metodo alcalino-alcoolico sequencial foi o mais eficiente, dentre os metodos quimicos testados, tendo alcancado 88,2% de rendimento. Por outro lado, o metodo alcalino (75,5% de rendimento) apresenta a vantagem de nao empregar etanol, reduzindo os custos do processo, pois se evita a etapa de remocao desse solvente. Para a extracao enzimatica, foi utilizada uma protease de Bacillus liccheniformis. As variaveis, tempo e temperatura, empregadas no metodo enzimatico influenciaram no rendimento da extracao proteica do fuba de milho. Os melhores resultados foram obtidos em 5, 15 e 24 h a 55 °C, que nao apresentaram diferenca significativa, sendo que a condicao mais vantajosa do ponto de vista economico foi a de 5 h a 55 °C com um rendimento de 83,8%.

Extração enzimática das proteínas da farinha de arroz

The enzymatic extraction of proteins from a commercial rice flour was studied in this work. In order to increase the Protein Extraction Yield (PEY), the following parameters were evaluated: enzyme type (alkaline and neutral protease); temperature (40, 50 and 60 °C); pH (9.5, 10.5 and 11.0); physical treatment of the sample (no treatment; Ultra-Turrax at 16.000 rpm and ultrasound at 120 W, both for 5, 10 and 15 minutes); enzyme:substrate ratio (E:S) of 5:100 and 10:100 and initial concentration of raw material (1:3, 1:5 and 1:10 w/v). The PEY was calculated using the protein contents of rice flour and the extraction residues. The results showed that the best condition for protein extraction, which gave the highest PEY (63.4%), was that using an initial concentration of raw material of 1:10 (w/v), no physical treatment, pH 10.5, the alkaline protease, an E:S of 10:100, at 50 °C.