An Aspergillus niger UFV-1 phytase was characterized and made available for industrial application. The enzyme was purified via ultrafiltration followed by acid precipitation, ion exchange and gel filtration chromatography. This protein exhibited a molecular mass of 161 kDa in gel filtration and 81 kDa in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), indicating that it may be a dimer. It presented an optimum temperature of 60 °C and optimum pH of 2.0. The K M for sodium phytate hydrolysis was 30.9 mM, while the k cat and k cat / K M were 1.46 ×10 5 s −1 and 4.7 × 10 6 s −1 .M −1 , respectively. The purified phytase exhibited broad specificity on a range of phosphorylated compounds, presenting activity on sodium phytate, p-NPP, 2- naphthylphosphate, 1- naphthylphosphate, ATP, phenyl-phosphate, glucose-6-phosphate, calcium phytate and other substrates. Enzymatic activity was slightly inhibited by Mg 2+ , Cd 2+ , K + and Ca 2+ , and it was drastically inhibited by F − . The enzyme displayed high thermostability, retaining more than 90% activity at 60 °C during 120 h and displayed a t 1/2 of 94.5 h and 6.2 h at 70 °C and 80 °C, respectively. The enzyme demonstrated strong resistance toward pepsin and trypsin, and it retained more than 90% residual activity for both enzymes after 1 h treatment. Additionally, the enzyme efficiently hydrolyzed phytate in livestock feed, liberating 15.3 μmol phosphate/mL after 2.5 h of treatment.

Based on an observed decrease of effective thermal conductivity of milk during coagulation, a heated thermistor sensor was developed for monitoring curd formation. The thermistor was heated with a constant direct current, and its voltage was measured during milk coagulation, indicating a drop after the enzymatic reaction. The sensor was studied in the laboratory for different milk acidities, rennet concentrations, added calcium chloride, and coagulation temperatures. It was also tested in a commercial cheese plant for more than a month. The cutting time established by the cheesemaker in 16 experiments was compared with a prediction equation, and the standard error of prediction was 1.9 min.

Five lactating goats were used in a 5x5 Latin square experiment to determine the effects of feeding whole sugarcane (WSC) on intake, total tract nutrient digestibilities, milk yield and milk composition. Goats were fed diets containing 0, 100, 200, 300, and 400 g kg(-1) WSC and 400, 300, 200, 100, and 0 g kg(-1) tifton hay (TH). Intake of dry matter and neutral detergent fiber (NDF) decreased linearly (p<0.05) as the level of WSC in the diet increased. Total tract nutrient digestibilities were not influenced by WSC inclusion except for the digestibility of NDF which decreased linearly (p<0.05) as the level of WSC in the diet increased. Inclusion of WSC linearly (p<0.05) decreased milk yield without affecting milk composition. It was concluded that WSC had a lower feeding values than TH for lactating goats.

This work aimed to study the partition of cheese whey proteins alpha-lactoalbumin and beta-lactoglobulin using aqueous two-phase system by applying the cloud point extraction technique. The cloud point temperatures were determined under different concentrations of copolymer and salt. The system providing the best protein separation conditions was 20 mass% of copolymer PE61 and potassium phosphate salt solution of 100 mM, at pH 7. The protein alpha-lactoalbumin remained preferentially in the aqueous phase and the beta-lactoglobulin was transferred to the copolymer phase.

O Simpósio de Alimentos (SIMAL) e a Semana Acadêmica de Ciência e Tecnologia de Alimentos (SEACAL) são eventos organizados pelos professores e estudantes do curso de Ciência e Tecnologia de Alimentos da Universidade Federal de Viçosa, Campus Rio Paranaíba.