Mirna Lúcia Gigante

Microencapsulation of Lactobacillus acidophilus La-5 by spray-drying using sweet whey and skim milk as encapsulating materials

The aim of this study was to evaluate the effect of encapsulating material on encapsulation yield, resistance to passage through simulated gastrointestinal conditions, and viability of Lactobacillus acidophilus La-5 during storage. Microparticles were produced from reconstituted sweet whey or skim milk (30% total solids) inoculated with a suspension of L. acidophilus La-5 (1% vol/vol) and subjected to spray-drying at inlet and outlet temperatures of 180°C and 85 to 95°C, respectively. The samples were packed, vacuum-sealed, and stored at 4°C and 25°C. Encapsulation yield, moisture content, and resistance of microencapsulated L. acidophilus La-5 compared with free cells (control) during exposure to in vitro gastrointestinal conditions (pH 2.0 and 7.0) were evaluated. Viability was assessed after 0, 7, 15, 30, 45, 60, and 90d of storage. The experiments were repeated 3 times and data were analyzed by ANOVA and Tukey test for the comparison between means. The encapsulating material did not significantly affect encapsulation yield, average diameter, or moisture of the particles, which averaged 76.58±4.72%, 12.94±0.78μm, and 4.53±0.32%, respectively. Both microparticle types were effective in protecting the probiotic during gastrointestinal simulation, and the skim milk microparticles favored an increase in viability of L. acidophilus La-5. Regardless of the encapsulating material and temperature of storage, viability of the microencapsulated L. acidophilus La-5 decreased on average 0.43 log cfu/g at the end of 90d of storage, remaining higher than 10(6)cfu/g.

Quality of minas frescal cheese prepared from milk with different somatic cell counts

The objective of this work was to evaluate the effects of using bulk milk with different somatic cell counts (SCC) on the quality of minas frescal cheese. A randomized complete block design was used, with 3x5 factorial treatments, with three SCC levels (low, 125,000 cells mL-1; intermediate, 437,000 cells mL-1; and high, 1,053,000 cells mL-1) and five storage durations. Cheese was vacuum-packed in plastic bags and analyzed after 2, 9, 16, 23 and 30 days of storage at 4oC. Somatic cell counts did not affect dry matter, fat, ash content, pH, free fatty acid concentrations and sensory parameters of minas frescal cheese. However, SCC in milk increased losses of protein in whey and decreased the cheese protein content. These changes did not affect the moisture-adjusted cheese yield and proteolysis during 30 days of storage. An interaction effect between SCC and time of storage was observed for firmness and sensory grades of cheeses. Results indicated that raw milk used to produce minas frescal cheese should not contain high SCC, in order to avoid lower acceptance of the product after 30 days of storage.

Yield, changes in proteolysis, and sensory quality of Prato cheese produced with different coagulants

The objective of this research was to compare the effect of 2 fungal proteases, one that is already commercially established as a milk-clotting agent and another produced at the laboratory scale, on Prato cheese composition, protein and fat recovery, yield, and sensory characteristics. Cheeses were produced according to the traditional protocol, using protease from the fungus Thermomucor indicae-seudaticae N31 and commercial coagulant from Rhizomucor spp. as clotting agents. A 2×6 factorial design with 3 replications was performed: 2 levels of coagulants and 6 levels of storage time. After 5, 12, 19, 33, 43, and 53d of refrigerated storage (12°C), cheeses were monitored for proteolysis, firmness, and casein degradation by capillary electrophoresis. Sensory acceptance was evaluated after 29d of manufacturing. The different coagulants did not statistically affect Prato cheese composition, protein and fat recovery, and yield. Both cheeses presented good sensory acceptance. Proteolysis increased and firmness decreased for both cheeses during the storage time, as expected for Prato cheese. Caseins were well separated by capillary electrophoresis and the results showed, with good resolution, that the cheeses exhibited similar protein hydrolysis profile. Both cheeses presented good sensory acceptance. The gathered data showed that the protease from T. indicae-seudaticae N31 presented similar action compared with the commercial enzyme, indicating its efficiency as clotting agent for Prato cheese manufacture.

A Survey of the Peptide Profile in Prato Cheese as Measured by MALDI-MS and Capillary Electrophoresis.

In this study, we describe the characterization of the peptide profile in commercial Prato cheese by matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) and capillary electrophoresis (CE). Ten commercial Prato cheese brands were characterized via their physicochemical composition and subjected to fractionation according to solubility at pH 4.6. The pH 4.6 insoluble fraction was evaluated by CE, whereas MALDI-MS was applied to the fraction soluble at pH 4.6 and in 70% ethanol. CE revealed a characteristic pattern of hydrolysis, with formation of para-κ-casein, hydrolysis of αs1 -casein at the Phe23 - Phe24 bond, and hydrolysis of β-casein. For the MALDI-MS data, a complex peptide profile was observed, with the identification of 44 peptides previously reported (24 peptides from αs1 -casein, 14 from β-casein, 3 from κ-casein, and 3 from αs2 -casein). It was also observed that cheeses with salt-in-moisture content greater than 5% showed an accumulation of a bitter-tasting peptide (m/z 1536, αs1 -CN f1-13), suggesting a relationship between the higher salt concentration and the abundance of this peptide. In conclusion, the results showed that even commercial cheeses produced with different raw material and processing conditions showed very similar peptide profiles when assessed at the molecular level, and only 9 peptides were responsible for discrimination of cheeses.

Coalho Cheese Made with Protease from Thermomucor indicae-seudaticae N31: Technological Potential of the New Coagulant for the Production of High-Cooked Cheese.

The aim of this study was to explore the use of a new coagulant from Thermomucor indicae-seudaticae N31 for the manufacture of a high-cooked starter-free cheese variety, by evaluating its physicochemical and functional characteristics in comparison to cheeses made with a traditional commercial coagulant. Coalho cheese was successfully produced with the new protease as it exhibited comparable characteristics to the one produced using the commercial enzyme: pH behavior during manufacture; cheese composition; protein and fat recovery; and cheese yield. In addition, during storage, melting was low and not affected by storage time; the increase of TCA 12% soluble nitrogen (% of total nitrogen) was lower than half of that of pH 4.6 soluble nitrogen (% of total nitrogen); concentration of β-CN significantly decreased, whereas αs1 -CN concentration was not affected by storage time.

Obtenção e caracterização de bases lipidicas a partir da gordura do leite e óleo de girassol alto oleico

Resumo O objetivo deste trabalho foi produzir e caracterizar bases lipídicas obtidas a partir de misturas de gordura anidra do leite (GAL) e óleo de girassol alto oleico (OGAO). As misturas foram preparadas nas proporções 100:0; 90:10: 80:20; 70:30; 60:40; 50:50 (GAL:OGAO % m/m). De acordo com o comportamento de cristalização e fusão e a microestrutura da rede cristalina, a adição de OGAO afetou o equilíbrio entre gorduras líquida e sólida em todas as formulações. Adições iguais ou superiores a 30 % de OGAO à GAL resultaram em bases lipídicas indicadas para aplicações tecnológicas em que espalhabilidade, resistência à exsudação de óleo e ponto de fusão abaixo da temperatura corporal são desejáveis.

Avaliação da estabilidade de emulsões com proteinas do leite como emulsificantes

Resumo O objetivo deste trabalho foi avaliar a estabilidade de emulsões do tipo óleo em água, obtidas a partir da gordura do leite e diferentes emulsificantes naturais (caseinato de sódio, isolado proteico de soro e lecitina). Adicionalmente, utilizou-se emulsificante sintético (Tween80) para efeito de comparação da estabilidade das emulsões. Emulsões estabilizadas com proteínas do leite apresentaram menor estabilidade do que as estabilizadas com Tween80 e lecitina devido, possivelmente, ao maior diâmetro das partículas obtidas após homogeneização.