Rheological, physicochemical and authenticity assessment of Minas Frescal cheese

Effect of starter cultures on properties of soft white cheese made from camel (Camelus dromedarius) milk

This experiment was conducted to investigate the effect of starter cultures on the physicochemical properties, texture, and consumer preferences of soft white cheese (SWC) made from camel (Camelus dromedarius) milk. The experiment was laid out in a completely randomized design with 5 treatments [starter cultures; i.e., 1 thermophilic (STI-12), 2 blended (RST-743 and XPL-2), and 2 mesophilic (R-707 and CHN-22) cultures]. Starter cultures STI-12 and RST-743 were inoculated at 37°C, whereas XPL-2, R-707, and CHN-22 were inoculated at 30°C. Camel milk inoculated using STI-12 and RST-743 cultures resulted in faster acidification than XPL-2, R-707, and CHN-22 cultures. Camel milk SWC made using STI-12 and CHN-22 cultures gave lower pH (4.54) and titratable acidity (0.59), respectively, whereas R-707 culture resulted in high cheese yield (13.44 g/100 g). In addition, high fat (20.91 g/100 g), protein (17.49 g/100 g), total solids (43.44 g/100 g), and ash (2.40 g/100 g) contents were recorded for SWC made from camel milk made using RST-743 culture. Instrumental analysis of cheese texture revealed differences in resistance to deformation in which camel milk SWC made using RST-743 culture gave higher firmness (3.20 N) and brittleness (3.12 N). However, no significant difference was observed among camel milk SWC adhesiveness made using different starter cultures. Consumer preference for appearance, aroma, taste, and overall acceptances of SWC were affected by inoculation of starter cultures. Considering curd firmness, cheese yield, compositional quality, and textures using STI-12, RST-743, and R-707, these cultures were found to be better for the manufacture of camel milk SWC.

ANÁLISE DA VARIABILIDADE ESPACIAL DA RESISTÊNCIA À PENETRAÇÃO DO SOLO EM DIFERENTES PROFUNDIDADES

A compactação do solo em áreas cultivada cana-de-açúcar é muito acentuada devido ao uso intenso de máquinas e implementos agrícolas, é um dos fatores que ocasionam sérias restrições ao desenvolvimento radicular das plantas. Objetivou-se neste trabalho caracterizar a variabilidade espacial da resistência do solo a penetração (RSP), de uma área reformada após acomodar por cinco anos plantio de cana-de-açúcar. O experimento foi conduzido em abril de 2015 na Fazenda Santa Martha localizada em Espírito Santo do Turvo, SP. A coleta da RSP foi feita por meio de um penetrômetro elétrico, em pontos previamente georreferenciados totalizando 56 pontos, distribuídos em um talhão irregular. Utilizou-se a geoestatística para análise das variações espaciais da RSP de cinco diferentes profundidades do perfil do solo (1, 10, 20, 30 e 40 cm), foi feita também a coleta da umidade do solo, somente nos pontos centrais. O modelo de semivariograma que melhor se ajustou aos valores de resistência do solo à penetração foi o esférico. Este estudo resultou em altos e moderados graus de dependência espacial, nos perfis de 1, 10 e 20 cm, e efeito pepita nas profundidades 30 e 40 cm. Foi possível avaliar a variabilidade espacial da RSP por meio da geoestatística, sendo que a maior homogeneidade foi no perfil de 1, 10 e 20 cm.

A control method to inspect the compositional authenticity of Minas Frescal cheese by gel electrophoresis

This study introduces a qualitative method to inspect the compositional authenticity of white nonripened cheeses like Minas Frescal, a typical Brazilian cheese, especially when irregular replacement of milk by whey is suspected. A sodium dodecyl sulfate gel electrophoresis (SDS-PAGE) method, followed by image densitometry, was validated. Cheeses were freeze-dried to electrophoresis, and β-lactoglobulin (β-LG) was chosen as the adulteration marker. In gel trypsin digestion followed by matrix assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry provided its identification. Cheeses with a minimum of 14 mg·g(-1) of β-LG are considered to be adulterated. The method shows satisfactory precision with a detection limit of 7 mg·g(-1). Forty-two commercial samples from inspected establishments were then assessed and subjected to cluster analysis. Compliant and noncompliant groups were set with 24 (57%) authentic samples and 18 (43%) adulterated samples, respectively, showing that proper analytical monitoring is required to inhibit this practice.