Changes in the chemical and in-vitro antihypertensive properties of sweet whey obtained from miniature fresh, Chanco and Gouda-style model cheeses.

This Technical Research Communication evaluated the influence of various cheese manufacture methods on the composition and in vitro antihypertensive activity of sweet whey samples obtained from miniature models for fresh, Chanco and Gouda-style cheese processing using bulk-tank milks throughout a year. Raw milks from morning milking were standardized, pasteurized and used to obtain sweet whey using cheesemaking protocols for each variety on 200 g scale, as well the use of whey dilution at levels of 0, 15, 30 and 45% in Chanco and Gouda-style making. The composition of sweet whey obtained within each cheesemaking variety was similar among different timepoints of the year (P > 0.05), which was attributed to similar composition of milks and the use standardized cheesemaking protocols used for this study. As expected, the use of whey dilution led to sweet whey samples with reduced levels of total solids (P < 0.05), but they exhibited an improvement of the in vitro antihypertensive properties, which may be attributed to the formation of low-molecular weight bioactive peptides due to increased cheese making times. The results of this study suggest that modifying cheese manufacture protocols may have a direct impact on the bioactive properties of sweet whey. Future work will be required to identify and evaluate the feasibility to purify bioactive peptides obtained from sweet whey.

Evaluation of the milk clotting properties of an aspartic peptidase secreted by Rhizopus microsporus.

Traditionally, chymosin has been used for milk-clotting, but this naturally occurring enzyme is in short supply and its use has raised religious and ethical concerns. Because milk-clotting peptidases are a promising substitute for chymosin in cheese preparation, there is a need to find and test the specificity of these enzymes. Here, we evaluated the milk-clotting properties of an aspartic peptidase secreted by Rhizopus microsporus. The molecular mass of this enzyme was estimated at 36 kDa and Pepstatin A was determined to be an inhibitor. Optimal activity occurred at a pH of 5.5 and a temperature range of 50-60 °C, but the peptidase was stable in the pH range of 4-7 and a temperature as low as 45 °C. Proteolytic activity was significantly reduced in the presence of Cu2+ and Al3+. When enzyme substrates based on FRET were used, this peptidase exhibited the highest catalytic efficiency for Abz-KNRSSKQ-EDDnp (4,644 ± 155 mM-1.s-1), Abz-KLRSSNQ-EDDnp (3,514 ± 130 mM-1.s-1), and Abz-KLRQSKQ-EDDnp (3,068 ± 386 mM-1.s-1). This study presents a promising peptidase for use in cheese making, due to its high stability in the presence of Ca2+ and broad pH range of 4-7, in addition to its ability to efficiently clot milk.

Influence of sanitary inspection on the physicochemical quality of coalho cheese / Influência da inspeção sanitária na qualidade físico-química do queijo de coalho

This study aimed to evaluate the influence of sanitary inspection on the physicochemical characteristics, colour and texture of coalho cheese commercialised in the semiarid region of Brazil. One hundred and thirty-eight coalho cheese samples from commercial establishments in 46 Brazilian cities were evaluated, and physicochemical analyses (acidity, moisture, fat content, pH and ashes), as well as colour and texture tests were performed. The averages for the parameters in cheeses without the official sanitary inspection seal were 4,31, 0.34%, 50.34%, 55.9 and 4.83, for ash, relative acidity, moisture, fat content and pH and in samples with the official sanitary inspection seals we found values of 4,41, 0.32%, 51.51%, 55.37 and 4.92, for the same parameters, respectively. There was no difference in the colour and texture parameters, which for the samples with the official seal were 71.15, 1.43, 13.52 and 1.65; and for the ones without the official seal were 69.58, 1.50, 13.15 and 1.71 for L*, a*, b* and texture, respectively. The fact that the coalho cheese was commercialised with an official inspection seal did not influence the physicochemical, texture or colour analyses.(AU)

Com oobjetivo de avaliar a influência da inspeção sanitária nas características físico-químicas, cor e textura do queijo de coalho comercializado no semiárido do Brasil,138amostras de queijo de coalho de estabelecimentos comerciais de 46 cidades foram avaliadas quanto as análises físico-químicas (acidez, umidade, teor de gordura, pH e cinzas), além de testes de cor e textura. As médias dos parâmetros de queijos sem selo de inspeção sanitária oficial foram 4,31, 0,34%, 50,34%, 55,9 e 4,83, para cinzas, acidez relativa, umidade, teor de gordura e pH e nas amostras com selos sanitários oficiais encontraram valores de 4,41, 0,32%, 51,51%, 55,37 e 4,92, para os mesmos parâmetros, respectivamente. Não houve diferença nos parâmetros de cor e textura,as amostras com selo oficial apresentaram71,15, 1,43, 13,52 e 1,65; e as amostras sem o selo oficial foram 69,58, 1,50, 13,15 e 1,71 para L *, a *, b * e textura, respectivamente. Tanto os queijos com selo de inspeção quanto os sem inspeção apresentam grande variabulidade quanto aos caracteres físico-químicos, de cor e textura, não hvendo diferença entre os dois grupos, comprovando uma falta de padronização na produção do queijo de coalho, evidenciando assim uma diferenciação individual que pode influencair na escolha do consumidor no momento da compra.(AU)

Influence of sanitary inspection on the physicochemical quality of coalho cheese / Influência da inspeção sanitária na qualidade físico-química do queijo de coalho

This study aimed to evaluate the influence of sanitary inspection on the physicochemical characteristics, colour and texture of coalho cheese commercialised in the semiarid region of Brazil. One hundred and thirty-eight coalho cheese samples from commercial establishments in 46 Brazilian cities were evaluated, and physicochemical analyses (acidity, moisture, fat content, pH and ashes), as well as colour and texture tests were performed. The averages for the parameters in cheeses without the official sanitary inspection seal were 4,31, 0.34%, 50.34%, 55.9 and 4.83, for ash, relative acidity, moisture, fat content and pH and in samples with the official sanitary inspection seals we found values of 4,41, 0.32%, 51.51%, 55.37 and 4.92, for the same parameters, respectively. There was no difference in the colour and texture parameters, which for the samples with the official seal were 71.15, 1.43, 13.52 and 1.65; and for the ones without the official seal were 69.58, 1.50, 13.15 and 1.71 for L*, a*, b* and texture, respectively. The fact that the coalho cheese was commercialised with an official inspection seal did not influence the physicochemical, texture or colour analyses.

Com oobjetivo de avaliar a influência da inspeção sanitária nas características físico-químicas, cor e textura do queijo de coalho comercializado no semiárido do Brasil,138amostras de queijo de coalho de estabelecimentos comerciais de 46 cidades foram avaliadas quanto as análises físico-químicas (acidez, umidade, teor de gordura, pH e cinzas), além de testes de cor e textura. As médias dos parâmetros de queijos sem selo de inspeção sanitária oficial foram 4,31, 0,34%, 50,34%, 55,9 e 4,83, para cinzas, acidez relativa, umidade, teor de gordura e pH e nas amostras com selos sanitários oficiais encontraram valores de 4,41, 0,32%, 51,51%, 55,37 e 4,92, para os mesmos parâmetros, respectivamente. Não houve diferença nos parâmetros de cor e textura,as amostras com selo oficial apresentaram71,15, 1,43, 13,52 e 1,65; e as amostras sem o selo oficial foram 69,58, 1,50, 13,15 e 1,71 para L *, a *, b * e textura, respectivamente. Tanto os queijos com selo de inspeção quanto os sem inspeção apresentam grande variabulidade quanto aos caracteres físico-químicos, de cor e textura, não hvendo diferença entre os dois grupos, comprovando uma falta de padronização na produção do queijo de coalho, evidenciando assim uma diferenciação individual que pode influencair na escolha do consumidor no momento da compra.

Comparison of the milk-clotting properties of three plant extracts.

Several proteases from plant sources have been proposed as milk coagulants, however, limited research has been done on their milk-clotting properties. The effect of temperature on the milk-clotting activity of kiwi fruit, melon and ginger extracts was evaluated, as well as the effects of the different extracts on curd properties. Melon extracts showed high milk-clotting activity over a broad temperature range (45-75 °C) while kiwi fruit and ginger extracts showed high activity over a narrower temperature range, with a maximum at 40 and 63 °C, respectively. Curds produced using kiwi extracts had textural properties comparable with those obtained using commercial rennet, while melon extracts produced a fragile gel and low curd yield. The milk-clotting behavior of the three plant extracts was related to the protease specificity present in these extracts. The kiwi proteases displayed chymosin-like properties and thus hold the best potential for use as a milk coagulant in cheese production.