Maximiliano Soares Pinto

Binding thermodynamics of synthetic dye Allura Red with bovine serum albumin.

The interaction between Allura Red and bovine serum albumin (BSA) was studied in vitro at pH 7.4. The fluorescence quenching was classified as static quenching due to the formation of AR-BSA complex, with binding constant (K) ranging from 3.26±0.09 to 8.08±0.0610(4)L.mol(-1), at the warfarin binding site of BSA. This complex formation was driven by increasing entropy. Isothermal titration calorimetric measurements also showed an enthalpic contribution. The Allura Red diffusion coefficient determined by the Taylor-Aris technique corroborated these results because it reduced with increasing BSA concentration. Interfacial tension measurements showed that the AR-BSA complex presented surface activity, since interfacial tension of the water-air interface decreased as the colorant concentration increased. This technique also provided a complexation stoichiometry similar to those obtained by fluorimetric experiments. This work contributes to the knowledge of interactions between BSA and azo colorants under physiological conditions.

Effects of nisin on Staphylococcus aureus count and physicochemical properties of Minas Frescal cheese

The aim of this work was to evaluate the effects of nisin on in vitro and in situ Staphylococcus aureus counts. For in vitro experiment, milk was inoculated with 5.0 log cfu·mL(-1) of S. aureus and nisin was added at concentrations of 0, 100, 200, 400, and 500 IU mL(-1). The main effect of the bacteriocin was lag phase extension from 0h, for 0 and 100 IU·mL(-1) to 8h, when 200, 400, and 500 IU·mL(-1) of nisin were used; however, log phase was not affected. Microbial growth rate was found to be exponential and around 0.11 log cfu·mL(-1)·h(-1) for all treatments. For in situ experiments, 0, 400, and 500 IU·mL(-1) of nisin were directly added to pasteurized milk previously inoculated with 5.0 log cfu·g(-1) of S. aureus. Milk, curd, and whey were analyzed to S. aureus counts. Nisin at concentration of 500 IU·mL(-1) was able to reduce S. aureus count in curd and whey, demonstrating nisin partition between both phases. Throughout storage at 4°C, S. aureus count increased for all treatments, but the bacterial grew slower when nisin was added in both concentrations, maintaining S. aureus count about 1.5 log cycles lower than the control, despite abusive initial S. aureus count. Therefore, nisin seems to play an important role in reducing S. aureus initial count in cheese made with highly contaminated milk. Nisin showed potential to be used as an additional, important hurdle to improve Minas Frescal cheese safety, without replacing good manufacturing practices.

Interaction of cinnamic acid and methyl cinnamate with bovine serum albumin: A thermodynamic approach

Cinnamic acid (CA) and methyl cinnamate (MC) have attracted interest of researchers because of their broad therapeutic functions. Here, we investigated the interaction of CA and MC with bovine serum albumin (BSA) at pH 3.5, 5.0, and 7.4 using fluorescence spectroscopy, differential scanning nanocalorimetry, and measurements of interfacial tension, size, and zeta potential. BSA formed a complex with the ligands with stoichiometry of approximately 1.0. At pH 7.4, CA-BSA complex formation was entropically driven. The interaction between MC and BSA was more favorable than with CA and was enthalpically driven under the same conditions. The pH played an important role in BSA conformation, which altered the manner in which it interacts with the ligands. Interestingly, both CA and MC had no effect on the surface tension of BSA/air interfaces. These data contribute to the knowledge of CA/MC-BSA interactions and provide important data for application in the food industry.

Probiotics in Dairy Fermented Products

Interest in the role of probiotics for human health began as early as 1908 when Metchnikoff associated the intake of fermented milk with prolonged life (Lourens-Hattingh and Vilijoen, 2001b). However, the relationship between intestinal microbiota and good health and nutrition has only recently been investigated. Therefore, it was not until the 1960’s that health benefit claims began appearing on foods labels.

Efeito da nisina na contagem de Lactococcus e Lactobacillus em queijo Minas artesanal da região de Araxá - MG

The Minas artisanal cheeses from Araxa region are produced in Araxa, Campos Altos, Ibia, Pedrinopolis, Perdizes, Sacramento, Santa Juliana, Uberaba, Conquista, Pratinha e Tapira cities. These cheeses are made from raw milk and they are fairly handled, so they can carry pathogenic micro-organisms, from the milk itself and also from the hygienic and sanitary conditions to which they are subjected. Nisin can adjuvant to reduce the contamination of these cheeses, combined with good manufacturing practices to getting the milk and is a product easy to use. Nisin acts against Gram positive bacteria, some of which are pathogenic, such as Staphylococcus aureus. However, nisin can also inhibit the lactic acid bacteria, depending on the dose used in cheese manufacture and can consequently affect the desired sensory characteristics of the cheese artisan. Therefore, the objective of this study was to evaluate the effect of adding different concentrations of nisin on the behavior of two groups of lactic acid bacteria, Lactobacillus and Lactococcus , in Minas artisanal cheese from Araxa region, during the 60 days of ripening. The search result was satisfactory because it was found that nisin not interfere with the multiplication of Lactobacillus and Lactococcus along the cheese ripening of Minas artisanal from Araxa region

Use of coalho cheese whey in the pasteurized dairy drink elaboration

In Brazil, dairy drink is basically defined as the dairy product resulting from the mixing of milk and cheese whey. As they are economically viable, pasteurized dairy drink 1 Doutor em Ciencia e Tecnologia de Alimentos (UFV). Pesquisador e Professor da EPAMIG/ILCT. Rua Tenente Freitas, 116, Juiz de Fora, MG, Brasil. E-mail: junio@epamig.br. 2 Biomedico (UNIPAC). Campus VI Juiz de Fora. Av. Juiz de Fora, 1100, Granjas Betania. CEP 36047-362. Juiz de Fora, MG, Brasil. E-mail: felipealvesdealmeida@yahoo.com.br. 3 Doutor em Ciencia e Tecnologia de Alimentos (UFV). Pesquisador e Professor da UFMG. Montes Claros, MG, Brasil. E-mail: maxonze@yahoo.com.br. 4 Doutoranda em Ciencia e Tecnologia de Alimentos (UFV). Pesquisadora e Professora da EPAMIG/ILCT. Rua Tenente Freitas, 116, Juiz de Fora, MG, Brasil. E-mail: Vanessa.teodoro@epamig.br. 5 Doutora em Ciencia dos Alimentos (UFLA). Pesquisadora e Professora da EPAMIG/ILCT. Rua Tenente Freitas, 116, Juiz de Fora, MG, Brasil. E-mail: renata.costa@epamig.br. * Autor para correspondencia: EPAMIG/ILCT Rua Tenente Freitas, 116, Juiz de Fora, MG, Brasil. CEP: 36045-560 E-mail: junio@epamig.br. Recebido / Received: 22/12/2011 Aprovado / Approved: 07/05/2012 Pag. 14 Rev. Inst. Latic. “Cândido Tostes”, Jul/Ago, no 387, 67: 13-20, 2012

Easy classification of traditional Minas cheeses using artificial neural networks and discriminant analysis

The classification of traditional Minas cheese (TMC) from different regions is important to ensure authenticity. Different chemometric approaches were used to discriminate TMCs from three different regions (Serro, Canastra and Araxa) of Minas Gerais, Brazil. The data obtained from the literature were used to develop an artificial neural network and to obtain linear discriminant functions, which were able to classify 100% of cheeses from different regions as a function of physico-chemical composition. Both chemometric methods can be very useful tools to discriminate TMC from different regions based on physico-chemical data which are obtained in a very quick and simple way.

CARACTERIZAÇÃO DE UNIDADES AGRÍCOLAS FAMILIARES PRODUTORAS DE LEITE NO NORTE DO ESTADO DE MINAS GERAIS

Milk production in the middle region of northern Minas Gerais state is the lowest in the state. However we noticed a considerable growth in recent years. It is important to conduct socioeconomic and generators technicians guiding information for the adoption of policy measures to boost production diagnostics. The aim of this study was to diagnose the production of milk in 30 family dairy farms in Juramento (15) and Montes Claros (15) city, Northern Minas Gerais; by a case study, semi-structured questionnaires that included information about general and sanitary handling, socio-economic characteristics and also surveyed the use of agro-ecological practices in milk production. A systemic approach was used in the application of questionnaires. Out of the 30 properties, 86% have the dairy activity as the main one, followed by 14% of mixed activities. They have low to average technology and most farmers have another source of income in addition to milk production. The absence of agro-ecological practices in the production process was observed in 100% of the properties. It was concluded that milk production in family farms is very widespread, and the main characteristics are of properties with general and sanitary handling problems; the socio-economic characteristics are of families with low to average income and dependent on the milk production to complement it. Regarding the agro-ecological practices, it can be concluded that they were rarely used in the properties surveyed.

Efeito in-vitro de nisina sobre pool de Staphylococcus aureus isolados de queijos minas artesanal da região do Campo das Vertentes-MG

Minas traditional cheeses currently have a prominent role in the scientific depending on their social and economic importance to the country legally. Although the cheese can be marketed within the state, is notorious its presence outside of Minas Gerais. Because it is made with raw milk, the cheese has a risk for consumers to be potential carrier of pathogens such as Listeria, Salmonella and Staphylococcus aureus . The use of raw milk implies the need for studies to significantly decrease their contamination by S. aureus . Studies have shown that the addition of nisin to cheese manufacturing process can significantly reduce the contamination. The aim of this study was to evaluate the effect of Nisin on pool S. aureus isolates from traditional cheeses of Campo das Vertentes. Four levels (100, 200, 400 and 500 IU. mL -1 ) of the commercial preparation Nisaplin ® in autoclaved reconstituted skim milk at 10%. The analysis of S. aureus were made using 3M Petrifilm at zero; 3, 5, 8, 10, 12, 16, 24, 36, 48, 72, and 96 of incubation. There was no significant difference (p > 0.05) between control and doses of 200 IU mL -1 . However differences were observed between the other doses (p <0.05) in the two mentioned and also among themselves. The results of this study confirm those already made elsewhere showing that nisin can be effective in reducing counts of S. aureus in cheeses made with raw milk.