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.

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.

Polydiacetylene/triblock copolymer nanosensor for the detection of native and free bovine serum albumin.

Bovine serum albumin (BSA) has been recognized as a marker of the cow's health, milk quality, an allergenic protein and as a carrier. Its detection is important in the food, pharmaceutical and medical industries. However, traditional techniques used to detect BSA are often time-consuming, expensive, and show limited sensitivity. This paper describes properties of polydiacetylene-triblock copolymer (L64) nanosensors, synthesized to easily detect BSA. Sensor efficiency was studied as a function of nanosensor composition, polydiacetylene chemical structures, BSA conformation and hydrophobic domain availability, using spectroscopic, calorimetric, light scattering, and electrokinetic analyses. Nanosensors were sensitive to detect the average BSA concentration of milk and dairy products and discriminated between native and denatured protein through naked-eye detectable blue-to-red transition. The standard Gibbs free energy (-10.44<ΔG°<-49.52kJM), stoichiometry complex (1<"n"<3), and binding constant (6.7×102

Performance of two alternative methods for Listeria detection throughout Serro Minas cheese ripening

ABSTRACT The ability of pathogens to survive cheese ripening is a food-security concern. Therefore, this study aimed to evaluate the performance of two alternative methods of analysis of Listeria during the ripening of artisanal Minas cheese. These methods were tested and compared with the conventional method: Lateral Flow System™, in cheeses produced on laboratory scale using raw milk collected from different farms and inoculated with Listeria innocua; and VIDAS®-LMO, in cheese samples collected from different manufacturers in Serro, Minas Gerais, Brazil. These samples were also characterized in terms of lactic acid bacteria, coliforms and physical-chemical analysis. In the inoculated samples, L. innocua was detected by Lateral Flow System™ method with 33% false-negative and 68% accuracy results. L. innocua was only detected in the inoculated samples by the conventional method at 60-days of cheese ripening. L. monocytogenes was not detected by the conventional and the VIDAS®-LMO methods in cheese samples collected from different manufacturers, which impairs evaluating the performance of this alternative method. We concluded that the conventional method provided a better recovery of L. innocua throughout cheese ripening, being able to detect L. innocua at 60-day, aging period which is required by the current legislation.

Performance of two alternative methods for Listeria detection throughout Serro Minas cheese ripening.

The ability of pathogens to survive cheese ripening is a food-security concern. Therefore, this study aimed to evaluate the performance of two alternative methods of analysis of Listeria during the ripening of artisanal Minas cheese. These methods were tested and compared with the conventional method: Lateral Flow System™, in cheeses produced on laboratory scale using raw milk collected from different farms and inoculated with Listeria innocua; and VIDAS(®)-LMO, in cheese samples collected from different manufacturers in Serro, Minas Gerais, Brazil. These samples were also characterized in terms of lactic acid bacteria, coliforms and physical-chemical analysis. In the inoculated samples, L. innocua was detected by Lateral Flow System™ method with 33% false-negative and 68% accuracy results. L. innocua was only detected in the inoculated samples by the conventional method at 60-days of cheese ripening. L. monocytogenes was not detected by the conventional and the VIDAS(®)-LMO methods in cheese samples collected from different manufacturers, which impairs evaluating the performance of this alternative method. We concluded that the conventional method provided a better recovery of L. innocua throughout cheese ripening, being able to detect L. innocua at 60-day, aging period which is required by the current legislation.

Efeito do processamento sobre as características físico-químicas de queijos artesanais produzidos na região do Serro, MG / Effect of processing on the physicochemical characteristics of artisanal cheeses produced in the region of Serro, MG

O presente estudo surgiu a partir da necessidade de caracterização do Queijo Minas Artesanal a fim de padronizar a tecnologia nas regiões tradicionais do Estado de Minas Gerais. Foram avaliados os efeitos dos diferentes processos de fabricação de três queijarias da Região do Serro sobre suas características físico-químicas. Conclui-se que há diferenças na composição dos queijos e, algumas delas são devidas às variações das etapas de fabricação. Sugere-se um estudo mais detalhado das etapas de fabricação, a fim de padronizar os queijos artesanais produzidos na região do Serro, melhorando o padrão e a qualidade dos mesmos.