The aim of this research paper was to characterize coagulase-positive and coagulase-negative staphylococci from raw milk, Minas cheese, and production lines of Minas cheese processing. One hundred isolates from 3 different cheese producers were characterized using molecular approaches, such as PCR, molecular typing, and DNA sequencing. Staphylococcus aureus (88% of the isolates) was the most abundant followed by Staphylococcus epidermidis, Staphylococcus hyicus, and Staphylococcus warneri. Among the 22 enterotoxin genes tested, the most frequent was seh (62% of the isolates), followed by selx and ser. Hemolysin genes were widely distributed across isolates, and Panton-Valentine leukocidin and toxic shock syndrome toxin genes were also identified. Methicillin-resistant S. aureus were staphylococcal cassette chromosome mec III, IVa, IVd, and others nontypeable. In the phenotypic antibiotic resistance, multiresistant isolates were detected and resistance to penicillin was the most observed. Using spa typing, we identified several types and described a new one, t14969, isolated from cheese. These findings suggest that antibiotic resistance and potentially virulent strains from different sources can be found in the Brazilian dairy processing environment. Further research should be conducted with collaboration from regulatory agencies to develop programs of prevention of virulent and resistant strain dissemination in dairy products and the processing environment.

Green coconut water has unique nutritional and sensorial qualities. Despite the different technologies already studied, its enzymatic stability is still challenging. This study evaluated the use of ultrasound technology (US) for inactivating/sensitizing coconut water peroxidase (POD). The effect of both US application alone and as a pre-treatment to thermal processing was evaluated. The enzyme activity during US processing was reduced 27% after 30min (286W/L, 20kHz), demonstrating its high resistance. The thermal inactivation was described by the Weibull model under non-isothermal conditions. The enzyme became sensitized to heat after US pre-treatment. Further, the use of US resulted in more uniform heat resistance. The results suggest that US is a good technology for sensitizing enzymes before thermal processing (even for an enzyme with high thermal resistance). Therefore, the use of this technology could decrease the undesirable effects of long times and/or the high temperatures of the conventional thermal processing.

Enzymes are protein complexes compounds widely studied and used due to their ability to catalyze reactions. The food processing mainly aims the inactivation of enzymes due to various undesirable effects. However, there are many processes that can be optimized by its catalytic activity. In this context, different technologies have been applied both to inactivate or to improve the enzymes efficiency. The Ultrasound technology emerges as an alternative mainly applied to achieve the enzyme inactivation. On the contrary, very few investigations show the ability of this technology under certain conditions to achieve the opposite effect (i.e. increase the catalytic activity of enzymes). The objective of this study was to correlate the ultrasonic energy delivered to the sample (J/mL) with the residual enzymatic activity and explain the possible mechanisms which results in the enzymatic activation/inactivation complex behavior. The activity of POD in coconut water was evaluated as a model. The enzymatic activity initially increased, followed by reduction with a trend to enzyme inactivation. This complex behavior is directly related to the applied ultrasonic energy and their direct mechanical effects on the product, as well as the effect in the enzymatic infinite intermediate states and its structural conformation changes. The obtained results are useful for both academic and industrial perspectives.

Species within the Staphylococcus genus are important mastitis pathogens. Studies to describe virulence and antibiotic resistance as well as rapid techniques that permit analyses strains are needed. The aims were to identify and characterize Staphylococcus spp. isolated from mastitic milk, and to optimize multiplex polymerase chain reactions (PCR). Staphylococci previously isolated from milk of dairy cows with subclinical mastitis were analyzed. PCR was completed to amplify nuc, sodA, spa, agr locus, virulence factors, and antibiotic resistance gene s. DNA sequencing of sodA and spa genes was performed and antibiograms were carried out on all isolates. In a group of 49 staphylococci, S. aureus was the most prevalent, followed by S. hyicus, S. xylosus, S. chromogenes. Following optimization of multiplex PCR, virulence factor genes were identified in the majority of isolates. The enterotoxin genes, seh and selx were highlighted. All hemolysin genes were detected in 28.6% of isolates. Antibiotic resistance was evaluated and the majority of isolate s (69.4%) were resistant to penicillin. Among the genes encoding antibiotic resistance , mecA was identified, while two methicillin-resistant S. aureus were typed as spa type 605, agr type II, and one identified as SCCmec type IVa. The types t605 and agr II were detected in the majority of S. aureus assessed. The findings emphasize d the importance of preventing Staphylococcus infection in dairy cows. Effective dairy herd management and information on milk quality are essential to prevent mastitis pathogens.