The effects of time and relative humidity on dry-aged beef: Traditional versus special bag.

The objective of this study was to evaluate the effects of relative humidity (RH) and different dry aging methods on the quality of beef. Sixteen loins, from eight carcasses, were used in this experiment. Each pair of loin was cut into eight sections with equal size, which were evenly assigned to eight treatments, by the combination of two dry aging methods (traditional and highly moisture-permeable special bag), two relative humidity (65 and 85% RH) and two aging times (21 and 42 days). At 85% RH, neither special bag nor the traditional dry aging methods were viable, since samples presented high microbiological counts, mucus and bad odor. At 65% RH, Enterobacteriaceae and lactic acid bacteria were not detected in any treatment. The highest aerobic plate count and psychrotrophic count were observed in the samples of the traditional dry-aged process whereas the special bag showed the greatest mold and yeast count. Regarding dry aging in special bag, there was a reduction in the weight loss (P < 0.05) and no change in the physical-chemical characteristics (P > 0.05) compared to traditional dry aging. The values of pH, moisture and Warner-Bratzler shear force were not affected (P > 0.05) by aging method and relative humidity. Thus, the results indicate that high RH should be avoided for both dry aging methods. Furthermore, the special bag dry aging can be considered an alternative to produce dry-aged beef, as it reduces weight losses even at conditions of lower relative humidity.

Behavior of Salmonella during fermentation, drying and storage of cocoa beans.

Due to cocoa being considered a possible source of Salmonella contamination in chocolate, the behavior of Salmonella during some cocoa pre-processing stages (fermentation, drying and storage) was investigated. The fermentation process was carried out on a pilot scale (2 kg beans/box) for 7 days. Every day a fermentation box was inoculated with a Salmonella pool (ca. 4 log MPN/g). The results showed that Salmonella did not affect (P>0.05) the growth of the main microorganism groups involved in cocoa fermentation. On the other hand, the pathogen was influenced (P<0.05) by yeast, acetic acid bacteria and pH. In spite of Salmonella showing counts ≤ 1 log MPN/g in the first days, at the end of fermentation it grew in all samples, reaching counts as high as 7.49 log MPN/g. For drying and storage, cocoa beans were inoculated during the fermentation (experiment A) or during the drying (experiment B). In these stages the decline of the water activity affected the pathogen behavior. In experiment A during the drying, Salmonella count increased in most of the samples. In experiment B either a slight growth or no growth in the samples inoculated up to 48 h was observed, whereas the other samples showed reductions from the initial count. After 30 days of storage at room temperature, the water activity decreased to 0.68, and reductions of Salmonella ranged from 0.93 to 2.52 log MPN/g. Despite the reductions observed during the storage, the pathogen was detected even after 120 days. Therefore, the results showed that Salmonella growth or survival depends on when the contamination occurs.

Antimicrobial activity of Enterococcus Faecium Fair-E 198 against gram-positive pathogens.

This study investigated the antimicrobial activity of Enterococcus faecium FAIR-E 198 against Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus. Using the critical-dilution method, the bacteriocin produced by E. faecium FAIR-E 198 inhibited all L. monocytogenes strains evaluated (1,600 to 19,200 AU mL(-1)). However, none of the B. cereus and S. aureus strains investigated were inhibited. The maximum activity of this bacteriocin (800 AU mL(-1)) was observed in MRS broth, while the activity in milk was 100 AU mL(-1). In the co-cultivation test in milk, B. cereus K1-B041 was reduced to below the detection limit (1.00 log CFU mL(-1)) after 48 h. E. faecium reduced the initial L. monocytogenes Scott A population by 1 log CFU mL(-1) after 3 h at 35°C, However, the pathogen regained growth, reaching 3.68 log CFU mL(-1) after 48 h. E. faecium did not influence the growth of S. aureus ATCC 27154 during the 48 h of co-cultivation, Therefore, it can be concluded that the effectiveness of the antimicrobial activity of E. faecium FAIR-E 198 is strictly related to the species and strain of the target microorganism and to the culture medium.