RESUMO
Two raw sausages were prepared: a soft and a dry-ripened one, both by local traditional and industrial manufacturing practices. Sausages were packaged under a CO2/N2 atmosphere at different targeted activity water (aw) values: 0.96 and 0.92 (soft sausages) and 0.88 and 0.82 (dry-ripened sausages). Sausages were then stored at 5 °C for 42 days or at 12 °C for 240 days (soft and a dry-ripened sausages, respectively). The time-related changes in dominant microbiota, pH and biogenic amine contents during storage were determined. Tyramine was the most abundant biogenic amine in all the sausages. Biogenic amine levels were higher in dry-ripened sausages than in soft sausages at packaging. However, during refrigerated storage soft sausages were fermented and the levels of biogenic amines increased (P<0.05). At the end of storage, traditional soft sausages with 0.96 aw presented comparable levels of biogenic amines to traditional dry-ripened sausages.
Assuntos
Aminas Biogênicas/análise , Embalagem de Alimentos/métodos , Armazenamento de Alimentos , Produtos da Carne/análise , Animais , Atmosfera , Contagem de Colônia Microbiana , Fermentação , Microbiologia de Alimentos , Concentração de Íons de Hidrogênio , Micrococcus/crescimento & desenvolvimento , Micrococcus/isolamento & purificação , Staphylococcus/crescimento & desenvolvimento , Staphylococcus/isolamento & purificação , Suínos , Temperatura , Tiramina/análise , Água/análiseRESUMO
The effect of C:N ratio, temperature and water content on ammonia volatilization during two-phase composting of sheep manure was evaluated. The aerobic phase was conducted under field conditions. This was followed by Phase II, vermicomposting, conducted in the laboratory under controlled conditions of water content (70% and 80%) and temperature (15 and 22 °C). The addition of extra straw lead to a 10% reduction in NH3 volatilization compared to sheep manure composted without extra straw. Temperature and water content significantly effected ammonia volatilization at 0 day in Phase II, with a water content of 70% and temperature of 22 °C leading to greater losses of ammonia. Nitrogen loss by ammonia volatilization during vermicomposting ranged from 8% to 15% of the initial N content. The addition of extra straw did not result in significant differences in total carbon content following vermicomposting.
Assuntos
Amônia/análise , Biotecnologia/métodos , Aerobiose , Amônia/química , Animais , Carbono/química , Concentração de Íons de Hidrogênio , Esterco , Modelos Estatísticos , Nitrogênio/química , Eliminação de Resíduos/métodos , Ovinos , Solo , Temperatura , Fatores de Tempo , Volatilização , Água/químicaRESUMO
A survey of raw pork and a raw fermented pork sausage, chorizo, was undertaken in Mexico City to assess the hygienic quality of these two products on retail sale in a variety of outlets. Total bacterial counts and Enterobacteriaceae counts were determined and the samples were analyzed for the presence of Salmonella spp. Pork sold from refrigerated display cabinets in supermarkets and butchers' shops was of a poor microbial quality similar to that sold in street markets. In all types of outlets, a high proportion (76%) of samples contained Salmonella spp. Hygiene scores for vendors did not correlate with microbiological quality. For chorizo, the microbial quality was related to the type of producer. The product of major commercial companies had a lower mean Enterobacteriaceae count than that of small-scale producers, but although this difference was statistically significant, counts were high for a fermented meat product. Twenty percent of chorizo samples from major producers were positive for Salmonella spp. Small-scale or "back-shop" production resulted in 72% of samples being positive for Salmonella spp. Thus neither type of chorizo could be described as being a good quality and hygienic product. It is apparent that both animal husbandry and slaughter procedures for pigs require further study, as does the pork-processing industry, in order to define how the meat becomes so heavily contaminated. Improving the quality of the raw meat will benefit consumers in the Mexico City area and will be an essential prerequisite for improving the quality of chorizo.