Browsing by Author "Gomes, Aline"
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- An assessment of the processing and physicochemical factors contributing to the microbial contamination of salpicão, a naturally-fermented Portuguese sausagePublication . Cadavez, Vasco; Gonzales-Barron, Ursula; Pires, P.; Fernandes, E.; Pereira, Ana Paula; Gomes, Aline; Araújo, José Pedro; Lopes-da-Silva, M.F.; Rodrigues, Paula; Fernandes, Conceição; Saavedra, Maria José; Butler, Francis; Dias, TeresaComplete microbiological, physicochemical and environmental longitudinal data were obtained from factory surveys in order to elucidate risk factors leading to the survival of Enterobacteriaceae, Staphylococcus aureus and Listeria monocytogenes in salpicão sausage. A total of six batches were surveyed from two factories; one added nitrite and polyphosphates in their formulation (Factory II). The addition of polyphosphates slowed down fermentation, which favoured the increase in Enterobacteriaceae (∼0.5 log CFU/g), S. aureus (∼0.5 log CFU/g) and L. monocytogenes (∼70 CFU/g) until maceration. Maceration should be regarded as a critical stage in the control of S. aureus in salpicão, as longer maceration (p = 0.033), higher temperatures of maceration (p = 0.018) and pH of macerated meat (p = 0.079) led to higher S. aureus counts in the final product. The main hurdle controlling S. aureus in salpicão is the pH. For L. monocytogenes and Enterobacteriaceae, at least three hurdles hinder their viability: low Aw (p = 0.010; 0.012), smoking (p < 0.0001; 0.020) and nitrite (p = 0.158; 0.105). Cross-contamination, especially during mixing, should be avoided as it is an important factor explaining the increase in Enterobacteriaceae (p = 0.041), S. aureus (p = 0.015) and L. monocytogenes (p = 0.082) on a batch basis. There is a need to optimise the acidification process and reinforce good hygiene practices
- Contaminación por Staphylococcus aureus en el procesamiento de un embutido fermentado português [linguiça]Publication . Cadavez, Vasco; Pereira, Ana Paula; Gomes, Aline; Lopes-da-Silva, M.F.; Estevinho, Leticia M.; Gonzales-Barron, Ursula; Dias, TeresaLinguiça is a Portuguese dry-fermented sausage, which has been found to harbour food-borne pathogens in the past. Hence, the objective of this study was to investigate the levels of total viable counts (TVC), Enterobacteriaceae, and S. aureus at the key production stages of linguiça by depicting their changes using principal component analysis. Unlike Enterobacteriaceae counts, which decreased from raw meat to final product, S. aureus increased significantly in the meats throughout processing. While Enterobacteriaceae was very sensitive to the decrease in water activity, S. aureus remained viable and developed during fermentation. The presence of S. aureus at all stages should prompt industries to reinforce good hygiene practices in the processing of linguiça.
- Levels of hygiene and safety quality indicators along the processing stages of a Portuguese traditional dry-fermented sausage (Linguiça)Publication . Gonzales-Barron, Ursula; Pereira, Ana Paula; Gomes, Aline; Lopes-da-Silva, M.F.; Rodrigues, Paula; Estevinho, Leticia M.; Cadavez, Vasco; Dias, TeresaWhile Portuguese fermented sausages are highly appreciated, research has shown that their microbiological quality is inconsistent due to the high variability in the production process and insufficient hygiene quality. Linguica is a dryfermented sausage, which has been found to harbour food-borne pathogens. Hence, the objective of this study was to investigate the changes in the levels of total viable counts (TVC), Enterobacteriaceae, L. monocytogenes and S. aureus at the key production stages of Linguica (raw meat, maceration, stuffing and smoking/drying). A microbiological survey followed a batch throughout production, extracting samples of raw meat (n=3), batter before maceration (n=3), batter after 3- or 4-day maceration (n=3) and sausages after curing/drying (n=5). Samples were taken from a total of three batches from each of the two factories under examination. Overall, TVC counts did not change considerably from raw meat to stuffing (5.5-5.9log CFU/g, 95% Cl: 5.15-5.82 log CFU/g), yet it increased significantly up to the end of drying (7.83 log CFU/g, 95% Cl: 7.57- 8.09 log CFU/g)- seemingly, because of the multiplication of lactic acid bacteria (LAB). Unlike the Enterobacteriaceae counts, which decreased (p<0.001) from batter before maceration (3.23 log CFU/g, 95% Cl: 2.80-3.66 log CFU/g) to the end of drying (1.56 log CFU, 95 percent Cl: 1.23-1.90 log CFU/g), S. aureus increased significantly between these two processing stages (2.58 log CFU/g; 95% Cl: 2.20-2.93 log CFU/g in the finished product). L. monocytogenes was detected in the products of one of the factories although their counts decreased after batter maceration. Because Linguica is a product that can be consumed without cooking, there is a need to further investigate the risk factors that determine their presence along processing. The presence of these two pathogens should also prompt industries to reinforce good hygiene practices in the processing of traditional sausages.
- Microbial quality indicators and physicochemical properties of a Portuguese traditional dry-fermented sausage along processingPublication . Cadavez, Vasco; Gonzales-Barron, Ursula; Pereira, Ana Paula; Gomes, Aline; Lopes-da-Silva, M.F.; Rodrigues, Paula; Estevinho, Leticia M.; Dias, TeresaLinguica is a traditional Portuguese dry1ermented sausage whereby chopped pork is macerated with water, wine, salt, garlic and pepper, and undergoes processes of maturation, smoking and drying. While they are highly appreciated, their production is subject to extensive process variability and quality. The objective of this study was to investigate the interrelationship between quality indicator microorganisms such as total viable counts (TVC), Enterobacteriaceae and S. aureus and the physicochemical characteristics of the batter/sausage along processing of Linguica. Microbiological surveys following a batch throughout production were completed for three batches in each of the two factories under study. In every batch, samples of raw meat (n=3), batter before maceration (n=3), batter after 3- or 4-day maceration (n=3) and sausages after curing/drying (n=S) were extracted. Counts of TVC, Enterobacteriaceae, S. aureus as well as pH and water activity (Aw) were determined in duplicate for each sample. A principal component analysis (PCA) of these variables was carried out using the R software 2.14.2. The two-component PCA solution explained 73% of the total variability. The fact that, within the first principal component (46%), S. aureus and TVC had both positive correlation coefficients while pH and Aw had both negative correlations, indicated that along processing (i.e., decrease in pH and Aw), there was a tendency for both indicators of hygiene to increase. It also showed that S. aureus had the capacity to develop in LinguiAga despite the increasingly-adverse conditions of the food matrix. In relation to the second principal component (27%), Enterobacteriaceae counts and Aw had both positive correlations, suggesting that as Aw decreases along processing, the Enterobacteriaceae levels also tend to diminish. In the hi-dimensional projection of the principal components, for both factories, the finished products tend to present lower levels of Enterobacteriaceae and higher levels of S. aureus.
- Microbiological and physicochemical aspects of “salpicão”, a traditional dry sausage produced in the northeast of PortugalPublication . Pereira, Ana Paula; Gomes, Aline; Cadavez, Vasco; Estevinho, Leticia M.; Gonzales-Barron, Ursula; Dias, TeresaCounts of total viable mesophilic bacteria (TVC), lactic acid bacteria (LAB), Microccocaceae, Enterobacteriaceae, Salmonella spp. and Listeria monocytogenes, in traditional Portuguese dry sausages from two industrial producers, were compared in batter and final product. During the production process, the TVC increased significantly, most likely due to the multiplication of fermentative flora. Enterobacteriaceae decreased from batter to final product while the S. aureus increased. Great variability was verified in detection of L. monocytogenes both between batches and industrial producers
- Relating microbiological and physicochemical patterns of a traditional Portuguese fermented sausage along processingPublication . Pereira, Ana Paula; Gomes, Aline; Cadavez, Vasco; Fernandes, Conceição; Rodrigues, Paula; Estevinho, Leticia M.; Gonzales-Barron, Ursula; Dias, TeresaLinguiça is a Portuguese popular ready-to-eat dry fermented sausage. Despite the high diversity of sausages produced in Portugal, all of them are made from cut pork meat macerated with water, wine, salt, garlic, pepper, and undergoes processes of maturation, smoking and drying. During the fermentation and drying of sausages, L. monocytogenes tends to decrease considerably. However, despite the various hurdles in the dry sausage manufacturing process, this foodborne pathogen is able to survive and is detected in the final product. Factors that may affect the growth or survival of foodborne pathogens in sausage products such as linguiça include water activity (aw), pH, temperature, use of starter cultures and use of ingredients with antimicrobial activity (e.g., garlic, smoke). The present study has evaluated the influence of the addition of a commercial starter culture and ripening temperature (10º C and 18ºC) on growth and survival of L. monocytogenes strains, isolated from sausage, in experimentally inoculated linguiça. Sliced raw meat was mixed with salt (20g/kg), dry garlic (4,5g/kg), sweet paper (12,5g/kg), laurel (0,5g/kg), dextrose (10g/kg), a mix of red/white wine (410ml/kg) and water (410ml/kg) and inoculated with L. monocytogenes (5 log10/g). Additionally Commercial starter culture (5 log10/g) was added to one batch. The batter was macerated for 3 days at 4ºC. After stuffing into natural pork casings, sausages were hung vertically in a climate controlled chamber, for ripening at 10℃ or 18ºC with 83% relative humidity (RH) during ten days. During maceration step was observed no changes in growth rate of LAB and L. monocytogenes. However during ripening step was verified an increase of the count of LAB and a concomitantly decrease of L. monocytogenes. In the batches not inoculated with a commercial starter culture was observed a decrease of L. monocytogenes of 1 log10/g at 10ºC and 1,57log10/g at 18ºC of ripening temperature. The addition of a commercial starter culture increased the reduction of pathogen at both temperatures (1,57log10/g at 10ºC and 2,24log10/g at 18ºC). This study points out the fact that the decrease of L. monocytogenes contamination rate during the manufacturing process of sausages is due to the drying and ripening step than to the maceration itself and is due mainly to the effect of starter culture and ripening temperature.
- Relating physicochemical and microbiological safety indicators during processing of linguiça, a Portuguese traditional dry-fermented sausagePublication . Gonzales-Barron, Ursula; Cadavez, Vasco; Pereira, Ana Paula; Gomes, Aline; Araújo, José Pedro; Saavedra, Maria José; Estevinho, Leticia M.; Butler, Francis; Pires, P.; Dias, TeresaLinguiça is a Portuguese traditional fermented sausage whose microbiological quality and safety can be highly variable. In order to elucidate risk factors and the particularities of the manufacturing technology that explain the between-batch variability in total viable counts (TVC), Enterobacteriaceae, Staphylococcus aureus and Listeria monocytogenes in the product; microbiological and physicochemical characterisation of linguiça at five stages of production (i.e., raw pork meat, mixed with ingredients, macerated, smoked and ripened) was carried out. A total of six production batches were surveyed from two factories; one utilised curing salts and polyphosphate in their formulation (Factory II). The delayed fermentation in the nitrite-formulated sausages was partly responsible for the increase (p < 0.01) in Enterobacteriaceae, S. aureus and L. monocytogenes from raw meat (3.21logCFU/g, 1.30logCFU/g and 22.2CFU/g, respectively) to the end of maceration (4.14logCFU/g, 2.10logCFU/g and 140CFU/g, respectively) while the better acidification process in the nitrite-free sausages (Factory I) led to lower counts of S. aureus (2.64logCFU/g) and L. monocytogenes (10CFU/g) in the finished products. In Factory II, although L. monocytogenes entered the chain at the point of mixing, it became steadily inactivated during smoking and ripening ( < 50CFU/g), despite the initially-delayed fermentation. Nitrite had a strong effect on reducing Enterobacteriaceae throughout smoking (r=-0.73) and ripening (r=-0.59), while it failed to control the growth of S. aureus. The main hurdle preventing the development of S. aureus in linguiça is the pH, and other factors contributing to its control are: longer ripening days (p=0.019), low S. aureus in raw meat (p=0.098), properly-washed casings (p=0.094), and less contamination during mixing (p=0.199). In the case of L. monocytogenes, at least three hurdles hinder its development in linguiça: low a w (p=0.004), low pH (p=0.040) and nitrite (p=0.060), and other factors contributing to its control are: longer ripening (p=0.072) and maceration (p=0.106) periods, lower a w at the end of smoking (p=0.076) and properly-washed casings (p=0.099). Results have shown that there is a need to standardise the productive process of linguiça, to optimise the initial acidification process, and to reinforce proper programmes of quality control of ingredients and good hygiene practices, so as to minimise the introduction of Enterobacteriaceae and pathogens from external sources.