Relating physicochemical and microbiological safety indicators during processing of linguiça , a Portuguese traditional dry-fermented sausage

Abstract

Linguiça 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 (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 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.

Microbiological and Physicochemical Assessment of Artisanally Produced “Alheira” Fermented Sausages in Northern Portugal

“…In addition, if S. aureus contaminates the sausage mixture, it can survive throughout processing if the drop in pH is not sufficient during the first stage of fermentation. On the other hand, if the matrix pH is lower than 5.6, S. aureus cells become inactivated with further acidification [10]. This would explain the weaker correlation of S. aureus with PC1, since, in some cases, this pathogen can increase, and in others, it can decrease during processing.…”

What is the Main Processing Factor Influencing Staphylococcus Species Diversity in Different Manufacturing Units?

“…In fact, the stabilization of final products was obtained by the fermentation associated with smoking and drying being corroborated by the microbial data presented and resulting from the effect of lower pH (5.26 ± 0.07) and a W (0.860 ± 0.013) values, registered for long‐curing products. These intrinsic factors influencing microbial inhibition result from the processes applied to meat products (Alves et al., ; Gonzales‐Barron et al., ).…”

Microbiological safety of Portuguese Dry-Fermented Chouriço Sausages as affected by Processing and Physicochemical Factors

“…Another fact that may have contributed to problems during fermentation was the high pH of the raw meats used (6.04, SD = 0.06; Table 1) since, ideally, pork meat should have a normal pH (5.5-5.8) [2]. A poor production of organic acids caused by unsatisfactory fermentation will have an impact on the pH decrease that is necessary for the release of meat's moisture in a quick and uniform way.…”

“…The production of chouriço starts by marinating diced pork meat in a mixture of water, salt, regional wine and spices, although some factories also include curing agents in the formulation. The following step, fermentation, is carried without the addition of starter cultures [2][3][4], as this process occurs spontaneously due to the natural occurring microflora. After few days of maceration, the mixture is filled into natural pork casings, and then smoked and ripened at low temperatures.…”