Sodium reduction in dry fermented sausages - Effects on the fermentation process, product quality and taste
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Dry fermented sausage is considered a traditional craft containing a high amount of salt. Lactic acid bacteria play an essential role in the production of fermented meat production. The bacteria are essential for lowering pH and producing flavour along with the adding of sodium chloride (NaCl) to ensure food safety. Sodium is an important nutrient for the body, but a high intake can cause several negative health effects. Reducing the content of salt affects the lactic acid bacteria, processing, taste, and food safety e.g. and has to be taken into consideration when reducing the content or by replacing with other ingredients. Due to this, there is a great requirement to increase the knowledge about the effect of salt reduction in dry fermented to enable the meat industry to produce more salt reduced products. The aim of the thesis was to study the effects of different starter cultures in combination with sodium reduction, by reducing the amount of added salt (NaCl) or by partial replacement with potassium chloride (KCl), in dry fermented sausages. In this thesis it was found that the type of starter culture had more effect on physiochemical and sensorial properties of the dry fermented sausages than the replacement of 14-29 % of the added NaCl with KCl on an equimolar amount. A partial replacement of NaCl with KCl reduced the NaCl content in the sausage with 14 -30% compared to the reference sausage made in this study (5.5% salt). These sausages reached a water activity below 0.90 after 16 days of drying, and with no texture defects. Sausages added the lowest concentration of NaCl had a reduction in NaCl of 22-26 % compared to the reference sausage made in this study (5.5% salt) and reached a water activity below 0.90 after 22 days of drying, but some texture defects were observed in those sausages. Sausages fermented with Bitec LS-25 and added KCl seemed to have lower concentrations lactic acid and acetic acid than sausages added only NaCl. Bitec LS-25 reduced pH to 4.6-4.8 in 24-48 h. A significantly chewier texture and stronger taste of lactic acid/salami were found in the sensorial evaluation compared to Bitec LK-30. Sausages fermented with Bitec LK-30 showed no obvious trend regarding the added concentrations of salt, and lowered pH to 4.9-5.0, but the starter culture required less dextrose than Bitec LS-25. The starter culture yielded sausages with a lower concentration of lactic acid, and important, a lower weight loss than the sausages fermented with Bitec LS-25. Bactoferm T-SPX seemed not to thrive in conditions added KCl, while Bitec B Mild & Fast seemed unaffected by the type of salt. An observation found in the thesis was that the water activity decreased after storage in vacuum packing. The sausages added the lowest concentrations of NaCl (1.5 g NaCl + 1.0 g curing salt/100 g meat mixture) had a higher water activity at start since the added salt was lower, but at the water activity approx. 0.93, all sausages actually more or less had the same weight loss and small amount of water had to evaporate from this point. The observations are important for the industry since it could give the opportunity to produce salt reduced sausages without drying a water activity below 0.90 and therefore reduce the risk of texture defects by vacuum packing the sausages at a earlier stage. A model system to study the initial fermentation phase (2-5 days) based on fermenting the meat mixture in 50 ml plastic tubes was tested. The system can be used to screen starter cultures in combination with different levels of salts (NaCl, KCl, others) and/or glucose. The results in the successful experiments were in reasonable agreement with the results of the sausage production studies, indicating that this may be a useful screening system. However, further refinement of the method is still required.