Starters acidification

The contribution of these agents, individually or in various combinations, has been assessed in model cheese systems from which one or more of the agents was excluded or eliminated, e.g. by using an acidogen rather than starter for acidification or manufacturing cheese in a sterile environment to eliminate non-starter lactic acid bacteria (NSLAB). Such model systems have given very useful information on the biochemistry of ripening. 

On acidification to pH 4.6, the caseins coagulate, which is the principle used to manufacture of a family of cheeses which represent about 25% of total cheese consumption and are the principal cheeses in some countries (Appendix 10B). Acidification is traditionally and usually achieved by in situ fermentation of lactose by a Lactococcus starter but direct acidification by acid or acidogen (gluconic acid-d-lactone) is also practised. The principal... 

Direct acidification with HCl or in situ production of lactic acid by a mesophilic lactic starter still dominate in the production of acid casein. A relatively recent development in the production of acid casein is the use of ion exchangers for acidification. In one such method, a portion of the milk is acidified to approximately pH 2 at 10°C by treatment with a strong acid ion exchanger and then mixed with unacidified milk in proportions so that the mixture has a pH of 4.6. The acidified milk is then processed by conventional techniques. A yield increase of about 3,5% is claimed, apparently due to the precipitation of some proteose-peptones. The resulting whey has a lower salt content than normal and is thus more suitable for further processing. The elimination of strong acid reduces the risk of corrosion by the chloride ion (Cl ) and hence cheaper equipment may be... 

Weeden, T.L., Nelssen, J.L., Hansen, J.A. and Richardson, K.L. (1991) The effect of diet acidification on starter performance and nutrient digestibility. Journal of Animal Science 69 105-106. 

Eurther evidence that complex carbohydrates such as EPS can be used preferentially to simpler sugars by gut microbes was provided by Semjonovs, Jasko, Auzina, and Zikmanis (2008) in this study, an enhancement was reported in the growth and acidification power of bifidobacteria and other typical dairy starter... 

However, when considering the use of probiotic strains as functional starters or co-cultures, it is important that they do not enhance acidification and thereby reduce the shelf-life of the product, and that they do not have adverse effects on the aroma or taste of the product (Heller, 2001). Uncertainty still exists as to whether multifunctional strains possessing all desirable metabolic features would result from modem isolation techniques and selection procedures. Therefore, recent studies focus on the improvement of selected strains by the application of recombinant DNA technology. By its application, certain beneficial features, such as health-promoting properties, accelerated acid production, wholesomeness and overproduction of specific enzymes or bacteriocins can be improved (Holzapfel, 2002). Gene dismption may be used to... 

One promising approach might be the application of defined starter cultures that are capable of growing rapidly and that are highly competitive in the environmental conditions under which the product is kept Therefore, numerous attempts have made especially to ferment cabbage to sauerkraut, but also to ferment cucumbers and olives by defined starter cultures. Especially in the case of sauerkraut, most of the experiments performed with pure cultures or mixtures of pure cultures led indeed to the desired uniform, sufficient and rapid acidification of the products. But they lacked the typical rounded sauerkraut flavour, which essentially is due to the lack of certain fermentation by-products or the insufficient decomposition of compounds characteristic for the respective raw material (Kandler, 1981). Sauerkraut with perfect sensorial characteristics was obtained with selected strains of L. mesenteroides, which simultaneously improved the uniformity of sauerkraut from different batches. However, even in this case, so far no such benefits could be achieved compared to spontaneous fermentation that would economically justify the cost of the production of starter cultures (Buckenhueskes Hammes, 1990). 

Acidification. The acidification course with starter cultures in sausage processing results in a lag phase of 1-2 days followed by a pH drop. The speed of the pH drop depends on parameters like salt concentration, sugar concentration, temperature and type of culture. 

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