Starter cultures for production of fermented milk products
A large collection of natural isolates of lactic acid bacteria (LAB) was made mostly from different homemade cheeses and fermented milk products that are produced in very specific ecologically isolated regions throughout Serbia. These regions such as, for instance, the high mountains, the river valleys, the seacoast, etc. are characterized by extremely clean surrounding. In addition, people inhabiting some of these regions are long living population. All strains have been biochemically and genetically characterized in the Institute for Molecular Genetics and Genetic Engineering, Belgrade, Serbia. On the basis of this research, the various starter cultures containing precisely characterized LAB were constructed for production of cheeses and fermented milk products. These starter cultures were tested on industrial scale in dairy plants in Serbia.
PRODUCTION OF “ACIDOVIT”
“Acidovit” is low fat, dietary fermented milk product made from the skimmed pasteurized milk. Manufacturing of “Acidovit” is possible in the standard yoghurt production line without any substantial changes or significant investments. For production of “Acidovit”, the only addition to the yoghurt production line is a vat with cooling system. The final product is dietary fermented milk beverage with 0.1% milk fat, 0.5% of minerals, 3.9% of protein and 5% of lactose (total dry mater of 9.5%). Energy value of “Acidovit” is 151.58 kJ/100gr or 312.57 kJ per 0.2 litre package. Except the good nutritive characteristics typical for all fermented milk beverages, “Acidovit” also has some additional properties because of the presence of Lactobacillus helveticus. It has strong antimicrobial activity and inhibits the growth of pathogenic and food spoilage microorganisms, such as bacteria from genus Escherichia, Proteus, Pseudomonas, Bacillus and Clostridium. “Acidovit” could be manufactured in two versions, according to the taste of consumers.
a) ”ACIDOVIT” from pasteurized skim milk with the strain Lactobacillus helveticus BGRA43. After the preparation of milk and starter culture by the procedure similar to that for yogurt production, the milk is inoculated with 2-3% of the culture, and fermentation is performed at 350C within 6 hours. During the fermentation, after the formation of curd (4-4.5 hours, 34-360SH), the fermentation vat is cooled with ice-cold water. At the end of fermentation, a gentle agitation of the curd (15-30 rpm) is recommended. The final fermented product is characterized by the high viscosity and pleasant thickness having a good flavour, and with shelf life of 5 days at 40C.
b) “ACIDOVIT” from pasteurized skim milk with mild flavour. In this case, the mixed starter culture consisting of strains Lactobacillus helveticus BGRA43 and Streptococcus thermophilus BGTMS1 is used under the same manufacturing conditions.
The starter culture for yogurt production (YOGO) is recently constructed from strains Lactobacillus bulgaricus BGPKM1 and Streptococcus thermophilus BGTMS2. Using this starter culture in the standard yoghurt production line, the final product (obtained after 2.5 to 3 hours of fermentation) had a generally good quality with appropriate viscosity and flavour.
3. WHITE SOFT CHEESE
Starter culture for production of white soft cheese (Lactococcus lactis, Lactococcus lactis subsp. diacetylactis) could be added as 3-5% inoculum during the initial steps of cheese making. This starter culture has the aromogenic properties and the very high level of salt tolerance, which enables its activity in the presence of higher concentrations of salt. The use of this culture in cheese making process resulted in much better final product with good flavour and less variations in overall quality.
4. SEMIHARD TRAPIST-TYPE CHEESE
Starter culture for production of semi hard cheeses using Trapist technology is mesophilic starter culture consisting of two species from genus Lactococcus and one Lastobacillus casei strain. Preparation of bulk starter was completed within 8 hours using 3-5% inoculum. The ripening period of the cheese was from 2 to 3 months. This starter culture was used on industrial scale in the processing of 3000 L of milk and compared with the activity of imported starter cultures. The cheese manufactured with our starter culture has very good flavour and the elasticity. In addition, during repeated cheese making with our starter culture, obtained cheese always had standard characteristics with minor variations.
Ljubiša Topisirović, PhD
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