Starter culture definition, starter culture selection, starter culture inhibitors

This is an overview on starter culture and theirs particularities

1. Starter Culture Definition, Starter Culture Selection, Starter Culture Inhibitors M. ANZA Adamou

2. Introduction The identification of solutions to improve the life and health of consumers, providing safe and nutritious foods, is the major concern in Food Science. Toward that goal, preservation methods such as salting, drying, high/low temperature application, fermentation, and more recently, pulsed electric field, high pressure and radiation - alone or in combination – may be applied ( Marcelino , 2013). Fermentation, a former practice of spontaneous food preservation, was revolutionized by the use of starter culture in order to obtain more satisfactory results.

3. Concept of starter culture A Starter culture can be defined as a culture of microorganisms, usually bacterial or fungal strains that are either pure or mixed, which is used to initiate a fermentation process. It can be obtained either as pure culture from a commercial laboratory or from a portion of previously cultured product. The microorganisms are selected for their ability to produce lactic acid for curd production and a low pH to prevent spoilage, produce metabolites that give desirable flavors, or produce enzymes that mature the dairy product (ORC International)

4. Concept of starter culture As it is known, various dairy products such as yoghurt, kefir, kımız are produced with microorganisms. The fermentation of the beans, the beer and the wine making are again through microorganisms. In addition to these, cheese and butter, sausage, pickles, olives and so on. There are direct benefits of microorganisms in the production of food. This is the reason why used in food production they are called "starter culture ’’ However with a simple definition, starter cultures are microorganisms used in the food industry to produce products with standard quality under controlled conditions.

5. Concept of starter culture The starter culture can be one or more microorganisms. It depends on which microorganism or microorganisms are used as starter Wine, for example, uses a single microorganism with acidophilus, while products such as yoghurt and kefir have two or more microorganisms. However, different strains of the same yeast (Saccharomyces cerevisiae) can be used in wine making, and other yeast strains can be used as a matter of course (Yarali, 2016)

6. Classification of starter culture

7. Choice of starter culture The use of starter cultures is function of the product to be fermented, they must meet certain criteria . The starter culture should : Not bring negative effects inside the food ingredient they are added to I mprove the flavor of the food they are in B e active even at low water concentrations B e able to inhibit other harmful microorganisms F orm a homogeneous structure and protect the stability of the product B e well tolerated against salt and sugar concentrations N ot enter into reactions with other organic substances in food Most importantly, not cause negative effect to disturb the health (Yarali, 2016)

8. Inhibitors of culture starters There are many factors that can cause inhibition or reduction of the activity of a starter culture. The resultant effect would be poor quality fermented products reaching the consumer and financial loss to the producer. These factors include ( Kevine Otienon , 2016): Antibiotics Bacteriophages Detergent and disinfectant residues Miscellaneous starter culture growth inhibitors

9. Inhibitors of culture starters : Antibiotic s For example in dairy products, other than the lactic acid bacteria (LABs), many other bacteria will produce acid to ferment milk if the conditions are not favorable for the LABs. Therefore, eliminating LABs (if that were possible) will not assure you of safety from acid producing bacteria. For instance, Coliforms will produce a mixture of acids, gases, and alcohols Some species of micrococci, micro-bacterium, and bacilli can produce acid in milk as well Clostridium spp. inhibits the growth of LABs and may produce butyric acid

10. Inhibitors of culture starters : Antibiotic s Please note that insufficient heat treatment of milk will still lead to milk spoilage. If the heat destroys all the vegetative forms of bacteria BUT fails to destroy the Clostridium botulinum spores, the spores will still vegetate and cause butyric acid fermentation ( Kevine Otienon , 2016) .

11. Inhibitors of culture starters : Bacteriophages Some viruses (also known as phages) can attack bacteria and destroy starter cultures. The result is a failure to produce lactic acid after inoculation in dairy products. The lactic streptococci and lactobacilli are the most vulnerable microorganisms in the dairy starter cultures. We can reduce the effect of the phages in the dairy industry by: Propagating starter cultures in very aseptic conditions i.e. adopt aseptic technique in handling dairy products and processes Proper heat treatment (temperature/time combination) of bulk starter milk to destroy the viruses in milk

12. Inhibitors of culture starters : Bacteriophages We can reduce the effect of the phages in the dairy industry by: Daily rotation of phage-resistant strains Effective filtration of air in the starter room Proper sanitation of the equipment and premise Location of starter room far away from production area Personnel, especially those from cheese room should NOT enter the starter room Propagate starter culture in phage inhibitory medium Develop phage-resistant strains Use mixed strain starter cultures ( Kevine Otienon , 2016)

13. Inhibitors of culture starters : Detergent and disinfectant residues Detergents and disinfectants for cleaning and sanitization in the dairy plant may cause contamination. The residues of these compounds (alkaline detergents, chlorine based materials, iodophors, quaternary ammonium compounds and ampholytes) do affect the activity of the starter culture. Yoghurt cultures are more tolerant to the activities of these residues at the inhibitory levels (mg/l) of culture compounds. Contamination of starter milk with these compounds is majorly due to human error, or malfunction of the automatic chain cycle (Kevine Otienon, 2016)

14. Inhibitors of culture starters : Miscellaneous starter culture growth inhibitors Natural antibodies (such as lacteris/agglutinins) that are present in some product like milk can inhibit the growth of the starter cultures. These antibodies are heat sensitive, and heat treatment of bulk starter milk ensures their destruction. Leucocytes in mastitis milk can cause phagocytosis of the starter microorganisms. Thiocyanates present in late lactation milk may also inhibit the growth of starters. Heating of the starter results in no significant improvement of the end product

15. Inhibitors of culture starters : Miscellaneous starter culture growth inhibitors You can attribute other inhibitors to environmental pollution factors, such as insecticides, volatile and non-volatile compounds. Such volatile compounds may include fatty acids, formic acid, formaldehyde, acetonitrile, chloroform, and ether. When their concentration reaches 100ppm, they will inhibit growth of Streptococcus spp. and Lactobacillus cremoris (Kevine Otienon, 2016)

16. Conclusion In conclusion, we can retain that starter cultures are pure or mixed microorganisms used to initiate the processes of fermentations. Their use makes it possible to save time, to master the fermentation process as well as to obtain certain desired organoleptic characteristics. The choice of the culture starter to be used must be according to the product to be fermented while creating the optimum conditions for their development.

17. References Kevine Otienon , 2016. Starter Culture Growth Inhibitors: Antibiotics And Phages. In Dairy Technologist (On line). http://dairytechnologist.com/starter-culture-growth-inhibitors/ Consulted the 13/12/2016 Marcelino , J. (2013). Lactic Acid Bacteria as Starter-Cultures for Cheese Processing: Past, Present and Future Developments. doi:10.5772/55937   ORC International. Starter culture (On line). Consulted the 12/12/2016. Available on: http://www.orcexperts.com/experts.asp?strSearchType=all&strQuery=starter+culture Yarali , D. E. (2016). Gida katki maddeleri