In the dairy industry, microorganisms are essential for producing high-quality products. It is vital to understand, select, and use these bacteria correctly. The use of selected or native cultures is an established practice that helps standardise processing. Proper acidification of milk within controlled timeframes ensures consistency in the final product, but choosing the right cultures can often lead to uncertainties.
Make an informed decision by considering these key aspects:
Types of Microorganisms and Growth Temperatures
Lactic acid bacteria used in the process have specific growth temperature ranges:
- Mesophilic: Grow between 15°C and 35°C, with optimal growth between 22°C and 34°C.
- Thermophilic: Grow between 35°C and 55°C, with optimal growth between 36°C and 44°C.
💡 Note: These temperatures are indicative, and each strain may have slightly different growth preferences.
Morphological Differences of Lactic Acid Bacteria
Lactic acid bacteria can also be categorised by their shape:
- Cocci (Lactococci): Spherical-shaped bacteria.
- Rods (Lactobacilli): Elongated bacteria.
These cultures convert lactose into lactic acid and other compounds, both aromatic and non-aromatic. Since many cheese defects arise from acidification errors, selecting the right cultures is crucial. Each type of culture, when at its optimal growth temperature, balances the speed of acidification with the production of aromatic substances or gas. Cheesemakers must choose the correct processing temperatures to achieve the best results.
Microorganism Metabolism
Lactic acid bacteria are also distinguished by their production of CO2:
- Homofermentative: Do not produce CO2.
- Heterofermentative: Produce CO2.
Interesting Fact!
The choice of cultures depends on the type of cheese being produced. Generally:
- Italian cheeses often use thermophilic cultures.
- Foreign cheeses, such as French and German varieties, tend to prefer mesophilic cultures.
Mesophilic acidification is slower and develops more complex aromas, while thermophilic acidification is faster and produces a fresher taste.
Rotating Culture Strains An important consideration is rotating culture strains to prevent attacks from bacteriophages. This risk is often underestimated, especially when the same equipment is used for identical processes daily. For those using natural starters (such as whey or milk starters), extra attention is needed. In the event of a bacteriophage attack, the cheesemaker must thoroughly sanitise all production areas with detergents and disinfectants, such as peracetic acid, and begin with new culture strains. In this context, prevention is always better than cure.
