What is yogurt bacteria?
Yogurt contains live active bacteria also known as probiotics. The primary group of bacteria contained in yogurt is Lactobacillus Bulgaricus which is believed to have originally lived among plants but somehow made it's way into yogurt. Making yogurt involves allowing the yogurt bacteria to culture or ferment in the milk; that is allowing the yogurt bacteria to multiply so the sugar in the milk (lactose) is converted to lactic acid allowing the milk to coagulate into the solid structure we associate with yogurt. Fermentation of milk through yogurt bacteria was a way to preserve milk and is thought to have heath benefits.
Yogurt bacteria has evolved over time and different strains are found in different regions. Therefore the specific type of yogurt bacteria varies between varieties of yogurt.
What types of yogurt bacteria are in yogurt starter cultures?
In general, there are two main types of yogurt cultures: Mesophilic and Thermophilic.
Mesophilic yogurt bacteria does not require heat to culture and create yogurt. Rather, mesophilic yogurt bacteria does best at room temperature (72-78 degrees is ideal). Therefore, mesophilic yogurt bacteria does not require a special appliance such as a yogurt maker--you can make yogurt just by setting it on your counter-top. Examples of yogurt varieties containing mesophilic yogurt bacteria include Viili, Filmjölk, Piimä, and Matsoni yogurts.
Thermophilic yogurt bacteria is a heat loving variety. Thermophilic yogurt bacteria cultures best at around 110 degrees and so you need a way to keep the yogurt warm while culturing. You can use a yogurt maker, low-temperature oven, crock pot or even a large food dehydrator (such as the Excalibur or Sausage Maker brands) to culture thermophilic yogurt. Examples of yogurt varieties containing thermophilic yogurt bacteria include Greek and Bulgarian yogurts.
Specific yogurt bacteria contained in different varieties of yogurt cultures:
- Viili Yogurt Bacteria: Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis biovar. diacetylactis, Leuconostoc mesenteroides subsp. cremoris
- Filmjölk Yogurt Bacteria: Lactococcus lactis and Leuconostoc mesenteroides
- Matsoni Yogurt Bacteria: L. lactis subsp. Cremoris and Acetobacter orientalis
- Piimä Yogurt Bacteria: S. lactis var. bollandicus and S. taette
- Traditional Greek Yogurt Bacteria: L. Bulgaricus, S. Thermophilus
- Bulgarian Yogurt Bacteria: L. Bulgaricus, S. Thermophilus
