Fermentation and CO₂ in Cheese Making — NEET Biology
✅ Asked in NEET 2026The dough, which is used for making foods such as dosa and idli is also fermented by bacteria. The puffed-up appearance of dough is due to the production of CO₂ gas. Can you tell which metabolic pathway is taking place resulting in the formation of CO₂? Where do you think the bacteria for these fermentations come from? Similarly the dough, which is used for making bread, is fermented using baker's yeast (Saccharomyces cerevisiae). A number of traditional drinks and foods are also made by fermentation by the microbes. 'Toddy', a traditional drink of some parts of southern India is made by fermenting sap from palms. Microbes are also used to ferment fish, soyabean and bamboo-shoots to make foods. Cheese, is one of the oldest food items in which microbes were used. Different varieties of cheese are known by their characteristic texture, flavour and taste, the specificity coming from the microbes used. For example, the large holes in 'Swiss cheese' are due to production of a large amount of CO₂ by a bacterium named Propionibacterium sharmanii. The 'Roquefort cheese' are ripened by growing a specific fungi on them, which gives them a particular flavour.
NTA tests fermentation pathways and the microbes responsible for food production. In Swiss cheese, Propionibacterium sharmanii produces large amounts of CO₂ through anaerobic fermentation, creating characteristic holes. Students often confuse which microbes produce CO₂ (bacteria like Propionibacterium) versus which ones don't (like Lactobacillus in yogurt). The trap: assuming all fermented foods have gas production or mixing up bacterial species with their metabolic outputs. Remember: Different bacteria produce different end products—CO₂ production is specific to certain species used in cheese making, not all fermentation processes.
What is the reason behind production of large holes in 'Swiss Cheese'?
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