Question

4 Yoghurt contains living bacteria. Bacteria are also capable of respiring anaerdica
sealed carton of yoghurt is left for a long time, the lid bulges upwards. Suggest​

Answer 1

Answer:

Suggest what???

Explanation:

Answer 2

Answer:

First of all, milk/yogurt has dissolved oxygen. Therefore aerobic bacteria survive for a long time.

Second: Unless you pull a full vacuum on the container, flush the headspace with Co2, and the seal on the bottle is 100 percent leak proof. You have not created an anaerobic condition.

Now the answer:

Yogurt culture does not produce gas, the gas you see is generated by residual bacteria because in the old yogurt the real yogurt culture is dying and the remaining bacteria from the milk has taken over. And some of them are gas formers, the bulging of foil is a result of residual bacteria from the original milk, they have taken over the dying yogurt bacteria.

I hope it helps,

Sam Arora, M.Sc. Dairy Science, U of Punjab, India, M.Sc. Food Science, U of Guelph, Canada.