Question

If a food ingredient had 1,000,000 viable vegetative cells plus 500,000 spores per gram, what would each of the following procedures reveal immediately after the “heat shock” treatment:

a. Viable plate count of (blank) per gram.

b. Direct microscopic count of (blank) per gram.

Answer 1

After "heat shock" treatment the viable vegetative cells will be died but the spores will survive as they contain protective coat. So, the number of spores will be the viable plate count. Direct microscopic count includes all the cells (both dead vegetative cells and living spores). So, the total number of vegetative cells and spores will be the direct microscopic count. Hence, we will get after "heat shock" -

a. Viable plate count of 500000 or 5 X 10⁵ per gram.

b. Direct microscopic count of 1500000 or 15 X 10⁵ per gram.