Question

10.(6 pts) The following food products are able to resist spoiling through different mechanisms. Explain how each food product stops or slows microbial growth.

Honey (supersaturated sugar solution):

Yogurt (pH 3):

Answer 1

The following products stop or slow microbial growth.

1)Honey(Supersaturated sugar solution) :-

a) Honey is hygroscopic in nature.So it can draw moisture out of the environment and dehydrate the microbes.

b) Also its high level of sugar solution and low pH can stop or slow the microbial growth.

c) High sugar concentrations cause the microbe to lose water by osmosis and it doesn't have any cellular machinery to pump it back in against the osmotic gradient.Without enough water microbes can't grow.

2)Yogurt (pH 3) :-

a) Yogurt contains lactic acic.The acidity of yogurt helps to preserve it and prevents potentially harmful bacteria from growing.

b) Inhibition by acid involves rapid diffusion of undissociated molecules through the plasma membrane.Dissociation of these molecules within cell liberates proton,thus acidifying the cytoplasm and preventing the growth of microbes.

c) It is possible to keep sealed yogurt in refrigerator for several days.