How do salts and sugars preserve foods? Why are these considered physical rather than chemical methods of microbial control? Name one food that is preserved with sugar and one preserved with salt. How do you account for the occasional growth of Penicillium mold in jelly, which is 50% sucrose?
Salts and sugars create a hypertonic environment. Salts and sugars (as preservatives) do not directly affect cell structures or matabolism; instead, they alter the osmotic pressure. Jams and jelly are preserved with sugar; meats are usually preserved with salt. Molds are more capable of growth in high osmotic pressure than are bacteria.