Answer:
Changes in color and smell.
Explanation:
In addition to bacteria and fungi, foods can be contaminated by viruses and parasites as well as by toxins produced and released by these microorganisms. As this contamination is not always perceived, but in the case of the action of spoilage bacteria, contaminated foods have changes in color and smell, which become extremely unpleasant changes. These changes are strong signals that make recognizing spoiled foods easier.
