Food spoilage results from microbial growth, enzymatic activity, and environmental factors that gradually degrade the sensory, nutritional, and safety qualities of food. Preservation techniques aim to slow or halt these processes to extend shelf life and maintain product quality.A key concept in food microbiology is the microbial growth curve, which includes four phases: lag, exponential (log), stationary, and death. During the lag phase, bacteria adjust to their environment without significant...

Protein digestion begins in the stomach, where the highly acidic environment can easily disrupt protein structure by exposing the peptide bonds of polypeptide chains. After polypeptide chains are broken into individual amino acids by a series of digestive enzymes, the amino acids are transported to the liver via the bloodstream to produce energy.

In biological systems, most metabolic pathways are interconnected. The cellular respiration processes that convert glucose to ATP—such as glycolysis, pyruvate oxidation, and the citric acid cycle—tie into those that break down other organic compounds. As a result, various foods—from apples to cheese to guacamole—end up as ATP. In addition to carbohydrates, food also contains proteins and lipids—such as cholesterol and fats. All of these organic compounds are used as energy sources to produce...