Carbohydrates are abundant in foods of plant origin, but are fairly limited in quantity in foods of animal origin. However, some of the biochemical changes and their effect(s) on food quality are common to all foods regardless of animal or plant origin, while others are specific to an individual food.
Shows the relationship between the enzymatic degradation of glycogen and starch (glycolysis) and lactic acid and alcohol formation, as well as the citric acid cycle. Even though glycogen and starch are glucose polymers of different origin, after they are converted to glucose by the appropriate respective enzymes, the glycolysis pathway is common to all foods.
The conversions of glycogen in fish and mammalian muscles are now known to utilize different pathways, but they end up with the same glucose-6- phosphate. Lactic acid formation is an important phenomenon in rigor mortis and souring and curdling of milk, as well as in the manufacturing of sauerkraut and other fermented vegetables.
Ethanol is an important end product in the production of alcoholic beverages, bread making, and to a much smaller extent in some overripe fruits. The citric acid cycle is also important in alcoholic fermentation, cheese maturation, and fruit ripening.
In bread making, -amylase, either added or from the flour itself, partially hydrolyzes the starch in flour to release glucose units as an energy source for yeast to grow and develop so that the dough can rise during the fermentation period before punching, proofing, and baking.