My major interest in food chemistry is how food changes during processing and storage. I am especially interested in how color changes take place. The reactions I am interested in are called Non Enzymatic Browning reactions to differentiate them from the browning that occurs when you cut an apple or banana, which involves an enzyme.
Non enzymatic browning (NEB, non enzymic browning) reactions are the most important reactions in food, and, no, I am not biased. Just image the aroma of melting chocolate, freshly baked bread or a roasting leg of lamb, the golden color of a croissant, the dark amber color of a well brewed beer; caramels, toast. These are all caused NEB reactions.
There are five different NEB reactions and I intend over the next few months to write about each of them:
- Caramelization – browning of sugar, especially sucrose
- Lipid Oxidation – the oxidation of fats and oils; including rancidity
- Break down of flavonoids – highly c0lored compounds can also lose their color
- Degradation of ascorbic acid (Vitamin C) – AsA is unstable even without oxygen
- The Maillard Reaction – reaction between carbonyl compounds and amino acids
Numbers (3) and (4) are not typically on a list of NEB reactions, but I did my thesis on ascorbic acid browning and it definitely goes brown without oxygen and without enzymes. The degradation of flavonoids is one I have added and came to me in flash of inspiration when at a conference. I am sharing it with you now, so this is new even though I had the idea three or four years ago.