Newsletter #8! MAILLARD REACTION! 🍏🍽️👄🍏🍽️👄Greetings from your local food scientist! 🍏🍽️👄🍏🍽️👄

Folks sometimes ask me, “is black garlic burnt?” It’s a simple question with a complex answer. The simple answer is, “no, black garlic is not burnt.” I guess it's a simple answer, too!

The complex answer: it raises an additional question, what is “burnt”? (at the chemical level.) There’s “ash” which is the most burnt thing, and consists generally of elements of the periodic table excluding carbon, nitrogen, oxygen and sulfur (ie, ash are things that don’t vaporize at 450F.) "Ash" is a term used in food science to describe the remainder of complete “combustion” of a food: which is done in a “bomb calorimeter” (awesome name of a lab instrument, btw). The bomb calorimeter is used to measure the theoretical calories of a food, and the lab-device literally burns (combusts) the food and measures the heat energy released. (Your body doesn’t derive energy from food’s chemical bonds this way, so a bomb calorimeter is considered not entirely accurate. Food calorie measurement is for another newsletter...) Regardless, when you burn food in the presence of air, you’ll release CO2, water vapor (H2O) and some nitrogen and sulfur gases, as proteins have approximately 6% nitrogen and to a smaller amount sulfur (although garlic is higher in sulfur than most foods.)

Burnt food generally start offs with the maillard reaction, but as the food heating continues, the flavorful maillard compounds are “broken down” (or destroyed, you might say), the food becomes more and more oxidized, dried out further and further, smoking, etc... "burnt." So, a major distinction between burnt food and black garlic: “burnt” food has no water. Black garlic retains its water. (Garlic is heated with the moisture kept in.)

Black garlic is best described as a “caramelized garlic”, although caramelization of a sugar molecule such as sucrose with another sucrose molecule is a different food chemical reaction. The specific “maillard reaction” caramelization is between a “reducing sugar” and an amino acid. ("reducing sugar" is for another newsletter.) Glucose and fructose are the most common monosaccharide reducing sugars. (whereas sucrose is a disaccharide composed of glucose bonded to sucrose.) Interestingly, allium vegetables such as garlic and onions are polymers of fructose called fructan, which is a less common carbohydrate food polymer, whereas glucose polymers are known as amylose, and are much more common and found in grains such as corn, wheat and potatoes. Fructose is naturally 60% sweeter than sucrose, so black garlic may taste especially sweet!

In black garlic caramelization, the heat energy (and presumably with help from natural enzymes in the garlic), slowly breaks down the carbohydrates in garlic to single sugar (fructose) molecules, and the proteins are broken down to amino acids. For the bonding of fructose and an amino acid to occur in the maillard reaction, water is released (specifically an OH and H, hydroxide and hydrogen) the OH and H separate and combine forming a water molecule, and a bonding can then occur where the OH and H depart; The initial reaction of fructose with an amino acid is a bonding reaction that releases water, which in chemistry is called a “dehydration reaction”.

1. Dehydration Reaction: water released in bond formation
2. Condensation Reaction: water released in bond formation, along with release of a second or even more molecules (eg NH3 ammonia with the H2O)
3. Hydrolysis: Water is split (consumed) in forming the bond (often in depolymerization into component monomers, whereas dehydration and condensation reactions are found in polymerizations (water released) and not hydrolysis in polymerization. (although water can act as a “plasticizer” to help unravel starch granules.)

Whew… a lotta food for the brain and for 25 more newsletters. If the black garlic is totally dried out and rock-hard, then you could say it’s “burnt” although not chemically the same as “ash” (or you can say "not as burnt as ash.")

Soft-spreadable black garlic, rich in antioxidants, takes 6-12 weeks to produce because the maillard reaction releases water, and the more atmospheric humidity surrounding the garlic during caramelization, the slower the maillard reaction rate, thus it takes so long to produce.

I hope you learned something new and I sparked some interest in food science!