More About Enzymes
Enzymes are complex proteins that facilitate, catalyze or speed up chemical reactions. The precise order of amino acids in the proteins from which they're made determines their shape, and their shape determines their function.
Typically, each enzyme does just one thing, so there are just about as many enzymes as there are different things for them to do. Without taking part themselves, they make possible hundreds of thousands of processes in our bodies: they can chop things up (hydrolases), put things together (ligases), split double bonds between atoms (lyases), and move chemical groups from molecule to molecule (transferases). If it's a biochemical reaction, there's an enzyme involved.
Enzymes have a life-span, just like other living things. Some only live for twenty minutes or so, while others can live for many weeks before some other enzyme comes along and seals their fate.
The slowest-acting known enzyme, lysozyme (an anti-bacterial enzyme found in raw milk), can process about thirty molecules a minute. Pretty fast, but compared to carboanhydrase, a 600,000 molecules/second speed demon, it's just an amateur... I'll bet the quick one is the twenty minute wonder mentioned above!
Every living organism needs enzymes to survive. Without them life would pretty much be impossible: the wrong substances would be made, reactions would happen too slowly- in other words, without enzymes, you'd die. And speaking of death, enzymes play a role there, too.
All plant and animal cells contain little sacs of digestive enzymes called lysosomes. When the cells die, these bags eventually break open and self-digestion begins. We know it as decay, but you can, say, throw the chicken or fish into the fridge and stave things off for a bit.
So now you know about food's own complement of digestive enzymes that help our bodies break it down. Heating food above 118°F./48°C. destroys most of these natural helpers, forcing us to make our own digestive enzymes to get at the nutrients. Having to make our own digestive enzymes puts an extra burden on our pancreas, which is typically busy enough with other metabolic needs.
I consider food enzymes to be right next to proteins, carbohydrates and fats, in importance. A fourth major food group, if you will. The late enzyme expert, Dr. Edward Howell, believed that life-span was related to the rate at which an organism's enzyme potential was exhausted. He felt the increased use of food enzymes (either from raw foods or supplements) reduced the rate of enzyme potential exhaustion.
Raw milk, especially that from grass-fed cows, has a full complement of the very food enzymes Dr. Howell held in such high regard. The short list below is far from comprehensive, and by no means implies that everyone is on the same page regarding enzymes.
This much is certain, though: heating milk substantially above the body temperature of a cow undeniably causes changes in its ingredients. Higher heat = more changes. Unwanted changes or not depends on who you ask and who pays his or her salary.
An ingredient in saliva and pancreatic juice as well as raw milk , amylase breaks down starch, glycogen and other related carbohydrates. It's also the most commonly found enzyme in plants, particularly abundant in sweet potato, corn and starchy grains like oats, wheat and barley. It appears to be inactivated by the pasteurization/homogenization processes.
Involved with waste management on the cellular level, catalase rids cells of hydrogen peroxide (H2O2), an unwanted by-product of cellular metabolism. A strong oxidizer, H2O2 can wreak havoc in the cellular environment. Catalase quickly locks onto it and cleaves it into oxygen and water. It appears to be inactivated at temperatures above 158° F./70°C.
Lactase (a member of the beta-galactosidase group of enzymes) splits milk sugar (lactose) into the two simple sugars glucose and galactose. Found exclusively in mammalian milk, lactose is only one sixth as sweet as cane or beet sugar (sucrose).
Many people lose the ability to make lactase as they mature, so must either get it in their food or take supplements to avoid unpleasant side effects (lactose intolerance). Other folks, from regions in Europe, Africa, India and the Middle East, through a helpful genetic mutation, produce the enzyme in their intestinal tracts, even as adults. The lactase in raw milk, present from bacterial synthesis, appears to be inactivated by the pasteurization/homogenization processes.
Identical to the peroxidase found in saliva and gastric juice, lactoperoxidase teams up with two other substances found in varying levels in milk (oxidized thiocyanate and hydrogen peroxide) to form an antimicrobial complex. I'd imagine there's tough competition from catalase for any free hydrogen peroxide floating around...
Lactoperoxidase appears to be fairly heat resistant at normal pasteurization temperatures (roughly 50% is inactivated in milk held at 158° F./70°C. for 20 minutes) but is completely inactivated at 176°F./80°C. in just 5 minutes. Lysozyme, the anti-microbial slow-poke mentioned above, is present in much lower quantities than lactoperoxidase.
Actually a class of water-soluble enzymes, lipases break down fats (triglycerides) into fatty acids, and improve utilization of lipids throughout the body. Disruption of the fat globules, as in homogenization, can lead to rancidity if lipase isn't destroyed first. Pasteurization makes short work of it. It's normally inactive in raw milk until triggered by the proper pH in the digestive tract.
A key enzyme in accessing two of milk's important minerals, phosphorus and calcium, phosphatase hydrolyses (breaks down with water) complex compounds in milk (called phosphate esters) to release phosphorus ions. Optimal calcium absorption is dependent on proper ratios of phosphorus and magnesium.
Phosphatase is completely destroyed at the lowest typical pasteurizing temperatures (which are also the highest needed to kill pathogenic bacteria). Food processors test for the total absence of phosphatase to determine if pasteurization was successful. Presumably, its absence also makes getting phosphorus and calcium out of the milk more difficult for our bodies.