While it is true that certain enzymes, usually those derived from animals, become less active in very acidic environments, this is not true for enzymes derived from plant, fungal or microbial sources. In nature, these organisms use enzymes to break down and digest materials under a wide variety of conditions. Even when exposed to extreme pHs and temperatures, these organisms don't put an enteric coating on their enzymes; instead their enzyme systems have evolved to survive a wide range of different pH. Therefore, enteric coatings are only important (in theory) for animal-based enzymes that are naturally released in the digestive tract after the stomach, giving them a narrow pH range.
Some studies have even shown that enteric-coated enzyme powder may make a supplement less effective. In a series of third-party tests, products containing enteric-coated serrapeptase powder lost more activity than supplements using non-enteric-coated serrapeptase powder.
Instead of using any type of enteric-coated serrapeptase, the serrapeptase supplement Serretia (formerly Serracel), as well as the enzyme blend Neprinol and probiotic formula Syntol, use a different technology known as Acid Armor. Acid Armor capsules are made of an extra-thick layer of cellulose (the main component of veggie caps) with a better-designed way of fitting the two sides of the capsules together, which limits leaking. Acid Armor capsules have also been designed to delay the release of the capsule's contents for up to an hour. When a product like Serracel is taken on an empty stomach, the capsule enters and leaves the stomach in 30 minutes or less. This means that the Acid Armor provides more than enough time for the serrapeptase enzyme to get through the stomach and into the more "enzyme friendly" environment of the intestines.
In addition, serrapeptase capsules themselves do not cause the stomach to start producing acid when they are taken on an empty stomach. Acid production only occurs when the stomach fills up with food and its lining is stretched. Therefore any tests that supposedly "prove" the necessity of enteric-coated serrapeptase by exposing enzymes to extremely acidic environments for several hours do not accurately replicate actual, real-life conditions in an empty stomach!