Acid proteases are also exploited for use in clearing beer and fruit juice, improving the texture of flour paste, and tenderizing the fibril muscle. Fungal species mostly produce these extracellular acid proteases. Acid proteases are stable and active between pH 3.5 and 5.5 and are frequently used in soy sauce, protein hydrolysate, and digestive aids and the production of seasoning material. The optimum pH of acidic proteases is 3–4 and the isoelectric point range is between 3 and 4.4 with a molecular weight of 31–46 kDa.
Neutral proteases are defined as, such as they are active at a Neutral or weakly acidic or weakly basic pH. Mostly neutral proteases belong to the genus Bacillus and with a relatively low thermo-tolerance ranging from pH 5 to 8. They generate less bitterness in the hydrolysis of food proteins due to an average rate of reactions; therefore, they are considered widely used in the food industries. Neutral protease is applicable in the brewery. Based on high affinity toward antihydrophilic amino acids, neutral proteases are identified and characterized. During the production of food hydrolyzes, it is slightly advantageous to control the reactivity of neutral proteases due to low thermo-tolerance.