Enzymes are indispensable in food processing. Enzyme products are applied in food manufacturing for purposes including (1) modification of flavor and texture, (2) improvement in preservation stability, (3) streamlined manufacturing, and (4) addition of health function.
Enzymes, which are proteins produced by living organisms, are catalysts that speed up various biochemical reactions. Enzymes have very high substrate specificity, and enzymatic reactions are dependent on substrate concentrations, temperature, pH, inhibitory agents, and other conditions. Therefore, it is necessary to identify optimal reaction conditions for efficient enzymatic reactions. In other words, the amount of enzymatic reaction can be controlled by changing these conditions.
Enzymatic reactions, compared with other chemical reactions, have advantages on the following points: (1) no side reactions occur, (2) many enzymes react under mild conditions (temperature, pressure, and pH), and (3) continuous operation is possible by enzyme immobilization. Additionally, clean labels can be achieved because enzymes do not have to be indicated on the labels when the enzymes are deactivated.
In the current feature articles, industry professionals, who are active at the forefront, will explain the current state-of-the-art development of enzyme products and their applications in the food industry, as well as enzymes that are expected to be utilized in the future.

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Enzymes are at the center of the development of plant proteins and foods that use them. Among them, protein-glutaminase deamidates proteins, lowering their isoelectric point and improving their solubility in more acidic conditions. In addition, the intramolecular electrostatic repulsive force generated between the carboxyl groups loosens the higher order structure of the protein, which is thought to expose hydrophobic regions buried within the molecule to the molecular surface. This gives plant proteins excellent functionality as emulsifiers and foaming agents. They are widely used in food processing abroad to improve these food functions.
One of the challenges of vegetable milk replacer is its low protein content compared to cow's milk, but the use of protein-glutaminase in the production process of oat replacer solubilizes the protein and increases the amount of protein transferred to the centrifuge supernatant, improving the dispersibility and dispersion stability. In addition, when the tribological smoothness of protein-glutaminase-treated soy milk was measured as an index to evaluate the mouthfeel, the enzyme-treated soy milk reduced the coefficient of friction of the soy milk, regardless of whether saliva was present or not. This is considered a result that may be associated with improved mouthfeel. Another issue is that vegetable milk substitutes do not disperse when added to hot coffee as coffee milk, resulting in protein aggregation. This is because the isoelectric point of vegetable proteins is weakly acidic to acidic, so they tend to aggregate when added to coffee, which is an acidic beverage. When enzyme-treated almond milk was added to coffee and allowed to stand, protein aggregation was observed in the untreated sample, but not in the enzyme-treated sample, and dispersion was maintained.
Other enzyme applications include the use of starch-related enzymes to control the type and amount of carbohydrates in milk substitutes to adjust the desired (mainly sweet) taste quality. Transglucosidase treatment can impart a full-bodied sweet taste, which may be due to the formation of isomaltooligosaccharides. In addition, glucoamylase treatment can enhance sweetness by producing glucose, β-amylase treatment can impart mild sweetness by producing maltose, and maltotriohydrolase treatment can impart refreshing sweetness by producing maltotriose. Thus, the taste of the vegetable milk substitute can be adjusted according to the product concept. On the other hand, it is difficult to reproduce the unique flavor of plant-based meat substitutes, but by treating them with protease and peptidase, it is possible to impart a flavor and aroma typical of cooked meat. The amino acids in the baked enzyme-treated meat alternatives were quantified, and the amounts of glutamic acid and cysteine were increased. Glutamic acid was thought to contribute to the umami flavor, while cysteine was thought to enhance the savory flavor of the meat through the Maillard reaction. In addition, bean odor is a factor that negatively influences consumer purchasing decisions for plant-based meat substitutes. The entrapment ability of cyclodextrins produced by enzymatic treatment with the cyclodextrin glucanotransferase reduced the volatiles of hexanal, 1-octen-3-ol and benzaldehyde, the major contributors to soy odor, to less than half.

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We started research on Protein phosphatase (PPase), which dephosphorylates phosphoproteins, as a new food property-modifying enzyme. We searched for an enzyme that efficiently releases phosphate groups from milk casein and found an extracellular enzyme produced by Trichoderma virens. As a result of LC-MS/MS analysis of the purified enzyme, this enzyme was estimated to be an unidentified protein belonging to the acid phosphatase family. Characterization analysis showed maximum activity at pH5.6 and 50°C, suggesting that it could be applied to food products such as fermented milk. For the formulation of the enzymes, we attempted to maximize and stabilize enzyme activity by examining culture conditions and breeding. As a result, we finally achieved enzyme productivity 2,000 times higher than that of the wild-type strain, and thereby established it as a PPase preparation.
We obtained some application data for the developed PPase for food products. The PPase not only increased the number of bifidobacteria in yogurt, but also increased the amount of exopolysaccharides (EPS) produced by the Lactic acid bacteria, and changed the physical properties of the yogurt curd to be firmer and smoother. PPase-mediated dephosphorylation of milk casein is assumed to have a variety of effects on protein properties, leading to these results. In soy yogurt, it improved the viability of lactic acid bacteria and suppressed water separation, which is expected to contribute to improved product stabilization and preservation. It was also observed to improve the foaming properties of soy milk, confirming its various effects on food proteins. In the future, it is expected to be applied to various food products such as wheat, rice and plant-based foods.

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Enzyme application technology continues to evolve, with food processing being the most typical application, but enzymes are also used in the manufacture of chemical products, to improve the function of everyday items, and in the medical field. Among enzymes for food processing, the application of phospholipase A2, which hydrolyzes lecithin, has been expanding in recent years. When lecithin is hydrolyzed by phospholipase A2 to lysolecithin, the hydrophilicity of amphiphilic lecithin becomes stronger, and its surface activity is dramatically improved. Taking advantage of this feature, the trend to add phospholipase A2 directly to foods to give it functionality as an emulsifier is accelerating. Phospholipase A2 manufactured by Nagase Viita has the property of being inactivated at around 60°C while showing high activity at around 50°C. This means that it is very easy to use, as it is effective at temperatures where the risk of bacterial growth is not a major concern and can be easily inactivated under general food pasteurization temperature conditions. Phospholipase A2 can impart functionality in foods made with lecithin-rich eggs and was found to be effective in imparting heat resistance and maintaining foaming properties in mayonnaise and sponge cakes, respectively. In addition, it is also expected to be effective in manufacturing soybean lysolecithin for use in animal feed and in improving the yield of cheese made from milk. Further utilization is anticipated in the future.

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The price of surimi remains high, so surimi-based product manufacturers are struggling to make a profit. Since the price of starch is lower than other ingredients such as surimi, replacing some part of surimi with starch seems to be an ideal solution, but it is not easy in reality. The first challenge is the change in texture. Surimi forms an elastic gel, while starch forms a hard and brittle gel. The texture of the final product is determined by a balance of these ingredients. In other words, products with a high inclusion of starch form a hard and brittle gel which is not suitable for surimi-based products. The other challenge is that the products with high inclusion of starch become hard quickly when they are stored under refrigerated conditions. The cause of this change is starch staling. This phenomenon makes the gel harder and more brittle than before storage.
Our test results indicated both maltogenic amylase and a branching enzyme were found to change the hard and brittle products made with high inclusion of starch to a desirable texture. Maltogenic amylase dramatically improves the texture even though the dosage is very small, and it produces an anti-staling effect, particularly in products with potato starch. The branching enzyme can be used to control the texture improvement as it works in a dose-dependent manner. In addition, it reduces the unique chewy texture of modified tapioca starch without losing its anti-staling effect.
In conclusion, it is suggested that the two types of enzymes can be used to solve the problems associated with products with high inclusion of starch.

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Alliaceous and cruciferous vegetables are rich in bioactive organosulfur compounds, including glucosinolates, which have a wide spectrum of health-promoting benefits. In mammals, including humans, it has been reported that supersulfides, such as cysteine hydropersulfide (CysS2H) and glutathione hydropersulfide, are endogenously produced and not only exhibit potent antioxidant activity but also function as key modulators of redox signaling in a variety of diseases. It is thought that animals utilize sulfur-containing compounds ingested from foods for the biosynthesis of other sulfur-containing compounds, including supersulfides. Few studies, however, have focused on supersulfides in foods. We recently established a quantitative analysis method of supersulfide profiling in foods using liquid chromatography-tandem mass spectrometry, and investigated the supersulfide profile in foods including meats and fresh vegetables such as garlic, onions, and broccoli sprouts. The results showed that alliaceous and cruciferous vegetables were relatively abundant in supersulfides and broccoli sprouts had the highest total polysulfide content among the foods analyzed to date. Furthermore, the supersulfide profiling and quantitative supersulfide metabolomics revealed that the total supersulfide content dramatically increased during the germination and growth of broccoli sprouts and that CysS2H and cysteine hydrotrisulfide were the predominant organic supersulfide metabolites. Interestingly, by untargeted supersulfide omics analysis, a variety of unknown supersulfide candidates were detected in the broccoli sprouts. These results suggest that intake of supersulfides from foods such as broccoli sprouts may contribute to the reported health-promoting effects. In addition, further studies to identify novel supersulfides in foods and to investigate their physiological and pharmacological effects will shed new light on the field of food science, contributing to discovering novel drug seeds and developing functional foods.

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Unique phenolic compounds derived from seaweeds collected around Hokkaido were reviewed from the viewpoint of structural and functional diversity. Bromophenols are brominated polyphenols. The bromophenols derived from Rhodomelaceae algae consist of a brominated 2,3-dihydroxybenzyl unit as a monomeric unit. They exist in the seaweeds as monomers or oligomers of the unit. The tribrominated monomer exhibited higher inhibitory activity against α-d-glucosidase than the monobrominated and dibrominated monomers that were examined. The symmetric dimers exhibited potent inhibitory activity against α-d-glucosidase, tyrosinase and glucose 6-phosphate dehydrogenase among the asymmetric oligomers examined. Thus, bromophenols are possible potent inhibitors of some enzymes. Phloroglucinol oligomers are obtained from brown seaweeds. But most of them are highly polymerized to be phlorotannins. Colpomenia bullosa contains phloroglucinol monomer, dimer, and trimers. The trimers, fucophlorethol C and triphlorethol C, exhibited potent tyrosinase and lipoxygenase inhibition. Inhibitory activity of triphlorethol C, a symmetric trimer, is higher than fucophlorethol C, an asymmetric one. This review focused only on seaweed-derived unique phenolic compounds. But many other unique compounds can be isolated from marine origins. The research to discover novel compounds and their functions from seaweeds remains important.

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In the Edo period, the kunenbo (Citrus nobilis Lour. var. kunep Tanaka) was one of the most common varieties of citrus fruit grown in Japan. Kunenbo are mentioned in important historical documents from Yamaguchi Prefecture, such as the menu for the banquet held for Admiral King of the British Royal Navy in 1867, and the records of refreshments provided for Yoshida Shoin during his imprisonment. There are records of kunenbo cultivation in Yamaguchi Prefecture from the middle of the Edo period, and in the 1840s kunenbo became the signature crop for Mitajiri. By the start of the Meiji period, Yamaguchi Prefecture was the largest producer of kunenbo in Japan. Today, few people know the name of kunenbo and it has become a forgotten variety of citrus. However, when considering the food culture of the Edo and Meiji periods, the kunenbo was an important agricultural product. With the intention of utilizing the kunenbo in the modern age as a regional resource, this is a report of the quest to find kunenbo trees (as of yet, no trees have been discovered in Yamaguchi Prefecture) and efforts made to develop the kunenbo as a resource for food, tourism, and regional contribution.

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Since ancient times, humanity has eaten insects such as ants, cicadas, bees, locusts, and silkworms. For example, locusts were not eaten out of poverty but served as a delicacy for royalty. In Japan, various insect species including locusts and bee larvae are consumed, with records showing that there are about 150 species eaten. Insects are still consumed as food worldwide, but it cannot be denied that localized insect eating cultures have developed in various regions. In Japan, Japanese grasshoppers are still eaten, but their consumption declined to a local delicacy level during the high economic growth period. However, since around 2013, there has been increasing interest in environmental issues, the United Nations Sustainable Development Goals, and food tech, leading to a resurgence in insect consumption. The global edible insect market is expected to grow by nearly 25% annually and exceed $800 million by 2029. In Japan, cricket senbei (rice crackers) are now sold in supermarkets and 100-yen shops. Nevertheless, insects, which also have a negative image as pests, are still somewhat challenging for people to accept as a food source. Just as beef consumption was once viewed with aversion during the Edo period, food cultures evolve over time. It is necessary to continue monitoring how the recent insect consumption boom transitions from a cultural perspective in the future.

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