Enzyme preparations are widely used in food, and this article will detail the roles of different enzyme preparations in food.
Catalase:
Catalase is a protein made up of four subunits that is found in aerobic organisms and helps in the decomposition of hydrogen peroxide. It can be produced from microbial sources like Aspergillus niger, Micrococcus luteus, and from bovine liver. Microorganisms are preferred for enzyme production due to their advantages such as fast growth, easy handling, and genetic tuning for a desired product. Some bacteria like Bacteroides fragilis, Enterococcus faecalis, Bacillus maroccanus, Pyrobaculum calidifontis, Bacillus halodurans LBK 261, Oceanobacillus oncorhynchi ssp. incaldaniensis, and Psychrobacter piscatorii T-3, and fungi like Aspergillus niger and Metarhizium anisopliae can produce catalase.
Catalase finds its use in the fabric industry for removing excess hydrogen peroxide from fabric. In the food processing industry, it is used along with other enzymes, such as glucose oxidases, for food preservation. It is also applied in milk processing industry, baking industry, and in food wrappers to prevent oxidation and control perishability of food. However, its use is limited in cheese production.
Peroxidase
Peroxidases are oxidoreductase proteins that utilize iron(III) protoporphyrin IX as their prosthetic group. They have the ability to reduce peroxides and oxidize a variety of inorganic and organic compounds. These enzymes have a molecular mass that ranges from 30,000 to 150,000 Da and consist of a group of unique enzymes, including iodide peroxidase, NADH peroxidase, and glutathione peroxidase, as well as a group of other nonspecific enzymes. Peroxidases are present in plants, microorganisms, and animals, and they play a role in plant lignification processes and defense mechanisms against damaged or infectious tissues.
Phanerochaete chrysosporium is the most well-characterized peroxidase-secreting microorganism. Although industrial scale applications of fungal peroxidases are limited due to challenges associated with post-translational modification of proteins, bacterial peroxidases are easier to produce and have better stability and activity suitable for industrial applications. Bacterial peroxidases are often used in conjunction with bacterial laccases for dye decolorization, and peroxidase activities have been reported in bacterial taxa such as Firmicutes, Proteobacteria, Actinobacteria, and Acidobacteria. Actinomycetes, which are soil bacteria, are also capable of producing peroxidases for lignin degradation.
Peroxidase can catalyze a wide range of substrates using hydrogen peroxide or other peroxides. This enzyme has various applications in the food industry, including producing flavor, color, and texture and improving the nutritional quality of food. It is also used as biosensors, in polymer synthesis, and in managing pollutants in the environment. Peroxidase can treat phenolic effluents from industries, and thermal inactivation of peroxidases is used in the food industry to measure the efficiency of blanching treatment, which enhances the shelf life of food. However, peroxidases also have a negative effect in that they cause undesirable browning of fruits and off-flavors of vegetables.
α-Acetolactate Decarboxylase
α-Acetolactate decarboxylase plays a crucial role in the fast maturation of beer. This enzyme can be produced from natural microbes such as Brevibacillus brevis or from recombinant Saccharomyces cerevisiae. The enzyme catalytically converts acetolactate to acetoin via a two-step reaction involving direct decarboxylation of substrate to an enol derivative and its further protonation to final product.
The use of α-acetolactate decarboxylase assists in overcoming the rate-limiting step of beer maturation, resulting in maturation within 24 hours depending on the source of enzyme. Moreover, the off-taste due to the presence of diacetyl in beer is nullified by the action of this enzyme. Both free and encapsulated forms of this enzyme work efficiently in the process, thus aiding the use of immobilized enzymes at reduced costs. Novel inorganic nanoflowers or alginate microbeads immobilized with α-acetolactate decarboxylase are promising strategies with better thermal stability, reusability, and catalytic efficiency.
Asparaginase:
Asparaginase is a type of enzyme derived from microorganisms that is widely used in pharmaceutical, nutraceutical, and industrial applications. Its primary function is to break down asparagine into aspartic acid and NH3, making it an important asparagine-depleting enzyme. Asparagine is a non-essential amino acid for humans but an essential amino acid for cancer cells. As a result, the depletion of asparagine can significantly impact the growth of cancer cells, making asparaginase an effective anticancer agent.
Certain food processing methods, such as frying and baking, can convert asparagine into acrylamide, a known carcinogen. Enzymatic treatment to deplete asparagine has been found to effectively reduce acrylamide formation from asparagine by 97%, among other methods attempting to overcome this issue .
Naringinase:
Naringinase (EC 3.2.1.40) is an enzyme responsible for breaking down naringin, the main bitter flavanone glycoside found in citrus fruits. Naringinase breaks down naringin into a glycon called naringenin and rhamnose through its α-rhamnosidase and β-glucosidase actions. This enzyme is primarily produced by fungal isolates, such as Aspergillus niger, Circinella, Eurotium, Fusarium, Penicillium, Rhizopus, and Trichoderma, as well as bacteria like Bacillus sp., Burkholderia cenocepacia, Bacteriodes distasonis, Thermomicrobium roseum, and Pseudomonas paucimobilis. Fungal sources are preferred for naringinase production due to higher yield.
Naringinase plays a significant role in food processing as a debittering enzyme added to fruit juices. Both free and immobilized forms of this enzyme are used to achieve better results. Immobilization of naringinase has been accomplished using various substrates such as polyvinyl alcohol cryogels, packaging films, cellulose triacetate nanofibers, graphene, etc. Rhamnosidase or naringinase can be used to synthesize various food additives such as biopolymers and sweeteners. Naringinase, along with β-glucosidase and arabinosidase, can also be used to enhance the aroma of wine. Naringinase is also used in tomato pulp preparation, kinnow peel waste treatment, and prunin preparation.
The Versatility and Potential of Microbial Enzymes in Industry
In conclusion, enzymes have become increasingly important in various industries such as food, detergent, pharmaceutical, and paper industries. Enzymatic hydrolysis and enzyme-based processes are now favored over chemical ones due to their eco-friendly nature, high process control, low refining costs, and process safety. Compared to plant and animal enzymes, microbial enzymes can be produced more efficiently using various fermentation techniques such as solid-state and submerged fermentations. Additionally, it is easier to produce microbial enzymes on a large scale, and they can be readily modified using different molecular and biochemical approaches. By overexpressing the genes responsible for microbial enzyme production, hyperproduction of these enzymes with high specific activity can be achieved. Furthermore, there are still many unexplored microbial enzymes with untapped potential for wider industrial application, particularly in the food sector.