Copyright © 2019 IJAIR, All right reserved 62 International Journal of Agriculture Innovations and Research Volume 8, Issue 1, ISSN (Online) 2319-1473 Microbial enzymes produced by fermentation and their applications in the food industry - A review Qais Ali Al-Maqtari 1, 2, 3, 4* , Waleed AL-Ansi 1, 2, 3 and Amer Ali Mahdi 1, 2, 3 1 State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China. 2 National Engineering Research Center for Functional Food, Jiangnan University, Wuxi, 214122, China. 3 Department of Food Science and Technology, Faculty of Agriculture, Sana'a University, Sana'a, Yemen. 4 Department of Biology, Faculty of Science, Sana'a University, Sana'a, Yemen. Abstract – Microbial enzymes are widely used in different industries mainly because of vast availability of sources. Microbial enzymes could be genetically modified and are considered as economical in comparison to plant and animal enzymes. Production of microbial enzymes by application of fermentation procedures involves microbial propagation like bacteria, mold and yeast to get desired product. The process of fermentation is classified based on specific parameters. There are different techniques employed to produce microbial enzymes using downstream processing methods that are aimed at enzyme purification and recovery. The improvement in concentration, purity and percentage of recovery of enzymes can be achieved based on standard principles which are microbial sources, improvement of strain and application of membrane augmented downstream processing method to improve specific activity of enzyme. There are two methods of fermentation used to produce enzymes. These are submerged fermentation and solid-state fermentation. Submerged fermentation involves the production of enzymes by microorganisms in a liquid nutrient media. Solid-state fermentation is the cultivation of microorganisms, and hence enzymes on a solid substrate. Carbon containing compounds in or on the substrate are broken down by the microorganisms, which produce the enzymes either intracellular or extracellular. Microbial enzymes exhibit wide variety of applications in different industries. Industries that use enzymes generated by fermentation are the brewing, wine making, baking, cheese making, dairy, milling, beverages, and cereals. Keywords – Microbial Enzymes, Fermentation, Submerged Fermentation, Solid-State Fermentation. I. INTRODUCTION Enzymes are “green” biological catalysts that have changed the way we prepare our food. Enzymes are worldwide used in various feed and food industries, widely covering dairy, brewing, meat, baking, juice and beverages, vegetable processing, dietary supplements, oils and fats [1, 2]. The application of enzymes and microorganisms to food processing is traditionally a known method. Enzymes and microorganism have been used in the brewing of bread baking, beer, wine and cheese making process for ages [3]. Biotechnology for food offers different ways to improve the processing of raw materials for conversion to food products of high nutritional value [4]. Fermentation is a microbial biotechnology whereby natural renewable substrates are converted to value-added products such as enzymes, organic acids, alcohols, polymers and more. Fermentation end-products such as ethanol and lactic acid are proton sinks, whereby NADH is recycled to NAD + , which allows the cell to continue producing energy via glycolysis by substrate-level phosphorylation. Thus, microorganisms generate many end- or by-products to maintain energy balance. Today, enhanced production of economically important fermentation products has benefited from targeted genetic engineering techniques to established industrial microbial strains [5]. The formation of end or by-products is dependent on microbial strain and the environmental conditions employed. For an optimum fermentation process, a microbial strain should be selected and developed based on the desired product. Strain development technologies include mutation and recombinant DNA technology [6]. Manuscript Processing Details (dd/mm/yyyy): Received: 23/07/2019 | Accepted on: 12/08/2019 | Published: 27/08/2019