Journal of Applied and Natural Science 10(1): 247 - 252 (2018) Calf rennet production and its performance optimization Asfawosen Mamo and Nedumaran Balasubramanian* Chemical Engineering Program, School of Mechanical, Chemical and Materials Engineering, Adama Science and Technology University, POBox 1888, Adama, Ethiopia *Corresponding author. E-mail: nedumaran_b@yahoo.co.in Received: August 26, 2017; Revised received: October 10, 2017; Accepted: January 31, 2018 Abstract: Milk clotting enzymes are one of the most significant cheese making raw materials impacting and regulat- ing milk coagulation activity. Calf rennet is one of the enzymes which extracted from suckling calf abomasum. The rennet extracted was optimized for its clotting time t (s) by varying three levels of temperature (30, 35 and 40 o C), pH (4, 5 and 6) and CaCl 2 concentration (0.1, 0.2 and 0.3 gm/500 ml of milk) using response surface method (RSM) and also its milk clotting activity (MCA) was determined. Based on the optimized result, temperature 39.13 o C, pH 4 and CaCl 2 concentration of 0.21 gm/500ml had resulted minimum clotting time of 91.27 s. Using this minimum clot- ting time, the strength was found to be 1: 13148, establishing the fact that the calf rennet is the best natural coagu- lant of milk. Keywords: Abomasum, Calf rennet, Clotting time, Response surface method. INTRODUCTION The products obtained from Cows are well known to mankind, such as Gorochan (Sailaja et al., 2017), known as Gorojanam (Sanskrit, Tamil) is one of the products of cholelithiasis in the gall bladder and ducts of cow and bull which is laxative, antispasmodic, cho- lagogue and cooling and used as traditional Indian ayurvedic medicine in treatment of cholera, convul- sions and hysteria in the range of 50 – 250 (µg/ml) . Similarly Rennet is very important in the stomach of young mammals as they digest their mothers' milk. The active enzyme in rennet is called chymosin or ren- nin (EC 3.4.23.4) but there are also other important enzymes in it including pepsin and lipase. High pep- sin content results in bitterness of the product (Visser et al., 1987, Hubble and Mann, 1984, Libouga, 2004). The amino acid sequence of chymosin with summary of the data from which the sequence was derived have been presented (Bent et al., 1979). The dairy calf is a monogastric or simple stomached animal, whose digestive system is underdeveloped until two weeks from birth. The abomasum is the only stomach compartment actively involved in digestion. As a result, only liquid feed can be utilized effectively by pre-ruminant calves a few days old. As the calf be- gins to eat dry feeds, particularly grains containing readily fermentable carbohydrates, the rumen takes on a more important role. The stomach compartments grow and change as the calf develops into a ruminant animal. The fascinating differences between calves and mature ruminants create unique nutritional needs for pre-weaned calves (Moran, 2005). Milk coagulation properties (MCP) are an important aspect in assessing cheese-making ability. Several studies showed that favorable conditions of milk reac- tivity with rennet, curd formation rate, and curd strength, as well as curd synthesis, have a positive ef- fect on the entire cheese-making process and subse- quently on the ripening of cheese. Moreover, MCP were found to be heritable. Selecting for high casein content, milk acidity, and low somatic cell count might be an indirect way to improve MCP without reducing milk yield and quality traits (Cassandro et al., 2008). MCP is of great importance as it significantly influ- ence cheese yield and quality. Milk clotting enzymes are one of the most significant cheese making raw ma- terials impacting and regulating milk coagulation ac- tivity. Use of calf rennet as a milk clotting enzyme in the manufacturing of cheese has been predominant in the industry for years. Rennet is a complex of enzymes produced in any mammalian stomach. It contains many enzymes, including a proteolytic enzyme (protease) that coagulates the milk, causing it to sepa- rate into solids (curds) and liquid (whey) (Green et al., 1985). Short chain of free fatty acids produced by lipo- lytic enzymes contained in rennet extracted from a crude abomasum of mammals attribute to characteris- tic flavor of cheese (Moghaddam et al., 2008, Sengul et al., 2014). Composition, nitrogen fractions, α s1 - casein and β-casein degradation and certain textural properties of the cheese during ripening are associated with the type of coagulants used. (Sengul et al., 2014). Proteolytic degradation of casein can release active ISSN : 0974-9411 (Print), 2231-5209 (Online) | journals.ansfoundation.org This work is licensed under Attribution-Non Commercial 4.0 International (CC BY-NC 4.0). © 2018: Author (s). Publishing rights @ ANSF.