The Art of Cheesemaking: <ul><li>No one knows who first made cheese, but the most popular story is that an Arab put milk into a bag made from a sheep’s stomach to take with him on a trip. </li></ul><ul><li>By the time he was ready for a drink, the rennet from the sheep’s stomach, along with the warmth and gentle agitation had turned his milk into a type of cheese. </li></ul>
The Art of Cheesemaking: <ul><li>Milk is separated and standardized to obtain the desired fat content for the cheese. Some factories also add or remove protein to obtain a desired protein level. It is then pasteurized and transferred to tanks where starter culture and a rennet enzyme is added. </li></ul><ul><li>Curdling (Coagulation) - is due to the enzymatic activity of Rennet (aka Rennin) , which was traditionally obtained from the stomach of unweaned calves. It reacts with the casein protein in the milk to convert it into curd, the main element of cheese . This curd also contains a large proportion of whey, a watery substance full of sugar. </li></ul><ul><li>Cutting - The whey is separated from the curd by cutting it. The finer the cuts, the larger the total surface of the curd become and therefore the more whey that can be released. </li></ul><ul><ul><li>For the softer types of cheese the curd is hardly cut at all. For the hard varieties it is first cut into large pieces and then gradually into smaller ones, expelling as much whey as possible. </li></ul></ul><ul><ul><li>Continue </li></ul></ul>
The Art of Cheesemaking: <ul><li>After Cutting …… </li></ul><ul><li>Cooking - After the cutting step the curd is cooked, using a jacket of heated water around the vat. This is done to expel moisture. </li></ul><ul><li>Draining - Once a fairly solid mass of curd is obtained, it is pressed to expel further whey. This either done in block forming towers (dry salt production) or collected in moulds and pressed further (brine salt production). Salt is added before this process in dry salt production while brine salt production sees the cheese being immersed in a brine solution after being in moulds. </li></ul><ul><li>Ripening - The cheese is left to ripen in a temperature controlled environment. This ripening period allows the various enzymes, acids and bacteria to spread throughout the cheese, developing each cheese's distinctive taste. </li></ul>
The Art of Biotech Cheesemaking: <ul><li>The use of Chymosin (genetically-engineered rennin or rennet) for cheese-making was the first commercial application of food biotech ( 1988 ). </li></ul><ul><ul><li>In the 1960s the Food and Agriculture Organization of the United Nations predicted a severe shortage of calf rennet . It was anticipated that an increased demand for meat would lead to more calves being reared to maturity, and hence less rennet would be available. Over the last 30 years several substitutes for calf rennet have been developed, allowing the supply of enzymes to keep pace with cheese production. </li></ul></ul><ul><li>The first Chymosins in the early 1980s were derived from genetically-modified microbes ( Escherichia coli, Kluyveromyces lactis and Aspergillus niger). Numerous groups have since followed their lead, using other microbes, so that chymosin has now been obtained from food yeasts . Today about 90% of the hard cheese is made using chymosin from genetically-modified microbes </li></ul><ul><li>Chymosin is identical to the enzyme obtained from animals . This can be used to produce better quality cheese than the fungal or other animal (non-calf) rennets. These bioengineered enzymes behave in exactly the same way as calf rennin, but their activity is more predictable and they have fewer impurities. Such enzymes have gained the support of vegetarian organizations and of some religious authorities. Chymosin obtained from recombinant organisms has been subjected to rigorous tests to ensure its purity. </li></ul>
How Chymosin is marketed to the public and those seeking “natural alternatives” “ Highly recommended by some of the best known cheesemakers this is a high quality rennet, originating from animal sources, but containing no animal products itself. A vegetable product with animal origins…” www.cheesmaking.com Food for thought : Chymosin (Chymostar) is a genetically engineered enzyme, produced by yeast cells.
Try Your Hand at Making Cheese with Chymosin: <ul><li>Add 0.5 ml of skim milk (@ RT) to a microfuge tube. </li></ul><ul><li>Add approximately 20 microliters of Chymosin (curdling enzyme) to the tube containing the milk. </li></ul><ul><li>Gently mix and warm the tube between your hands for about 5 minutes (this mimics the conditions in the stomach of a calf . . . the churning action of the stomach). </li></ul><ul><li>Check the tube every 1-2 minutes to check for curdling. </li></ul><ul><li>The final product should resemble Cottage Cheese (the next step would be to separate the curd from the whey) </li></ul>