ISOLATION OF GLUTEN FROM WHEAT FLOUR AND ITS COLOR REACTION IN DIFFERENT QUALITATIVE TESTS Abstract: Gluten is isolated from wheat flour by washing it with water, dissolving the flour’s water soluble components and therefore separating gluten from it. The isolated gluten was then used in different qualitative colour reaction tests. These tests determine what amino acids are present in a protein, in this case gluten. Introduction: Proteins are large biological molecules that are made up of amino acids.
They serve as building blocks that form organic structures such as tendons, muscle, and cartilage. Enzymes – biological catalysts that allow important chemical reactions to occur in our body – are also made up of proteins. Thus, proteins play a fundamental role in the processes of life.  Protein purification is basically isolating a protein from complex mixtures. By isolating a protein, one will able to study its properties in detail and therefore be able to pinpoint which protein is responsible for a certain biological activity. Purified proteins also serve as valuable biochemical reagents. 2] Gluten – a protein composite most commonly found in wheat – possesses a unique property that allows it to be processed into bread and a variety of other foodstuffs. It is the ingredient responsible for adding texture and chewiness in baked goods. It can also serve as a protein supplement, which makes it useful for people who do not have access to other protein sources and/or are vegetarian.  Experimental: A. Materials Gluten Isolation: * 1 Cup Wheat Flour * Cheese Cloth * Iodine Solution * Water Qualitative Color Reaction Tests: * Isolated Gluten * 2. 5 M, 3 M,& 6 M NaOH * 10% & 20% NaOH Conc. NaOH solution * 5% NaNO2 * 10% Na2CO3 * 2% Nitroprusside solution * 0. 02% Naphthol solution * 1% Sulfanilic acid * 0. 1% Ninhydrin solution * Conc. HNO3 * Conc. H2SO4 * Hopkins-Cole reagent * Millon’s reagent * Red and blue litmus papers * 2% NaOBr * 0. 1 M CuSO4 * 5% (CH3COO)2 Pb * Beaker * Hot plate B. Procedure Gluten Isolation: – Add enough water to the flour to make thick dough. Wrap the dough in cheesecloth and place it under running water until all starch is removed. Washings are to be tested with the iodine solution; starch is confirmed to be removed when the test produces a negative result.
The pulp left in the cheesecloth is the isolated gluten. Qualitative Colour Reaction Tests: – Prepare intact gluten solution samples in separate test tubes by mixing 0. 5 g of gluten with 1mL of distilled H2O. These samples are to be mixed with various reagents depending on the test. The tests ran are as follows: Biruet, Ninhydrin, Xanthoproteic, Millon’s, Hopkins-Cole, Sakaguchi, Nitroprusside, and Amide. Note the colour of the resulting solution and check if the test gave a positive or negative result. Results and Discussion: Gluten Isolation: Gluten is separated from wheat flour by taking advantage of its insolubility in water. The other components of wheat flour – starch mainly, but also lipids, sugar and enzymes – are water-soluble and since gluten isn’t, it can be isolated by turning the flour into dough, wrapping it in cheesecloth, and placing it under running water. Qualitative Colour Reaction Tests: Biruet Test: This test checks for the presence of peptide bonds. A violet solution indicates a positive result. Gluten is
positive result for this test. Ninhydrin Test:
This test checks for the presence of amines including. -amino acids. A blue-purple solution indicates the presence of. -amino acids; a yellow-orange solution indicates the presence of proline, a secondary amine. Testing with gluten resulted in a blue-purple solution, which means. -amino acids are present in it. Xanthoproteic Test: This test checks for the presence of aromatic amino acids. A yellow solution indicates a positive result. Gluten is positive for this test. Millon’s Test This test checks for the presence of tyrosine. A red solution indicates a positive result.
Testing with gluten resulted in a flesh-coloured solution, so it is negative for this test. Hopkins-Cole Test This test checks for the presence of tryptophan. A violet ring in the boundaries of the solution indicates a positive result. Gluten is positive for this test. Sakaguchi Test: This test checks for the presence of arginine. A red colouration of the guanido group found specifically in arginine indicates a positive result. Gluten is negative for this test. Nitroprusside Test: This test checks for the presence of sulfur-containing amino acids.
A red colouration of the protein indicates a positive result. Gluten is positive for this test. Test for Amides: This test checks for the presence of Asparagine and Glutamine. Litmus paper turning/staying blue after being exposed to the gas of a heated gluten sample mixed with NaOH indicates a positive result. Gluten is positive for this test. References:  http:/www. answers. com/library/Sci%252DTech+Encyclopedia-cid-65383  http:/www-users. med. cornell. edu/~jawagne/proteins_&_purification. html  http:/www. wisegeek. com/what-is-gluten. htm