Browning final stage

In the final stage of the process this copper compound (1 part) is added to a solution of potassium ferricyanido (2 parts) and potassium hydroxide (0-4 part) in water (9 parts) this mixturo is allowed to stand till the red colour of tho copper compound disappears (24 hours). The green-brown residue is separated aud after drying, extracted with chloroform the di-phenyl-diacetyleue nitro-compound crystallises in yellow needles. 

In the final stages of the reaction, brown nitrogenous polymers and copolymers form. The chemical nature of the compounds concerned is little known. It has been shown1 that heating proteins and carbonyl-... 

The type of carbohydrates and proteins used and the conditions of the reaction have to be controlled to optimize functionality while minimizing excessive browning and formation of other undesirable products which can be obtained in the final stages of the Maillard reaction. Various researchers have examined the effects of type of protein and sugar or carbohydrate, amounts of reactants, and conditions of reaction on a range of functional properties of milk proteins (Chevalier et al., 2001a,b). 

Place 10 ml. of 1% starch solution (prepared as described above) in a boiling-tube, add 2 ml. of 1% sodium chloride solution and place the tube in a water-bath maintained at 38-40 . Place about 5 ml. of water in a series of test-tubes and to each add a few drops of 1% iodine solution. Now add 4 ml. of the diluted saliva solution to the starch solution, mix well and note the time. At intervals of about 30 seconds transfer 2 drops of the reacting mixture, by means of a dropping tube, to one of the test-tubes, mix and note the colour. As in the previous experiment, the colour, which is blue at first, changes to blue-violet, red-violet, red-brown, pale brown, and finally disappears at this stage the solution will reduce Fehling s solution. If the reaction proceeds too quickly for the colour changes to be observed, the saliva solution should be diluted. 

In countercurrent operation of several stages in series, feed enters This is of the same form as the Kremser-Brown equation for gas the first stage and final extract leaves it, and fresh solvent enters the... 

It is worth noting that Mauron7 calls the three stages Early, Advanced, and Final Maillard reactions, respectively. The way these reactions fit together is outlined in Scheme 1.1. The final products of nonenzymic browning are called melanoidins to distinguish them from the melanins produced by enzymic browning. Theoretically, the distinction is clear however, in practice, it is very difficult to classify the dark-brown products formed in foods, since they tend to be very complex mixtures and are chemically relatively intractable. 

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