Phosphate buffers, Maillard reaction

Since the basic amino group disappears in the Maillard reaction, the pH of an aqueous solution of the reactants will decrease. It is to be expected, therefore, that the initial pH of the solution, or the presence of a buffer, will have an important effect on the progress of the reaction. In an early investigation129 of the effect of pH on the reaction, individual solutions containing D-glucose and glycine were made in phosphate buffer solutions at pH 7.8, 7.9, 8.3, 8.7, and 9.2, respectively, and kept at 37°. The amino... 

Farmer, Mottram and Whitfield studied volatile compounds produced in Maillard reactions involving cysteine/ribose with and without an egg phospholipid upon autoclaving at 140 C for 1 hour. The pH was maintained at 5.7 with phosphate buffer. They found that Fur-SH was a major volatile component, and its generation was independent of the presence of phospholipid (10). 

The salt (buffer) type and concentration may also influence reaction rate. While buffers vary in their effect on the Maillard reaction, it is generally accepted that phosphate is the best catalyst [27], The effect of phosphate on reaction rate is pH dependent with it having the greatest catalytic effect at pHs between 5-7. Potman and van Wijk [27] found the Maillard reaction rate in a phosphate buffered model system increased from 10- to 15-fold compared to a phosphate free reaction system. 

These results indicate that 2-FEE was formed by the reaction of ethanol and FAL, which itself was formed by the hydrolysis of FAC during the storage of beer as shown in Fig. 6. This scheme is also supported by the experimental results on adding FAC and FAL to a phosphate buffer in the presence of 5% ethanol (11). FAL might be also have been formed by the Maillard reaction (15). FAC is thought to be produced by FAL and acetic add during the fermentation of beer, because of the formation of various volatile acetate compounds in beer. Another possibility that the direct interaction of FAC with ethanol leads to the formation of 2-FEE does not rule out. 

Maillard browning reactions were usually performed by refluxing 0.10 M aqueous phosphate, acetate, succinate or 2,2-bis(hydroxymediyl)-2,2 ,2 -nitrilotrie anol ( bis-tris ) buffer solutions containing various carbohydrates (0.10 M) and p-alanine (0.033 M) for a periods ranging up to 300 min. at... 

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