Maillard reaction sample

The influence of the carrot variety on Maillard reaction Samples of six freeze-dried carrot varieties were equilibrated at room temperature to a water activity of 0.33 (J 7), corresponding to an average water content of 6.3 % (related to wet matter). Then the samples were heated to 55 °C for 30 h and the concentrations of Amadori compounds as well as the corresponding sensory changes were determined. The results are listed in Table IV. The amount of Amadori compounds formed by the heating process seems to be correlated... 

The authors thank Dr. Tae Yung Chung for his assistance in preparation of the Maillard reaction samples. 

Fluorescence increased significantly in carious samples compared with sound samples, especially at 370/440, indicative of the Maillard reaction. Figure 1 displays emission spectra of digests of sound and carious dentin from the same tooth. 

The degree of Maillard reaction was estimated as amount of brown color produced. Samples were extracted in buffer of pH 8.0, proteins were precipitated by TCA and absorbance was measured at 375 nm spectrophotometrically according to a method by Laser Reutersward and Johansson (unpublished). 

Table IV. Effect of Maillard reaction products (2-methylpyridine or 2,5-dimethylpyrazine) on the mutagenic activity of different model reaction mixtures (creatinine, D-glucose, amino acid in diethylene glycol-water 6 1, v/v) after 4 h of refluxing, 10-yl samples being directly withdrawn from the reaction mixtures and assayed with TA98 after S9 activation.

Pyrazines are the most widespread Maillard reaction products found in processed foods. The quantity of each pyrazine identified is greater in the samples extruded at 165°C than in those at 120°C. Extrusion conditions have been noted to favor the production of pyrazines at high temperatures (12), but as extrusion temperatures continue to increase, the rate of volatilization may become greater than the rate of production. 

Fluorescence characteristically develops during the intermediate stage of the Maillard reaction. For analytical purposes, colour has always been the method of choice, even though it is far from ideal. Fluorescence, partly because of its greater sensitivity, particularly in the presence of colour due to sources other than the Maillard reaction, has frequently been found useful, especially for biological samples. 

Quantification of the pyrazines was accomplished using an internal standard metlxxd. 2-methoaypyrazine was chosai as internal standard due to its similar physical properties (HW, solubility) to the pyrazines of interest and because methosypyrazines have never been reported to form as a result of the Maillard reaction. Ihe amounts of each pyrazine presoit in the sample were determined by the relationship ... 

The Maillard reaction between reducing carbohydrates and amines is among the most important flavor generating reactions in thermally processed foods (5). Thus, it might be expected that in foods treated with HHP, but at low temperatures, some of the typical aroma compounds might not be formed. Only two studies about the influence of HHP on the formation of volatiles in Maillard model systems are currently available (6, 7). Bristow and Isaacs (d) reported that at 100°C, the formation of volatiles from xylose/lysine was generally suppressed when HHP was applied. Hill et al. (7) confirmed this observation for a glucose/lysine system. However, it has to be pointed out that the samples analyzed were not reacted in a buffered system and, also, the reaction time of the pressure-treated and untreated sample were not identical. 

Cooking starch in the presence of amino acids may favour the occurrence of Maillard reactions, lowering the bioavailability of lysine in the diet. 13C CPMAS was used to follow the effect of Maillard reactions on the bioavailability of potato starch.124 A loss of crystallinity was found for the three samples studied starch, amylopectin, and amylose, being more marked for amylose. A similar study on chestnut starch indicated that Maillard reactions do not influence significantly its digestibility.125 NMR was used to characterize some Maillard reaction products extracted from model reactive mixtures such as starch-glucose-lysine 126 and lactose-lysine.127... 

Decaffeinated samples are clearly poorer in free amino acids than are the corresponding samples with caffeine, and occasionally contain less-attractive flavor compounds after roasting, as amino acids react easily with reducing carbohydrates in the Maillard reaction (Tressl, 1981). On the other hand, the same author has shown that decaffeination increases the level of reducing sugar content from 0.53 to 2.9%. 

A. Cardelle-Cobas, F. J. Moreno, N. Corzo, A. Olano, and M. Villamiel, Assessment of initial stages of Maillard reaction in dehydrated onion and garlie samples, J. Agric. Food Chem., 53 (2005) 9078—9082. 

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