Reducing sugars roasting

Biedermann-Brem, S., Noti, A., Grob, K., Imhof, D., Bazzocco, D. and Pfeiferle, A. (2003). How much reducing sugar may potatoes contain to avoid excessive acrylamide formation during roasting and baking Eur. Food Res. Technol., 271, 3, 185-194. 

Many nitrogen- and sulfur-containing heterocycles have been identified in the aroma fractions of foods [214]. In roasted products (e.g., coffee) and heat-treated foods (e.g., baked bread or fried meat), these heterocycles are formed from reducing sugars and simple or sulfur-containing amino acids by means of Maillard reactions [215, 216]. Their odor threshold values are often extremely low and even minute amounts may significantly contribute to the aroma quality of many products [217, 218]. Therefore, N- and N,S-heterocyclic fragrance and flavor substances are produced in far smaller quantities than most of the products previously described. 

Pyrazines are mainly used in roasted, peanut and chocolate flavours. Alkyl pyrazines can be obtained by the reaction in an autoclave at high temperature (120-160 °C) of reducing sugars like rhamnose and ammonia. 

As for S-containing heterocycles, many N-containing heterocycles are also found in heat-treated foods as secondary flavours as a result of Maillard-type reactions between reducing sugars and amino acids. Pyrazines are N-heterocycles important contributors to the taste and aroma of roasted and toasted foods as well as vegetables and fermented foodstuffs. In cultures of Pseudomonas perolens ATCC 10757, amino acids such as valine, glycine and methionine were shown to... 

Sato et a2- (34) demonstrated that a variety of common meat additives, inclucnrTg cottonseed flour, nonfat dry milk, spray-dried whey, wheat germ, and textured soy flour, inhibited WOF in the meat system. These products may have exerted their inhibitory effect on WOF through the Maillard reaction, since most of them contain some reducing sugars. Pratt (40) reported soybeans and soy protein concentrate had an inhibitory effect upon development of WOF and was able to demonstrate that the active components are water soluble. Fractionation and analysis of the water-soluble fraction showed the antioxidant activity was due to the presence of isoflavones and hydroxylated cinnamic acids (40). This confirms earlier work showing that the flavonoTcis present in plant extracts inhibit oxidation in sliced roast beef (41 ). 

Most of the flavor compounds in fats and oils are produced by the reaction of oxygen with unsaturated fatty acids in triacylglycerols or polar lipids. On the other hand, some flavor compounds such as those present in cocoa butter, roasted sesame oil, or roasted peanut oil are generated by the interaction of reducing sugars with amino compounds during thermal processing. 

Watterson, J.J., Miller, K.B., Fuijanic, J.J., Stuart, D.A. Process of producing cacao flavor by roasting combination of amino acids and reducing sugars. US Patent, 1997, 5,676,993, assigned to Hershey Foods. 

The Middle Notes are based on reaction flavourings to impart specific complex roasted, meaty and smoky notes roasted chicken, boiled beef, smoked ham. They improve the overall taste with a general meaty background and a good mouthfeeling. Meaty middle notes are often based on the reaction of vitamin Bl, cystein and reducing sugars. Fat included in the reaction modifies the product into a specific animal direction chicken, beef, mutton, pork. 

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%. 

The effect of lipids in the Maillard reaction has been studied by many authors who cooked or roasted mixtures of amino acids and reducing sugars in various vegetable oils. The thermal oxidative degradation of lipids generates lower molecules, for instance aldehydes, that contribute to the formation of heterocyclic volatile compounds. 

Tressl et al. (1983) described the formation of aromatic substances in roasted coffee in relation to the levels of free amino acids and reducing sugars. They observed that over 99% of sucrose, glucose and fructose are degraded during roasting. 

Baltes W. and Knoch E. (1993) XIII. The formation of some uncommon N-heterocyclic compounds and furans after roasting of tryptophan with reducing sugars and sugar degradation products. Food Chem. 46, 343-9. 

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