Browning, non-enzymic

Ionizing radiations have been shown to increase the tendency for non-enzymic browning to occur in milk and also in a lactose-casein model system. Fluorescent compounds were formed, but no furans could be detected. Exclusion of carbonyl compounds prevented browning, but some coloration appeared in the absence of free amino groups.184... 

Since the non-enzymic browning of fruits and other foods is usually undesirable, much effort has been directed toward preventing the reactions which cause it. Such methods of inhibition can be classified under two headings firstly, imposition of unfavorable conditions and, secondly, addition of inhibitors. 

Saunders et al (13) reinvestigated the role of buffer salts in the non-enzymic browning, which term is also in use for the Maillard reaction. He used spectrophotometric measurement of the browning, the evolution of carbon dioxide (resulting from the Strecker degradation), and the change in the pH of the medium as the analytical techniques. The authors confirmed the findings of Schwimmer and Reynolds. 

D. J. McWeeny, The role of carbohydrate in non-enzymic browning, in Molecular Structure and Function of Food Carbohydrate, G. G. Birch, and L. F. Green (eds), Applied Science, London, 1973, 21-32. 

E. J. Mulders, Volatile components from the non-enzymic browning reaction of the cys-teine/cystine-ribose system, Z. Lebensm. Unters. Forsch, 1973, 152, 193-201. 

K.-G. Lee and T. Shibamoto, Toxicology and antioxidant activities of non-enzymic browning reaction products Review, Food Rev. Int., 2002, 18, 151-175. 

K. Eichner, The influence of water content on non-enzymic browning reactions in dehydrated food and model systems and the inhibition of fat oxidation by browning intermediates, in Water Relations of Foods, R.B. Duckworth (ed), Academic Press, London, 1975, 417 134. 

In processed foods, non-enzymic browning reaction is the major source of its desirable flavors. Flavors of the products of this reaction depend upon the molecular structure of nitrogenous compounds (amines, amino acids, peptides, glycopeptides, proteins,... 

Danehy, J.P. MailUard reactions non-enzymic browning in food systems with specific reference to the development of flavor. Adv. Food Res. 1986, 30, 77-138. 

Wedzicha, B.L. and McWeeny, D.J., Non-enzymic browning of ascorbic acid and their inhibition the production of 3-deoxy-4-sulphopentosulose in mixtures of ascorbic acid, glycine and bisulphite ion, J. Sci. Food Agric., 25, 577, 1974. 

A contamination with several C1-C4 alkylated pyrazines, cyclopentapyrazines and pyridines was discovered in the second extracts. These compounds are described in detail as primary products of the Maillard reaction, the non-enzymic browning reaction between carbohydrates and amino acids (e.g. Mulders, 1973 Chen et al., 1998). Therefore, the occurence of these specific pyrazines and pyridines suggested either contemporary degradation processes of carbohydrates with amino acids or ammonia within the deposit landfill or the emission of waste derived Maillard products generated already before deposition. 

Shaw P.E., Tatum J.H. and Berry R.E. (1968) Basic-catalyzed fructose degradation and its relation to non-enzymic browning. J Agric. Food Chem. 16, 979-82. 

Naturally Occurring Thiophens. - A review on the formation of heterocyclic compounds, including thiophen derivatives, by enzymic and non-enzymic browning in relation to food flavour has been published.Some thiophens have been found as trace constituents in the essential oil from Thymus capitatus " From steam-distilled hop oils, 3-(4-methylpent-3-enyl)thiophen... 

FIGURE 11.9 Reaction of aldose with amino compound to give an aldosylamine (R, = (CH0H)4CH20H). (From Hurst, D.T., Recent developments in the study of non-enzymic browning and its inhibition by snl-phur dioxide, B.F.M.I.R.A. Scientific and Technical Surveys, No. 75, Leatherhead, England, U.K., 1972. With permission.)... 

Ascorbic acid, dehydroascorbic acid, dlketogluconic acid, and glucose have been determined down to nanogram levels by h.p.l.c. on a hydrophilic, polyvinylalcohol gel, post-column derivatization with benzamldine, and fluorlmetric detection. The method was applied to ascorbic acid in fruit Juice.Ascorbic acid, its 2-sulphate, 2-phosphate, 2-0-methyl, and 6-bromo-6-deoxy derivatives, and a related non-enzymic browning product, 5-methyl-3,4-dihydroxy-... 

Initially, glucose was used as cryoprotectant however, colour problems were encountered due to the initiation of Maillard-type non-enzymic browning reactions. Sucrose was effective at the 8% level, but the resultant surimi was found to be too sweet. Currently, a combination of sucrose... 

The Maillard reaction (non-enzymic browning) is prevented by the addition of sulphur dioxide, either as the gas or as sulphite. Packaging that reduces the loss of SO2 due to oxidation or permeation (Davis et al., 1973) can decrease the need for this additive. 

The rate increasing influence of Cu(II) ions on the non-enzymic browning reaction between D-glucose and glycine (Maillard reaction) has been reinvestigated. At pH 3.00, melanoidin is formed which contains considerable amounts of Cu(II). In vitro experiments with model melanoidins and Cu(II) ions indicated that, in general, two protons are released for each ion bound. Melanoidins thus display the properties of acidic forms of anionic polymers. ... 

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