Caramel, detection

The treatment of sucrose with anhydrous HF89 results in the formation of a complex mixture of pseudooligo- and poly-saccharides up to dp 14, which were detected by fast-atom-bombardment mass spectrometry (FABMS). Some of the smaller products were isolated and identified by comparison with the known compounds prepared86 88 a-D-Fru/-1,2 2,1 -p-D-Fru/j (1), either free or variously glucosylated, was a major product, and this is in accord with the known stability of the compound. The mechanism of formation of the products in the case of sucrose involves preliminary condensation of two fructose residues. The resultant dianhydride is then glucosylated by glucopyranosyl cation.89 The characterization of this type of compound was an important step because it has permitted an increased understanding of the chemical nature of caramels. 

The chemical composition of caramel color is not yet fully understood but some compounds identified in the low weight fraction are considered caramel markers. All caramel classes contain 5-hydroxymethyl)-2-furaldehyde (5-HMF). In caramel classes in and TV, 4-methyUmidazole (4-MeI) has been detected, while 2-acetyl-4(5)-tetrahydroxybutylimidazole (THI) was found only in class HI caramel colors. The analysis of five caramel III samples by SPE/HPLC-MS revealed concentrations between 28.3 and 46.8 iglg THI and 73.3 to 187.8 for 4-MeP (see Figure 5.2.3). 

Frischenschlager, S., Hellwig, E., and Peteuly, R, Detection and identification of caramel colors in some liquid foodstuffs, Dtsch. Lebensm. Rundsch., 78, 385, 1982. Hellwig, E. et al., Detection and identification of caramel by gel-permeation chromatography, Dtsch. Lebensm. Rundsch, 77, 165, 1981. 

Optimise and validate methodology for extraction and detection of Class III and IV caramels in foods. 

Numerous CE separations have been published for synthetic colours, sweeteners and preservatives (Frazier et al., 2000a Sadecka and Polonsky, 2000 Frazier et al., 2000b). A rapid CZE separation with diode array detection for six common synthetic food dyes in beverages, jellies and symps was described by Perez-Urquiza and Beltran (2000). Kuo et al. (1998) separated eight colours within 10 minutes using a pH 9.5 borax-NaOH buffer containing 5 mM /3-cyclodextrin. This latter method was suitable for separation of synthetic food colours in ice-cream bars and fmit soda drinks with very limited sample preparation. However the procedure was not validated for quantitative analysis. A review of natural colours and pigments analysis was made by Watanabe and Terabe (2000). Da Costa et al. (2000) reviewed the analysis of anthocyanin colours by CE and HPLC but concluded that the latter technique is more robust and applicable to complex sample types. Caramel type IV in soft drinks was identified and quantified by CE (Royle et al., 1998). 

Food So far only a handful of studies have investigated the presence of OPFRs in food samples. In a market basket study performed by the US FDA [87], most of the OPFRs (EHDPP, TCEP, TC/PP, TnBP, TPP, TCP) were found only at the ng/g level. More than 91% of the results were below the quantification limit in most t3q>es of samples. Higher detection frequencies were observed for TPP in margarine and caramels (mean 45 ng/g). 

Twenty-nine odour-active compounds were detected by using aroma extract dilution analysis (AEDA) [60]. The results of AEDA together with GC-MS analysis showed ethyl 2-methylbutanoate (described as fruity flavour), followed by methyl 2-methylbutanoate and 3-methylbutanoate (fruity, apple-like), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (sweet, pineapple-like, caramel-like), d-decalactone (sweet, coconut-like), l-( ,Z)-3,5-undecatriene (fresh, pineapple-like), and a unknown compound (fruity, pineapple-like) as the most odour-active compounds. 

This difference in kinetics was exploited to develop a procedure to determine free and reversibly bound sulfite in food. The mobile phase consisted of an aqueous solution of 0.05 M tetra-butylammonium hydroxide adjusted to the desired pH by the addition of glacial acetic acid (34). Fluorimetric detection is also possible, because a reaction of the formaldehyde-bisulfite complex with 5-aminofluorescein gives a nonfluorescent product. The sulfite is measured indirectly by its suppresion of the fluorescence of the reagent (31). This method is applicable to the determination of S02 at > 10 ppm and is not applicable to dark-colored foods or ingredients where SO, is strongly bound, e.g., caramel color. This method does not detect naturally occurring sulfite. Sulfur dioxide is released by direct alkali extraction. 

In White Wines.—White wines may be coloured artificially with caramel or artificial organic dyes (substitutes for caramel, caramelin). The latter are detected as in red wines in this connection it should be borne in mind that the yellow colours usually added to wines do not consist of individual colouring matters but are mixtures of a yellow material with a brown, a red or, sometimes, a blue compound. 

Detection of Caramel.— Tliis is carried out as with wine (see p. 202). 

Addition (pg/L) Concentration in the beer sample (pg/L) Number of judges3 detecting a caramel-like odor note... 

Likewise, furfural (peak 16, 8.1 minutes) was observed in both microwave and conventionally baked cake, but at a significantly higher level in the latter. Methyl pyrazine (peak 15, 7.8 minutes), furan methanol (peak 17, 9.0 minutes), and acetyl furan (peak 22, 10.9 minutes), were present in the conventional cake samples as were two unidentified compounds (peaks 3 and 9, 3.3 and 5.0 minutes) observed to have buttery, caramel-like aromas. Several other minor peaks were also observed only in the conventional cake. It should be noted that a few nutty, brown, and potato type smells were detected in areas of the conventional cake chromatogram where no peaks were integrated. These aromas suggest the presence of other Maillard compounds in the extract at levels too low for instrumental detection. 

Analysis of the volatile compounds of tamarind revealed the presence of more than 80 compounds. Aromatic and furan derivatives were dominant. The major constituents were 2-phenyl acetaldehyde (25.4% of total volatiles), which has a fruity and honey-like odour, 2-furfural (20.7%), having a caramel-like flavour, followed by hexadecanoic acid (18.1%) and limonene, which has a citrus flavour. A list of the volatile compounds detected in tamarind is given in Table 20.5. 

Psilocybe cyanescens, a large species with an undulating caramel-colored cap, is the most potent psilocybian mushroom, detected anywhere. It fruits prolifically from fall through winter in the Pacific Northwest. 

Hewala II, ZoweU AM, Onsi SM. Detection and determination of interfering 5-hydroxymethylfurfural in the analysis of caramel-colored pharmaceutical syrups. J CUn Pharm Therapeut 1993 18 49-53. 

Furan-3,4-diol derivatives are often written in the monoenolic form which is believed to be the parent nucleus of several important compounds responsible for the flavorings of various foodstuff s. The 2(5)-methyl derivative (56) has been detected in both soy sauce140 and beef broth.141 Related compounds occur in coffee and onion. The chief member of the series, furaneol (57), has a fruity flavor when dilute, changing to caramel as the concentration increases.107 The substance isolated from the nonenzymatic browning" of... 

Cyclopentenolones with a planar vicinal enol-oxo configuration are known to be powerful aroma active substances with distinct caramel notes. By methylation of the enolic function, this flavour impression is changed drastically to a sweet, mildew, and mouldy odour in the case of 2,5-dimethyl-4-methoxy-3-[2H]-furanone (2). This so-called mesifurane as well as pineapple ketone (1) were stereodifferentiated with modified cyclodextrin [103], Although (1) and (2) can be stereoanalyzed without any racemization, both compounds were detected in strawberries, pineapples, grapes and wines as racemates (Fig. 6.43). 

Omission of furaneol (no. 1 in Table 6.41) led to a very significant aroma defect which was perceived by all six members of the panel. The model smelt green and fruity. When (Z)-3-hexenal (no. 2) was missing, the caramel-like/sweetish note of furaneol predominated ]75]. In contrast, a lack of odorants nos. 9-12 was only detected by one or two panellists, respectively, indicating a lower aroma impact of these substances. 

Detection of Caramel, and Some Aspects of the Analysis of Caramel. 234... 

These chemical reactions and tests for caramel are complemented by a group of physical methods based on size-exclusion chromatography. These methods may be applied for the detection of caramel in beverages, beer, and wine. Caramel may be detected in bread and in various slightly colored products from the sugar industry (raw sugar, molasses, sugar syrups, and the like). Spectral methods are most useful for these purposes. 

A great deal of work has been devoted to recognition of the structure of melanoidins. A wide variety of methods has been employed for this purpose. First, melanoidin shows a hyperfine structure in the e.s.r. spectrum and that means that stable free-radicals are present in caramel. Amino acids and ammonia were also detected in nondialyzable melanoidin after acid hydrol-ysis, indicating that amides are present in melanoidin. 

High performance liquid chromatography (HPLC) has, to date, failed to provide satisfactory methods for the separation of the 14 DFAs present in sucrose caramel. In 1999 an analytical method based on GC for the identification and quantification of DFAs in commercial sucrose caramel was reported [85]. The protocol has proven extremely useful over the years, allowing not only the proving of caramel authenticity, but also the detection of adulteration by fraudulent addition of partially... 

The authors observed that an exhaustive list of all the chemicals present in coffee flavor had not yet been compiled, but they believed they had identified the components that are present at the higher ratio of weight, and those which principally control the odor note. Most of the substances identified were well-known compounds present in other roasted products as well, for instance in caramel sugar, cocoa, baked bread and—partially—even in wood tar. However, some of the chemicals detected were new and, obviously, characteristic of roasted coffee. Traces of methyl mercaptan, which was already known at that time and which smells even worse, were also detected in coffee aroma. Commenting on this observation, Reichstein and Staudinger note that it is generally known that many popular raw materials and synthetic perfume compounds owe their characteristic note, which is extremely pleasant to the olfactory sense, to their content of small quantities in additives which carry a rather unpleasant odor in themselves but prove very attractive in thinned solutions and in admixture with other oils. The authors tried to reconstitute coffee aroma, and only by combining over 40 of the substances extracted from coffee... 

Common maize derivatives are any form of starch (modified, bleached, etc.), maltodextrins, dextrose, caramel color, fmctose com symp, glucose symp, sorbitol, maltitol, and mannitol. The DNA is usually detectable in starch but not the other derivatives listed. 

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