Caramel classes

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). 

To provide data on the composition and heterogeneity of caramels Class I and IV and to provide test results on concentrated colour and flavour properties. 

According to EU purity criteria, color intensity is defined as the absorbance of a 0.1% (w/v) solution of caramel color solids in water in a 1 cm cell at 610 nm. The color intensity must be 0.01 to 0.12 for class I (E 150a), 0.05 to 0.13 for class II (E 150b), 0.08 to 0.36 for class III (E 150c), and 0.10 to 0.60 for class IV (E 150d). Ammonia caramels show the highest tinctorial power and are most commonly used as food colorants. Class I has the weakest coloring properties and is mostly used as flavor. 

Coffey, J.S. et al., A liquid chromatographic method for the estimation of Class HI caramel added to foods. Food Chem., 58, 259, 1997. 

Coffey, J.S. and Castle, L., Analysis for caramel colour (Class III), Food Chem., 51, 413, 1994. 

Royle, L. et al., A new method for the identification and quantification of class IV caramels using capillary electrophoresis and its application to soft drinks, J. Sci. Food Agric., 76, 579, 1998. 

To develop a method capable of extracting Class III caramel from foods, and to apply it to the quantification of Class III caramel in a small range of foods by capillary electrophoresis. 

To develop a validated method for the quantitative analysis of Class IV caramels in soft drinks. 

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

There is a recent trend towards simultaneous CE separations of several classes of food additives. This has so far been applied to soft drinks and preserved fruits, but could also be used for other food products. An MEKC method was published (Lin et al., 2000) for simultaneous separation of intense sweeteners (dulcin, aspartame, saccharin and acesulfame K) and some preservatives (sorbic and benzoic acids, sodium dehydroacetate, methyl-, ethyl-, propyl- and isopropyl- p-hydroxybenzoates) in preserved fruits. Ion pair extraction and SPE cleanup were used prior to CE analysis. The average recovery of these various additives was 90% with good within-laboratory reproducibility of results. Another procedure was described by Frazier et al. (2000b) for separation of intense sweeteners, preservatives and colours as well as caffeine and caramel in soft drinks. Using the MEKC mode, separation was obtained in 15 min. The aqueous phase was 20 mM carbonate buffer at pH 9.5 and the micellar phase was 62 mM sodium dodecyl sulphate. A diode array detector was used for quantification in the range 190-600 nm, and limits of quantification of 0.01 mg/1 per analyte were reported. The authors observed that their procedure requires further validation for quantitative analysis. 

Pyrroles are found in the volatiles of most heated foods [29], although they have received less attention than some other classes of aroma volatiles. Some pyrroles may contribute desirable aromas, e.g. 2-acetylpyrrole has a caramel-like aroma, and pyrrole-2-carboxaldehyde is sweet and corn-like, but alkylpyrroles and ac-ylpyrroles have been reported to have unfavourable odours [22]. Many more volatile pyrroles have been found in coffee than in other foods [30], and they are common products of amino acid-sugar model systems. Pyrroles are closely related in structure to the furans, and they are probably formed in a related manner from the reaction of a 3-deoxyketose with ammonia or an amino compound followed by dehydration and ring closure (cf Scheme 12.2). 

By applying the concept of odour values (2j[) to this class of compounds only Furaneol and Maltol contribute to coffee flavor. Both constituents are known as important flavor compounds and are used as nature identical flavorings in many foods. Furaneol contributes a fragrant caramel note to coffee and is known as important compound in pinapple and strawberries. The consumption of Furaneol in the USA in these products is respectively 41,800 to 2,650 to 1,100 kg (per year) compared to 2,718 kg of synthesized Furaneol used in nature identical flavoring. Similar figures were presented for Maltol and other coffee compounds by Stofberg and Grundshober (8J. 

Coffee flavor is a complex mixture of compounds belonging to many classes in distinct concentration ratios. Flament (2 ) listed 1 7 typical constituents of coffee aroma with buttery, woody, green, earthy caramel, burnt, smoky, roasted and sulfury notes, aroma and flavor qualities. 

Clearly, Class III and IV caramels are close to melanoidins produced by the Maillard reaction, but detailed structures for the coloured components cannot be given for any of these commercial caramels. 

Primary usage of the four classes is in spirits and desserts, ice cream and liqueurs, beers and baked goods, and soft drinks, respectively. In the UK, Class III accounts for almost 70% of total caramel consumed, Classes IV and I contributing 25 and 5%, respectively. World-wide usage is very different, Class IV constituting 70%, Class III 28%, Class I 2%, and Class II1%. 

Determining Class III caramel in food products is more difficult. Semiquantitative results have been achieved with some food products by ion-pair reversed-phase HPLC.201... 

Aspartame (a-L-asparfyl-L-phenylalanine methyl ester) is widely used as an intense sweetener, particularly in diet soft drinks. In colas, Class IV caramel is the predominant ingredient, a typical concentration being 1400 ppm. Such a concentration has been shown to affect the stability of aspartame at the typical pH of 3.0-3.2.202 Thus, at 55 °C, about 90% of the aspartame in a simulated beverage (4 mM phosphate, pH 3.1) has been lost in 27 d by peptide hydrolysis, rearrangement, ester hydrolysis, and cyclisation to the diketopiperazine. The degradation of aspartame was not affected by 250 ppm caramel, but started at 700 ppm. 

R. Hardt and W. Baltes, The analysis of caramel colours. Part 1. Differentiation of the classes of caramel colours by Curie-point pyrolysis-capillary gas chromatography-mass spectrometry, Z Lebensm. Unters. Forsch., 1987, 185, 275-280. 

Four distinct classes of Caramel can be distinguished by the reactants used in their manufacture and by specific identification tests ... 

Class I (Plain Caramel, Caustic Caramel) Prepared by heating carbohydrates with or without acids or alkalis no ammonium or sulfite compounds are used. 

Identification of Classes The four classes of Caramel may be distinguished from each other by the following methods ... 

The WHO/FAO Joint Expert Committee on Food Additives - distinguishes three general kinds of caramel ( / caramel color plain, (2) caramel color, ammonia process, and (3) caramel color, ammonium sulfite process. Both the European Technical Caramel Association (EUTECA) and the International Technical Caramel Association (ITCA) have standardized the properties of four classes and ten types of caramels they are given in Table I. The content of heavy metals cannot exceed values reported in the footnote to that Table. 

Analytical Characteristics of All Classes, Sorts, Types, and Sub-groups of Caramel Colors ... 

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