Caramel preparation

Other compounds identified in caramels are di-D-fructose and poly(glycosyl) dianhydrides (DFAs). DFAs were found in caramels prepared from D-fructose, D-glucose, and sucrose. The analysis was done after derivatization as TMS (per-0-trimethylsilyl) derivatives or as TMS-oxime (per-O-trimethylsilyl oxime) by... 

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

To prepare caramel, com symp and the appropriate reactants are cooked at about 121°C for several hours or until the proper tinctorial power has been obtained. The product is then filtered and stored cool to minimise further caramelization. Often it is dmm- or spray-dried to produce free-flowing powders containing 5% or less moisture (61,62). 

Similar anomalous distributions are observed in other thermal product mixtures. A commercial soft caramel made by heating sucrose and 0.1% acetic acid to 160°C contained 18% of a mixture of di-D-fructose dianhydrides.94 fi-D-Fru/-1,2 2,1 - 3-D-Fru/(now assigned as a-D-Fru/-l,2 2,l -a-D-Fru/83), ot-D-Fru/-1,2 2,1 -p-D-Fru/(5), ot-D-Frup-1,2 2,l -0-D-Fnjp (4), ot-D-Fru/-l,2 2,1 - 3-D-Frup (1), and p-D-Fru/-l,2 2,3 - 3-D-Fru/ (2) were found in the ratio 4 12 1 6 2. The first three of these, constituting 68% of the mixture, are considered to be kinetic products. The authors commented on this, but did not offer any explanation. Notice, however, that the preparation of such commercial caramels commences with heating of an acidic aqueous solution of sucrose, which almost certainly results in hydrolysis. Hence, the final dianhydrides are probably derived from the reaction of fructose, rather than sucrose. 

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). 

The complexity of the mixtures made it impossible to define the chemical composition so the commercial preparations were divided into four groups (Table 8.2) on the basis of a series of sophisticated chemical assay procedures. Caramel colorants must be compatible with the food products in which they are used, which usually means the absence of flocculation and precipitation in the food. These undesirable effects result from charged macromolecular components of caramel which react with the food. Hence the net ionic charge of the caramel macromolecules at the pH of the intended food product is the prime determinant of compatibility. Caramel colorants are used in a variety of foods (Table 8.2) but over 80% of the caramel produced in the US is used to color soft drinks particularly colas and root beers. 

CeHgOs, Mr 128.13, was found in, e.g., fenugreek, coffee, sake, and flor-sherry. Its aroma characteristic changes from caramel-like at low concentrations to currylike at high concentrations. A method described for its preparation comprises condensation of ethyl propionate with diethyl oxalate and reaction of the intermediately formed diethyl oxalylpropionate with acetaldehyde. Acidic decarboxylation of the ethyl 4,5-dimethyl-2,3-dioxodihydrofuran-4-carboxylate gives the title compound [199]. 

Many Italian producers use refined beet sugar for sweetening, whereas in France mistelas (fortified grape must) is preferred. Caramel is an important constituent where color intensification is desired and is prepared carefully for that purpose (Goswell and Kunkee, 1977). In American vermouth, wine of higher natural acidity is used. 

Brandy is added to raise the alcohol content of vermouth to a specified limit. The base wine, brandy, spice extract, and sugar syrup are combined according to a proprietary formula appropriate for each type of vermouth. For Italian vermouths, extracts are prepared by soaking the herbs and spices (7-11 g/L) in highly rectified alcohol ( 85%). For a darker color, after flavoring, caramel may be added. In French vermouth, fewer herbs and spices are used. The spice mixture of (4-8 g/L) is typically infused for flavor development, to avoid the uptake of undesirable herbaceous flavors. 

This sequence was used to prepare the important flavouring compound Corylone which has, it is claimed, a sweet and powerful spicy-coffee-caramel odour , You may imagine how popular it is with food-additive chemists and this sequence provides a short process for its manufacture. 

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