Condensation, caramel

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 preferred source of milk solids for making toffee and caramel products remains sweetened condensed milk. This was one of the earliest ways of producing a stable product from milk. Both full cream and skimmed milk forms are used. The advantage of skimmed sweetened condensed milk is that the milk fat can be replaced with vegetable fat if so required. Products made from sweetened condensed milk are... 

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]. 

Decolorizing Power. — Dissolve 50 gm. of caramel (sugar coloring burnt sugar) in 50 cc. of water, add 100 cc. of 85 per cent alcohol, dilute the whole to 1 liter, allow to stand for several days, and then filter. Dilute 5 cc. of this caramel solution with 50 cc. of water, add 1 gm. of animal charcoal, boil the mixture ten minutes under a reflux condenser, and then filter. The filtrate should be perfectly colorless. 

With alkaline degradation, the formation of 1,2-enols is also the initial step. This reaction in turn can produce three-carbon compounds which yield a series of intramolecular reactions involving condensation and polymerization. Both acidic and alkaline caramelization produce numerous volatile and nonvolatile compounds that significantly contribute to aroma, taste, and color. 

Another predominant furan, namely furfural, is described as sweet and bread-like caramellic. This furan can interact with hydrogen sulfide of juice to produce thiofurfural, a compound with a skunky odor (35). Furfural has an important role in the monitoring of citrus juice quality (36), and has an especially significant relationship to browning (34). The main source of furfural in aged citrus products is by oxidative degradation of ascorbic acid. Furans, such as deoxyfuroin, furoin and furil are probably formed by self-condensation of furfural (37). 

The polymeric material from the plain caramel is generated from the condensation reactions of the aldehydes and ketones formed by heating the sugar with bases or acids. The ammonia caramel is formed in a Maillard type reaction [2] where carbonyl compounds react with amino groups or ammonia. This type of compound will be further presented in Sections 11.2 and 11.3. Sulfite caramel is also a Maillard type polymer. However, as hydrogen sulfites form stable adducts with aldehydes and ketones, the sulfite caramels include in their structure sulfite groups. 

Maltol naturally occurs in many foods, e.g. baked goods, cocoa, chocolate, coffee, caramel, malt, condensed milk, cereals, soy sauce, and beer ]10, 20, 21 ]. It is formed when carbohydrates are heated (Fig. 3.61). It is a white, crystalline powder with a caramel-like odour and a threshold of 35 ppm in water at 20°C ]21 ]. 

Caramels and toffees contain basic ingredients like saccharose, corn syrup and fat. Milk (mostly condensed milk), gelatine, fondant mass, emulsifier, sorbitol, flavouring, fruit pulp, cocoa, coffee etc. are additional ingredients. Caramels compared to high boilings have higher water content (4-8%) which results in a plastic consistency in the mouth. 

When sucrose is heated above its point of fusion it becomes coloured and ends by becoming transformed into a brown mass, caramel. Glucose also yields a like product. Caramel is evidently a carbohydrate of high molecular weight and a condensation product of sucrose or glucose. From cryoscopic determinations and analysis of its barium compound its formula has been given as Ci26Hx8808o. 

C7H10O3, Mx 142.15, has been identified in, e.g., coffee and melon. The tautomer mixture is a clear slightly yellowish liquid, bpQ02 tpa 82-83 °C, elf 1.137, nf 1.511 with sweet, caramel, fruity, bread-like odor. One commercially applied synthesis is the condensation of 2-pentene nitrile with ethyl lactate followed by oxidation of the intermediate 4-cyano-5-ethyl-2-methyldihydro-3(2/f)-furanone with monoperoxysulfate [189]. 

The sterilization of unsweetened condensed milk is a much harder problem than the sterilization of sweetened condensed milk. Also the danger of coagulation and caramelization during sterilization is much greater. 

It involves the heat-induced decomposition of sugars, normally monosaccharides. They undergo initial enolization and progress to subsequent complex reactions, such as dehydration, dicarboxylic cleaving, and aldol condensation [11]. Caramelization products vary in chemical and physical properties and in their constituents depending on the temperature, the pH, and the duration of heating [12,13]. 

The furanones and pyranones are oxygen-containing heterocyclic compounds associated with both caramelized and Maillard flavors [57]. The odor characters most common to this group of compounds would be caramel-like, sweet, fruity, butterscotch, nutty, or burnt. They predominate both in proportion and absolute amount in condensates of carbohydrates that are subjected to browning reactions [47]. 

The compounds formed in fructose syrup of pH 8-10 heated for 3h are listed in Table 4.12. The cyclopentenolones are typical caramel-like aroma substances. The formation of 2-hydroxy-3-methyl-2-cyclopenten-l-one as an example is shown in Formula 4.46. The compound l,3,5-trideoxy-2,5-hexulose is formed as an intermediate via the aldol condensation... 

The mutual condensation of some degradation products of sugars yields important alicychc substances called cyclopentenolones, which are characterised by a caramel flavour similar to maltol, and other secondary reaction products of sugars. For example, condensation of hydroxyacetone with lactic aldehyde yields the basic member of the homologous series 2-hydroxy-3-methylcyclopent-... 

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