Info

(TCarbonates, hydroxides, < ammonium compounds, ((.and sulfites

Heating

Liquid mixtureof polymers and low molecular weight compounds

Cooling ( = 80°C) and filtering (100-^ mesh screen)

Adjustment of r pH and specific

▼ gravity Caramel a

FIGURE 9.5 Caramel preparation. (Adapted from Myers and Howell28 and Francis.3)

The color additive caramel is the dark brown liquid or solid resulting from carefully controlled heat treatment of the following food grade carbohydrates: dextrose, invert sugar, lactose, malt syrup, molasses, starch hydrolysates and fractions thereof, or sucrose.

1. Caramel Preparation

The caramelization process is an ancient one used to produce a tan-colored, flavorful sauce or candy. Caramel is prepared by heating a carbohydrate source (Figure 9.5), which may be sucrose or hydrolysates of corn or tapioca.3,28 The better sources must have high levels of glucose because caramelization occurs only via the monosac-charide. The heating process is continued until the desired temperature is reached, after which temperature is controlled by cooling, taking into account that caramel-ization is an exothermic process. Caramels may be produced in open or closed pans with pressures ranging from 0 to 5.3 kg/cm2. The heating induces several chemical reactions resulting in the generation of a complex mixture of polymeric substances, and of low-molecular-weight compounds in the range from 2000 to over 10,000. When caramel is obtained without the addition of any reactant, the product is called caramel syrup or burnt-sugar syrup. The first commercial caramel was produced more than 160 years ago by heating sucrose in an open pan. However, the caramel color demanded by the food industry requires high tinctoreal power, which is reached only by the addition of different reactants used during its preparation. In fact, the functional properties of caramel (e.g., color, stability, emulsifying properties) are determined by the chemical composition, which in turn is determined by the reac-tants.28,29

Caramels are very stable colorants and an empirical process has been developed to produce a colorant with the functional attributes that must be compatible with the specific application. Thus, the term compatibility refers to the stability of a caramel color in a given food, preventing phenomena such as flocculation, haze formation, or precipitation. The undesirable effects are associated with colloidal interactions by charged molecules. In this respect, the main compatibility characteristic of caramel is its ionic charge; that is, the precipitation phenomenon may be produced by the interaction of oppositely charged molecules.28 Four classes of caramels are recognized: burnt sugar, caustic, ammonia, and ammonium sulfite. The first is used mainly as a flavoring additive, whereas the other three classes are regarded as coloring agents (Table 9.4).2830 Ammonia caramels are the most common coloring agents in industry and are used in foods and drinks. However, ammonia caramels contain 4(5)-methylimidazole (4-MeI), which is neurotoxic.31

During caramel preparation a complex mixture of compounds is produced; thus, the complete characterization of caramel is a difficult task. Additionally, the color of caramel results from a large number of chromophores and the hue index and the tinctoreal power have been used to characterize a caramel formulation:3

where

A510 and A610 = the absorbances at 510 and 610 nm, respectively.

A560 = the absorbance at 560 nm c = concentration (g/L) b = cell thickness (cm)

The tinctoreal power is the most essential property of caramels.

2. Caramels as Food Additives

Caramel imparts color and has important functional properties: stabilizes colloidal systems and prevents the haze formation of beers; has emulsifying properties, facilitating the dispersion of water-insoluble materials; retards the flavor changes and preserves the shelf life of beverages exposed to light. Some caramel preparations have foaming properties, which is desirable in products such as root beer.27 These interesting characteristics have contributed to the wide use of caramel colorant by the food industry and its regulation has been restricted only by good manufacturing practices (GMP) (Tables 9.5 and 9.6).24 The FDA permits the use of caramel color in foods in general.25,26

Caramel color is water-soluble but insoluble in most organic solvents. Commercial preparations vary from 50 to 70% total solids and have a range of pH values. Over 80% of the caramel produced in the United States is used to color soft drinks,

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