Global Color Quality of Beverages Utilizing Caramel Color - ACS

Chapter 18

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Global Color Quality of Beverages Utilizing Caramel Color 1

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Hilary A. Sepe , Owen D. Parker , Alexander R. Nixon , and William E. Kamuf 2

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FB3 Development, LLC, 624 East Market Street, Louisville, KY 40202 D. D. Williamson Company, Inc., 100 South Spring Street, Louisville, KY 40206 2

Caramel color, from the palest yellow to the deepest brown, has a simple job to do - create visual appeal. Caramel, accounts for more than 90% by weight of all the colors, and is produced by the controlled heat treatment of carbohydrates. Over 70% of world caramel color consumption is in soft drinks, where liquid caramel colors are almost exclusively used. High demand for caramel color in the soft drink industry lead to trials of alternative applications for caramel, primarily alcoholic and non-alcoholic beverages, such as blended whiskey, beer, and fruit juices. Combining natural and caramel colors allows for the creation of vivid beverages, such as elderberry juice concentrates that resemble grape juice and red soft drinks that develop depth as you view them. The flexibility of caramel allows for the creation of a wide variety of beverages that cater to all the senses of the consumer.

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© 2008 American Chemical Society

Culver and Wrolstad; Color Quality of Fresh and Processed Foods ACS Symposium Series; American Chemical Society: Washington, DC, 2008.


227 As members of the food industry know, the color of foods and beverages is of the utmost importance. Since color is often the only characteristic consumers can easily evaluate before making a purchase, they rely heavily on the color to be an indicator of appeal, quality, flavor, and consistency. Food producers are very aware of this mindset and know how important it is for a product to look just right. For this reason, a wide variety of approved food colors are added to foods and beverages. Addition of color can help to make up for color lost in processing, add consumer appeal to a "colorless" product, or help the color of the product match the flavor. If a grape-flavored beverage appeared orange, many consumers would be unsure of the product. Their senses would be confused as what they taste would be nothing like they anticipate from its appearance. Colors added to food products can help protect light sensitive components, provide consistency to the product, so that it appears the same no matter where in the world it is purchased, and can help to add color where a matured product doesn't gain enough. When a blended whiskey has "aged" fully, it is removed from a barrel and bottled. If the beverage hasn't gained enough color from the wooden barrel during the aging process, caramel color may be added to help provide a product that is more consistent with other batches of whiskey.

Food Color Consumption Dr. Fergus Clydesdale from the University of Massachusetts, USA aptly stated the importance of color in food products. He indicates that taste thresholds, sweetness perception, food preference, pleasantness and acceptability are all greatly influenced by the visual aspects, particularly the color, of a food (7). Due to the significance of color, it is important to understand the opportunities and challenges that colors pose during their incorporation into products. Generally producers struggle with determining what color a consumer would expect the product to be and finding a colorant that will provide the necessary hue while easily functioning as a component in the production system. Suppliers, on the other hand, are challenged by the fact that quite often, color is one of the last parameters considered in the research and development process. This poses an extreme challenge as replacing the color is not always a straightforward process. Annual consumption of caramel color exceeds 200,000 tons on an annual basis and accounts for more than 80% (by weight) of all colorants added to the foods we eat and drink. It is estimated that every day over 1 billion servings of caramel color are consumed world-wide. Caramel color is an important component in many products. Major uses include pet foods, baked goods, sauces, soups, and seasonings. However, the majority of caramel color is used in the beverage industry (Figure 1).



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Figure 1. Global uses of caramel color, by weight.

Browning Reactions Caramel color is a dark-brown to black liquid or solid having an odor of burnt sugar and a pleasant, somewhat bitter taste. It is totally miscible with water and contains colloidal aggregates that account for most of its coloring properties, and its characteristic behavior toward acids, electrolytes and tannins. There are two types of caramelization reactions in food products; enzymatic browning, illustrated when damaged or cut fruit darkens at the exposed surface (Figure 2), and non-enzymatic browning which occurs when food products such as coffee beans, meat, bread or sugars are heated (Figure 3X2,3). Non-enzymatic browning in foods proceeds in several ways with two of the most important being 1) the well-known Maillard reaction in which sugars, aldehydes and ketones, react with naturally occurring nitrogen containing compounds such as amines and proteins, to form brown pigments known as melanins and 2) caramelization reactions in which sugars are heated in the absence of nitrogen containing compounds. In the latter reaction the sugars initially undergo dehydration and then condensation or polymerization into complex molecules of varying molecular weight. Lightly colored, pleasant tasting caramel flavors are produced in the initial stages but as the reaction continues more high-molecular-weight color bodies are produced and the flavor characteristics become more bitter.



Figure 2. Unstable Quinones proceed to Melanin, producing brown color on cut or damaged surfaces of fruits during enzymatic browning.

Figure 3. The Maillard reaction is the most closely related to the reaction which produces caramel color.


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Caramel Color Chemistry Caramel color first gained commercial importance as an additive in brewery products-porter, stout, dark beers and ales and as a colorant for brandy. In 1858, the first known published technical study of caramel color was authored by the French chemist M. A. Gelis (4, 5). Gelis' work indicated that caramelized sucrose contained three main products; a dehydration product, Caramelan C i 2 H 0 , and two polymers, Caramelen C36H50O25 and Caramelin C H 2 O i . Greenshields indicated that it is common for both Maillard and caramelization reactions to give aldehydes and dicarbonyl compounds but the former type incorporates nitrogen containing components (6). For this case Hodge and Greenshields grouped the reaction mechanisms as follows (7): 1 8


96

1.

2.

3.

10

9

5

Starting reactions a. sugar-amino condensation b. Amadori or Heyns rearrangement Degradative reactions causing the formation of colorless or yellow products with strong ultraviolet absorbance and the release of carbon dioxide a. Sugar dehydration b. Ring splitting (Strecker degradation). Polymerizing or condensing reactions forming the strongly colored components of relatively high molecular weight a. Aldol condensations b. Aldehyde/amino polymerization and formation of hetero cyclic nitrogen compounds.

Production Standards for Caramel Color Caramel color is prepared by the controlled heat treatment of carbohydrates. The carbohydrate raw materials are commercially available foodgrade nutritive sweeteners which are the monomers, glucose and fructose, and/or polymers thereof (e.g., glucose syrups, sucrose and/or invert sugar, and dextrose). To promote caramelization, food grade acids, alkalis and salts may be employed in amounts consistent with Good Manufacturing Practices (GMP) (*). The ammonium compounds that are employed are ammonium hydroxide, carbonate, bicarbonate, phosphate, sulfate, sulfite and bisulfite. The sulfite compounds are sumptuous acid, and potassium, sodium and ammonium sulfites and bisulphates. The compounds that can be used for all four types or caramel



231 color are sulfuric and citric acid, and sodium, potassium and calcium hydroxide. Food grade polyglycerol esters of fatty acids may be used as processing aids (antifoam) in amounts not greater than that required to produce the intended effect. There are four types of caramel color which are of commercial importance and which have distinctive applications in foods and beverages. Each type of caramel color has specific functional properties which ensure compatibility with a product and eliminate undesirable effects such as haze, flocculation and separation. The four types of caramel color are Class I (also known as Plain or Spirit caramel), Class II (Caustic Sulfite caramel), Class III (Ammonia or Beer caramel), and Class IV (known as SulfiteAmmonia, Soft Drink, or Acid-Proof caramel).

Caramel Standards Caramel colors have been used for so long and in such a wide variety of food products that consumers tend to think of them as a single substance when in reality they are a family of similar materials with slightly differing properties. There are, in fact, four distinct types of caramel color to satisfy the requirements of differing food and beverage systems. When the FAO/WHO Joint Expert Committee on Food Additives (JECFA) first examined caramel colors in 1919, they were thought to be a large number of ill-defined and complex products for which no adequate specifications existed. All that was known at that time was that they were formed from various carbohydrates when heated with a range of acids, bases and salts. In addition, an interim report by the United Kingdom Food Additives and Contaminants Committee on the Review of Coloring Matter in Food Regulation 1973, published in 1979, reported caramels to be a multiplicity of ill-defined products geared to meet the special needs of particular users" (9, 10, 11) Many studies of caramel color were undertaken thereafter with the largest and most comprehensive being initiated by the International Technical Caramel Association (ITCA). ITCA is the industry group composed of major users and manufacturers throughout the world formed to sponsor studies to further assure consumers and government agencies of the safety and suitability of caramel color ah a food and beverage colorant. ITCA commissioned the Ontario Research Foundation (ORF) of Mississauga, Ontario, Canada to do characterization work on caramel color to prove its homogeneity. The project began in November 1979 and was completed in May 1985. The main objective of the program was to develop an analytical procedure for the characterization of caramel color that was quantitative, reproducible and comprehensive. Caramel color was separated into size fractions using ultra filtration, which were in turn resolved into subtractions by techniques based M


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on charge, polarity, solubility and functional groups. The subtractions were then profiled using chromatographic procedures along with other physical and chemical techniques. These studies defined the four distinct types of caramel color and showed that, while each of the four types gave differing chemical profiles, the profiles of colors varying in color intensity within a type were essentially the same. This data was submitted to JECFA and other interested regulatory agencies throughout the world in June 1987 (72).

Caramel Color Classification At this time, ITCA also submitted the proposed specifications and classification scheme which were based on the ORF database and on consultations with regulatory agencies and industry groups worldwide, including the European Technical Caramel Association, the British Caramel Manufacturers Association, the Canadian Caramel Association and the Japanese Caramel Industrial Association. The specifications and classification which are under review by JECFA and have been accepted as tentative by the European Economic Community (EEC) are described below (75). Class I caramel colors can be produced from a variety of carbohydrate sources including glucose and sucrose. Recent research has led to Class I caramels from apple, onion and garlic sources as well as the development of Organic caramel color for use in Organic foods and beverages. Ammonium and sulfite compounds cannot be used as reactants for Class I caramel colors. Class I caramels possess a slightly negative colloidal charge. They have a high Hue Index, indicating that they impart a yellow color to products and are stable in solutions containing up to 70% alcohol. Additionally, Class I's are known to contain high levels of fiirfuryl and furfural alcohol, which can bring out important flavors when incorporated into foods and beverages. For this reason, Class I caramel colors are widely used in alcoholic beverages and coffee products. For the production of Class II caramel colors, sulfite compounds must be used and ammonium compounds cannot be used as reactants for Class II caramel color. These colors have a negative colloidal charge and are stable in alcohol up to 70%. These properties give Class II's a unique property; stability in high proof alcohols containing tannins, such as Cognac. Like charges on tannins and Class II caramel colors will repel, helping to keep the product in solution. This characteristic is also advantageous in other high proof spirits containing vegetable extracts. Ammonium compounds must be used and sulfite compounds cannot be used as reactants for Class III caramel color production. Class III caramel colors have a positive colloidal charge, making them stable in beers which contain positively charged proteins. The same principle of like charges repelling one another



233 applies with Class III caramel colors and beer. These caramels impart a redbrown to yellow-brown to products due to their Hue Index. Also, Class Ill's help to maintain foaming properties, making them the appropriate choice for malt based beverages such as malta and beers. Class IV caramel colors must be produced using both ammonium and sulfite compounds as reactants. Class IV caramel color accounts for over 70% of all caramel color and will provide color which can vary from red-brown to gray-brown in food products. These caramels have foaming properties which are beneficial in root beer and cola-type beverages. Class IV caramels have a negative colloidal charge and are the most versatile caramel colors as they have good alcohol, acid, and salt stability. Additionally, with the increase in popularity of diet colas, double strength Class IV caramel colors were developed. These products have comparable color intensity, yet contain less residual sugars. This helps to insure that the caloric content of these diet beverages is kept low.

Consistency of Color One challenge faced by food ingredient suppliers is to provide consistent food color and insure product quality around the world when so many different raw materials and manufacturing facilities are utilized. Quality control becomes a very important aspect for these suppliers and insuring that test methodologies are standardized across locations can play a large role in the quality of product manufactured. When producing a color additive, insuring consistent color is of the utmost importance. Color intensity is compared to standardized color references and measured using a documented (Food Chemicals Codex) method using a spectrophotometer. Of additional importance is product pH. Measuring the acidity or alkalinity of a product and insuring that a consistent pH is maintained helps the customer be sure that caramel color will act in the same fashion every time it is formulated into that product. Hue index (HI) is another useful tool to assist with color determination in a final product. The HI is calculated as

.

(Absorbance)^

log-

,.

—xlO

(1)

{Absorbance)™™ and indicates varying degrees of redness in a finished product. A low HI indicates a more brown product, whereas a higher HI indicates a more yellow product. For example, a chocolate of coffee liquor would have a lower HI than beer. Different classes of caramel color will provide a different HI to a final product (Figures 4 & 5) (14).


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Hue Index Calculated Value Descripton

Class I

Class II

Class HI

Class IV

> 7.0-6.3

5 . 5 - < 4.5

6.3-5.0

5 . 5 - < 4.5

Pale to

Amber to

Golden

Reddish

bright

dark brown

yellow to

brown to


yellow

reddish

dark

brown

brown

Figure 4. Hue Index of Different Classes of Caramel Color

Another important characteristic of caramel color is how it functions over the entire spectrum of visible light. While most other colors will have a maximum absorbance (^ ) and "peak" somewhere between 400 and 700 nm, caramel color does not have such a peak. The absorbance values of each class of caramel color vary as the product is scanned across the wavelengths, yet the shape of the curve will be similar for all classes (Figure 5). This is an important characteristic of caramel color which provides a quick indication of the sample having been blended with a different class of caramel color or adulterated by other materials, such as synthetic food colors. max

i—i—R—I—I—R

HI =4.4 V

Global Color Quality of Beverages Utilizing Caramel Color - ACS

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