Juice color enhancement

Rein, M.J. and Heinonen, M., Stability and enhancement of berry juice color, J. Agric. Food Chem., 52, 3106, 2004. 

The colors of muscadine grape juice and wine were enhanced by copigmentation with formonetin, biochanin A, and prunetin, the major isoflavonoids extracted from red clove leaves, at ratios of 1 2, 1 4, and 1 8. The 1 8 ratio representing the maximum amount of isoflavonoids used due to its limiting solubility yielded the maximum color enhancement when compared to standard solutions of anthocyanins, at 23 and 60°C. ... 

Talcott, S.T., Pelle, J.E., and Brenes, C.H., Red cloves isoflavonoids as anthocyanin color enhancing agents in muscadine wine and juice. Food Res. Int., 38, 1205, 2005. 

Since the synthesis of N-nitroso compounds is accomplished through reaction of secondary amines and nitrous acid, it was demonstrated that nitrosamines could be produced biochemically by the naturally acidic conditions in the stomach with ingestion of secondary amines (2). The nitrosating agent would be formed by the reaction of gastric juice with nitrite compounds that are widely used as food preservatives and for food color enhancement (2). Vitamin C was found to be a potent inhibitor of this reaction (I). 

Chlorogenic acid enhanced the colors of strawberry and chokeberry juices in concentrations higher than those of the anthocyanins present. However, the effects on purified pigments were lower, indicating the presence of other stabilizing compounds in the juices. ... 

Preservatives. Sulfur compounds, such as sulfur dioxide and sodium bisulfite, are used commercially to preserve the color of various food products, such as orange juice, dehydiated fruits and vegetables, such as apricots, carrots, peaches, pears, potatoes, and many odiers. Concentrated sulfur dioxide is used in wine-making to destroy certain bacteria. The color preservation of canned green beans and peas is enhanced by dipping the produce in a sulfite solution prior to canning. In 1986, some of these compounds and uses were put under closer regulation in the United States. 

In beverages, carrot pomace, or citrus waste will stabilize the natural color, improve the vitamin and fiber content, enhance the viscosity (mouthfeel) (Laufenberg et al., 1996), and enrich or adjust the cloudy appearance (Sreenath et al., 1995). The organoleptic and chemical properties offer a widespread use in healthy and functional drinks and selected fruit juices. 

Pre-fermentation processing enzymes have been used for a long time by the wine and juice industries (van Rensburg and Pretorius, 2000). The first commercial enzyme preparations used were pectinases, enzymes responsible for the breakdown of pectin. Conventional application of pectinases pre-fermentation can enhance juice yield by degrading polysaccharides (e.g., pectin) that interfere with juice extraction. These preparations also improve the extraction of color (red wines) and flavor molecules trapped in grape skins as well as reduce the potential for post-fermentation instabilities. Newer commercial preparations may also contain secondary activities such as the ability to degrade cellulose to further enhance cell wall breakdown. 

Some effervescent pop drinks are imitations of fruit juices and lemonade-type drinks, however, their sugar content is fully or partially replaced by artificial sweeteners and the natural essence of flavoring ingredients are replaced by artificial or artificially-enhanced essences. Coloring substances are usually added. 

Very few works dealing with the determination of these synthetic colorants in foods have been published. In 2012, Medeiros et al. developed a single-line flow injection system for the simultaneous determination of two pairs of synthetic colorants Tartrazine-Sunset Yellow and Brilliant Blue-Sunset Yellow in several food products (juice drinks, gelatines, and nutrient-enhanced sports drinks), without a previous separation step, by coupling FIA with multiple pulse amperometry (MPA) with a boron-doped electrode [42]. The influence of flow conditions on the MPA response was evaluated by varying the flow rate from 0.45 to 3.5 mL/min, obtaining a maximum electrical current at... 

Hydrogen peroxide, a strong oxidizing agent, may react with organic material and cause, aside from degradation of antioxidant components, an undesired loss of the product color. The synthesis of exopolysaccharides is another important metabolic trait, either for the viscosity of juices and purees or for nutritional properties (Di Cagno et al. 2008). In addition, the capacity of LAB to synthesize protopectinases, which may enhance the viscosity of the fruit matrices, may be an important characteristic for starters. 

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