Research on New Methods to Enhance and Stabilize Natural Colorants

2018 CLC/Monica Giusti - Research on New Methods to Enhance and Stabilize Natural Colorants

FDA approval of “fruit juice concentrates” as colorants, enables the use of plants rich in anthocyanins or other pigments, as long as processing methods meet certain parameters.

Food colorants have joined consumers’ growing demand for clean label and natural ingredients, particularly considering mainstream and social media’s outpouring of information, whether accurate or not, regarding adverse health effects from the consumption of synthetic colors. Colorants made from natural sources may have an added-value ability to provide health benefits, such as antioxidant potential, and can increase consumers’ perception of a product’s all-natural, clean label, simplified ingredient statement, noted M. Monica Giusti, Ph.D., Professor, Department of Food Science and Technology, The Ohio State University. Plus, some pigments from plant sources may even be classified as superfoods, added Giusti.

Although there is a wide variety of colorants exempt from certification by the FDA, as listed in 21CFR73, ensuring consistency, quality and stability are not necessarily easy tasks. Pigments can interact with the product’s matrix and change color; may not be stable under processing or storage conditions; may be affected by texture; and certain colorants are allowed for use in a limited number of applications.

Yet, abundant research of colorants from natural sources is in process. Opportunities exist for improved stability, as well as added health benefits, including potential use as antibacterials, antivirals and anti-inflammatories. Research is also being conducted in analytical, horticultural, bioavailability and processing areas.

Giusti’s research focuses mainly on the color enhancement and stability of anthocyanins. Currently, grape color extract and grape skin extract (enocianina) are the only anthocyanin-based colorant extracts approved for use in the U.S. However, the approved category of “fruit juice concentrates” and “vegetable juice concentrates” open an opportunity to utilize a wide variety of plants rich in anthocyanins or other pigments as sources of colors, as long as the processing conditions of the plants have followed typical processes for juice. This approval status leaves opportunity for expanding the applications of anthocyanins as food colors, as there are numerous sources in nature with this pigment, and fruit and vegetable juices are label-friendly to consumers.

“Anthocyanins are water soluble,” said Giusti. “The color is due to the main structure, a flavonoid, but you can have several [types of] sugars and acids attached [to this molecule]. In general, the bigger the molecule, the more stable it becomes and the more resistant it becomes to processing, storage and stresses. Pigments from vegetables usually have the larger pigment structures that last longer, while most fruit pigments degrade faster. However, there are some exceptions, such as grape, which is a fruit source but has the more complex chemical structure that is a little more stable. That’s why grape extracts are popular for applications.”

One approach Giusti has used to extend the life of the color is co-pigmentation, where a component with little or no coloration can be added to enhance and stabilize the pigments. For instance, her re-search team is investigating the use of soy products, as an innovative way to incorporate isoflavones—a functional, healthful component to the diet—while stabilizing the color. Additionally, Giusti is looking into the formation of pyranoanthocyanin pigments, pigments derived from anthocyanins and commonly found in wine, to explore their formation or addition to vegetable juices to enhance color stability.

Some of the blue color in plants is due to the presence of metals together with anthocyanins. So, the presence of certain metals in the matrices’ environment can allow for formation of those blue hues by anthocyanin-metal complexation, suggested Giusti. Natural sources of blue and green pigments allowed for use in foods are currently limited, and many desired colors are currently achieved through use of synthetic compounds. Increased under- standing of the pigment-metal complexation would allow us to provide natural alternatives for those synthetic colors.

Microencapsulation is another approach to achieving stability of anthocyanin-based pigments and could improve the distribution of pigments in a wider variety of matrices, such as those high in protein, which are susceptible to color loss or more hydrophobic matrices that could have poor dispersion. Work is being done on bioavailability and bioactivity, as well.

Consumer perception has increased demand for use of colorants from natural sources. Suppliers that commercialize pigments know a lot about those behaviors in different types of matrices, as well as stability in processing, noted Giusti. Further research can only expand the availability of pigments from natural sources and improve their stability.

“Natural Colorants: Challenges and Opportunities,” M. Mónica Giusti, Ph.D., Professor, Dept. Food Science and Technology, The Ohio State University, Columbus, Ohio,

This presentation was given at the 2018 Clean Label Conference. To download free presentations and the Post-conference summary of this event, go to