In a recent review published in the journal Dr foodResearchers from Spain and Portugal reviewed existing data on the potential of natural foods as coloring agents.
Synthetic and natural artificial food colors are commonly used in children’s items due to their high intensity, stability, consistency and cost-effectiveness. Their use, however, has been controversial, with studies showing a rapid improvement in attention deficit and hyperactivity disorder (ADHD) behavior in hyperactive children and an increase in the prevalence of ADHD in the general child population as a result of the use of artificial food colors. Additives such as sodium benzoate preservatives.
About the review
In the current review, researchers reviewed natural alternatives to artificial food colors. Web searches of the Science Scopus, ScienceDirect, and PubMed databases were conducted for relevant scientific articles, opinions, and proceedings from official databases published between 2008 and 2023.
Primary coloring compounds in natural foods
Anthocyanins, betalains, carotenoids and chlorophyll are plant chemicals with color properties. Anthocyanins range in color from blue to red, while betalains can be red-purple, yellow-orange, or pink. Carotenoids range in color from red to yellow and are very sensitive to destruction by oxygen, light, heat, acids and enzymes.
90% of the anthocyanins found in plants are cyanidin, delphinidin, pelargonidin, peonidin, malvidin and petunidin. Contains berries, red sweet potatoes and purple corn. However, temperature, light, metal ions, pH, oxygen, co-pigments and enzymes limit their stability. Betalains are the nitrogen-containing water-soluble pigments betacyanin and betaxanthin, which exhibit pink-purple and yellow-orange colors. They are found in flowers, fruits, roots and leaves. Red beetroot, amla, dragon fruit and cactus fruit are the most common culinary sources of betalain.
Carotenoids are lipophilic, yellow-red pigments present in fruits, seeds, flowers, and roots. They have antioxidant and color-attracting properties and act as precursors to plant hormones. About 50 distinct carotenoid pigments have been identified in popular human foods such as tomatoes, jackfruit, and persimmons.
Chlorophyll is the natural green color of many green vegetables and fruits, including alfalfa, spinach, nettles, and grasses. Several processes can degrade these pigments, causing a green to brown color change, most notably the replacement of magnesium ions by two hydrogen ions.
Natural food sources as possible alternatives to artificial food colors
Plant extracts, such as anthocyanins, carotenoids and chlorophyll, have been approved for use as colorants by the Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA). However, certain natural colors are restricted to certain products, such as butter pea extract, which has limited use in juices, beverages, desserts, and ice cream in the United States.
Natural red food coloring can be made using anthocyanins to replace artificial red dyes of various shades of red. Anthocyanin (E-163), a food color obtained from purple carrots, grapes, radish and red cabbage, is approved in the European Union. This pigment is also found in banana bracts, red onions, Hibiscus subdarifa L., red calyces, red cabbage, purple or black carrots, and berries.
Examining the anthocyanin content of blueberries, researchers found that microencapsulation with xanthan gum and carboxymethyl starch increased anthocyanin stability by 76% after one month of storage. They discovered optimal conditions for anthocyanin extraction using supercritical carbon dioxide-assisted extraction, resulting in 92% material recovery.
Researchers tested 30 to 50% maltodextrin as an encapsulation agent for anthocyanin extraction from blueberries; They obtained color parameters of L*: 54 and 53, a*: 37 and 38, and b*: 1.40 and 2.90, where L* indicates lightness, a* is the red (+)/green (−) coordinate, and b * is the yellow (+)/blue (−) coordinate, according to the CIELAB color model.
Blackberry (Rubus species) extracts have also been extensively tested. The researchers increased the shelf-life and color stability of spray-dried blackberry extract by adding ferulic acid and rutin, increasing its half-life from 151 days to 158 days and 193 days, respectively. Morus nigra L. is another blackberry cultivar with a high anthocyanin content, primarily cyanidin-3-O-glucosides and its derivatives.
chokeberry fruit (Aronia melanocarpa (Michx.) Britton) has a high anthocyanin content, most of which is cyanidin glucoside (98%). Researchers have made an anthocyanin-rich red-purple extract from its leaves Rhoeo spathacea (Swartz) Stearns.
In the European Union and the United States, synthetic blue dyes such as brilliant blue FCF and blue carmine/indigotine are approved for use as food dyes. Natural blue food dyes include anthocyanins in blue flowers and fruits such as butterfly pea petals and Centaurea cyanus L. Carotenoids from different natural sources can also be used as food colorants, increasing the quality and safety of food products.
Briefly, colored chemical compounds such as anthocyanins, betalains, carotenoids, chlorophyll, and phycocyanins are found in plants, fruits, flowers, and grains, making them potential sources of natural food colors. These natural sources, which may not have the same effects as manufactured ones, exhibit biological activity that may provide health benefits.
Several techniques have been investigated for the extraction of colored chemicals; However, the large diversity and heterogeneity of potential in the matrix due to different growing and cropping sites or periods makes it difficult to generate uniform results.
Furthermore, the inability of natural dyes to withstand light, pH, temperature and oxygen is a significant drawback. According to the authors, further research is needed to increase the availability and stability of naturally derived food coloring agents.