The glittering yellow of the Chanukah flames; the deep blue of the ocean; the crisp white of the clouds – each color is innately connected to the object it represents, so much so that shades of color are often named by the object with which they are most associated. Pick up a paint chip card at Home Depot and you will see colors called "Summer Sun", "Caribbean Blue", or "Autumn Wheat" and you will immediately make the correct association. Color permeates every aspect of our world. It defines mood in paintings and literature. It can even impact one’s disposition. Red is associated with energy and actually enhances human metabolism, while green, the most restful color for the human eye, promotes healing.
This same principle applies to foods. In fact, colors far outweigh flavors in the impression they make on consumers, especially when color is the prevailing quality that enables the customer to determine the initial quality of a food. Through learned experience, we are conditioned to associate color with quality and even with a food’s identity. In the grocery store, consumers are drawn to the brightest and deepest colored fruits and vegetables and make an immediate association between the vibrancy of the colors and the quality of the produce. Sometimes foods have their color enhanced to meet our expectations; for example, some ripe oranges are a mottled green but the skin is dyed orange to be more appealing. As our society has become more health conscious, food colorings have taken on new importance as health concerns regarding colorants abound.
Studies have demonstrated that color is often the deciding attribute when determining food perception. Taste panels have often misidentified soft drinks, yogurts and sherbets when the colors and flavors were intentionally mismatched. The majority of the testers also rated the quality of the product as "poor quality" when the color was changed. Many consumers recall a famous cola company’s short lived attempt to market "Crystal" cola in the 1990s. While the company assumed consumers would seek out soft drinks without caramel coloring because it would be perceived as healthier, the marketing experiment failed because our preconception was that cola drinks must be brown despite the identical taste.
Despite the high-tech methodology used to color foods, it is not a modern invention at all. Even the Talmud describes instances of coloring mustard with egg yolks.1 Unscrupulous food manufactures marketing poor quality and spoiled foods by artificially altering the color. Pickles were dyed green with toxic copper sulfate, candy with lead salts, and watered down milk was dyed yellow, all to mislead the consumer. Some of our earliest food laws were designed to protect the public from improperly colored food, including the federal Pure Food and Drug Act of 1906, which regulated dyes in food.
The Physics of Colors
Understanding food colorants requires a brief explanation on the physics of colors. Light is the area on the electromagnetic energy spectrum that corresponds with the section between 400 nanometers and 700 nanometers. Color is the light reflected back from a compound to the eye. When an object appears white, the entire light is reflected off the object, whereas when it appears black, all the light is absorbed and the eye perceives a lack of light. (This is why black cars are hotter when sitting in the sun.) However, many compounds absorb parts of the light spectrum and reflect other areas and are perceived as colors by the color receptors in the retina.
And now for some "tech talk"… The atomic structure of a given compound is what determines the light reflection and absorption, creating the perceived color. A trait that plays a large role in a compound’s color is the level of conjugation (consecutive multiple bonds). A double bond, which is made up of delocalized electrons, requires less energy to shift electrons to an "excited" state. When a compound has less conjugation, more energy is needed to "excite" the electrons.
This amount of energy affects the actual color because there is a range of energy levels in the various colors of the color spectrum. In the rainbow of colors, red has the least amount of energy, while violet has the highest level. The colors in between (orange, yellow, green, blue and indigo) gradually increase in energy. A compound with more conjugation would reflect the red-orange energy portion of light and absorb higher energy blue-green, therefore appearing somewhere in the range of green to violet. A less conjugated compound would absorb the red-orange and reflect blue-green, therefore appearing somewhere in the range of red to yellow.
An example of these concepts would be carotenoids, highly conjugated compounds found in carrots, tomatoes and certain algae, responsible for the red-orange colors of these items. In nature these carotenoids are consumed by wild salmon and certain song birds which create the red tint in their appearances. (Farmed salmon need to be fed this carotenoid in order to resemble their wild relatives.) On the other hand, retinol (vitamin A) has less conjugation and appears as yellow because it absorbs more of the blue-violet portion of the spectrum.
Types of Colorants
It is very important to understand a given colorant both on the micro and macro levels. Ideal colorants are pure and non-toxic, are soluble and/or dispersible, don’t contribute to the taste/fragrance of the food, are stable in heat/freeze situations, do not react with other compounds in the food, have uniform characteristics, are widely available and economically feasible, and conform to the government regulations of most countries.
There are three classic types of colorants: natural, nature identical, and synthetic, with each class having benefits and drawbacks. Natural pigments are those extracted from animals, plants or minerals. Common examples are carotenoids, anthocyanins (for instance, grape skins) and chlorophylls. Natural colors are more regulated than natural flavors. In order to be a "natural color" the added coloring has to actually be native to the item. If the pigment is not naturally found in the particular food (example beet juice in strawberry ice cream) the product label cannot state "natural color added". Drawbacks for the manufacturer include greater variability, insufficient supply, and higher expense.
Nature identical pigments are artificially produced replicas of natural pigments. They are more regulated and less costly but are still subject to the drawbacks of variability and insufficient supply.
Lastly, there are two types of synthetic colorants: FD&C dyes and FD&C lakes. Dyes are water soluble and lakes are oil soluble. These colorants are heavily regulated and are generally only provisionally approved (the government can revoke the approval at any time). In addition, different countries ban various synthetic dyes which can complicate foods destined for export. For instance, Red #40 is allowed in the US and Canada but not in the European Union and Switzerland. Many of the synthetic dyes have been subjected to controversial toxicity studies and conflicting results have been claimed. The benefits for manufacturers, however, are great – synthetic colorants are cheap, stable and reliable.
Kashrus Implications
Natural colorants are sometimes manufactured on non-kosher equipment, such as spray dryers. While most synthetic food colorants do not require a hechsher, FD&C lakes can be problematic. Lakes often utilize dispersion agents which can include oils, glycerin and corn based syrups (which are not approved for Passover). Natural colors are, for the most part, kosher, assuming that the facility does not produce non-kosher colors on the same equipment.
The famous exception to this rule is cochineal, a red pigment extracted from female insects of the coccoides and aphimiden families. It takes 80,000 to 100,000 insects to produce one kilogram of this pigment. The purified version of this dye is called carmine or carmine acid lake. It was highly coveted as a dye in the 16-19th centuries, but its appeal has fallen sharply due to high cost and availability of synthetic colorants. However, carmine is still added to some meat products and maraschino cherries. There is a dispute amongst halachic authorities regarding carmine.2 If a color adds no additional taste is it problematic as a kashrus concern? As there are opinions on both sides of this issue, the OK follows the approach that when the forbidden color source is biblically prohibited, it is not allowed. However, when the prohibition is rabbinically sourced it would not be forbidden. Carmine is forbidden biblically as an insect derived colorant3 and is therefore not used in OK certified products.
There is another related principle that if a non-kosher food is no longer edible even for a canine (turned into dust), it loses its forbidden status.4 Carmine fits this description and, therefore, some authorities permit its use. Those who forbid carmine in kosher products do not state it is forbidden outright. They remain concerned that the carmine might not have been properly dried to render it "turned into dust". As there are other alternatives available, most kashrus agencies advise utilizing alternatives instead and the mainstream kosher supervisions do not allow certified products to contain carmine. In fact, prohibiting the use of carmine is the unofficial litmus test to regard a hechsher as "mainstream."
There is an interesting halachic debate about the kosher status of dyes used in the service of the Beis HaMikdash. Only materials that are derived from kosher items may be used to perform mitzvos (for example parchment must come from a kosher species that was shechted).5 As such, the outfit of the Kohen Gadol and the red heifer sacrifice contained a dye translated as "worm red".6 Some authorities claim it did not consist of actual worm but either resembled a worm or was derived from hard objects found in the worm’s intestine.7 Others claim it was the actual dried out worm which lost its forbidden status because it was no longer fit for canine consumption and was considered "dust".8 This qualification is derived from the aforementioned dispute regarding carmine.
Like the Maccabees who merited to reclaim and rededicate the Beis HaMikdash, may we merit the Final Redemption and the Beis HaMikdash HaShlishi where we can experience the vibrant colors of the Temple service and once again make the red dye for the clothes of the Kohen Gadol.
1. Gemara, Shabbos 139b.
2. Pri Chodosh, Darkei Teshuva 102:5; Minchas Yitzchak, Chelek Gimmel, 96:2; Rav Ovadia Yosef, Yabia Omer 8:11.
3. Vayikra 11:20-23.
4. Minchas Yitzchak, Chelek Gimmel, 96:2 (Noda B’Yehuda Siman 25).
5. Gemara, Shabbos 28b; Shulchan Oruch, Orach Chaim 32:12. The Magen Avraham (586:3) states that in this principle all mitzvos are patterned after tefillin. However, the Shu”t Beit Shlomo (Orach Chaim 108-109) permits candles made of non-kosher fats for Chanukah and Shabbos.
6. Shemos 25:4.
7. Rambam, Hilchos Para Adumah, Perek Gimmel, Halacha Beis.
8. Me’am Lo’ez, Parshas Terumah 25:4.