Knowing the ingredients of packaged foods is very important while buying food. Why? Suppose you go to a bakery shop for buying special creamy orange cakes and there you see a lot of varieties of orange colored bakery products, how will you select the right flavor of your choice? Ask the salesperson? Even then a little doubt prevails. Is he or she speaking the truth? So as to free your mind from all these troublesome thoughts, you should know that only food grade ink is used for printing related to foods. When you read the ingredients which is mandatory in most of the countries, you can see the food dyes that are used in the food and for the printing. It identifies or rather reveals the specifics and classification of the food product and helps you in picking the right one. You should also be aware that about 19 states have "toxins in packaging laws", that regulate heavy metal content used in packaging. Most of the states do not allow intentional use metals such as cadmium, hexavalent chromium, lead, or mercury in any amount. The laws also prohibit the incidental use of these metals, not exceeding 100ppm total.
Printing on food is always tricky for one the ink has to be non smearing and stay together which means it has to have a certain viscosity and other technical requirements as per printing scale. But the most important aspect of using food grade ink is what goes into them. Manufacturers use food grade ink for various reasons, to code their products for both security and safety reasons. They also use UV ink which is not visible to the consumers but only to their UV scanners. Manufacturers use UV ink for both aesthetic purposes and security reasons. The food grade ink in food packaging could come directly in contact with the food such as dry food packaging, or could be used to directly print on food surfaces itself such as individual confectioneries. Food grade inks aren't certified by FDA as there is no certification at this point but the companies have to follow the materials and dilutants listed in the 21 CFR Chapter 1, Section 73.1 (b) which is "GRAS" which means generally recognized as safe practices in using the materials for the food grade ink.
Ink jet printing is generally used for printing and decorating the surface of various edible food items. A few things have to be adjusted for the food medium such as using food grade ink which is compatible with the surface on which it is to be written. The food grade ink should have the appropriate viscosity, smear resistance, solubility, surface tension and drying times. ink and make-up fluid. The continuous industrial inkjets have two things, the ink and the make-up fluid. The Make-up fluid is required to be mixed with the ink to make sure proper chemistry of the printed fluid is maintained. Part of its function is to "make-up" for the solvent that evaporates during the process to maintain a consistent ink performance. There are different types of food grade inks for different inkjets used.
But at present there are only couples of food grade inks which match this compatibility level. Many times the components of this ink carry harmful substances which if ingested could cause health problems. While many times the water level is too high due to which the needed viscosity is not reached causing the ink to create smear patch, new methods have been tried to gain perfection in this printing or for obtaining a different method of applying ink but until now no ideal printing technique has been evolved. Printing on edible rice paper and then sticking them on the food surface has been tried. But this unnecessarily increases the labor manifold and is not suitable for food products of varying shapes and sizes. The food grade ink category is still developing in terms of being totally chemical free and the European standards are much more stringent than other countries.
Typically food grade coloring fluids contain at least one food grade dye and a food grade glycol, such as 1,2-propanediol, for printing directly onto the surfaces of various food substrates. A good quality food grade ink should consist of non-toxic substances. The percentage of water ranges from 20 wt % to 35 wt % and mostly is closer to 1 wt%. Another important component included in food grade ink making is glycerin. It acts as a co-solvent and is present in many colored ink fluids. Dyes too are used in this ink to add color. These can be synthetic or natural dyes or a blend of both. These dyes are soluble in water or other co-solvent like glycerin or glycol.
The synthetic dyes which are used with food are FD&C Red #3, FD&C Red #40, FD&C Yellow #5, FD&C Yellow #6, FD&C Blue #1, and FD&C Green #3. The natural dyes used for preparing food grade ink are vegetable juices, chlorophyll extract, beet extract, grape skin extract or spinach extract, turmeric oleoresins, cochineal extracts, gardenia extracts. A minimum of 85 wt% purity is expected in the standard food grade ink category which means the dyes should contain not more than 15 wt % contaminants and impurities, including moisture. Lastly, the ink has additives which are used as thickening agents, surface tension modifiers, antioxidants, buffering agents, antimicrobial agents and preservatives. A small percentage of alcohol like ethanol or isopropanol are added in the food grade ink.
Some of the food items on which this ink is more commonly used are rice cakes, cookies, pie crusts, taco shells, granola bars, biscuits, cereals, chewing gums, crackers, waffles, cakes such as snack cake, candies, pasta, marshmallows. Food grade ink is also used on bakery products like buns, tortillas, bagels and toasts.