The edible ink developed by Shenzhen Micolorprint Technology Co., Ltd. is relatively mature and has been put into use in the market. Traditional inks are composed of binders, pigments, and additives. The connecting material is composed of resin, oil (vegetable oil, mineral oil), organic solvent, and auxiliary materials. Colorants are mainly pigments and dyes. In theory, edible ink is also composed of binder, colorant, and auxiliary, but its composition elements are completely different. For edible ink, it has a higher standard, which is to meet the printing adaptability and color requirements, to ensure that the printing ink can be transferred to the substrate well, and to meet its edible characteristics. From the overall point of view, each component of the ink must meet the requirements of people’s consumption, and the substances produced by the physical or chemical action after they are mixed with each other should also be harmless to the human body and meet the edible requirements to ensure the final product. The obtained ink can meet the relevant standards specified by the state. Therefore, the research of edible ink is mainly on the selection of its ingredients.
1. The choice of pigment
Because of its edible properties, its colorant should not be a pigment but an edible pigment. Pigments can be divided into natural pigments and synthetic pigments. There are many kinds of natural pigments with natural color and luster. Many varieties have both nutritional value, and some have certain medicinal effects (such as gardenia yellow, safflower yellow, etc.), especially since their safety is trusted by people, but most of them have certain medicinal effects. Natural pigments are not stable enough. When they are affected by external factors such as acid, alkali, and heat, their intermolecular structure will change, resulting in their discoloration. Although most of synthetic pigments are harmful to human health, they have the advantages of bright color, strong tinting strength, good stability, soluble in water, easy to color, uniform quality, low cost, etc., and have been widely used. In recent years, due to the trend of people’s pursuit of green health and the emphasis on food safety, countries around the world have increased the development and application of natural pigments. At present, in some countries, the amount of natural pigments has far exceeded that of synthetic pigments. usage. Therefore, the pigments of edible inks use natural pigments in principle, which is in line with the current people’s requirements for green food.
2. Selection of connecting material
The binder of edible ink can also be composed of oil, solvent, and auxiliaries. Its oil is edible vegetable oil, such as peanut oil, salad oil, and other vegetable oils, and the solvent can be liquid sugar. However, the specific choice of connecting material also needs to be determined according to the storage method of the food. Because some foods need to be refrigerated and some foods don’t, they should be considered separately when choosing a linking material. For both cases, an organic formulation and an aqueous formulation can be used, respectively. For foods that need to be refrigerated, organic formulations require that there are ingredients that can form a barrier layer in the formulation of the binder, and should also contain desiccants, film-forming substances, emulsifiers, water, and hydrophobic agents, etc., which can generate a barrier layer. The ingredient acts as a pigment carrier, which has two roles.
1 is to improve the adsorption force of ink and printing plate.
2 is to form a surface layer.
It is used to protect the printed graphic content from the water generated when the food is thawed. For foods that do not require refrigeration, an aqueous formulation can be used, and the main ingredients such as water, sweeteners, emulsifiers, hydrocolloid stabilizers, humectants, etc., are used as connecting materials. Among them, the sweetener can increase the fragrance of the ink, and can also be used as the carrier of the pigment to dilute and improve the adsorption force of the ink on the printing plate. The substances that can be used as sweeteners include sucrose, sorbitol, etc.; emulsifiers and hydrocolloid stabilizer act as a stabilizer and thickeners in the ink, and the optional materials are lecithin, gum arabic, etc.