Spray Dryer for Food Additives

Definition of Food Additives

Food additives are non-nutritive substances intentionally added to food, generally in small quantities, to improve the food’s appearance, flavor, texture, or storage properties. According to this definition, food fortifiers intended to enhance the nutritional content of food should not be included in the category of food additives.

Introduction to Spray Dryers for Food Additives

Spray drying is a process commonly used in the liquid processing and drying industry. It is suitable for producing powdered or granular solid products from liquid raw materials such as solutions, emulsions, suspensions, and pastes. Therefore, spray drying is an ideal process when the particle size distribution, residual moisture content, bulk density, and particle shape of the final product meet the required standards.

Working Principle of Spray Dryers for Food Additives

Filtered and heated air enters the air distributor at the top of the dryer, where the hot air is evenly distributed in a spiral pattern into the drying chamber. The feed liquid is atomized into extremely fine droplets by a high-speed centrifugal atomizer at the top of the tower. These droplets come into contact with the hot air in a co-current flow and are dried into the final product within a very short time. The finished product is continuously discharged from the bottom of the drying tower and the cyclone separator, while the exhaust gas is vented by a fan.

Performance Features of the Food Additive Spray Dryer

◎ Fast drying speed: After atomization, the surface area of the feed liquid increases significantly. In the hot air stream, 95%–98% of the moisture can evaporate instantly, with the entire drying process taking only a few seconds. This makes it particularly suitable for drying heat-sensitive materials.

◎ The product exhibits excellent uniformity, flowability, and solubility, with high purity and superior quality.

◎ The production process is simplified, and operation and control are convenient. Liquids with a moisture content of 40–60% (up to 90% for special materials) can be dried into powdered or granular products in a single step. No grinding or screening is required after drying, which reduces production steps and improves product purity. Product particle size, bulk density, and moisture content can be adjusted within a certain range by altering operating conditions, making control and management very convenient.

Examples of Common Food Additive Materials That Can Be Dried

Preservatives—Common examples include sodium benzoate, potassium sorbate, sulfur dioxide, and lactic acid. These are used in the processing of foods such as jams and candied fruits.

Antioxidants—Similar to preservatives, these extend the shelf life of food products. Common examples include vitamin C and ascorbyl palmitate.

Colorants — Common synthetic colorants include carmine, amaranth, tartrazine, and indigo. They alter the appearance of food to enhance its appeal.

Thickeners and Stabilizers — These improve or stabilize the physical properties of frozen desserts, giving them a smooth and delicate texture. They help frozen foods like ice cream maintain a soft, airy texture over time.

Leavening agents—Leavening agents are added to some candies and chocolates to promote the production of carbon dioxide within the sugar mixture, thereby creating a leavening effect. Common leavening agents include sodium bicarbonate, ammonium bicarbonate, and compound leavening agents.

Sweeteners—Common synthetic sweeteners include sodium saccharin and cyclamate. Their purpose is to enhance the perception of sweetness.

Acidulants — Acidulants are often used in certain beverages and candies to adjust and enhance flavor profiles. Common examples include citric acid, tartaric acid, malic acid, and lactic acid.

Whitening Agents — Benzoyl peroxide is the primary component of flour whitening agents. In China, the maximum permitted additive level in flour is 0.06 g/kg. Excessive use of whitening agents can destroy the nutritional value of flour. The benzoic acid produced upon hydrolysis can cause liver damage. Benzoyl peroxide has been banned as a food additive in developed countries such as the European Union. China also banned benzoyl peroxide as a whitening agent in May 2011.