Blending and mixing processes in the food industry comprise similar operations, with terms that are often used interchangeably. Each indicates the combining of two or more components of a given food item. Blending typically implies a gentler, more careful integration of disparate elements, so that each component retains identifiable characteristics.
Think of a granola bar, for example, with identifiable pieces of whole oats, nuts and perhaps small pieces of dried fruit. Held together with a binding agent, such as honey, and infused with certain flavorings, such as cinnamon powder, each individual component remains identifiable.
Mixing unit operation in food processing, on the other hand, implies a greater degree of aggressiveness during blending. Some components may have undergone particle size reduction or alteration, to the extent that individual components are now indistinguishable. The goal here is a more homogenous mixture. Accordingly, the mixing process to achieve it is often called homogenization.
Thorough blending and homogenization are desirable when manufacturing food products precisely because these processes ensure consistency. Regardless of where or when a product is purchased, the consumer knows he or she will get the same quality and consistency every time. Consumers find this aesthetically desirable and ultimately reassuring.
Homogenization typically involves the application of shearing forces during mixing, to achieve particle size reduction and subsequent thorough blending of disparate ingredients. When it comes to liquid foods, such as homogenized milk, particle size reduction of milkfat globules results in a more stable emulsion — droplets of milkfat suspended in the aqueous phase of milk and dispersed evenly throughout the entire product.
When particles are sufficiently size-reduced, this type of homogenization results in a stable emulsion. In other words, the cream fraction will no longer rise to the top, but will remain dispersed throughout a given volume of whole, homogenized milk. Thus, the consumer gets a product with consistent quality and appeal.
Certain food items, such as mayonnaise or Greek-style yogurt, require a high degree of homogenization during manufacturing. As an oil-in-water emulsion, mayonnaise necessitates significant particle size reduction of oil droplets to form a stable emulsion in an aqueous medium. This aqueous fraction also contains flavorings (such as salt, sugar, and spices), plus acidifiers (such as vinegar or lemon juice), in the presence of a component known as an emulsifier. The latter is a compound that helps form a stable emulsion, which will not separate. In this instance, egg yolk is commonly used.
On the other end of the blending/mixing, scale is foods (such as the granola bars mentioned above) that consist of uniform blends of identifiably disparate elements. Ingredients for these types of items require more gentle blending. Home cooks typically refer to this type of blending as “folding in.” The goal when folding one or more ingredients into others is to mix as little as possible, so that individual components retain their identifiable characteristics while providing a thorough blending of all ingredients.
Clearly, there is no one-size-fits-all solution when it comes to mixing/blending food products. Depending on your ingredients (wet, dry, etc.) and the intended outcome (the uniformity of mayonnaise, for example, versus the recognizable textures of a granola bar) your process — and the equipment used to achieve it — will differ.
Fortunately, at Quadro® Liquids, we specialize in a wide range of uniquely engineered products and solutions tailored to meet a variety of mixing needs. Feel free to view our food processing equipment.