Industrial bakeries and mix plants rely on precision weighing and blending to achieve consistency and product quality. Many raw ingredients like flour, sugar, salt, spices, additives, or flavorings are inconsistently sized or contain lumps. Therefore, industrial food manufacturers will often utilize industrial size reduction equipment to condition them prior to use. After conditioning the ingredients, bakeries and mix plants will use various types of kneading equipment or horizontal blenders to mix them into ready-to-eat foodstuffs or pre-packaged mixes for consumers. Furthermore, blends that contain fats or shortening to bind the ingredients and build texture will contain prills, or soft lumps that must be conditioned prior to packaging. This is yet another area where industrial size reduction or sifting will improve product consistency and quality.
The Need for Consistency
Consumers expect their favorite foods to deliver a positive, consistent sensory experience. The need for consistency means ingredients need to be precisely measured and blended to look, feel and taste the same. Food manufacturers and commercial bakeries understand this, so they use equipment that ensures ingredients are mixed thoroughly. Some examples discussed in this article include lump breakers, hammermills and rotary sifters to help accomplish the task of conditioning raw ingredients and sifting finished blends.
Lump Breakers and Product Conditioning
One of the first steps in food processing involves conditioning of raw ingredients. Certain ingredients can compact, forming lumps that are difficult to break down, convey and blend. Many clients rely on labor intensive, costly work to manually condition them. Lump Breakers are one alternative to automate and simplify this process. Lump breakers utilize a low speed impact rotor that meshes with fixed combs to gently condition products without creating fine dust. Applications to process harder lumps will include a sizing screen to achive a more consistent finished product.
Lump breakers are simple to operate and easy to clean. They can also include hygienic build features and designs for simple break-down to ensure a thorough sanitation between batches.
Hammermills & the Milling Process
Hammermilling is another method used to achieve product consistency. In this process, manufacturers break down larger particles into smaller ones, enabling dry ingredients to mix easily with less chance for segregation.
Hammermills include a high-speed rotor with hammers attached at their pivot point to support pins equally spaced around its perimeter. These hammers strike with precision to break down substances against the surface of one or more screens. The rotor – suspended at each end between bearings – allows hammers to repeatedly strike the particles against the screen, thus reducing their size.
Hammermills work best for:
- Conditioning of dry granules and powders.
- Dry masa flour for tortillas and corn-based foods.
- Making flour out of bran and oats.
- Processing and producing animal feed.
Hammermills can be built up to 19 meters in diameter, with screen areas as large as 4.5 square meters. These larger industrial designs dry blenders require motors up to 600 horsepower and with operating speeds approaching 3600 rotations per minute.
Offering a simple design while permitting the grinding of various types of materials, these industrial mills are also easy to operate and clean. Screens can be removed without tools while more recent designs include rotors with fewer pieces for easier sanitation. Hammermills are also designed with multiple access points and split casings to improve cleanability and maintenance.
Industrial bakeries and mix plants will utilize hammermills to achieve particle size consistency across various ingredients used in a blend or to remove prills from blended dry mixes.
The food industry also utilizes other types of milling processes to reduce the size of particles. These include:
- Ball mills use horizontal steel cylinders – half-filled with steel balls – that rotate slowly, with particle size depending on the size of balls and rotation speed.
- Pin mills efficiently and quickly break down material using metal disks that are fitted with pins.
- Roller mills use two or more steel rollers to separate parts of grain kernels then grind these into fine flour particles.
Rotary Sifters
Commercial baking also involves sifting, a process dependent on the manufacturing process and the ingredients utilized. One type is a rotary sieve or screen, which uses centrifugal force to accelerate powders toward a cylindrical, static screen. When accelerated at high speed, larger particles impinge on the screen surface, causing it to flex. This natural flex helps to prevent the screen apertures from blinding when handling products with higher amounts of fat, oil or moisture. These larger particles are expelled from the end of the screen cylinder and collected separately from the fine material, which passes through the sieve and is transferred downstream in the process.
This type of sifting is gentle, material comes out unadulterated, making rotary screens ideal for handling fragile powders, agglomerates and spray dried ingredients. Mainly used to remove oversize debris or lumps in dry powdery products, the rotary sifter is ideal for removing contamination from dry powders that have been stored in silos.
Rotary sifters enable the food industry to achieve higher capacities in a compact foot-print. Furthermore, they are packed with features that make them easy to inspect and clean. In certain operations, this is vital where FSMA requires the routine removal and inspection of the screening surface. Unlike other types of screens, rotary sifters allow for easy removal, inspection and replacement of the screens with a minimal amount of tools and effort. This allows these sifters to operate at full capacity for longer periods with reduced downtime. These designs also operate quietly and efficiently, eliminating vibration, hazards associated with exposed motion, and external dust. These sifters can size, sift, scalp, classify, and even break down clumps of dry ingredients using centrifugal force.
Easy to Clean, Reliable Dry Blending Equipment
Prater makes a wide selection of durable, easy-to-clean machinery for commercial bakeries and mix plants, including lump breakers, hammermills and rotary sifters. Prater’s industrial dry blender solutions assist the food industry in making cakes, cookies, biscuits, bread, tortillas, candies, and other delicious foods. Providing customized solutions, the company helps condition raw ingredients and finished blends before they’re used in the baking process, ensuring a uniform taste with every bite.
