Plant-based foods have been on an upward growth trend over recent years and, in particular, the use of Yellow Peas and Chickpeas is rapidly increasing as a sustainable crop source.
Established manufacturers with experience in starch-based or oilseed manufacturing have already started to add higher value protein-based ingredients to their product list. By adapting the traditional wet fractionation process, plant-based proteins become the focus along with the co-products. When applying peas as the feedstock, four (4) main products are produced:
These four streams can be manufactured as separate products or combined for specific applications. For example, the fiber and starch streams can kept together and dried simultaneously, or the solubles can be concentrated in a Dedert evaporator then added to the fiber stream for drying into a feed product.
A Feed-Type Ring Dryer for pea fiber is the most appropriate technology for drying pea fiber with the centrifugal classification manifold directing the solids recycle back to the higher-temperature feed zone for maximum dryer efficiency. With a short residence time, the ring dryer prevents exposure of the solids in the high-heat environment to only a few seconds which results in the highest product quality compared to product from other drying technologies. The versatility of the ring dryer design also accommodates variations in product grades and characteristics, including changes in moisture content, evaporation rate, and product composition that could affect drying behavior.
In particular, the ring drying system must be configured according to the specific application. In food applications, pea fiber would be dried on an Open-Circuit (OC) Ring Dryer while animal feed applications would benefit from a Partial Gas Recycle (PGR) Ring Dryer:
As a food product for human consumption, pea fiber has to meet specific nutritional, taste, and marketability profiles. Special care is needed to ensure these requirements, especially in the final processing stage for product drying. An OC configuration on the ring dryer ensures a high-quality pea fiber suitable for Food applications in part due to the low temperature environment. Using ambient fresh air in a 1-pass configuration, the product always remains in contact with a clean, unadulterated, low-humidity drying medium to prevent risk of contamination or changes to the product's natural state. Additionally, a heat source could be selected to be indirect heating or steam-heating avoids product-contact with combustion products. As a result, the ring dryer configuration prevents discoloration, off-tastes, and other unwanted pea fiber characteristics for Food applications.
For animal feed applications, pea fiber is combined with concentrated solubles from a Dedert evaporator then dried in a ring dryer with a Partial Gas Recycle (PGR) solution to access energy-recovery for improved efficiency. PGR recirculates the majority of the dryer exhaust stream back to the air heater as a preheated drying medium. Since the bleed-off stream contains high-humidity, a Gas Heated Evaporator (GHE) recovers the energy to concentrate the pea solubles prior to addition to the fiber. Dedert's proven GHE technology is designed to remove fine particulate and to saturate the stream to maximize the evaporator's performance, which eliminates the need for a wet scrubber and reduces the vent stream sent to the emissions-control device. Integration with the fluid bed cooler allows warm exhaust air to be diverted to the ring dryer as preheated combustion air for further energy-recovery and elimination of a dust particulate emissions source.
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