Dry fractionation process operations in the production of protein concentrates: A review

Abstract

The market for plant proteins is expanding rapidly as the negative impacts of animal agriculture on the environment and resources become more evident. Plant proteins offer competitive advantages in production costs, energy requirements, and sustainability. Conventional plant‐protein extraction is water and chemical‐intensive, posing environmental concerns. Dry fractionation is an energy‐efficient and environmentally friendly process for protein separation, preserving protein's native functionality. Cereals and pulses are excellent sources of plant proteins as they are widely grown worldwide. This paper provides a comprehensive review of the dry fractionation process utilized for different seeds to obtain protein‐rich fractions with high purity and functionality. Pretreatments, such as dehulling and defatting, are known to enhance the protein separation efficiency. Factors, such as milling speed, mill classifier speed, feed rate, seed type, and hardness, were crucial for obtaining parent flour of desired particle size distribution during milling. The air classification or electrostatic separation settings are crucial in determining the quality of the separated protein. The cut point in air classification is targeted based on the starch granule size of the seed material. Optimization of these operations, applied to different pulses and seeds, led to higher yields of proteins with higher purity. Dual techniques, such as air classification and electrostatic separation, enhance protein purity. The yield of the protein concentrates can be increased by recycling the coarse fractions. Further research is necessary to improve the quality, purity, and yield of protein concentrates to enable more efficient use of plant proteins to meet global protein demands.

Insights into Grain Milling and Fractionation Practices for Improved Food Sustainability with Emphasis on Wheat and Peas

“…The latter cereals can also be processed to render oil, β-glucan, or arabinoxylan. In general, dry and wet milling are commonly employed by the grain industry to fractionate grains or pulses into their constituents of protein, starch, and fiber [9,[22][23][24][25][26][27][28][29]. Dry milling uses different types of mills, air classifiers, and electrostatic separators to break down and fractionate grains or pulses into flours and ingredients [9,22], while wet milling applies wet extraction methods to separate protein, starch, and fiber from grains [24,26,28,29].…”

“…Studies have shown that wet milling is obsolete and uneconomical, with intensive uses of water and energy [34,47]. On the other hand, dry milling has shown great potential as a sustainable system for the separation of protein, starch, fiber, and other ingredients [9,22,27]. In this respect, a hybrid model would improve the efficiency of wheat milling and fractionation by minimizing waste and reducing water consumption, in addition to improving the quality of fractions and ingredients.…”

“…In another study, a hybrid method of dry and aqueous fractionation was used to produce protein fractions from quinoa with minimal impact on functionality [75]. Additionally, the use of the pre-and post-treatment of pulses, such as tempering, defatting, soaking, or freezing cycles, can also be applied to improve the purity of protein fractions obtained from pulses through dry milling and air classification [9,25]. In general, these studies have emphasized the benefits of dry fractionation in making protein or starch fractions with high purity and improved functionality and nutritional properties without the use of organic solvents.…”

“…Furthermore, plant foods have competitive advantages over animal proteins due to the higher greenhouse gas (GHG) emissions produced from the production of animal-based foods which are approximately twice as that of plant-based foods [8]. Besides, plant foods require lower production cost and energy than animal foods [9]. These attributes signify the importance of cereals and legumes in human nutrition and the health of environment.…”

Dry fractionation of oil-rich legumes for recovery of functional protein ingredients

“…Thus, also for rapeseed deoiling is strongly advised to improve the milling yield, reach sufficient disclosure of protein bodies from the cells and to enable consecutive electrostatic separation. Furthermore, it is recommended to aim for ambient milling conditions unless the lower temperature is desired to preserve volatile compounds (Pulivarthi et al, 2023).…”