Are you overwhelmed by the wide variety of protein powders in the sports nutrition aisle and aren’t sure which will best meet your individual needs? This article is part of a series, written by Harmons Dietitian Hannah Langley, to take an extensive look at protein powders and help you make the most informed choice when shopping for your health
Plant-based protein sources typically come from legumes, grains, seeds, and nuts. Some of the most commercially available plant-based protein powders are pea, soy, hemp, and brown rice protein. While there are a variety of other plant-based protein sources that are used as secondary ingredients, less is known about their individual bioavailability and rate of utilization. Many plant-based protein powders use a combination of protein sources to offer a complete protein. Individual plant-based proteins may contain all 9 essential amino acids, but not in sufficient amounts for health. The rate of utilization of each protein source may vary depending on how it has been processed.
Manufacturing - Concentrates vs Isolates
Most plant-based protein powders undergo a similar method of manufacturing of hulling, milling, filtering, and drying. First, the plant product is hulled to remove any hard outer coatings and insoluble fiber. Next, the plant product is milled into a fine-ground plant meal. Soybeans, hemp hearts, and nuts must be pressed to remove their oil, which may occur before or after milling. Filtering is the next step, and the method of filtration will determine how concentrated the protein becomes. Two of the most common methods are dry and wet fractionation, or a combination of the two.
During dry fractionation, the milled plant meal is typically filtered using an air classifier or by electrostatic separation. Protein, carbohydrates, fiber, and other minerals have different shapes, weights, and electrostatic charges. The air classifier can filter the protein from other materials based on its shape and weight, and only requires air. Electrostatic separation, on the other hand, uses an electrostatic charge to separate the protein from other particles. Dry fractionation is used to make plant protein concentrates while using fewer energy and resources. The protein content in the final product can range widely, with research suggesting anywhere between 30-80% percent total protein content.
Wet fractionation is a method used to make plant protein isolates and is filtered by isoelectric precipitation or ultrafiltration. The milled plant meal is treated with an alkaline water solution to dissolve the protein in water and separate it from other particles. For brown rice protein specifically, the water and ground rice mixture is treated with enzymes to separate the rice protein from naturally occurring carbohydrates. The solution is then spun in a centrifuge to separate and remove the insoluble particles like carbohydrates and minerals.
For isoelectric precipitation, an acid is added to the remaining liquid to adjust the pH and form a plant protein ‘curd’. The curd is then washed with a basic water solution to neutralize the pH and can then be dried into a powder.
For ultrafiltration, the water and protein solution undergoes an ultrafiltration method using a membrane and pressure, similar to that of whey protein, to remove carbohydrates, minerals, and other particles. The pH of the filtered solution is then neutralized to create a plant protein isolate that can be dried into a powder.
Pea Protein is a common main ingredient as it has a medium-high bioavailability and rate of utilization, though it lacks a sufficient amount of methionine. It is best suited for post-exercise recovery and increasing total daily protein intake. If using pea protein for post-exercise recovery, consider opting for a pea protein isolate as it will have a higher rate of utilization and total protein content.
Soy protein has a high bioavailability, medium-high rate of utilization, and is one of few plant-based complete proteins. It is less frequently used due to being a common allergen but is best suited for either post-exercise recovery or increasing total daily protein intake. If using soy protein for post-exercise recovery, consider opting for a soy protein isolate as it will have a higher rate of utilization and total protein content.
Brown rice protein has a medium-high bioavailability and a medium rate of absorption. It lacks a sufficient amount of lysine. Due to its medium rate of absorption, its best use is increasing total daily protein intake.
Hemp Protein has a high bioavailability and medium rate of absorption. It lacks sufficient amounts of isoleucine, valine, lysine, and phenylalanine. Due to its medium rate of absorption, its best use is increasing total daily protein intake.
- Many plant-based protein powders use a combination of protein sources to offer a complete protein. Individual plant-based proteins may contain all 9 essential amino acids, but not in sufficient amounts for health.
- If using a protein powder to increase total daily protein intake, protein concentrates are best.
- If using plant protein powder for post-exercise muscle recovery, pea or soy protein isolate-based is best. Protein hydrolysates are typically beneficial for only high-level athletes.