Description
Soy protein isolate at 90 percent protein by weight, 2.2 pounds to the bag, 33 servings at about 97 cents each. Soy is the only common single plant protein with a complete essential amino acid profile, which is why soy protein isolate sits on the shelf without a partner powder beside it. Pea runs low in methionine and rice runs low in lysine, so those two are nearly always blended.
The numbers on the bag
| Protein | about 90 percent by weight, with grams per scoop printed |
|---|---|
| Net weight | 2.2 lb, about 1 kg, 33 servings |
| Scoop | around 30 g yielding about 27 g of protein |
| Beans | identity preserved non-GMO |
| Amino profile | complete, published in full per lot |
| Cost | about 97 cents a serving, near 3.6 cents a gram of protein |
| Flavour | unflavoured, beany, mixes thin |
Why soy protein isolate is 90 percent and concentrate is not
A soy protein isolate is washed further than concentrate, which removes most of the carbohydrate, the fat and the soluble sugars that cause complaints. Concentrate sits nearer 70 percent and costs less per bag. The percentage is what decides the gap between scoop weight and grams of protein, and both figures are printed here along with the percentage they imply.
A 30 gram scoop yielding 27 grams is 90 percent. A 30 gram scoop yielding 21 grams is 70 percent, and that is a concentrate whatever the front of the bag says. The protein page prices everything by the gram for this reason.
The isoflavone figure almost nobody prints
Soy carries isoflavones, chiefly genistein and daidzein, and how much survives into an isolate depends on whether the material was water washed or alcohol washed. Alcohol extraction removes most of them. Water processing keeps more.
Very few soy protein isolate labels state the isoflavone content at all, including the ones that advertise their beans. If that number matters to you, ask for it before buying any brand, and treat a non-GMO claim as a statement about the seed rather than about the processing.
What the comparison trials measured
Studies feeding matched amounts of soy and whey, generally 20 to 40 grams, sampled blood afterwards and measured plasma leucine and amino acid appearance along with muscle protein synthesis rates. Whey produced a faster, higher leucine peak in those protocols. That describes what the measurements showed and is not a claim about either powder.
Soy protein isolate against a pea and rice blend
A pea and rice blend reaches a complete amino profile by pairing two incomplete proteins, which works and means reading two sets of figures instead of one. Soy protein isolate arrives complete in a single ingredient and at a higher protein percentage, usually 90 against 80 for a pea isolate.
The trade is allergen status. Soy is one of the major declared allergens and pea is not, and some buyers avoid soy on grounds of their own. Both are stocked here, both are priced per gram of protein, and the amino figures for each are published, so choosing between them is arithmetic rather than argument.
Amino spiking, and why the full profile is published
A nitrogen based protein figure reads the same whether the nitrogen came from complete protein or from added free glycine and taurine. Our certificates carry the whole amino acid breakdown rather than total nitrogen, which is the only thing that makes spiking visible from outside a factory.
Testing
Every lot goes to a laboratory outside this business for protein content by a method that is not nitrogen alone, a full amino acid breakdown, heavy metals and microbials. Lots assaying below their stated grams are withdrawn from sale and the failing certificate stays published rather than quietly replaced.
Reference reading
The NIH fact sheet on supplements for exercise and athletic performance summarises what protein supplementation trials have measured and at what doses, free of charge and without selling anything. The certificate for your bag of soy protein isolate is linked on this page and archived on lab results.
Reviews
There are no reviews yet.