Soy Protein Concentrate

Soybean oil production leaves defatted flakes. Protein processors wash soluble sugars out of those flakes, then dry the solids. The extra step makes a more concentrated protein ingredient than ordinary soy flour.^1,6,7

1. 01 // Source Soybean flakes Processors remove the hulls and most of the oil, leaving flakes rich in protein and carbohydrate.
2. 02 // Process Solubles washed out An aqueous alcohol, acid or hot water wash removes much of the soluble carbohydrate.
3. 03 // Process Solids dried The retained protein and insoluble fiber are separated from the liquid, dried and milled.
4. 04 // Output Soy protein concentrate A dry powder with roughly 70% protein that manufacturers mix into dog food.

1. 01

   Adds plant protein

   Removing soluble carbohydrate leaves a protein-rich powder. It raises crude protein in the finished food, so the protein number alone does not reveal how much came from meat.^1,6

2. 02

   Helps kibble expand

   In an extrusion trial, coarse concentrate increased starch cooking and kibble expansion. That gives manufacturers another way to adjust kibble structure while choosing a protein source.²

3. 03

   Uses the oil stream

   Soybean oil production supplies the defatted flakes. Washing adds cost: an FAO processing guide reported concentrate costlier than soy flour, though it is less expensive than soy isolate.^6,7

How much A dog trial made concentrate about a third of several test diets by weight; that is a tested amount, not a usual recipe amount.¹

1. Critics say

   Soy concentrate raises protein without adding meat

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   Three concentrates measured in a dog feeding study contained 70.4 to 72.2% protein on a dry basis. Crude protein counts plant protein, so a higher number cannot tell you how much meat the recipe contains.¹

2. Brands say

   Dogs digest it just like poultry meal

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   Small controlled dog trials found concentrate diets comparable to poultry meal for protein digestibility. Another tested concentrate less digestible than soybean meal. Processing and the rest of the recipe affect the result, so equal digestibility is not guaranteed.^1,2,3

3. Owners say

   Soy protein triggers food allergies in dogs

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   A review found soy reactions in 18 of 297 dogs with identified food reactions. In a separate challenge, 11 of 14 dogs already selected for soy and corn sensitivity reacted to soy. Neither group represents all dogs.^4,5

4. Owners say

   Soy concentrate makes dogs gassy

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   In a dog study comparing soy ingredients, soybean meal produced more intestinal gas, while concentrate did not differ from the reference food. The blanket claim transfers a finding about soybean meal to a different ingredient.³