Skip to main content
ARS Home » Pacific West Area » Aberdeen, Idaho » Small Grains and Potato Germplasm Research » Research » Publications at this Location » Publication #434473
Research Project: Innovations in Feed Science, Farming Practices, and Broodstock Management to Improve Sustainability of Salmonid Aquaculture

Location: Small Grains and Potato Germplasm Research

Title: Comparison of AOCS Ba 15-2023 and ISO 14244:2014 methods for measuring soluble proteins in protein products

Author
item Liu, Keshun

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/2/2026
Publication Date: 4/24/2026
Citation: Liu, K. 2026. Comparison of AOCS Ba 15-2023 and ISO 14244:2014 methods for measuring soluble proteins in protein products. Meeting Abstract. https://annualmeeting.aocs.org/program/technical-program/.

Interpretive Summary:

Technical Abstract: For describing protein quality, protein solubility is the primary parameter that affects both nutritional values and functional properties of a protein product and determines how it can be used for specific applications. There are two official methods for measuring protein solubility index based on hydroxide extraction: ISO Method 14244:2014 and AOCS Method Ba 15-2023. The ISO method was initially developed several decades ago, while development of the AOCS method was rather recent. Although the two methods share a few minor similarities, they have several major differences with respect to procedures and features. First, for extracting proteins, the ISO method uses 0.2% KOH (35.7 mM) solution, while the AOCS method uses 5 mM hydroxide solution (0.02% NaOH or 0.028% KOH). This is because the ISO method was developed mainly for heated or overheated protein products, while the AOCS method covers all kinds of samples: raw, under or overheated. Consequently, the AOCS method has wider sample scope (oilseeds, pulses and cereals) and higher sensitivity. Second, the ISO method measures soluble nitrogen (proteins) in extracts directly by the Kjeldahl method. The AOCS method determines soluble nitrogen in extracts indirectly by measuring dried precipitates with the Dumas (combustion) method. The Dumas method is gaining popularity because it is simple, fast, and generates no chemical waste. Simply replacing Kjeldahl with Dumas method to measure soluble nitrogen in extracts can introduce variable results. Third, the AOCS method has higher correlation with trypsin inhibitor activity, which is widely considered the best index for the nutritional value of soy protein products. Due to its wider sample scope, higher sensitivity, modern technology for sustainability, safety and efficiency, and higher correlation with trypsin inhibitor activity, the AOCS method has been proposed for an ISO standard.