Overview
EN ISO 14244:2016 (ISO 14244:2014) defines a laboratory method for determining soluble proteins in oilseed meals (soya meals, rapeseed meals and sunflower pellets) by extraction in a potassium hydroxide solution followed by nitrogen assay using the Kjeldahl method (ISO 5983‑1 / ISO 5983‑2). The method reports the soluble protein content as grams of soluble protein per 100 g of total protein.
Key topics and technical requirements
- Scope: Applicable to soya, rapeseed meals and sunflower pellets; sampling and sample preparation are referenced to ISO 5500 and ISO 5502.
- Extraction chemistry: Sample dispersed in a KOH solution of approximately pH 12.5 (prepared as c(KOH) = 0.036 mol/L).
- Sample preparation:
- Grind to pass 250 µm sieve (soya, rapeseed) or 500 µm sieve (sunflower).
- If fat > 5%, defat by cold extraction with n‑hexane or equivalent.
- Procedure highlights:
- Typical test: 1.5 g milled sample + 75 ml KOH solution, stirred ~20 min to suspend solids.
- Centrifuge clarified extract at ~800 g (±100 g) for 10 min; filter if necessary.
- Analyse 25 ml aliquots of filtrate by Kjeldahl; determine nitrogen of original milled sample in duplicate. (A 25 ml aliquot corresponds to 0.5 g of original milled sample.)
- Result expression: Soluble protein (%) = (N_s / N_t) × 100, where N_s is nitrogen in the soluble fraction and N_t is nitrogen in the whole sample. Report to one decimal place.
- Apparatus/controls: analytical balance (0.001 g), magnetic/mechanical stirrer, appropriate centrifuge, volumetric pipettes, sieves and grinders.
- Quality & precision: Precision data, repeatability and reproducibility values are provided from interlaboratory studies (Annex A).
- Safety & environment: Warnings on reagent hazards and disposal; use analytical‑grade reagents and follow environmental precautions.
Applications and users
- Who uses it: feed and oilseed testing laboratories, quality control in oilseed processing plants, animal feed manufacturers, regulatory and research labs.
- Practical uses:
- Assessing protein solubility to inform feed formulation and protein quality evaluation.
- Comparing processing effects (e.g., heat or solvent treatments) on protein solubility.
- Compliance testing and specification verification in trade of oilseed meals.
Related standards
Keywords: EN ISO 14244:2016, ISO 14244:2014, oilseed meals, soluble proteins, potassium hydroxide extraction, Kjeldahl, protein analysis, soya meal, rapeseed meal, sunflower pellets, laboratory method.