Protein Solubility Calculator
Calculate protein content and solubility using the Kjeldahl method with titration analysis
Kjeldahl Method Analysis
Titration volume without analyte (control)
Titration volume with sample
Concentration of sodium hydroxide solution
Weight of the protein sample analyzed
Protein Analysis Results
Kjeldahl Formula: P = 1.401 × 6.25 × 5 × (B - T) × N / M
Input values: B: 0 mL, T: 0 mL, N: 0.000 g/L, M: 0.000 g
Constants: 1.401 (conversion factor), 6.25 (protein factor), 5 (dilution factor)
Solubility Analysis
Example Calculation
Soy Protein Analysis Example
Sample: Soy protein isolate (2.5 g)
Blank titer: 7.0 mL (control without sample)
Sample titer: 6.0 mL (with protein sample)
NaOH normality: 98 g/L
Effective weight: 55 g
Step-by-Step Calculation
1. Calculate constant: 1.401 × 6.25 × 5 = 43.78
2. Calculate titer difference: 7.0 - 6.0 = 1.0 mL
3. Calculate normality ratio: 98 ÷ 55 = 1.782
4. Final calculation: 43.78 × 1.0 × 1.782 = 78.01%
Result: 78.01% protein solubility
Kjeldahl Method Steps
Digestion
Heat sample with H₂SO₄
Converts nitrogen to NH₄⁺
Distillation
Add NaOH and distill
Converts NH₄⁺ to NH₃
Titration
Titrate with standard acid
Quantify nitrogen content
Factors Affecting Solubility
Temperature: Higher temperatures generally increase solubility
pH: Optimal pH varies by protein type and structure
Ionic strength: Salt concentration affects protein interactions
Solvent additives: Buffers and stabilizers enhance solubility
Understanding Protein Solubility Analysis
What is Protein Solubility?
Protein solubility refers to the ability of proteins to dissolve in aqueous solutions. It's a critical parameter in food science, biotechnology, and pharmaceutical applications, determining how proteins behave in different formulations and processes.
Kjeldahl Method Principle
- •Determines total nitrogen content in organic compounds
- •Converts protein nitrogen to measurable ammonium
- •Uses protein factor (6.25) to estimate protein content
- •Widely accepted standard method for protein analysis
Formula Breakdown
P = 1.401 × 6.25 × 5 × (B - T) × N / M
- P: Protein solubility percentage
- 1.401: Conversion factor for nitrogen
- 6.25: Protein factor (100/16, assuming 16% N in protein)
- 5: Dilution factor
- B: Blank titer volume (mL)
- T: Sample titer volume (mL)
- N: NaOH normality (g/L)
- M: Effective weight of sample (g)
Note: The protein factor 6.25 is average for most proteins, but specific factors exist for different protein types
Applications & Importance
Food Industry
Quality control of protein ingredients, nutritional labeling, and functional properties assessment in food products.
Biotechnology
Protein purification optimization, formulation development, and stability studies in biopharmaceuticals.
Research
Protein characterization, structure-function relationships, and development of protein-based materials.