Optimised methodology for the extraction of protein from quinoa (Chenopodium quinoa Willd.)

Quinoa is a highly appreciated Andean pseudo-cereal and has sparked attention worldwide due to its excellent nutritional value. The protein extraction parameters for defatted quinoa seed meal (DQSM) were optimised in this study. Initially, a Plackett-Burman design was applied to screen the factors displaying a potential effect on the quinoa protein extraction yield (Y %, g soluble protein/100 g total protein) being the main evaluated factors: pH, NaCl concentration, time, temperature, solvent type, particle size and solvent/meal ratio. Four main factors: temperature, solvent/meal ratio, pH and time selected from the screening step were optimised with a central composed design (CCD). The obtained response surface model (RSM) produced a satisfactory fitting of the results (R² = 0.9308). Optimal quinoa protein extraction conditions of 36.2 °C, solvent/meal ratio of 19.6/1 (v/w) and 90 min resulted in a protein yield of 62.1% (9.06 g of protein/100 g DQSM) which closely agree with the predicted value of 62.5%.The model was experimentally validated by extracting the quinoa protein using the optimal conditions revealed by RSM. The optimised conditions could be successfully employed in the design process of protein extraction from quinoa seed meal to obtain optimal yields.