Comprehensive Characterization of Raw and Processed Quinoa from Conventional and Organic Farming by Label-Free Shotgun Proteomics.

Quinoa is widely recognized for its exceptional nutritional properties, particularly its complete protein content. This study, for the first time, investigates the effects of processing methods (boiling and extrusion) and farming conditions (conventional and organic) on the proteomic profile. Following a label-free shotgun proteomics approach, a total of 1796 proteins were identified and quantified across all quinoa samples. Regarding processing, both boiling and extrusion produced protein extracts with lower total protein content, with the number of identified proteins decreasing from 1695 in raw quinoa to 957 in processed quinoa. Boiling led to a reduction in protein diversity and expression, while extrusion, which involves high temperatures and pressures, specifically decreased the abundance of high molecular mass proteins. Concerning cultivation practices, organic farming was associated with a broader protein diversity, especially proteins related to translation (28 vs 5%), while conventional farming showed a higher abundance of catalytic and enzymatic proteins (67 vs 46%). These findings highlight the distinct proteomic changes induced by different processing methods and farming conditions, offering valuable insights to manage quinoa's nutritional, bioactive, and functional properties across various production practices.