Alkaline Extraction and Purification of Huauzontle (Chenopodium berlandieri subsp. Nuttalliae) Seed Proteins by Ultrafiltration Membranes

Abstract

Huauzontle (Chenopodium berlandieri subsp. Nuttalliae) is a species native to Mexico. Over the centuries, important nutritional and medical properties have been attributed to this species in ancient Mexican tradition. In contrast, quinoa (Chenopodium quinoaWilld.), an Andean crop genetically related to huauzontle, has been widely studied and acknowledged for its outstanding potential as a high quality protein source. Considering this, the main objective of this study was to obtain and purify the protein fractions of huauzontle seeds using alkaline extraction, isoelectric precipitation, and ultrafiltration membrane technology. Different pH settings were tested for the extraction and precipitation operations and pH 11 and 3.5 were selected, respectively. The protein mass balance for both extraction and precipitation, accounted for 96.6% and 98.7% of the proteins respectively. Using a 10 kDa ultrafiltration membrane, the protein was concentrated and purified by ultrafiltration and diafiltration at 45-50 °C with a concentration factor of 4 and a diafiltration volume of 4. A precipitated protein isolate was obtained with 78.96% purity. In this study, a process that combines alkaline extraction, isoelectric precipitation and ultrafiltration membrane technology was successfully employed to separate and purify huauzontle protein fractions to a level comparable to those reported in the literature for other proteinaceous seeds. In addition, this work will help to establish huauzontle, an ancient native Mexican crop, as an important source of protein, which can also be used as a protein supplement for staple foods.