Recovery and purification of proteins from grape seed byproducts using proteomic and separative techniques

Abstract

Grape seeds account for around 5% of the weight of the whole grape berry, representing approximately 40%-50% of the solid by-products that the different wine industries generate during the winemaking process. Among all the grape seed components, proteins account for 10-13%. The use of these proteins could be of interest in technological applications for the food industry and others.
According to their solubility in different solvents, vegetable seed proteins have been classified into albumins (soluble in water), globulins (soluble in salt), prolamins (soluble in aqueous alcohol) and glutelins (soluble in acid or alkaline solution), respectively.
So far, most of the polypeptide components identified by electrophoretic analysis and mass spectroscopy in grape seed endosperm showed high homology with 11S globulin-like seed storage proteins from other plant species.
The ability of proteins to modulate food properties is highly dependent on their structural features. In this respect, there are still no studies that reveal the three-dimensional structure of these proteins in grape seed using x-ray or nuclear magnetic resonance techniques. However, there are studies using computational techniques for a 7S-type globulin from grape seed.  Therefore, the identification and subsequent elucidation of the morphology of proteins is crucial to define their potential uses and technological applications.
The aim of this work was to identify the different types of grape seed endosperm proteins from the by-product of the wine industry. For this purpose, the industrial by-product was subjected to different extractions to fractionate and purify the proteins into albumins, globulins and prolamins. In addition, quantification of the different fractions was carried out to clarify which type of protein is the majority. To carry out this work, a proteomic study based on SDS-page electrophoresis and mass spectroscopy was developed. These studies will provide new knowledge that will help to develop possible applications of seed proteins in the food industry.