Enzyme-assisted extraction of proteins from Citrus fruits and prediction of their cultivar using protein profiles obtained by capillary gel electrophoresis

• Development of an improved method to extract proteins from Citrus fruit using enzymes.
• The method showed a faster extraction and higher recoveries.
• Establishment of Citrus fruit protein profiles by CGE.
• Protein profiles have been used to distinguish the genetic variety of Citrus fruit.

The suitability of protein profiles established by capillary gel electrophoresis (CGE) as a tool to discriminate between 11 cultivars of Citrus (orange and tangerine) peel and pulp was evaluated in this work. Before CGE analysis, different extraction buffers (which included enzyme-assisted treatments) were compared. The best results were achieved using 5% (v/v) Celluclast® 1.5 L and 5% (v/v) Palatase® 20,000 L buffers for Citrus peel and pulp protein extracts, respectively. The resulting protein profiles obtained were used to construct linear discriminant analysis (LDA) models able to distinguish Citrus peel and pulp samples according to their cultivar. In both cases, all samples were correctly classified with an excellent resolution among all categories, which demonstrated that protein patterns are a powerful tool to discriminate Citrus samples coming from different cultivars.