The quality of virgin olive oils gradually deteriorates during the phase of storage after their production. Moisture, microorganisms, enzyme activities and proteins such as lipases, lipoxygenases and oxidases present in oils are in part responsible for the quality losses. A more efficient control of the clarification stage of production, either by optimizing the variables of the horizontal centrifuge, the vertical centrifuge or by using different types of filtration to eliminate solid particles, proteins, moisture, and microorganisms may originate olive oils of better quality.
The characterization of the protein and amino acid contents present virgin olive oils during their different production stages has not been investigated so far. We investigated the protein concentration of virgin olive oils obtained from green, turning and mature olives, after the horizontal centrifuge, vertical centrifuge and filtration phases of production. Olive oils from olives collected at the turning phase ripening contained the highest concentration of proteins (55,8 mg/100g of olive oil), measured by LECO, followed by matured (25,7 mg/100g) and green olives (19,7 mg/100g). The vertical centrifugation step reduced the protein concentration of olive oils by approximately 90% compared with the horizontal phase of centrifugation. The industrial filtration step originated olive oils with negligible amounts of protein. The clarification steps of production exerts a great impact on the protein concentration of olive oils and may influence olive oil quality.