Valorization of the Olive Oil Production Residue: Healthy Ingredient for Developing High Value-Added Spread

Abstract

This study focused on the development of a new olive-based product enriched with proteins, antioxidant compounds and functional properties, aiming at valorization of the olive residue from the typical olive oil extraction process. Olive oil was extracted using a patented cold pressing machine, resulting in a valuable source of bioactive compounds in the form of olive residue (pulp ~70%, pit- and skin-free). Conventional (solid: water ratio 1:4, 25 °C, 2 h) and HP-assisted (200 MPa, solid:water ratio 1/4, 10 min) de-bittering processes were carried out in order to remove oleuropein content (up to 50%) from olive residue, thus decreasing its bitter taste. The olive spread was prepared with olive residue (50%) and honey (25%), enriched with proteins (24.5%) from nuts. Quality parameters, nutritional attributes, microbiological analysis, phenolic compounds and oxidative stability as well as sensory evaluation of the olive spread were conducted during storage. Its shelf-life was estimated (prediction through accelerated tests) as 9.5 months when stored at 4 °C. The organoleptic evaluation showed that the proposed olive spread had a texture similar to peanut butter and could potentially be consumed as a health-promoting spread due to its high content of proteins (~10 g/100 g), crude fibers (>6 g/100 g) and essential fatty acids.