The effect of using water and talc to improve oil yield was examined for the case of the Carrasqueña cultivar for the first time. The influence of these treatments to the antioxidant content (phenols and tocopherols) and quality parameters of the oil are discussed with regard to findings for Picual cultivar (a cultivar extensively studied in the past for various reasons) oils extracted and analyzed under the same conditions. Before the oil extraction the fruits from both cultivars were characterized for the ripening index, flesh/stone ratio, moisture, oil content, and instrumental color of fruits and crushed fruits. Water addition caused a decrease in oil yield and extractability, an increase in the peroxide index and a decrease in K270 and the total phenol content, whereas the instrumental color was scarcely affected. Talc addition resulted in an increase in oil yield and extractability, a decrease in the peroxide index and α-tocopherol content and a marked effect on the instrumental color measurement. Results show that for both Carrasqueña and Picual cultivars (fruits with a ripening index of 5.14 and 4.92, and a moisture content of 53.0 and 56.2%, respectively) water addition at a 42.9% w/w is not advisable. Conversely, talc addition increases oil yield without affecting negatively the quality parameters, although it decreases α-tocopherol content and has a marked effect on oil color.
Practical applications: This paper shows the effect at a laboratory scale of adding talc and water to olive fruits from two different cultivars on oil yield, some quality parameters, tocopherol and phenol content and color. Results indicate that water addition to the paste during malaxation has important drawbacks such as a negative effect on some quality parameters which are relevant in the official olive oil grading (peroxide index and K270), and also in oil yield and phenol content. Conversely, talc addition has important advantages such as an increase in oil yield without affecting negatively the quality parameters, although it decreases α-tocopherol content and affects oil color.