Micronized natural talc (MNT) has demonstrated to be very useful to break down emulsions formed during the virgin olive oil extraction process, improving the oil yield. This study was aimed to obtain more insights into the mechanisms of MNT to break down oil‐in‐water emulsions. For this purpose, laboratory scale experiments were performed in order to evaluate the effect of different pectin concentrations (0.5, 1, 1.5, and 2%), used as an emulsifier agent, on the behavior of an oil‐in‐water interface. Afterward, to evaluate the effect of MNT dosage as well as its physicochemical characteristics on breaking o‐reducing emulsions, four MNTs differing in their particle size (D50) and carbonate rate were assayed at doses ranging from 0 to 1%. Increasing pectin concentration gave a rise in the emulsifying activity (EA). The emulsifier effect of pectins was weakened by the addition of increasing MNT dose. MNT physicochemical characteristics markedly affected the breaking of oil‐in‐water emulsions. Nonetheless, its effect depends on the dose of MNT applied to the emulsion. The highest decrease in EA was observed for MNT with the lowest D50 (2.4 μm) and the highest carbonate rate (4%) at 0.5%. In general, MNT containing lower D50 and high rate of carbonate showed better capacity for breaking oil‐in‐water emulsion. Practical applications: So far as can be ascertained, no quantitative study has been made, in vitro, on the relative merits of MNT addition as a technological aid in breaking down oil‐in‐water emulsions. This study provides deeper insights into the clarification of the effect of pectins as emulsifier agents, on aqueous emulsions of Hojiblanca virgin olive oil and how the addition of different doses of MNT, with different physicochemical characteristics, carried out the breaking of the oil‐in‐water emulsions. Effect of micronized natural talc physicochemical characteristics and dosage on the break‐down of oil‐in‐water emulsion.

The aim of this work was to assess the effect of physicochemical characteristics of micronized natural talc (MNT) and its dosage on the industrial oil yield (IY) during virgin olive oil (VOO) extraction of Hojiblanca fruits. For this purpose, laboratory scale experiments were performed testing four commercial MNTs differing in their particle size (D50) and carbonate rate at doses ranging from 0 to 3%. The most efficient MNT was characterized by the highest carbonate rate and the lowest particle size achieving the highest improvement of the IY for a dose of 2%. It was also found that the effect of particles size and carbonate rate depends on the MNT dose, being much more pronounced at lower doses and that the use of MNTs with low carbonate levels or high particle size could be compensated using higher doses of talc. Practical applications: This study provides deeper insights into the clarification of the effect of the addition of different doses of MNT, with different physicochemical characteristics on oil yield of Hojiblanca olive fruits. The information contained in this study should be taken into account to choose the suitable MNT dose considering its physicochemical characteristics in order to improve the oil yield for the so‐called difficult pastes. Physical and chemical characteristics of talc affect VOO yield.

This work studies how using MNT affects cell wall polysaccharides and proteins of “Hojiblanca” paste during virgin olive oil extraction. Four doses of MNT were assessed: 0, 0.25, 0.5, and 1%. Three pectic fractions were extracted from alcohol insoluble solids (AIS): water‐soluble pectin (WSP), chelate‐soluble pectin (CSP), and non‐soluble pectin (NSP). In general, the content of the three pectic fractions decreased throughout the kneading step. This indicated a significant degradation and solubilization of pectins during processing. The same trend was observed for protein content and total pectin content while AIS yield increased. Addition of MNT at doses lower than 0.5% favored the formation of a chemical bound through electrostatic interactions between proteins and pectic polysaccharides which are held together and adsorbed onto the talc surface giving a decrease in their content. Higher MNT doses (1%) produced the opposite behavior. The lowest dose of MNT (0.25%) reduced the oil losses in the pomace. A certain tendency for the loss of oil in the pomace to decrease as the amount of total pectin and protein decreased was observed, indicating that the oil yield is at least in part, related to the pectin and protein content depending on the dose of MNT added during malaxation step. Practical application: We have demonstrated that the use of talc during the malaxation step greatly lessens the effect of the pectic substrates and proteins, principal emulsifier agents that influence the formation of oil‐in‐water emulsions during oil extraction process and enhance the extraction of the oil from the mesocarp cells by reducing its loose in the pomace. Excess of talk addition presented a reverse effect, though. It is, therefore, of the utmost importance that the information contained in this study is fully taken into account to establish the suitable dose of talc that should be applied when difficult pastes are formed during malaxation step and which at least partially depends on the content of proteins and pectin compounds of the processed olive paste. Proteins and pectic cell wall polysaccharides as affected by talc addition during virgin olive oil extraction.