Sodium chloride compared to talc as processing aid has similar impact on volatile compounds but more favourable on ortho-diphenols in virgin olive oil

The possibility of improvement of olive paste extractability by addition of talc or NaCl (1%, 2% and 3% mass ratio in olive paste), or their combinations (“talc 1.5% + NaCl 1.5%” ; “talc 1% + NaCl 2%” ; “talc 2% + NaCl 1%”), was investigated on a laboratory scale. Volatiles in oil samples were determined by headspace solid-phase microextraction with GC-MS, while ortho-diphenols by solid phase extraction and UV-VIS spectrophotometer. Significantly higher extractability of oil (from 25 to 29% compared to control, P < 0.05) was obtained by 3% of talc or NaCl and their combinations in mass ratio 1:2 or 2:1. At 3% addition level, no significant decrease of C6 aldehydes was observed, while significant increase of C6 alcohols (talc or salt) as well as of C5 compounds and terpenes (salt) occurred. Mass ratio of ortho-diphenols in oil was not influenced by talc, while NaCl led to significantly higher values compared to control (by 10-15%, P < 0.05). Practical applications: The influence of processing aids on characteristics of virgin olive oil has mainly been evaluated through the standard chemical quality parameters, while limited information about desirable volatile compounds of thus obtained extra virgin olive oils has been published so far. The results of this research show that NaCl can be used not only as a tool for enhancing the extractability, but also as a means for improving the nutritional value of virgin olive oils from cultivars which generally shows low levels of hydrophilic phenols