Evaluation of the pressing process during oil extraction from grape seeds

Abstract

This study evaluated the physical properties and oil extraction from grape seeds from three white (Welschriesling, Green Veltliner, Hibernal) and two red (Zweigelt and Saint Laurent) must varieties of grapevine by cold screw pressing as the appropriate extraction process. Pressing was carried out by a screw press UNO FM 3F by Farmet Company, Czech Republic. The pressing device consists of a matrix, 220 mm screw, head, heating mantle, nozzle holder, and a nozzle of 10 mm in diameter. The minimal and maximal screw rotation speeds were chosen within the press characteristics in order to achieve a correct expression and to avoid press overload. For successful pressing of the seeds and their storage, their initial moisture content was lowered from 40 to 45% to about 5 to 8% in a chamber dryer. The temperature in the chamber dryer did not exceeded 40 °C. Seeds of all varieties were pressed at the same speeds of 20, 40, 60, and 80 rpm. The characteristics of the grape seeds are as follows: The density ranges from 602.7 to 606.3 kg.m -3 , thousand seeds weigh is between 21.9 -26.6 g, humidity between 5.6 -7.1% of dry matter and seed oil content, determined by extraction and depending on the variety, ranges from 15.3 to 17.5% in dry basis. The results have confirmed that when the screw rotation speed is changed from 20 to 80 rpm, the press capacity increases on average from 0.84 kg.h -1 to 1.75 kg.h -1 , but simultaneously the oil yield reduces from 9.85 to 6.75%. This means that one kilogram of seed may produce 67.5 to 98.5 g of oil. The quantity of the pressed oil ranges from 67.5 to 98.5 g.kg -1 and thus depends on the variety. The measured results can be used in commercial practice for optimizing the pressing process for pressing of oil from grape seeds.

Cold press in oil extraction. A review

“…Burg [16] aimed evaluation of grape seed oil extraction process and 3 white (Welschriesling, Green Veltliner, Hibernal) and 2 red (Zweigelt ve Saint Laurent) grape seeds used for oil production. All seeds moisture and oil contents, 1000 grain weight, density were determined.…”

Thermal aging of edible oils: spectrophotometric study

“…On the other hand, triesters can hydrolyze and produce glycerides and free fatty acids, and non-saturated chains can react with oxygen to produce oxidative products responsible for lipids deterioration. These two phenomena are the cause of two major forms of changes in food fats, i.e., acidification and oxidation (Burg et al, 2017).…”

Optimization of cold press and enzymatic‐assisted aqueous oil extraction from tomato seed by response surface methodology: Effect on quality characteristics

“…The highest oil yield was obtained the inlet temperature of 80°C, the feed flow rate of 0.4 kg/h, and screw rotation rate of 20 rpm, while the lowest oil yield was found in the highest inlet temperature. There are some other studies, which investigated the critical parameters affecting oil amount in cold pressing extraction such as characteristics of the raw material (moisture content, oil content, and type of raw material) (Burg et al., 2017; Rombaut et al., 2015), feed rate (Teh, 2016), temperature (Rabadán et al., 2018), cold rotation speeds (Teh, 2016), and, pre‐treatment (Pare et al., 2014), etc. Since the effects of parameters used in this study on the oil extraction were found significant in the previous studies and the effects of these parameters on tomato seed oil extraction by the cold‐pressing method have not been searched before, these parameters were chosen for the optimization.…”

“…Burg et al. (2017) were found the significant effect of screw rotation rate on the oil extraction from grape seed (Burg et al., 2017). Rabadan et al.…”

“…In this study, oil yield obtained by cold pressing was found between 5.12% and 6.65%. Burg et al (2017) were found the significant effect of screw rotation rate on the oil extraction from grape seed (Burg et al, 2017). Rabadan et al (2018) extracted oil from almond, walnut, and peanut using cold-pressed extraction and investigated the effect of temperature and screw rotation rate on the oil extraction.…”