Extracting oil from grape seed using a combined wet enzymatic process and pressing

The novel method of wet enzymatic extraction and pressing (WEEP) was used to extract grape seed oil. Low-field nuclear magnetic resonance (LF-NMR) was applied to elucidate the water mobility and distribution of grape seeds during the process. The extraction variables were selected in accordance with a Plackett-Burman (PB) design, and the statistical model was constructed using response surface methodology (RSM). The results revealed that water mobility variations of the samples could be discriminated using the signal amplitude and peak position of the T2 inversion spectrum. The increase in water content was affected by the time and temperature of the process. The water migration of the samples was monitored clearly and intuitively using magnetic resonance imaging (MRI). Three significant factors out of the six variables (enzyme additive amount, hydrolysis temperature, hydrolysis time, comminution degree, screw speed, squeezed water) were determined. The ideal values of the significant factors were confirmed to be 1% of enzyme additive amount, 60 mesh of comminution degree, and 8% of squeezed water. The residual oil proportion to the initial oil content decreased significantly with parameter optimization (33.24% ± 5.98%) compared with that of the unoptimized parameters (57.79% ± 4.13%).