Impact of Hydro-Alcoholic Solvents on the Oil and Phenolics Extraction from Walnut (Juglans regia L.) Press-Cake and the Self-Emulsification of Extracts

Abstract

The objective was to evaluate the performance of four hydro-alcoholic solvents to simultaneously extract oil and more polar molecules as phenolics, among others, to produce complex extracts that eventually could self-emulsify after solvent removal. Walnut press-cake was selected as the sourcing material. Extractions were performed as a semi-continuous operation up to a solvent-to-solid ratio of 28, with a fractional collection of the effluent. Among the solvents, labelled by their alcohol content EtOH 58, EtOH 86, iPro 60 and iPro 90 for ethanol (EtOH) and isopropanol (iPro), iPro 90 allowed to reach an oil extraction efficiency of 97% while the recovery for the other solvents was in the range of 30–40%. For both alcohols, the increase of the solvent hydration negatively influenced the oil extraction but positively increased the recovery of phenolics that reached 17.6 mg GAE/gcake when EtOH 58 was used. Several fractions contained enough surface-active material and oil to self-assemble as emulsions. IPro 90 and EtOH 86 showed better performances in the sense that most extracts were able to emulsify, though extraction kinetics pointed out differences. The most hydrated solvents behaved equally, with extraction yields in the same range and a similar but limited emulsifying capacity of only few fractions.

Physicochemical properties and fatty acid profile of oil extracted from black soldier fly larvae (Hermetia illucens)

“…Hydraulic compression-producing oil (M method) showed a yellow cloudy oil, which may be due to the pigment content [38,39]. The high polarity of E is This finding is in agreement with previous studies in which E-based solvents appear slightly more colored [41,42]. Similar to a previous study by Wu et al [43], our study found that the color of the BSFL oil extracted by the aqueous method is clear yellow.…”

Selective Recovery of Polyphenols from Discarded Blueberries (Vaccinium corymbosum L.) Using Hot Pressurized Liquid Extraction Combined with Isopropanol as an Environmentally Friendly Solvent

“…For example, Bánvölgyi et al [30] have demonstrated that an increase from 30 to 60 • C with 50% isopropanol improved the total polyphenol content by ~9.2 times compared to pure water under the same conditions. Subra-Paternault et al [31] reported that the use of 60% isopropanol allowed for the recovery of 77% more total polyphenol content compared to use of 86% ethanol at 60 • C. Isopropanol presents a lower dielectric constant (ε: 19.92) compared to pure water (ε: 80) and ethanol (ε: 24.3) [32,33]. Thus, the presence of isopropanol in the solvent reduces its polarity, improving the solubilization of polyphenols.…”

“…Additionally, isopropanol presents two functional groups (polar and nonpolar), where the hydroxyl group (polar) and isopropyl group (nonpolar) can interact with the hydroxyl groups and aromatic rings of the polyphenols, respectively. Consequently, the solubility of polyphenols can be improved [31,34].…”

Supercritical Carbon Dioxide Extraction of Vegetable Oils: Retrospective and Prospects

“…[ 5,34,35 ] Though use of non‐distilled alcohols can cut down the cost of extraction it will preferentially extract other polar compounds along with non polar triglycerides. [ 36 ] The recovery of alcohols is also a major concern as these form azeotropes. [ 37 ] Various bio‐based solvents like d‐limonene, p‐cymene were also tried.…”