Rapid Salt‐Assisted Microwave Demulsification of Oil‐Rich Emulsion Obtained by Aqueous Enzymatic Extraction of Peanut Seeds

Abstract

Aqueous enzymatic extraction (AEE) is an environmentally friendly edible-oil-extraction process that can also provide edible protein. However, the AEE process may form a stable emulsion in most cases, which seriously limits the large-scale industry applications for producing vegetable oils. In this study, the salt-assisted microwave radiation demulsification of the oil-rich emulsion prepared with AEE from peanuts is investigated. The microwave demulsification method is compared with other conventional demulsification methods, including heating, and freezing-thawing. The salt-assisted microwave demulsification of the emulsions shows a greater free oil yield than conventional heating demulsification. Moreover, the microwave demulsification shows a similar free oil yield in less time than freezing-thawing method. Under the optimal operating conditions of demulsification, the free oil yield can reach 92.3% with CaCl 2 -assisted microwave demulsification for only 2 min. In addition, the oxidative properties and the fatty acid compositions of the demulsified peanut oil are investigated. No significant difference in the fatty acid composition is observed among salt-assisted microwave, freezing-thawing, and heating demulsified oil. The oxidative properties of the salt-assisted microwave demulsified peanut oil is better than the conventional heating demulsified oil. Thus, salt-assisted microwave demulsification provides a quick and effective demulsification method to obtain vegetable oils with high quality. Practical Applications: Aqueous enzymatic extraction (AEE) is an environmentally friendly edible-oil-extraction process. To solve the problem of stable emulsion formed during AEE process, the salt-assisted microwave demulsification of the oil-rich emulsion prepared with AEE is developed with high efficiency (demulsification for 2 min). In addition, the oxidative properties of the microwave demulsified oil is better than the conventional heating demulsified oil.

Low-Temperature Esterification to Produce Oleic Acid-Based Wax Esters Catalyzed by 4-Dodecylbenzenesulfonic Acid

“…When 100% water was added (Figure 7b), the reaction system formed a white turbid emulsion, which was consistent with the speculation of Manabe et al [16]. However, when the same amount of salt solution (saturated CaCl2 solution) was added (Figure 7c), the reaction system showed obvious stratification phenomenon, which indicated that inorganic salt (e.g., CaCl2) played a demulsifying effect [19]. Thus, DBSA indeed exhibited as a surfactant-combined acid catalyst, and the water generated by esterification will be removed from the reaction system due to its internal hydrophobicity (Figure 8).…”

Aqueous Integrated Process for the Recovery of Oil Bodies or Fatty Acid Emulsions from Sunflower Seeds

“…Many studies have reported the development of ultrasound-assisted AOE [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ], but other methods are also used, including microwave- [ 29 ], pulsed electric field-[ 9 ], pressure shockwave- [ 30 ] and surfactant-assisted [ 31 , 32 ] extraction. Unlike conventional extraction with an organic solvent, aqueous extraction from oilseeds often gives rise to emulsions, and the recovery of lipids and proteins with good yields involves a de-emulsification step leading to disorganization of the inherent structure of the oil body [ 24 , 33 , 34 ]; however, the use of OBs as a formulated emulsion may be of considerable utility, as emulsions of this type have a remarkable physical stability and contain many valuable natural compounds, such as phospholipids and tocopherols. Several studies have recently focused on isolated OBs, highlighting their physical stability [ 35 , 36 ], organization and functional properties [ 13 , 35 , 36 , 37 , 38 ] and their interactions with other substances [ 39 ].…”

Development of sustainable downstream processing for nutritional oil production

“…While cell disruption methods and solvent types are frequently replaced or modified more than the solvent extraction method (which generally follows a standard procedure), successful modifications have been achieved previously and newer methods such as supercritical fluid extraction (SFE) and aqueous enzymatic extraction (AEE) are increasingly available for exploitation ( Patil et al, 2018 ; Anto et al, 2020 ; Liu et al, 2020 ). These newer methods are comparatively lower in toxicity and energy requirements than traditional solvent extraction procedures.…”

“…Unfortunately, saponification is unsuitable for PUFAs due to low yields; while trans-esterification allows a greater FA yield than normal extraction, yet conversion of esterified products back to FAs is energy consuming (involves additional steps), making wider use undesirable ( Lewis et al, 2000 ; Li et al, 2019 ). AEE (otherwise known as enzyme-assisted aqueous extraction processing or EAEP) utilises different enzyme compositions to extract lipids out of cell biomass using water as the solvent for oil extraction ( Liang et al, 2012 ; Du et al, 2017 ; Kumar et al, 2017 ; Liu et al, 2020 ). AEE is highly environment-friendly, safe and more cost effective than conventional extraction ( Wu et al, 2017 ).…”

“…However, temperature and pH must be tightly controlled for maintaining the enzyme activity, and AEE often forms an emulsion which is limiting due to the requirement of adding a demulsification step ( Kumar et al, 2017 ). Use of microwave demulsification may address this and has previously improved oil quality ( Liu et al, 2020 ). Multiple disruption methods have been combined with AEE achieving relative success, such as the combination of AEE and alkaline pre-treatment resulting in the extraction of 90% of total lipid ( Wu et al, 2017 ).…”