Extraction of oil from high-moisture tuna liver by subcritical dimethyl ether: feasibility and optimization by the response surface method

Effect of microwave (MW)-subcritical extraction on oil recovery, oxidative stability, and lipid types from Katsuwonus pelamis livers

Katsuwonus pelamis is a tuna species mostly sold for canned fillets, its livers were lack of utilization. This study thus investigated an oil production method combining microwave (MW) pretreatment and subcritical dimethyl ether (SDME) in aim to reach improved efficiency and oil quality. The heating characteristics from different MW powers (400, 600, and 800 W) were evaluated, and SEM showed MW having hydrolysis effect on matrix lipoprotein, the fortified recovery rate was also found. Under the MW-SDME condition with 600 W power, 1:5 solid-to-liquid ratio, and 100 min, the recovery reached 93.21% in maximal (SDME ∼50%). To further improve quality, MW powers was noticed affecting lipid types, fatty acid composition, and oxidative stability of produced oils. 1286 lipid types (mostly glyceride and phospholipid-type) were identified, while higher MW lowered the emulsifying phospholipids prompting phase separation. Several oxidation indexes consistently increased with the rising MW power, GC-MS suggested 400 W for higher DHA.

Statistical Tools to Optimize the Recovery of Bioactive Compounds from Marine Byproducts

Techniques for extracting important bioactive molecules from seafood byproducts, viz., bones, heads, skin, frames, fins, shells, guts, and viscera, are receiving emphasis due to the need for better valorization. Employing green extraction technologies for efficient and quality production of these bioactive molecules is also strictly required. Hence, understanding the extraction process parameters to effectively design an applicable optimization strategy could enable these improvements. In this review, statistical optimization strategies applied for the extraction process parameters of obtaining bioactive molecules from seafood byproducts are focused upon. The type of experimental designs and techniques applied to criticize and validate the effects of independent variables on the extraction output are addressed. Dominant parameters studied were the enzyme/substrate ratio, pH, time, temperature, and power of extraction instruments. The yield of bioactive compounds, including long-chain polyunsaturated fatty acids, amino acids, peptides, enzymes, gelatine, collagen, chitin, vitamins, polyphenolic constituents, carotenoids, etc., were the most studied responses. Efficiency and/or economic and quality considerations and their selected optimization strategies that favor the production of potential bioactive molecules were also reviewed.

Extraction and Separation of Natural Products from Microalgae and Other Natural Sources Using Liquefied Dimethyl Ether, a Green Solvent: A Review

Microalgae are a sustainable source for the production of biofuels and bioactive compounds. This review discusses significant research on innovative extraction techniques using dimethyl ether (DME) as a green subcritical fluid. DME, which is characterized by its low boiling point and safety as an organic solvent, exhibits remarkable properties that enable high extraction rates of various active compounds, including lipids and bioactive compounds, from high-water-content microalgae without the need for drying. In this review, the superiority of liquefied DME extraction technology for microalgae over conventional methods is discussed in detail. In addition, we elucidate the extraction mechanism of this technology and address its safety for human health and the environment. This review also covers aspects related to extraction equipment, various applications of different extraction processes, and the estimation and trend analysis of the Hansen solubility parameters. In addition, we anticipate a promising trajectory for the expansion of this technology for the extraction of various resources.

Bioactives from Crude Rice Bran Oils Extracted Using Green Technology

Crude rice bran oils from different rice cultivars and extraction methods bear different contents of nutraceuticals. The health benefits of lowering cholesterol activity of rice bran oil being confirmed by many reports are partly attributed to non-nutrient nutraceuticals, especially γ-oryzanol, phytosterols, and policosanols. As the world has been facing the global warming crisis, green extraction technology is gaining attention from many sectors. The current study aims to compare the nutraceutical composition with respect to γ-oryzanol, phytosterol, and policosanol content as well as the antioxidant properties of crude rice bran oils extracted from white and red rice bran using three green technologies, comparing with conventional hexane extraction. The data show that the traditional solvent extraction gave the highest oil yield percentage (26%), but it was not significantly different from subcritical liquefied dimethyl ether extraction (24.6%). Subcritical liquefied dimethyl ether extraction gave higher oil yield than supercritical CO2 extraction (15.5–16.2%). The crude rice bran oil extracted using subcritical liquefied dimethyl ether extraction produced the highest total phenolic contents and antioxidant activities. The highest γ-oryzanol content of the crude rice bran oil was found in oil extracted by conventional cold press (1370.43 mg/100 g). The γ-oryzanol content of the oil obtained via subcritical liquefied dimethyl ether extraction was high (1213.64 mg/100 g) compared with supercritical CO2 extraction. The red rice bran yielded the crude rice bran oil with the highest total phytosterol content compared with the white bran, and the oil from red rice bran extracted with subcritical liquefied dimethyl ether generated the highest total phytosterol content (1784.17 mg/100 g). The highest policosanol content (274.40 mg/100 g) was also found in oil obtained via subcritical liquefied dimethyl ether extraction.

High Levels of Policosanols and Phytosterols from Sugar Mill Waste by Subcritical Liquefied Dimethyl Ether

Extracting nutraceuticals with high value from bagasse, filter mud, and sugarcane leaves discarded as sugar mill by-products, is crucial for the development of a sustainable bio-economy. These by-products are important sources of policosanols and phytosterols, which have a cholesterol-lowering effect. This research focused on using a promising green technology, subcritical liquefied dimethyl ether extraction, with a low pressure of 0.8 MPa, to extract policosanols and phytosterols and on application of pretreatments to increase their contents. For direct extraction by subcritical liquefied dimethyl ether without sample pretreatment, the highest extraction yield (7.4%) and policosanol content were found in sugarcane leaves at 2888 mg/100 g, while the highest and lowest phytosterol contents were found in filter mud at 20,878.75 mg/100 g and sugarcane leaves at 10,147.75 mg/100 g, respectively. Pretreatment of filter mud by ultrasonication in hexane solution together with transesterification before the second subcritical liquefied dimethyl ether extraction successfully increased the policosanol content, with an extract purity of 60%, but failed to increase the phytosterol content.

Sustainable Synthesis of Omega-3 Fatty Acid Ethyl Esters from Monkfish Liver Oil

The search for economic and sustainable sources of polyunsaturated fatty acids (PUFAs) within the framework of the circular economy is encouraged by their proven beneficial effects on health. The extraction of monkfish liver oil (MLO) for the synthesis of omega-3 ethyl esters was performed to evaluate two blending systems and four green solvents in this work. Moreover, the potential solubility of the MLO in green solvents was studied using the predictive simulation software COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS). The production of ethyl esters was performed by one or two-step reactions. Novozym 435, two resting cells (Aspergillus flavus and Rhizopus oryzae) obtained in our laboratory and a mix of them were used as biocatalysts in a solvent-free system. The yields for Novozym 435, R. oryzae and A. flavus in the one-step esterification were 63, 61 and 46%, respectively. The hydrolysis step in the two-step reaction led to 83, 88 and 93% of free fatty acids (FFA) for Novozym 435, R. oryzae and A. flavus, respectively. However, Novozym 435 showed the highest yield in the esterification step (85%), followed by R. oryzae (65%) and A. flavus (41%). Moreover, selectivity of polyunsaturated fatty acids of R. oryzae lipase was evidenced as it slightly esterified docosahexaenoic acid (DHA) in all the esterification reactions tested.

Upgrading of marine (fish and crustaceans) biowaste for high added-value molecules and bio(nano)-materials

Currently, the Earth is subjected to environmental pressure of unprecedented proportions in the history of mankind. The inexorable growth of the global population and the establishment of large urban areas with increasingly higher expectations regarding the quality of life are issues demanding radically new strategies aimed to change the current model, which is still mostly based on linear economy approaches and fossil resources towards innovative standards, where both energy and daily use products and materials should be of renewable origin and 'made to be made again'. These concepts have inspired the circular economy vision, which redefines growth through the continuous valorisation of waste generated by any production or activity in a virtuous cycle. This not only has a positive impact on the environment, but builds long-term resilience, generating business, new technologies, livelihoods and jobs. In this scenario, among the discards of anthropogenic activities, biodegradable waste represents one of the largest and highly heterogeneous portions, which includes garden and park waste, food processing and kitchen waste from households, restaurants, caterers and retail premises, and food plants, domestic and sewage waste, manure, food waste, and residues from forestry, agriculture and fisheries. Thus, this review specifically aims to survey the processes and technologies for the recovery of fish waste and its sustainable conversion to high added-value molecules and bio(nano)materials.

Extraction of oil from wet Antarctic krill (Euphausia superba) using a subcritical dimethyl ether method

In this study, a novel method for obtaining high-quality krill oil from wet Antarctic krill by using subcritical dimethyl ether (SDE) was proposed. A response surface design was used to obtain the best SDE extraction parameters. The optimum extraction efficiency of 93.77 ± 0.92% was obtained at a stirring speed of 1030 rpm, temperature of 47 °C and dynamic extraction time of 90 min. Compared with n-hexane, ethanol, supercritical CO2 and subcritical n-butane extraction, the krill oil extracted by SDE exhibited low peroxide values (1.46 ± 0.26 mmol kg-1), high astaxanthin (218.06 ± 4.74 mg kg-1), phosphatidylcholine (PC) (33.95 ± 0.65%), and phosphatidylethanolamine (PE) (11.67 ± 0.23%) content. Moreover, krill oil extracted by SDE has high levels of EPA (16.38 ± 0.05%) and DHA (7.91 ± 0.07%). SDE extraction proved to be an efficient and safe method for extraction of quality krill oil from wet Antarctic krill, and it could be a promising method for oil extraction in wet food in future.

The comparison of krill oil extracted through ethanol-hexane method and subcritical method

This study aimed to develop a safe method EH (ethanol-hexane) to extract two kinds of krill oil (KO) simultaneously and analyze their composition. Meanwhile, subcritical butane and subcritical butane-dimethyl ether extraction were used to extract KO for analysis comparison. Folch method was used to extract total lipids. When the volume ratio of ethanol to hexane is 4:6, the separation effect of ethanol layer and hexane layer is best. At this condition, the EH method yielded similar amount of lipids (up to 97. 72% of total lipids) with subcritical butane extraction method (97.60%). The recovery rate of ethanol and hexane was 83.6% and 86.86%, respectively. KO in hexane layer and extracted by the subcritical butane method are abundant in astaxanthin (910 and 940 mg/kg respectively), while KO in the ethanol layer had the highest phospholipid (PL) content (47.34%), n-3 polyunsaturated fatty acids (PUFA) content (45.51%), and the lowest fluorine content (11.17 μg/g), making it a potential candidate in the nutraceutical and antioxidant industry.

Fish Oil Emulsions Stabilized with Caseinate Glycated by Dextran: Physicochemical Stability and Gastrointestinal Fate

Incorporation of fish oil containing ω-3 polyunsaturated fatty acids (PUFAs) into functional foods remains challenging. In this study, caseinate and glycoconjugates (CD6, CD40, CD70, CD100) of caseinate to dextrans of different molecular weights (D6, D40, D70, D100 kDa) were used to stabilize fish oil emulsions, and the impact on physicochemical stability and gastrointestinal fate was investigated. The glycoconjugate of CD6 exhibited significantly higher conjugation efficiency, lower surface hydrophobicity ( H0), and lower surface activity than other glycoconjugates. The glycoconjugate of CD70 displayed the best emulsifying activity and emulsion stability. Except CD6 stabilized emulsions, all other emulsions showed fine storage stability over 14 d at 22 ± 1 °C. The glycoconjugate stabilized emulsions exhibited significantly lower peroxide value (PV) ( P < 0.05) than that of the caseinate stabilized one. During in vitro gastrointestinal tract digestion, the glycation of caseinate with dextrans changed the ζ-potential, average particle size ( D₃₂), and particle size distribution of the emulsions, which influenced flocculation and coalescence of droplets, as demonstrated by confocal microscopy. Caseinate after glycation with dextrans significantly retarded the release of free fatty acids from emulsions ( P < 0.05) during in vitro lipolysis. These results suggested that the dextrans attached to caseinate by glycation played a vital role in physicochemical stability and gastrointestinal fate of emulsions, mainly by its steric hindrance to effectively prevent flocculation and coalescence of droplets.