Membrane Technology in Degumming, Dewaxing, Deacidifying, and Decolorizing Edible Oils

Activated carbons from open air and microwave-assisted impregnation of cotton and neem husks efficiently decolorize neutral cotton oil

The decolorization of cottonseed oil with activated carbons (ACs) from neem and cotton husks has a dual interest: elimination of undesirable pigments in oil and valorization of the husks; by-products of neem and cottonseed processing, which would otherwise be dumped along riverbanks and farms causing environmental pollution. ACs were produced from neem and cottonseed husks after acid impregnation assisted by microwave heating and in ambient air for the decolorization of neutral cottonseed oil. The experimental data were analyzed by the intraparticle diffusion and the pseudo-second-order kinetic models as well as the Langmuir and Freundlich isotherm models. The method of impregnation and carbonization time had dramatic effects on the specific surface area (800-1500 g/m2), the quantity of burn-off (50-70 %), and methylene blue index (300-5000 mg/g) values which indicated the potential of the prepared activated carbons in the bleaching of vegetable oil and in other applications such as environmental clean-up and in agriculture. Pigment adsorption increased with temperature for all ACs indicating that the decolorization process was endothermic. The quantity of adsorbent equally had a significant effect on the pigment adsorption process for all ACs. All the activated carbons prepared in this work were 30-80 % more efficient in pigment adsorption than bleaching earth that is normally used in decolorizing neutral cotton seed oil in industries. All tested models are adequate to describe pigment adsorption by the ACs. Both methods of preparation of ACs were effective for oil decolorization, but microwave impregnation is more appealing because it requires only 1 h compared to 6 h for ambient air. Optimum decolorization conditions were 90 °C for 40min and adsorbent concentration of 2 %.

Color Reversion of Refined Vegetable Oils: A Review

During the transport, storage, and consumption of edible vegetable oils, the color of some freshly refined oils is gradually darkened, which is known as the color reversion. The oil industry has been plagued by the issue for a long time because the dark color of the oil is related to its poor quality and low acceptability for consumers. Color reversion of refined vegetable oils is primarily related to the processing pigments, especially tocored, which is the oxidation product of γ-tocopherol. However, the underlying molecular action mechanism of tocored is not yet fully understood due to the complex transformations of tocored in oil systems. This paper presents a brief description of oil color, followed by an overview of research progress on the mechanism of color reversion. In particular, the effect of minor components (phospholipids and metal ions) on color reversion is highlighted in an attempt to explain the remaining mysteries of color reversion. Furthermore, the measures to restrain color reversion by quality control of the oilseeds, the adjustment of technical parameters of processing, and the storage conditions of refined oils are summarized to provide some references for the oil industry.

Sunflower Oil Winterization Using the Cellulose-Based Filtration Aid-Investigation of Oil Quality during Industrial Filtration Probe

Waxes, phospholipids, free fatty acids, peroxides, aldehydes, soap, trace metals and moisture present in crude sunflower oil have a negative effect on the oil quality and are, therefore, removed during the refining process. Waxes crystallizing at low temperatures are removed during winterization by cooling and filtration. Waxes have poor filtration characteristics and an industrial filtration process must be enhanced by the use of filtration aids, which improve filter cake structure and properties, and consequently prolong the filtration cycle. Today, traditional filtration aids (diatomite, perlite, etc.) being used in the industry are frequently replaced by cellulose-based aids. The aim of this study is to examine the effect of oil filtration assisted by two cellulose-based filtration aids on the chemical parameters (wax, moisture, phospholipids, soaps, and fatty acids), oil transparency, carotenoids, and Fe and Cu content of sunflower oil obtained in an industrial horizontal pressure leaf filter. In order to investigate the mentioned parameters, the following techniques were used: gravimetric (waxes and moisture content), spectrophotometric (phospholipids and carotenoid content and oil transparency), volumetric (soaps and free fatty acids content) as well as inductively coupled plasma mass spectrometry (ICP-MS) for Fe and Cu content. An artificial neural network model (ANN) was employed for the prediction of removal efficiency based on the chemical quality, oil transparency, Fe and Cu content in oils before filtration, as well as filtration aid quantity and filtration time. Cellulose-based filtration aids had multiple beneficial effects; on average, 99.20% of waxes, 74.88% of phospholipids, 100% of soap, 7.99% of carotenoids, 16.39% of Fe and 18.33% of Cu were removed.

A review on membrane technology application for vegetable oil purification processes

In current paper, a comprehensive review to contribute the present insight an implementations and the recent improvements through the diverse endeavor made by the researchers utilizing a membrane technique for degumming, deacidifying, dewaxing and discoloration edible vegetable oils with and without solvent availability and also the solvent recovery has been evaluated. Endeavors made with NF, UF, MF and non-porous membranes, have shown the capability of these membranes to predicate vegetable oil treatment. A membrane technique is noticeably simple and potentially provides many usefulness in vegetable oil purification. It appears that oils treatment with membranes, which carried out at low temperatures that provides saving energy, with real cancellation of stages, provides a promising alternate to conventional procedure, towards the accomplishment of eco-friendly and cost-effective operations that are technically sophisticated. Generally, the solvent (hexane-dilution) technique enhances the membrane oil flux. For dewaxing undiluted vegetable oils, the effective membrane was MF, whereas in dewaxing solvent-diluted oils process UF membranes were more energetic.

Refining Vegetable Oils: Chemical and Physical Refining

This review presents recent technologies involved in vegetable oil refining as well as quality attributes of crude oils obtained by mechanical and solvent extraction. Usually, apart from virgin oils, crude oils cannot be consumed directly or incorporated into various food applications without technological treatments (refining). Indeed, crude oils like soybean, rapeseed, palm, corn, and sunflower oils must be purified or refined before consumption. The objective of such treatments (chemical and physical refining) is to get a better quality, a more acceptable aspect (limpidity), a lighter odor and color, longer stability, and good safety through the elimination of pollutants while minimizing oil loss during processing. However, the problem is that refining removes some essential nutrients and often generates other undesirable compounds such as 3-MCPD-esters and trans-fatty acids. These compounds directly influence the safety level of refined oil. Advantages and drawbacks of both chemical and physical refining were discussed in the light of recent literature. Physical refining has several advantages over chemical one.

Membrane technology for vegetable oil processing-Current status and future prospects

Vegetable oil processing has been identified as one of the potential nonaqueous applications of membrane technology. Membrane-based processing has been largely attempted on individual steps of the conventional refining process with reasonable success. With the advent of organic-solvent-nanofiltration, membrane desolventizing of hexane oil miscella has received greater attention, revitalizing the prospects of integrated membrane processing. A practical evaluation of membrane augmented desolventizing revealed that approximately 65% energy savings towards solvent evaporation could be achieved in an industrial environment. Further, a pragmatic appraisal advocated that an integrated membrane process with a focus on pretreatment and desolventizing along with physical refining would be a desirable approach for fortifying the benefits. The present review intends to channelize the efforts to overcome the current limitations and highlights the importance of developing better membranes, process evaluation under appropriate practical conditions, and developing suitable cleaning protocols for stable performance. In the case of alternate solvents to hexane, membrane solvent recovery would be a favorable approach to overcome the limitation of associated higher thermal energy requirements. Nevertheless, solvent selection should be based on a composite evaluation of extraction and membrane desolventizing, specific to the type of oil. Finally, a comprehensive process scheme has been proposed to realize the benefits in extraction-refining plants. In this direction, a few pilot demonstration plants need to be established and operated for 1-2 years to understand and overcome the practical difficulties and limitations of the technology, leading to its industrial adoption.

Biodiesel from oil produced in vegetative tissues of biomass - A review

Biodiesel is a green, renewable alternative to petroleum-derived diesel. However, using vegetable oil for biodiesel production significantly challenges the food security. Progress in metabolic engineering, understanding of lipid biosynthesis and storage have enabled engineering of vegetative tissues of plants such as sugarcane, sorghum, and tobacco for lipid production. Such sources could be cultivated on land resources, which are currently not suitable for row crops. Besides achieving significant lipid accumulation, it is imperative to maintain the fatty acid and lipid profile ideal for biodiesel production and engine performance. In this study, genetic modifications used to induce lipid accumulation in transgenic crops and the proposed strategies for efficient recovery of oil from these crops have been presented. This paper highlights that lipids sourced from vegetative biomass in their native form would pose significant challenges in biodiesel production. Therefore, different strategies have been presented for improving feedstock quality to achieve high-quality biodiesel production.

Membrane-based zero-sludge palm oil mill plant

The palm oil industry is one of the most important agro-industries for tropical countries because of the unique properties and wide range of uses of palm oil for various end products. In a palm oil extraction process, a large quantity of water is required, of which half the quantity will end up as effluent. This palm oil mill effluent (POME) has an extremely high content of organic matter, which can cause severe pollution of waterways and other environmental problems. Disposal of this highly polluting effluent has become a major problem for the palm oil mills. Therefore, several methods have been proposed either to treat the POME so it could comply with environmental regulation while discharged or to recover water and other valuable components from the effluent. Membrane technology has emerged as a feasible alternative to conventional treatment in vegetable oil processing because of its attractive features such as low energy consumption, reduction in the number of processing steps, high separation efficiency, and improvement of the final product quality. In the case of POME treatment, an integrated membrane-based process promises efficient water recycling and total solid recovery from the effluent, thus eliminating the environmental problem. Recently, a novel concept combining oil–oil extraction and continuous filtration using a superhydrophobic membrane has been proposed to achieve a zero-sludge palm oil mill. In this concept, the huge wastewater effluent generated from the conventional process can be eliminated and the palm oil milling process simplified. Furthermore, the superhydrophobic membrane enables the production of high-purity palm oil. In this paper, we review the prospect of a zero-sludge palm oil mill concept and strategies to achieve the proposed concept. In addition, we also highlight the development of the superhydrophobic membrane and phytonutrient recovery.

Membrane applications in functional foods and nutraceuticals

The functional foods and nutraceuticals market is growing at a rapid pace. Membrane processing offers several advantages over conventional methods for separation, fractionation, and recovery of those bioactive components. In this review, membrane applications of lipid-, carbohydrate-, and protein-based nutraceuticals and some minor bioactive components have been critically evaluated. Both non-porous and porous membranes were employed for lipid-based nutraceuticals separations. The use of non-porous membranes together with non-aqueous solvents brought about the impact of solution-diffusion theory on transport through membranes. Both organic and inorganic membranes gave encouraging results for the recovery of lipid components with single- and/or multi-stage membrane processing. Two-stage ultrafiltration (UF)-nanofiltration (NF) systems with polymeric membranes provided an efficient approach for the removal of high- and low-molecular weight (MW) unwanted components resulting in higher purity oligosaccharides in the NF retentate. The charged nature of protein-based nutraceutical components had a major effect on their separation. Operating at optimizal pH levels was critical for fractionation, especially for low MW peptide hydrolysates. Processing of minor components such as polyphenols, utilized all types of porous membranes from prefiltration to concentration stages. Coupling of membrane separation and supercritical fluid technologies would combine unique advantages of each process resulting in a novel separation technology offering great potential for the nutraceutical and functional food industry.

Minor components in food oils: a critical review of their roles on lipid oxidation chemistry in bulk oils and emulsions

Food oils are primarily composed of triacylglycerols (TAG), but they may also contain a variety of other minor constituents that influence their physical and chemical properties, including diacylglycerols (DAG), monoacylglycerols (MAG), free fatty acids (FFA), phospholipids (PLs), water, and minerals. This article reviews recent research on the impact of these minor components on lipid oxidation in bulk oils and oil-in-water emulsions. In particular, it highlights the origin of these minor components, the influence of oil refining on the type and concentration of minor components present, and potential physicochemical mechanisms by which these minor components impact lipid oxidation in bulk oils and emulsions. This knowledge is crucial for designing food, pharmaceutical, personal care, and other products with improved stability to lipid oxidation.