Bleached Oil Research Articles

Effects of pre‐deacidification on 3‐MCPDE and GE contents of high‐acid oils during refining

SummaryCrude fats and oils may have high free fatty acid (FFA) content depending on raw material quality and processing conditions. Their refining is always a challenge due to refining loss and the formation of some process contaminants such as 3‐monochloropropane‐1,2‐diol esters (3‐MCPDE), and glycidyl esters (GE). In this study, crude hazelnut oil having 12.10% FFA was degummed, bleached, and pre‐deacidified by a molecular distillation (MD) unit before neutralisation and deodorisation. Changes in FFA, diglyceride(DG), 3‐MCPDE, GE, and tocopherol contents were monitored. Almost no changes were detected in FFA and DG contents during degumming and bleaching while the latter resulted in the 3‐MCPDE formation and GE reduction. Some tocopherol losses were also observed after these steps. On the other hand, a huge amount of FFA was distilled (from 12.10% to 1.71%) by the MD process performed at 200 °C, 0.25 mbar, as well as with a 53.6% loss of tocopherol. The samples were then subjected to deodorisation before (MD‐PHY) and after neutralisation (MD‐CHE) at 230 °C under 2 mbar absolute pressure for 2, 4, and 8 h. While some 3‐MCPDE and GE formations were detected during MD‐CHE, there were almost no formations in these contaminants after MD‐PHY. When the bleached oil having 12.10% FFA was also directly deodorised at given conditions, no formations but some reductions in 3‐MCPDE and GE contents of the oils were determined, possibly because of esterification of FFA with DGs that are an important precursor of these contaminants.

A comparative study on bath and horn ultrasound‐assisted modification of bentonite and their effects on the bleaching efficiency of soybean and sunflower oil: Machine learning as a new approach for mathematical modeling

AbstractIn this study, the effect of high‐power bath and horn ultrasound at different powers on specific surface area (SBET), total pore volume (Vtotal), and average pore volume (Dave) of bleaching clay was examined. After subjecting the bleaching clay to ultrasonication treatment, the SBET values demonstrated an escalation from 31.4 ± 2.7 m2 g−1 to 59.8 ± 3.1 m2 g−1 for HU200BC, 143.8 ± 3.9 m2 g−1 for HU400BC, 54.4 ± 3.6 m2 g−1 for BU400BC, and 137.5 ± 2.8 m2 g−1 for BU800BC. The mean pore diameter (Dave) declined from 29.7 ± 0.14 nm in bleaching clay to 11.3 ± 0.13 nm in HU200BC, 8.3 ± 0.12 nm in HU400BC, 16.7 ± 0.14 nm in BU400BC, and 9.6 ± 0.12 nm in BU800BC. Therefore, horn ultrasound‐treated bleaching clay significantly increased SBET and Vtotal, indicating improved adsorption capacity. Moreover, to establish the relationship between bleaching parameters, seven multi‐output ML regression models of Feedforward Neural Network (FNN), Random Forest (RF), Support Vector Regression (SVR), Multi‐Task Lasso, Ridge regression, Extreme Gradient Boosting (XGBoost), and Gradient Boosting are used, and compared with response surface methodology (RSM). ML has revolutionized the understanding of complex relationships between ultrasonic parameters, oil color, and pigment degradation, providing insights into how various factors such as temperature, ultrasonic power, and time can influence the bleaching process, ultimately enhancing the efficiency and precision of the treatment. The XGBoost model showed outstanding performance in predicting the target variables with a high R2‐train up to 1, R2‐test up to .983, and a minimum mean absolute error (MAE) of 0.498. The lower error between the predicted and experimental values implies the superiority of the XGBoost model to predict outcomes rather than RSM. It represents the suitability of bath ultrasound as a mild condition for low‐pigmented oil bleaching. Finally, the Bayesian optimization method in conjunction with XGBoost was used to optimize the amount of bleaching clay and energy consumption, and its performance was compared with RSM. It was observed that the consumption of bleaching clay was reduced by approximately 60% for sunflower oil and 30%–35% for soybean oil.

Effect of refining process on some quality attributes of screw-pressed avocado oil

Avocado (Persea americana) is a source of vegetable oil abundant in unsaturated fatty acids, vitamins, and diverse nutrients, rendering it a valuable source of functional oil. Refining is a necessary step to achieve avocado oil with high-quality attributes. This research delved into the impact of the refining procedure on some quality attributes of avocado oil obtained through screw pressing. The study encompassed four distinct samples, each corresponding to a specific stage in the refining process, i.e. degumming, neutralization, bleaching, and the crude oil as the control. Findings from the experiments revealed that the yield of avocado oils subjected to cooking pre-treatment (49.19±0.65 %) exceeded those without pre-treatment (45.10±1.71 %). Compared to crude oil, the quality of bleached oil was improved by reducing free fatty acid (52.94 %) and peroxide value (59.38 %). There were noticeable increases in free fatty acid and peroxide value during storage. The physicochemical properties of the extracted oil were affected by the stages of refinement and the duration of storage. FTIR analysis showed that the bleaching stage played a role in removing peroxides, hydroperoxides, and residual moisture. There were no significant changes in fatty acid composition during refinement. Oleic acid (52.0–53.1 %) constituted the largest proportion, trailed by palmitic acid (24.0–24.4 %), linoleic acid (17.2–17.8 %), and palmitoleic acid (4.9–5.6 %). However, unsaturated fatty acids content in avocado oil decreased significantly during storage.

Characteristics of Pumice from Cicurug and Its Application as a Bleacher for Crude Palm Oil

Pumice is relatively abundant in Indonesia, especially in Cicurug District, Sukabumi. Pumice has unique characteristics, so it has the potential to be an alternative bleaching agent or a bleacher for crude palm oil. Bleaching is one of the stages in processing crude palm oil into palm cooking oil. In the cooking oil industry, the bleaching of crude palm oil generally uses bentonite as a bleacher. This research aims to determine the characteristics of pumice and the optimum conditions for the bleaching process of crude palm oil with pumice as a bleacher. The research method consists of pumice activation, activated pumice characterization, degumming of crude palm oil, bleaching of crude palm oil, and analysis of processed palm oil. The results show that the metal oxide composition in activated pumice is dominated by silica (62.99%) and alumina (14.79%) and has a non-uniform pore size distribution. Optimum bleaching conditions are achieved when using 30% pumice and a bleaching temperature of 105 oC for 30 minutes. Under optimal bleaching conditions, pumice can reduce the color brightness level of crude palm oil from 600 to 125 mg/L Pt, or a bleaching power of 79.2%.

Valorization of waste seashells as bioadsorbent for sunflower oil bleaching

AbstractIn this study, the performance of waste seashells (SS) in adsorbing color and oxidation parameters during the bleaching process of sunflower oil was evaluated and compared with that of commercial clay. Seashell activation methods included microwave treatment (900 W for 30 min), acid treatment (7 N H2SO4), and a combination of both. Interestingly, the unactivated SS demonstrated superior adsorption performance compared with the activated SS. SS, which have the ability to eliminate color pigments like chlorophyll and carotenoid, were found to be effective in this regard. However, their effectiveness in reducing the peroxide and p‐anisidine value was not as successful as that of commercial clay. Free acidity content remained constant across all treatments. SS emerged as a cost‐effective alternative adsorbent, promising in preventing environmental pollution. Their use signifies a valuable contribution to sustainability. This study sheds light on SS potential as an eco‐friendly solution in industrial processes, warranting further exploration and application.Practical applicationsBiowaste valorization is a process that involves converting organic waste materials into valuable products, energy, or resources, instead of simply disposing of them in landfills or incinerating them. This approach has gained significance owing to its potential to address environmental, economic, and social challenges. In this respect, this study presents that bioadsorbent obtained from waste SS can be utilized for bleaching of sunflower oil.

SPENT BLEACHING EARTH: SYNTHESIS, PROPERTIES, CHARACTERISATION, AND APPLICATION

Spent bleaching earth (SBE) is hazardous solid waste generated from the edible oil industry through the oil bleaching process, as it is used to purify the edible oil to accomplish the strict standards required for edible oil on colour, taste and hence oil’s shelf-life. It has diverse applications for energy, construction, and agriculture, which are attributed to its remarkable physical and chemical properties. Waste generation can be reduced by utilising SBE for applications that include biogas production, bio-organic fertiliser, lubricating grease, and foamed concrete incorporating SBE. In line with this background, this paper compiled and reviewed the literature on the synthesis of SBE through the activation of bentonite, edible oil bleaching process, properties of SBE and characterisation techniques for SBE. Finally, the merits and demerits of the application of SBE are expounded. The overall performance of SBE in their respective applications is enhanced by free cations and residual oil present. Finally, future research considerations are also discussed for the co-pyrolysis application of SBE and other biomass substrates as an economically significant prospect. It is noted that reusing SBE appears to improve the oil refining industry’s sustainability and in turn the cities and communities.

Ultrasound bleaching and quality evaluation of rice bran oil

AbstractRice bran oil (RBO) contains rich nutrients that are beneficial to the human body, but RBO suffers from severe nutrient loss due to bleaching difficulties. This article investigates low‐power ultrasound‐assisted bleaching as a new method for RBO during the bleaching process, which could potentially reduce nutrient loss and lipid oxidation. First, florisil (FL), magnesium trisilicate (MAT), and activated blending earth (ABE) were selected to use a mixture design for formula optimization from six adsorbent types, and then, central composite design was employed to optimize the parameters of the bleaching process for the ultrasound‐assisted adsorbent formula. The results showed that the optimal formula was 66% FL, 10% MAT, and 24% ABE, the highest L* value and the lowest a* value is obtained at ultrasound power of 50 W for 9 min. The various parameters of RBO were subjected to comparison before and after ultrasound‐assisted bleaching. Following this bleaching procedure, the color and quality of RBO experienced notable enhancements, all the while maintaining micronutrient and fatty acid compositions within acceptable ranges. The characterization analysis of the adsorbent by FT‐IR spectroscopy and atomic force microscopy confirmed its adsorption of pigments and other substances. The results indicate that the low‐power ultrasound‐assisted bleaching is effective for RBO bleaching and may provide a promising alternative to the adsorption‐based bleaching method.Practical ApplicationsRBO is made from pressed rice bran and has high nutritional value, such as fatty acids, vitamin E, sterols, and oryzanol, with over 90% absorption by the body. The dark color of RBO makes it difficult to produce clear, transparent, and light‐colored rice bran oil, and even if bleaching is achieved, it results in significant nutrient losses. Conventional bleaching methods are commonly inefficient while emerging technologies cannot be applied industrially. Three adsorbents were selected for formulation optimization based on the fact that the bleaching effect of a single adsorbent is not obvious. Low‐power ultrasound‐assisted bleaching was performed to reduce nutrient loss and lipid oxidation. The aim is to find new bleaching methods that achieve bleaching results with acceptable nutrient losses.

Reactivated Spent Bleaching Earth as a New Path in Waste Resource Utilization for the Crude Palm Oil Bleaching Process

The palm oil refining process usually uses adsorbents. The commonly used adsorbent is Bleaching Earth. However, this raises a new problem: hazardous waste in the refining process, namely Spent Bleaching Earth (SBE). For this reason, one of which is the utilization of SBE as an adsorbent through a reactivation process. This study aims to determine the characterization of RBE produced from the microwave reactivation process and acid solution as an adsorbent in the palm oil (CPO) bleaching process. The SBE reactivation process was carried out using microwaves and sulphate acid solution at concentrations 3N. RBE characteristics were analyzed using Scanning Electron Microscopy - energy dispersive X-ray spectroscopy (SEM-EDS) and Brunner Emmet Teller (BET) - Barrett-Joyner-Halenda (BJH). The resulting RBE characteristics include surface area, pore volume, and pore size of 436,820 m2/g, 0.544 cc/g, and 2.488 nm, respectively. Patricelli model is more appropriate to use to explain the mechanism of the SBE desorption process using the MAE method with the coefficient of determination value of 0.9931. The palm oil adsorbed using RBE has 10R/20Y/0.9W of color quality, 3.93% free fatty acid number, and 11.61 meq O2/kg peroxide number. In this study, SBE was successfully converted into RBE by microwave reactivation process, and the excellent performance of RBE in palm oil bleaching was verified. This research not only helps to solve the environmental problems in the process of palm oil refining but also provides a new way for waste resource utilization.

Progressive methods of alkaline refining and bleaching of cottonseed oil

The article presents data from a study of the refining process of cottonseed oil, which differs from other vegetable oils in its complex composition and the presence of gossypol, which requires the use of alkali solutions (NaOH) of high concentration and in excess quantities. The use of magnetized solutions of sodium aluminate with a concentration of 15 to 25% has been proposed as an alkaline agent. Studies have shown that with the action of this reagent, a decrease in the acid number and color index of both press oil and oils obtained by extraction is observed.

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 %.

Reactivation of used bentonite (Spent Bleaching Earth) and its reuse as adsorbent for CPO (Crude Palm Oil) bleaching process

Used bentonite or spent bleaching earth (SBE) is one of agro-industrial solid wastes in palm oil bleaching process. SBE has potential to be reactivated and reuse as adsorbent of crude palm oil (CPO). Reusing reactivated SBE is an effort to utilize waste so that it can increase added value while also preventing environmental damage due to waste accumulation. This study aimed to determine the effect of repeated use of reactivated SBE as adsorbent in the CPO bleaching process. The research methods consisted of 4 stages: characterization, reactivation of SBE and CPO bleaching process, then analysis of bleached oil, and cost analysis of the process. This study used two different types of SBE whose oil content had previously been recovered. Repetitive use of both SBE samples affected the quality of bleached oil. Maximum repetitive use that could be received by using SBE samples A was at fourth level and B was at the second level. Costs analysis of reactivation and two times repeated use of SBE was higher than fresh bleaching earth (FBE) purchase with equivalent amount for bleaching process. However, reactivation and reuse of SBE could increase the added value of the waste and prevent negative impacts on the environment.

The Influence of the Used Bleaching Earth on the Content of Natural Dyes in Hemp (Cannabis sativa L.) Oils

Cold-pressed hemp oils are characterized by an intense color, which is undesirable when used directly. Therefore, research was undertaken on removing chlorophyll and carotenoids effectively. This publication presents the results of tests that verified the adsorption properties of seven bleaching earths (BE1–BE7) in two doses (2.5% and 5.0%) in the low-temperature bleaching process of hemp oils. These oils were obtained by cold and hot pressing of the seeds of three varieties of hemp (Cannabis sativa L.): Finola, Earlina 8FC, and Secuieni Jubileu. The color change and the content of carotenoid and chlorophyll pigments in the bleached oils were verified using the colorimetric method (CIE-Lab). The BEs used had different abilities to reduce the content of natural dyes connected with oil decolorization. The conducted research allowed us to characterize the influence of BEs on the organoleptic properties of the tested oils. Hemp oil obtained from the Secuieni Jubileu CP and HP hemp variety should be bleached with unmodified magnesian bentonite at 2.5%. Unmodified attapulgite clay is not recommended for this variety, as it strongly adsorbs carotenoids from the oil.

Application of Activated Rice Husk for Adsorptive Bleaching of Groundnut Oil: Kinetic, Equilibrium and Thermodynamic Study

Kinetic, equilibrium and, thermodynamic studies of the bleaching of crude groundnut oil at optimized conditions were carried out using activated rice husk as an adsorbent for the bleaching process. The efficiency of bleaching was estimated by measuring the absorbance using a double- beam spectrophotometer at a wavelength of 450nm. The effects of adsorbent dosage, bleaching temperature and, contact time on the bleaching efficiency were studied. A directly proportional relationship was found between dosage and contact time and the bleaching efficiency while a bell curve was discovered for temperature increase. The surface area of the rice husk increased from
 150.32 to 1450.32 m2/g while the pore volume decreased from 0.15524 to 0.12844 cm3/g after activation which was determined via a Brunauer-Emmet-Teller (BET) analysis and the results further validated by the Scanning Electron Microscopy (SEM) images obtained. The kinetic data of the bleaching process were best described by the pseudo-second order kinetic model while the equilibrium adsorption isotherm analysis showed that the results from the Temkin isotherm were the most significant. The thermodynamic study revealed that the adsorptive bleaching process is feasible, spontaneous and, exothermic with a decrease in entropy. The enthalpy value also showed that the adsorption process is predominantly physisorption. This study has revealed that an effective adsorbent can be produced from rice husks under optimized process conditions.

Design of Recyclable Carboxylic Metal-Organic Framework/Chitosan Aerogels for Oil Bleaching.

Novel hierarchical metal-organic framework/chitosan aerogel composites were developed for oil bleaching. UiO-66-COOH-type metal organic frameworks (Zr-MOFs) were synthesized and integrated onto a chitosan matrix with different contents and named MOF-aerogel-1 and MOF-aerogel-2. Due to the compatibility of chitosan, the carboxylic zirconium MOF-aerogels not only maintained the inherent chemical accessibility of UiO-66-COOH, but the unique crystallization and structural characteristics of these MOF nanoparticles were also preserved. Through 3-dimensional reconstructed images, aggregation of the UiO-66-COOH particles was observed in MOF-aerogel-1, while the MOF was homogeneously distributed on the surface of the chitosan lamellae in MOF-aerogel-2. All aerogels, with or without immobilized MOF nanoparticles, were capable of removing carotenoids during oil bleaching. MOF-aerogel-2 showed the most satisfying removal proportions of 26.6%, 36.5%, and 47.2% at 50 °C, 75 °C, and 100 °C, respectively, and its performance was very similar to that of commercial activated clay. The reuse performance of MOF-aerogel-2 was tested, and the results showed its exceptional sustainability for carotenoid removal. These findings suggested the effectiveness of the MOFaerogel for potential utilization in oil bleaching treatments.

Synthesis of biodiesel from residual oil extracted from spent bleaching earth using spent bleaching earth-supported catalyst

Proper disposal of spent bleaching earth (SBE) is much anticipated to create a circular economy. In this study, a two-pronged approach was employed to utilise SBE from palm oil refinery for its suitability to act as second-generation biofuel feedstock and catalyst. The SBE was first wet-impregnated and doped with potassium hydroxide (KOH) to further enhance the catalytic activity. The hexane-extracted bleached oil of SBE at conditions of 40 g SBE, 1:4 ratio of oil to n-hexane, and 6 hr extraction time was subjected to different transesterification parameters i.e., catalyst loading, oil: methanol ratio, reaction temperature, and reaction time. The obtained catalysts were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy with energy dispersive X-ray, temperature programmed desorption of carbon dioxide (TPD-CO2) and Brunauer-Emmett-Teller (BET) techniques. The N2 adsorption-desorption and TPD-CO2 analyses indicated that SBE/KOH (600 °C) had the highest attainable BET surface area (22.62 m2/g) and basicity (25.82 cm3/g). SBE/KOH (600 °C) exhibited the highest biodiesel yield (80.3%) at the optimised reaction conditions: (80 °C, 2 wt% catalyst loading, 1:20 oil: methanol ratio and 2 h reaction time) compared to 67.3% via the unmodified control. The kinetics study revealed that the experimental results followed the first order reaction kinetics. The activation energy, enthalpy (ΔH) and entropy (ΔS) were determined to be 90.06 kJ/mol, 6.92 × 10−4 kJ/mol and −0.0414 kJ/mol K, respectively while the Gibbs free energy (ΔG) was 15.443 kJ/mol. Overall, SBE has enormous potential as one of the alternative sources for second-generation biofuel production.

Mitigation of 3-MCPDE and GE in palm oil in Indonesia

Among consumed-vegetable oils, RBDPO (refined, bleached and deodorized palm oil) is indicated containing higher level of 3-MCPDE and GE, which have been classified as potentially carcinogenic and/or genotoxic to human. Those contaminants in RBDPO are formed during deodorization process with high temperature and also correlate with chloride content and quality of CPO as raw material. The maximum limit for 3-MCPDE and GE content in vegetable oil has been set at 2500 and 1000 µg kg-1, and as low as 750 and 500 µg kg-1 when used for production of baby food and cereal-based foods for infants and young children. The mitigation of 3-MCPDE and GE in RBDPO is quite challenging for palm oil refineries in producing a good quality of palm oil in term of sensory, stability, safety, and nutritional value, especially in Indonesia. It has been proven that modification of conventional refining process can reduce the 3-MCPDE and GE content. They are including pre-treatment of CPO by water washing to reduce the chloride content, alkali neutralization to remove any acids present in the oil prior to deodorization, using neutral bleaching earth, adding antioxidants after bleaching to reduce free radical-mediated formation of 3-MCPDE and GE, lowering the deodorization temperature with a longer time, and even double bleaching and/or double deodorization of the palm oil. Post-refining treatment using specific adsorbents is also applied to remove the 3-MCPDE and GE. However, palm oil refineries have to apply combination of several mitigation strategies to adequately reduce the levels of 3-MCPDE and GE, including using good quality of CPO with low FFA, chloride, and oxidized components content.

Mitigation of 3-MCPDE and GE in palm oil in Indonesia

Among consumed-vegetable oils, RBDPO (refined, bleached and deodorized palm oil) is indicated containing higher level of 3-MCPDE and GE, which have been classified as potentially carcinogenic and/or genotoxic to human. Those contaminants in RBDPO are formed during deodorization process with high temperature and also correlate with chloride content and quality of CPO as raw material. The maximum limit for 3-MCPDE and GE content in vegetable oil has been set at 2500 and 1000 µg kg-1, and as low as 750 and 500 µg kg-1 when used for production of baby food and cereal-based foods for infants and young children. The mitigation of 3-MCPDE and GE in RBDPO is quite challenging for palm oil refineries in producing a good quality of palm oil in term of sensory, stability, safety, and nutritional value, especially in Indonesia. It has been proven that modification of conventional refining process can reduce the 3-MCPDE and GE content. They are including pre-treatment of CPO by water washing to reduce the chloride content, alkali neutralization to remove any acids present in the oil prior to deodorization, using neutral bleaching earth, adding antioxidants after bleaching to reduce free radical-mediated formation of 3-MCPDE and GE, lowering the deodorization temperature with a longer time, and even double bleaching and/or double deodorization of the palm oil. Post-refining treatment using specific adsorbents is also applied to remove the 3-MCPDE and GE. However, palm oil refineries have to apply combination of several mitigation strategies to adequately reduce the levels of 3-MCPDE and GE, including using good quality of CPO with low FFA, chloride, and oxidized components content.

High-power ultrasound bleaching technique for canola oil (Brassica napus L.): Pigments removal and quality parameters

Canola seeds (Brassica napus L.) are among the most commonly used seeds in Mexico for vegetable oil production. This is based on the high yield and content of polyunsaturated and monounsaturated fatty acids. During oil bleaching, it is important to maintain fatty acids in their cis configuration because of the health concerns associated with trans-fatty acid consumption. In this sense, the industrial processing parameters employed for this purpose present some limitations, such as high temperatures and long times, which may change the cis configuration to trans. In addition, the amount of bleaching clay employed for this process could be a source of contamination because it is disposed of after treatment. Therefore, the aim of this study was to develop a bleaching process for canola oil using high-power ultrasound (US). US processing was applied to nine treatments with different processing times (60, 75, and 90 min), clay percentages (1, 2, and 3%), and temperatures (60 and 80 °C) to determine the concentrations of chlorophyll a and b (µg chlo/100 g oil), carotenes (µg β-carotene/100 g oil), color (L*, a*, b*, C*, and h°), iodine value (g I2/100 g oil), and finally carrying out a spectroscopic analysis (ATR-FTIR and Raman). A conventional bleaching treatment (100 °C for 180 min, 3% bleaching clay) was used as a control. The results revealed that US treatments with 2% clay at 60 °C for 60 and 90 min eliminated most of the chlorophyll compounds (98%). However, in terms of carotenes reduction, these identical treatments exhibited a similar tendency to that of the control (approximately 30% decrease). These findings also affected the sample color, in which US treatments revealed chromatic coordinates that indicated yellow tones with chroma values that were more intense than those in the control samples. In terms of the iodine value, such treatments fulfilled the international standards for vegetable oils (90–100 g I2/100 g oil). Finally, the spectroscopic study revealed no trans configurations or the presence of different chemical compounds after US treatment, because neither of them presented typical peaks for those molecular configurations. In this regard, US can be a useful methodology for bleaching vegetable oils, helping to reduce time, and bleaching clay with similar pigment reduction results.

Spent Earth

This essay considers the multiscalar manifestations of loss and the destruction of loss through the material-semiotic figure of “spent earth,” a toxic waste by-product generated by the industrial bleaching of crude oils into edible oils. Drawing on two distinct encounters with spent earth in the Indonesian palm oil sector, the essay reflects on the substance's unevenly distributed effects across peoples, places, and generations; its association with visions of purity and realities of complicity; and the importance of attending to loss through both its situated, localized manifestations and its partial connections across sites, scales, and subjects.

Features of removal of coloring substances during bleaching vegetable oils

In modern conditions of vegetable oil processing, the issues of improving the quality and safety of refined oils remain relevant. It has been noted that the most effective one is complex or complete refining of vegetable oils, which ensures the removal of the main groups of related substances by traditional and improved methods. The complexity of the organization of refining technology is associated with the accompanying oxidation of oils at certain stages and a decrease in their resistance to oxidation during storage. Moreover, this is most characteristic of the time-consuming operation of adsorption bleaching when using acidactivated mineral adsorbents containing active metals that contribute to the activation of oxidative processes. A new approach to the organization of the technology of removing coloring substances during bleaching involves the use of a «wet» method of clarification of hydrated wet oil. This technology helps to reduce the oxidation of bleached oil at a high level of clarification. The effectiveness of the method is increased due to the use of a mixture of mineral and vegetable adsorbents, the bleaching ability of which is enhanced by the use of mechanochemical activation (MHA). It has been noted that a plant adsorbent obtained from dried crushed pea leaves containing pectin and hemicellulose is effective. MHA contributes to the complex effect on the treated system due to local pressures and shear deformations, which activate the adsorption properties of the modified mineral-vegetable adsorbent and increases its selective effect. The proposed technology using a mixture of sorbents and MHA increases the resistance of oil to oxidation and reduces the accumulation of oxidation products in it during storage, it improves the quality of bleached oil, which should provide a high effect of the final stage of complete refining – deodorization.