Raw Rice Research Articles

Biomineralization, dissolution and cellular studies of silicate bioceramics prepared from eggshell and rice husk.

The current investigation aims to replace the synthetic starting materials with biowaste to synthesize and explore three different silicate bioceramics. Pure silica from rice husk was extracted by decomposition of rice husk in muffle furnace followed by alkali treatment and acid precipitation. Raw eggshell and extracted silica were utilized for the preparation of wollastonite, diopside and forsterite by the solid-state method. The TG-DSC analysis shows that the crystallization temperature of wollastonite, diopside and forsterite was found to be 883°C, 870°C and 980°C, respectively. The phase purity of wollastonite was attained at 1100°C whereas diopside and forsterite were composed of secondary phases even after calcination at 1250°C and 1300°C respectively. All three materials behaved differently when exposed to the physiological environment, as wollastonite exhibited remarkable apatite deposition within 3days whereas a distinct apatite phase was noticed on the surface of diopside after 2weeks and forsterite shows the formation of apatite phase after five weeks of immersion. The rapid dissolution of Mg2+ ion from forsterite lowered the leaching of silicate ions into the simulated body fluid leading to poor apatite deposition over its surface. Chemical composition was found to plays a key role in the biomineralization ability of these bioceramics. Hemolysis and Lactate Dehydrogenase (LDH) release assays were performed to evaluate the hemocompatibility of silicate ceramics cultured at different concentrations (62.5, 125, and 250μg/mL) with red blood cells and mononuclear leucocytes (MLs) of mice. The hemolytic activity of all the tested bioceramics was insignificant (less than 1%). The interaction between diopside and mouse multipotent mesenchymal stromal cells (MMSCs) caused a negligible increase in the number of apoptosis-associated Annexin V-binding cells whereas forsterite and wollastonite induced an increase in the number of the apoptotic cells only at the concentration of 250μg/mL. The LDH assay did not show statistically significant changes in the proliferation of MMSCs after treatment with the bioceramics at the tested concentrations when compared to control (p>0.05). This finding showed that the death of a part of cells during the first 24h of incubation did not prevent the proliferation of MMSCs incubated with diopside, forsterite and wollastonite for 72h.

(−)-Tetrahydroberberrubine∙acetate accelerates antioxidant potential and inhibits food associated Bacillus cereus in rice

A protoberberine alkaloid, (−)-tetrahydroberberrubine∙acetate (THBA) was assessed for its antioxidant potential and ability to inhibit the growth of a food hazard bacterium Bacillus cereus in vitro and in situ. THBA displayed significant and dose-dependent cellular antioxidant potential against hydrogen peroxide-induced oxidative stress in NIH 3T3 fibroblast cells and decreased the ROS levels as well as increased the expression levels of SOD1 and SOD2 enzymes. The inhibitory spectrum of THBA confirmed its mechanistic role in the disruption of the membrane integrity of B. cereus as evidenced by the results of time-inactivation, cell membrane integrity, NPN membrane uptake, membrane potential, and electron microscopy analyses. Moreover, THBA inhibited biofilm formation by B. cereus and disrupted pre-established biofilms on a glass surface. Furthermore, THBA was also able to inhibit B. cereus in raw rice with a significant amount of reduction in CFU counts, suggesting its potential role as a natural antioxidant and antimicrobial agent.

Impact of Cooking on Bioactive Compounds and Antioxidant Activity of Pigmented Rice Cultivars.

Pigmented rice cultivars, namely Venere and Artemide, are a source of bioactive molecules, in particular phenolics, including anthocyanins, exerting a positive effect on cardiovascular systems thanks also to their antioxidant capacity. This study aimed to determine the total phenol index (TPI), total flavonoids (TF), total anthocyanins (TA) and in vitro antioxidant capacity in 12 batches of Venere cultivar and two batches of Artemide cultivar. The rice was cooked using different methods (boiling, microwave, pressure cooker, water bath, rice cooker) with the purpose to individuate the procedure limiting the loss of bioactive compounds. TPI, TF and TA were spectrophotometrically determined in both raw and cooked rice samples. Rice samples of Artemide cultivars were richer in TPI (17.7–18.8 vs. 8.2–11.9 g gallic acid/kg in Venere rice), TF (13.1 vs. 5.0–7.1 g catechin/kg rice for Venere rice) and TA (3.2–3.4 vs. 1.8–2.9 g Cy-3glc/kg for Venere rice) in comparison to those of Venere cultivar; as well, they showed higher antioxidant capacity (46.6–47.8 vs. 14.4–31.9 mM Trolox/kg for Venere rice). Among the investigated cooking methods, the rice cooker and the water bath led to lower and comparable losses of phenolics. Interestingly, the cooking water remaining after cooking with the rice cooker was rich in phenolics. The consumption of a portion of rice (100 g) cooked with the rice cooker with its own cooking water can supply 240 mg catechin and 711 mg cyanidin 3-O-glucoside for Venere rice and 545 mg catechin and 614 mg cyanidin 3-O-glucoside for Artemide rice, with a potential positive effect on health.

Life cycle assessment of rice husk torrefaction and prospects for decentralized facilities at rice mills

Utilization of rice husk, an abundant global residual biomass, represent a large opportunity for increasing the share of bioenergy in the power sector. The present work assesses the life cycle emissions of rice husk torrefaction in different reaction conditions and the techno-economic prospects for decentralized torrefaction facilities at rice mills. First, a cradle-to-gate life cycle assessment (LCA) is performed for processing rice husk into torrefied pellets for energy generation. Four system configurations of different temperature and torrefaction medium are considered for torrefied rice husk (TRH) pellet production. Medium torrefaction in inert medium shows the highest GHG emissions of about 0.043 kg CO2 eq/MJ of TRH pellet whereas severe torrefaction in oxidative medium shows the lowest GHG emissions of 0.021 kg CO2 eq/MJ of TRH pellet. The environmental impacts of torrefaction in partially oxidative medium and at higher temperatures are lower, only if a significant portion of the torgas and condensate is efficiently utilized. Second, a techno-enviro-economic evaluation is performed for multiple scenarios of utilizing raw or torrefied rice husk (partially oxidative conditions) for power generation. A case study of the rice mills in the Sacramento valley of California is considered, with an annual supply of about 0.2 million tons of rice husk, to operate a 26.5 MW biopower plant. A centralized facility at the power plant resulted in highest GHG emissions, and a rented mobile facility resulted in highest annual costs. The most desired scenario of having localized facilities at the rice mills proved most cost-effective, with excess TRH breakeven price of 61 USD/ton for medium torrefaction and 471 USD/ton for severe torrefaction. Instead of excess TRH, if the entire TRH is available for sale, the same scenario estimated the average breakeven price of 14.9 USD/ton and 21.1 USD/ton respectively. Sensitivity analysis for a single mill explains the role of factors such as availability of rice husk (milling capacity), transportation distance, and solid mass yield on the breakeven price, costs, and the GHG emissions.

A Study on Quality Index of Raw Rice for Porridge Processability Evaluation

A Study on Quality Index of Raw Rice for Porridge Processability Evaluation

Thermogravimetric analysis-based characterization of suitable biomass for alkaline peroxide treatment to obtain cellulose and fermentable sugars

To characterize a suitable biomass for alkaline peroxide treatment, four types of lignocellulosic biomass (rice straw, two Miscanthus spp., and Japanese cypress) were characterized using thermogravimetric analysis. Before the alkaline peroxide treatment, rice straw had the lowest initial thermal degradation temperature and Japanese cypress had the highest. After alkaline peroxide treatment, this trend was reversed, such that the highest initial thermal degradation temperature was for alkaline-peroxide treated rice straw. Hemicellulose and lignin content significantly affected the thermal degradation behavior and alkaline peroxide treatment efficiency. Among the four lignocelluloses, raw rice straw exhibited the highest reducing capability, whereas the treated rice straw exhibited the lowest reducing capability. Surface morphology and crystallinity indicated that when the rice straw was subjected to AP treatment at room temperature for 10 min, crystalline cellulose microfibrils were exposed and concentrated on the surface. Thus, among the samples tested, rice straw was found to be the most suitable biomass for alkaline peroxide treatment.

Assessing the viability and storage life in pollen grains of rice (Oryza sativa L.)

In rice (Oryza sativa L.), the major cereal and staple food of millions in the world, hybridization programmes are very crucial for crop improvement. When the parents involved in crossing programme are varying in their flowering duration, storage of pollen grains for long time is highly advantageous for producing desirable hybrid combinations at any time. A study was undertaken to assess the viability and storage life of rice pollen grains through different storage methods. The anthers with pollen grains of the rice variety Uma, were collected from the field lab and transferred to various storage media. Aluminium foil and polythene bag were used as storage materials along with/without desiccators. Silica gel, Rice flour and raw rice were used as the desiccators. Samples packed in various storage media were kept under different conditions like Ambient, Refrigerator and Freezer. Afterwards, viability (%) of each sample was observed on 5th, 10th, 15th, 20th, 25th and 30th day of the storage using Acetocarmine dye method. The results after one month of storage indicated that pollen kept in Aluminium foil with silica in all the conditions showed better viability percentage, and the highest (87.24%) was in Freezer. Pollen grains had low viability in normal storage (without any media/dessicator) in all cases except ambient condition wherein, the lowest percentage of viability was noticed in Polythene bag without silica. This result indicates that the pollen storage in the Aluminium foil with silica gel in freezer condition is a highly effective and promising strategy for plant breeders and farmers, involved in plant breeding, hybridisation and genetic conservation programmes.

Biovalorization of the raw agro-industrial waste rice husk through directed production of xylanase by Thermomyces lanuginosus strain A3-1 DSM 105773: a statistical sequential model

The current work addresses a statistically optimized, economic, and efficient approach for the professional valorization of the massively accumulated non-efficiently utilized, raw agro-industrial waste rice husk (RH). Thermomyces lanuginosus strain A3-1 DSM 105773, a locally isolated strain, was employed for directed production of xylanase, an industrially important enzyme upon growing on RH-based medium. A three-step empirical sequential, statistical approach—one variable at a time (OVAT), Plackett–Burman design (PBD), and Box–Behnken design (BBD)—was employed to optimize the xylanase production through liquid-state fermentation of rice husk. Incubation temperature (50 °C) and ammonium sulfate concentration as an inorganic nitrogen source were the most appropriate parameters triggering the production of xylanase, deduced from OVAT. The three key determinants RH concentration, initial pH of the production medium, and incubation time did exhibit significant influences (P ≤ 0.001) on the production of xylanase, deduced from PBD. By the end of the optimization process, the optimal levels of RH, initial pH of the production medium, and incubation time were 3.8% (w/v), 4.5, and 8 days, respectively, with an agitation speed of 120 rpm to achieve a maximal xylanase level of 0.8344 U/mL with a fivefold enhancement deduced from the estimated ridge of the canonical path. Present data would reinforce the scaling up of xylanase production using the present powerful and reproducible approach for the simultaneous and proficient valorization of RH and production of xylanase for further exploitation in food, pharmaceutical, and textile industries.

In situ thermal characterization of rice straw envelope of an outdoor test room

The after-effects of human-induced climate change pose complex engineering challenges to the building sector. One of the ways of reducing the carbon footprint of buildings is the use of bio-based construction materials with capacity to passively manage the hygrothermal performance of buildings. Research during the recent years has led to the emergence of straw as a potential candidate. In the present study, with the aim of in situ data extraction from a straw envelope and the subsequent thermal characterization of straw, a test room of 10 cm thick raw rice straw envelope was designed and built. The effective thermal and moisture diffusivities of the straw envelope based on the collected temperature and relative humidity data were evaluated. Four commonly used models were selected to predict the outside heat transfer coefficient for the rough surface of the straw envelope. A comparison between the surface temperatures from the experiment and the 1-D transient numerical studies employing the model-derived outside heat transfer coefficients and sol-air temperatures pointed to the DOE-2 model being the best suited with 92% of the predicted surface temperatures within ±15% of the experiment values. A similar comparison study was employed to verify the ranges of inside heat transfer coefficient. The study provides a framework for the determination of the thermal transmittance of straw based walls and helps in the optimum thermal design of a straw envelope.

A low-cost approach for the generation of enhanced sugars and ethanol from rice straw using in-house produced cellulase-hemicellulase consortium from A. niger P-19

A natural variant of Aspergillus niger P-19 was used for the in-house production of cellulase-hemicellulase consortium for efficient and low-cost saccharification of rice straw. Solid-state fermentation of raw rice straw produced the highest enzyme titers corresponding to 126, 36, 47, 693, and 57 IU/g for CMCase, FPase, β-glucosidase, xylanase, and mannanase after 5 days. The enzyme characterization revealed that all the components of the consortium had the optima at 60 °C and pH 4.0 and were highly stable at 50-60 °C for up to 408 h. The crude in-house enzyme preparation worked well in the saccharification of 0.25 N NaOH pretreated rice straw releasing 70 g/l of reducing sugars with 10% solid loading thus proving to be a low-cost approach for producing high titers of sugars. The fermentation of C6 sugars resulted in an ethanol yield of 15.6 g/l with scope for improving the yield by simultaneously targeting the C5 sugars.

Sustainable Rice Straw Management Using Pyrolysis-Extraction Process Towards Value-Added Products

Rice straw, one of the main agricultural wastes of north of Iran, was utilized for extraction of two valuable products: high surface area activated carbon (AC) and nano-silica powder. The positive effect of silica extraction from activated rice straw ash on the porosity of resultant AC was determined. It was found that the performance of K 2 CO 3 was better than KOH for producing highly porous AC (2356 m 2 /g) under less severe conditions (relatively low impregnation ratio=1.5). The sensitivity analysis for several operating conditions was carried out, and the optimal conditions to reach the highest surface area, pore volume and silica extraction yield were determined for each chemical agent using Taguchi analysis. Among the factors changed, the highest contributions belonged to the impregnation ratio and activation temperature; therefore, other factors were selected based on economic considerations. The average production yield of activated carbon and silica from raw rice straw in this work was calculated around 9% and 7%, respectively. The average particle size of silica powder was estimated by SEM (around 35 nm) and DLS tests (200-300 nm), and an acceptable BET surface area and pore volume of 250 m 2 /g and 1 cm 3 /g, respectively, were obtained for this product.

Hydrodeoxygenation of guaiacol via rice husk char supported Ni based catalysts: The influence of char supports

Six different treatments were carried out on the pyrolyzed and raw rice husks, including hydrothermal carbonization (HI), pyrolysis-acidification (PAI), pyrolysis-steam activation (PSI), pyrolysis (PI), pyrolysis-impregnation-steam activation (PIS) and acidification-pyrolysis (API). The modified chars were used as the supports for Ni-based catalysts, and activated carbon (AC) was used as the comparison. In situ vapour-phase hydrodeoxygenation (HDO) of guaiacol was performed at atmospheric and low temperature. The effect of different char catalysts on the HDO activity of guaiacol was investigated. The physical and chemical properties of the catalysts were characterised by BET, XRD, SEM, H2-TPR, NH3-TPD, etc. The mass transfer process of char heterogeneous catalyst was analysed. The results showed that the catalyst 20Ni/RH-HI obtained a medium-strong acidity and a smallest grain size, and achieved the highest HDO ratio of 55.28% and BTX selectivity of 7.56%. BTX (benzene, toluene and xylene), phenols and cyclohexanones were the main products, indicating that most of hydrogenolysis occurred on the Caromatic-OH and O–CH3 skeleton. And small part of hydrogenolysis was on the phenyl-ring. The HDO activity was determined by the pore structure, acidity and active metal grain size of the char catalysts.

PRODUCTION OF SOLID BIOFUELS FROM GRAIN PROCESSING WASTES

The article is devoted to the issues of solid biofuel production. The classification of biomass used in the production of solid biofuels by origin is given. The main types of grain waste in the southern region for the production of solid biofuels are identified.The article analyzes the soybean market in the world and Ukraine, shows the trend of growing soybean production, which is caused by the growing demand for food and feed purposes. Soybean yield indicators in Ukraine are analyzed and it is found that Kherson region is one of the leaders of soybean yields for 2019. It is shown that in soybean cultivation in Ukraine a considerable amount of secondary resource is obtained - straw, as a by-product of crop production. It is established that the average yield of rice of Kherson region prevails in Ukraine, a large amount of rice husk is formed during processing of raw rice. Physico-mechanical properties of rice husk and soybean straw have been determined. The possibility of production of fuel briquettes from the waste was considered, technological scheme of production of fuel briquettes from waste, which are formed at the enterprises of processing industry and by-products of crop production is given. The technology of production of fuel briquettes from soy straw and rice husk was introduced at the enterprise of Kherson region, which is engaged in cultivation and processing of soybeans and rice. Quality indicators of fuel briquettes were determined: humidity, ash, sulfur, carbon content, volatile matter yield and specific combustion heat. It is established that the quality of fuel pellets is significantly influenced by humidity, degree of grinding and physical and chemical properties of raw materials. When the moisture content of raw materials more than 14% decreases the density of the granules and, due to the evaporation of moisture, cracks appear in the granules, which reduce their strength. With the reduction of the average particle size of the biomass to 2 mm, the quality of the fuel products increases, but the fine fraction of the biomass of the matrix is erased. The heat of combustion of the obtained solid briquettes exceeds the normative values of European standards at a level not lower than 18 MJ / kg. Ash content (0.5 %), normalized by European standards, is practically unavailable for Ukrainian producers, fuel briquettes made from soy straw and husks have higher normalized ash values in accordance with 7.0 and 14.0 %, which reduces their quality indicators.

Improvement of Thermal Insulation and Crack Resistance of Plaster of Paris Composites at High Temperature

In the present work, silica gel is extracted from raw rice husk, incorporated in Plaster of Paris formulations and casted into sheets of varying thicknesses. The sheets were tested for thermal insulation at 60, 100, 150 & 200 °C and compared with blank formulations. Plaster of Paris composites with silica gel have shown remarkable increase in thermal insulation properties and crack resistance. Thermally insulated Plaster of Paris composites with excellent crack resistance have been developed which can be used competently for prolonged times even at high temperatures offering better serviceability and safety to the buildings.

Effect bulking agent on composting mexican sunflower (Tithonia diversifolia L) biomass and utilization on pak choi production

Mexican sunflower or paitan in Indonesian (Thitonia diversifolia L) is a weed with high biomass production with nutrient quality that potentially use as composting material. However, there were problem for for optimize composting process due to low C/N ratio and high moisture content of this material. Therefore co-composting with higher C/N ratio and low moisture bulking materials to attain a proper composting process. Research to (1) Evaluate the effect of raw rice husk (RRH) and rice husk charcoal (RHC) as bulking agent on quality of compost T.diversifolia. Two composting mixture were TRRH = biomass T. Diversifolia + raw rice husk and TRHC = T. diversifolia biomass + rice husk biochar. Data were analyzed descriptively and compared with National Standards of Organic Fertilizer SNI 19-7030-2004. (2) To Compare the effect TRRH and TRHC compost on growth and yield of pakchoi (Brassica rapa var chinensis). Plant height, number of leaves, leaf area, edible and total fresh weight and N uptake analyzed with ANOVA and mean diference with Tukey/HSD test. The results showed that (1) T.diversifolia L compost has nutritional quality of N, P, K in accordance with SNI 19-7030-2004, but the levels of N, P and K in TRHC > TRRH. (2) TTRH.40 planting media gave maximum growth and yield of pakchoy compared to other treatments. The study confirms that composting T.diversifolia L biomass were potential to enhance pakchoi production while promoting cultivation of vegetables for food security.

Neuroprotective and hepatoprotective effect of whole red rice forms against oxidative stress in streptozotocin induced diabetic rats

Whole red rice ( Oryza sativa L.), consumed as staple food in many countries worldwide, is rich in phytochemicals, mainly antioxidants having health potency. The present study evaluated the neuro- and hepatoprotective efficacy of raw and parboiled whole red rice against streptozotocin (STZ) induced oxidative stress, and antioxidant metabolism both in diabetic and normal non-diabetic rats. Wistar rats were rendered diabetic by a single intraperitoneal ( i.p.) injection of streptozotocin (45 mg/kg body wt.), supplemented with raw and parboiled whole red rice for six weeks . Results revealed a drastic increase in oxidative stress markers, such as lipid peroxidation, nitric oxide (NO) level, hydroperoxide (HP) level; antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), thioredoxin reductases (TR), glutathione S-transferase ( GST), acetylcholinesterase (AChE) activity, and decrease in endogenous antioxidant, glutathione (GSH) in diabetic rat. On the other hand, addition of raw and parboiled whole red rice in the diet counteracted the STZ induced oxidative stress in diabetic groups and improved the neuro and hepatic antioxidant system. Both, parboiled and raw red rice forms, exercised similar impacts in diabetic as well as in normal rats suggesting improved antioxidant defence mechanism. Results have shown that the whole red rice possess antidiabetic potential with the antioxidant improving ability, and could be utilized as dietary supplements in diabetes management.

Study of the Relationship Between a Nutrient Element and Two Energy Elements During the Biochar Preparation Process

To investigate the relationship between the retention of the nutrient element nitrogen (N) and the release of the energy elements carbon and hydrogen (C and H) during rice straw pyrolysis, biochar samples were produced at a temperature of 800 °C under different atmospheres (N2 or CO2). Thermogravimetric/mass spectrometry monitoring was used to measure the gases released during pyrolysis. The straw samples were also pre-treated with alkaline solutions to improve the retention rate of the nutrient element N in the biochar, making it suitable to be used for soil amendment. These studies yielded some important results: (1) When the evolution of gases containing the nutrient element N was high, the release of gases containing energy elements also increased; i.e., the N and C/H release showed a consistent positive correlation. (2) Pre-treatment with an alkaline solution inhibits N loss during straw pyrolysis, and higher-concentration alkaline solutions more effectively reduce the release of N. The amounts of N-containing gases released during the pyrolysis of straw samples subjected to the different pre-treatment procedures followed the order raw straw ≈ 0.15% KOH > 0.15% Ca(OH)2 > 0.15% NaOH. (3) Raw rice straw is mainly composed of cellulose (32.1%), hemicellulose (35.7%), and lignin (22.3%). Soaking the straw in an alkaline solution increases the relative contents of cellulose and hemicellulose. Because cellulose has an ordered crystalline structure with high thermal stability, the energy and nutrient elements were not easily released from cellulose as gases during pyrolysis.

Storage characteristics of infrared radiation stabilized rice bran and its shelf-life evaluation by prediction modeling.

Rice bran is a nutrient-dense and resource-rich byproduct produced from the rice milling. The limitation of rice bran utilization is mainly caused by oxidative deterioration. Improvement of stability to prolong rice bran shelf-life has thus become an urgent requirement. The present study aimed to determine the characteristics of infrared radiation heat treatment of rice bran (IRRB) and raw rice bran stored under different temperatures. The effects of heating and storage time on physicochemical, microbial, storage stability and structural properties were investigated. Additionally, the prediction model for the shelf-life of rice bran was established based on free fatty acids and the peroxide value by fitting the curve of bran lipid oxidation. The results obtained demonstrated that infrared radiation heating at 300 °C for 210 s resulted in decreased lipase activity and peroxidase activity of 73.05% and 81.50%, respectively. The free fatty acids and peroxide value of IRRB stored at 4 and 25 °C for 8 weeks were only reached at 2.35% and 3.17% and 2.53 and 3.64 meq kg-1 , respectively. The shelf-life prediction model showed the the shelf-life of infrared radiation-treated samples increased to 71.6 and 25.8 weeks under storage at 4 and 25 °C, respectively. The stabilizing process could effectively suppress microbial growth and had no prominent effect on the physicochemical and microstructure properties of rice bran and, simultaneously, storage life was greatly extended. © 2020 Society of Chemical Industry.

Microwave absorption on a bare biomass derived holey silica-hybridized carbon absorbent

Developing lightweight and inexpensive absorbents with strong and broadband absorbing performance toward microwave radiation is a challenging but pressing task. Here we report that rice husk-derived silica-hybridized holey carbon fabricated by combining pyrolysis and plasma processing methods is active for the microwave absorbing. The obtained metal-free product is barely prepared from wasted biomass without any additive reagents addition. The results demonstrate at the thickness of 1.5 mm, its reflection loss reaches −43.0 dB at 13.36 GHz and the corresponding absorption bandwidth approaches 3.68 GHz (from 11.44 GHz to 15.12 GHz), over-performing most bare biomass-derived absorbents. The enhanced performance is attributed to the silica blocks existing on surface, which is inherited from the raw rice husk precursor and will construct abundant hybridized contact sites with the derived carbon matrix, thereby providing plenty of interfacial polarizations. Meanwhile, the post plasma treatment can generate rich tiny holes on the carbon matrix, and endow it with high surface areas associated with a great variety of defective sites, and hence regulating the dielectric loss of the final product. It is anticipated that these can represent a feasible addition to the family of wasted biomass-derived sustainable microwave absorbents.

Activated Kaolin Minerals as Bleaching Clays for Prolonging the Useful Life of Palm Oil in Industrial Frying Operations

AbstractDuring frying operations, vegetable oils break down and compounds with undesirable flavors are produced. Various procedures have been developed to extend the useful life of frying oils, including treatment with bleaching clays. In this article, we describe the activation of kaolin minerals by a combination of grinding and chemical treatments, and report their performance in removing breakdown products generated in palm oil that had been used for 20 hours continuous frying. There was little influence of the original kaolin mineral form on the ability to reduce the free fatty acid (FFA) contents, and grinding only changed FFA reduction from ∼32% to ∼36%. However, much greater FFA reductions were obtained after chemical treatment of the ground clays, and the best performing kaolin product gave similar FFA reduction to a commercial bleaching clay (∼76% and ∼77%, respectively). This activated kaolin also produced a reduction in viscosity at 40 °C from ∼73 to 48.4 cSt (compared to 45.5 cSt in the unused oil), and in the peroxide value from 30.0 to 22.0 meq/kg (compared to 10.0 meq/kg in the initial oil). Thus, activated kaolin samples represent a cheap and convenient alternative to conventional bleaching clay for improving common quality parameters in used palm oil, although we also found that the optimum kaolin preparation conditions were different from those that have been reported for raw rice bran oil refining.