Solid liquid extraction of Jatropha seeds by microwave pretreatment and ultrasound assisted methods

Jatropha curcas has a variety of uses which are of great economic significance. Jatropha oil can be used as fuel alternative and for making biodiesel that is supposed to overcome the source limitation problem. In this study, conventional, ultrasound assisted and microwave pretreatment solid liquid extraction of Jatropha seed were studied in terms of amount and quality of the extracted oil. The free fatty acid content which is an important oil quality index was also investigated for the obtained oil. Both ultrasonication and microwave pretreatment of the seeds had a positive effect on amount of yield. However, by application of ultrasound, more oil could be extracted compared with that obtained by conventional and microwave pretreatment extraction methods. The maximum amount of oil which could be extracted by conventional, ultrasound assisted and microwave pretreatment methods were 47.33, 51.4 and 49.36%, respectively. Regarding the quality, oil extracted by conventional, ultrasound assisted and micmicrowave pretreatment extraction methods did not show any significant difference in terms of Free Fatty Acids (FFA) content

Lignin and Cellulose Changes of Betung Bamboo (Dendrocalamus asper) pretreated Microwave Heating

This study highlighted the effect of microwave pretreatment on betung bamboo on the chemical structural and morphological changes. The hydrothermal condition was performed in varying power loading (330, 550, and 770 W) and microwave irradition time (5-12.5 min). FTIR spectroscopy, X-Ray diffraction and SEM-EDS analysis were utilized to confirm the characteristic changes after pretreatment. The results showed that the severe pretreatment condition tended to increase the carbohydrate losses. From FTIR spectra, microwave pretreatment tended to decrease absorbancy of functional group bands. After microwave pretreatment for 12.5 min (770 W), the band around 1736 cm-1 (C=O in xylan) disappeared in the samples. The syringil propane unit was lower than that of guaiacyl lignin under microwave pretreatment. The disruption of the structure of the cell wall increased the accessibility of cellulase to lignocellulose. Except microwaving for 5 min (330 W), the microwave heating caused carbon and oxygen increasing compared to untreated samples. The increase in crystallinity index of pretreated bamboo suggested the selective degradation of amorphous components.

Steam Distillation of Essential Oil from Lemongrass (Cymbopogon citratus) using Microwave Pretreatment

Essential oils from lemongrass (Cymbopogon citratus) containing citral are very potential to be used in food and pharmacy industries. The process of isolating essential oils is still constrained by its low yield. In order to increase yield, in this research, isolation of essential oil by steam distillation method was carried out using microwave pretreatment. The results showed that pretreatment using microwave for 2 minutes had the effect of increasing yield up to 1.4 times compared to without pretreatment. The essential oil produced using microwave pretreatment had physical properties (colour, odor, density, and refractive index) similar to those without pretreatment. Composition analysis by GC-MS showed that essential oils extracted using microwave pretreatment and without pretreatment contain geranial (Ecitral or citral-a), neral (Z-citral or citral-b) and mircena as the main components

Microwave pretreatment for the extraction of anthocyanins from saffron flowers: Assessment of product quality

Producción CientíficaThe potential of saffron flowers as a source of polyphenols, and in particular anthocyanins, for the extraction of bioactive compounds and the production of a cyanic colorant was analyzed. A microwave pretreatment, prior to the conventional solid–liquid extraction process, was proposed as a feasible intensification step. The effectiveness of microwave pretreatment was assessed in terms of increased yield and improved quality of the final product. The operational variables studied were the pretreatment temperature (60–120 °C) and the solid–liquid ratio (0.30–0.50 g/mL). It was found that the addition of the microwave pretreatment to the conventional process allowed one to reduce extraction time by up to 12 times and to greatly improve the characteristics of the final product, using microwave energy densities as low as 0.16–0.54 kJ/mL. The extract quality was evaluated in terms of polyphenol richness (25% increase), product composition (80% of the anthocyanins was delphinidin), antioxidant capacity (boosted by the pretreatment) and color (variations in red and blue hue depending on conditions). To conclude, a microwave pretreatment in which the material is heated to a temperature of 65 °C with a solvent ratio of 0.30 g/mL was selected as the optimum to maximize process efficiency and product quality.Junta de Castilla y León - (Project VA040U16

Enhancement of the total phenolic compounds and antioxidant activity of aqueous <i>Citrus limon </i>L. pomace extract using microwave pretreatment on the dry powder

The effect of microwave pretreatment on the levels of total phenolic compounds, flavonoids, proanthocyanidins, and individual major compounds as well as the total antioxidant activity of the dried lemon pomace was investigated. The results showed that microwave pretreatment significantly affected all the examined parameters. The total phenolic content, total flavonoids, proanthocyanidins, as well as the total antioxidant activity significantly increased as the microwave radiation time and power increased (e.g., 2.5-fold for phenolics, 1.4-fold for flavonoids, and 5.5-fold for proanthocyanidins); however, irradiation of more than 480 W for 5 min resulted in the decrease of these parameters. These findings indicate that microwave irradiation time and power may enhance higher levels of the phenolic compounds as well as the antioxidant capacity of the dried lemon pomace powder. However, higher and longer irradiation may lead to a degradation of phenolic compounds and lower the antioxidant capacity of the dried lemon pomace.Practical applicationsLemon pomace could be a good source of bioactive compounds and antioxidants. Microwave irradiation could be applied for the enhancement of the total phenolic compounds and antioxidants of the lemon pomace-dried powder. The findings of this study can be applied for enhancing the bioactive compounds and the antioxidant activity of the dried lemon pomace for further extraction, isolation, and utilisation

Process intensification by microwave pretreatment

Arbutus unedo L., commonly known as the strawberry-tree fruit, is an endemic species of the Mediterranean flora. Microwave extraction technology has been considered as a fast and "green" method for the production of extracts rich in bioactive compounds, although the energy consumption is high. To overcome this bottleneck, microwave was used as a pretreatment procedure in short time periods. This technique promotes the burst of intracellular vacuoles leading to an increase in the lixiviation of phenolic compounds. Different approaches were tested, namely a solvent-free irradiation (SFI), a solvent-assisted irradiation (SAI) and a pressurized solvent-assisted irradiation (PSAI). After irradiation, a solid-liquid extraction procedure was performed using a mixture of water and ethanol. A kinetic evaluation of the total phenolic content (TPC) was performed using the Folin-Ciocalteu method. For the total anthocyanin content, a UV-spectrophotometric method was used. HPLC-UV and LC-MS were used for TPC and identification of present compounds. Microwave irradiation led to an increase in TPC of extracts after SAI (52%) and PSAI (66%) along with a reduction in time of extraction from 30 min to less than 2 min. The anthocyanin content also increased by 66% for the SAI and PSAI extractions.publishersversionpublishe

Microwave-assisted alkali pretreatment, densification and enzymatic hydrolysis of canola straw and oat hull

Production of bioethanol from lignocellulosic biomass is very challenging due to the complex nature of the feedstocks. Pretreatment is a necessary step for efficient and effective conversion of lignocellulosic biomass to biofuel. This study investigated the effects of microwave-assisted alkali pretreatment, microwave pretreatment (distilled water) and untreated canola straw and oat hull on the pellet quality, and the conversion of microwave pretreated and alkali treated substrates into sugar for cellulosic bioethanol production. Microwave pretreatments were carried out by immersing the biomass in dilute alkali solutions (NaOH and KOH) at various concentrations of 0, 0.75 and 1.5% (w/v) for microwave-assisted times of 6, 12, and 18 min, and at a fixed microwave power of 713 W. Alkali treatments were carried out by soaking and the same alkali used for the microwave pretreatment. The biomass and alkali concentrations remained unchanged. Chemical composition analysis of canola straw and oat hull showed that the application of microwave-assisted alkali pretreatment on the biomass disrupted and broke down the lignocellulosic structure of canola straw and oat hull compared to microwave pretreatment and alkali treatment. Images acquired using a scanning electron microscope (SEM) revealed the structural changes caused by microwave-assisted alkali pretreatment on biomass samples. Pellet characteristics such as density, tensile strength and dimensional stability were used to describe the pellets produced from single pelleting technique. The results showed that the interaction effects of alkali concentration and microwave heating time significantly affected the physical characteristics of canola straw and oat hull pellets. Upon enzymatic saccharification, microwave-assisted alkali pretreatment and alkali treatment of canola straw and oat hull on enzymatic saccharification were investigated. Microwave-assisted alkali pretreatment showed the highest glucose yield in treatment combinations of 1.5% NaOH/18 min for canola straw and 0.75% NaOH/18 min for oat hull sample ground in a1.6 mm hammer mill screen size. Overall, microwave/NaOH pretreatment resulted in better physical quality pellets from both canola straw and oat hull samples than microwave/KOH pretreatment. Also, microwave pretreatment and alkali treatment using NaOH solution at different concentrations resulted in higher glucose yields compared to KOH in both feedstocks

Kinetics for Enzymatic Conversion of Biomass to Glucose

Biofuels are a sought-after alternative for fossil fuels in today’s society. More specifically, cellulose-based biofuel is an avenue of research intending to limit waste and provide new renewable energy. Cellulose is a rigid polymer of glucose monomers that is found abundantly across different agriculture crops. However, its stability is a barrier to energy production from this source. Pretreatment followed by hydrolysis of cellulosic materials serves a potential to produce glucose to be used in biofuels in larger quantities compared to other methods. This project studied the effect microwave pretreatment and oxygenation have on hydrolysis of cellulose in Arundo Donax. Arundo Donax ground samples are used in solution with acetic acid buffer (pH= 5.0) along with cellulase and maintained at 50°C. The solution’s concentration, in parts per million (ppm), of glucose after hydrolysis was measured over 96 hours using the dinitro salicylic acid method. The Michaelis-Menten constant for cellulase using Arundo Donax and Microcrystalline cellulose before pretreatment were found to be 29.965 g/L and 6.684 g/L, respectively. The concentration of glucose found in Arundo Donax reached a maximum of 310 ppm after 72 hours. In addition, oxygenation, and deoxygenation of buffer and Arundo solution as pretreatment did not yield significantly higher concentrations than Arundo without oxygen manipulation averaging a glucose production of 214.5 ppm with deoxygenation and 209.2 ppm with oxygenation. Microwave pretreatment of Arundo Donax followed by hydrolysis resulted in 29.2 ppm glucose

Optimization and Kinetics of Solid Liquid Extraction of Malaysian Jatropha Curcas Seeds

The Jatropha is a plant which grows in most of tropical and subtropical regions of the world. The oil from the Jatropha seeds can be used as fuel alternative and for making biodiesel. This work aimed to determine the optimum parameters to achieve maximum oil yield in solid liquid extraction of Jatropha seeds under experimental conditions. The optimum condition was then applied in ultrasound assisted and microwave pretreatment extraction methods to determine the amount of yield. The kinetics of the extraction was also studied based on the assumption of a second order mechanism. The extraction was carried out using a soxhlet extractor equipped with condenser and hot plate. The effects of five main factors which are namely type of solvents, temperature, solvent to solid ratio, reaction time and size of the raw material were investigated experimentally on the solid liquid extraction of Jatropha seed to optimize the extraction process. The optimum condition was found at eight hours reaction time, temperature of around 68°C, coarse particle size (0.5-0.75 mm), solvent to solid ratio of 6:1 (v/w) and using hexane as the solvent. The maximum amount of yield at optimized condition was at 47.3 % by wt. The activation energy was found to be 7145.05 (J/mol) and the highest initial extraction rate was calculated to be and 4.21 (g/L min). The maximum amount of oil extracted by ultrasound assisted and microwave pretreatment methods were 51.4 and 49.4% respectively. The oil extracted by conventional, ultrasound assisted and microwave pretreatment extraction methods contained, respectively, 0.62, 0.67 and 0.63% free fatty acid and 98.3, 97 and 97.7% triglyceride