Polygonum minus is a plant rich with bioactive components that contribute to food, pharmaceutical, and perfume industries. However, high moisture content in fresh plants will allow
microbial activity that leads to the degradation of plant quality. This can be prevented by
drying the fresh plants to preserve the characteristics of their bioactive components. The
present work was conducted to determine the effect of different drying methods such as
air-drying, oven-drying (40 and 60°C), and freeze-drying on essential oil (EO) yield and
chemical compounds of P. minus roots. For comparison purposes, all samples were extracted
by maceration with n-hexane at room temperature. Then, the samples were analysed and
identified by using gas chromatography-mass spectrometry (GC-MS). The highest EO yield
extract was obtained from freeze-drying (4.15 ± 0.5), followed by air-drying (3.79 ± 0.19). EO
yield from oven-drying at 40 and 60°C was 3.4 ± 0.14 and 0.86 ± 0.04, respectively. Results
showed that by increasing the drying temperature, the EO yield would decrease and cause a
loss of major chemical compounds in the P. minus root. Air-drying was found to be the best
method in preserving the presence of important chemical compound in P. minus roots such as
β-caryophyllene (1.43%), pentadecane (4.34%), hexadecanoic acid (3.91%) and oleic acid
(3.97%).
A preliminary study was conducted to study the effects of different types and concentrations of co-solvents based on yield, composition and antioxidants capacity of extract prior to optimization studies of supercritical fluid extraction (SFE) of Labisia pumila (locally referred to as 'kacip fatimah'). The following co-solvents were studied prior to the optimization of supercritical carbon dioxide (SC-CO2) technique: ethanol, water, methanol, as well as aqueous solutions of ethanol-water and methanol-water (50% and 70% v/v). By using the selected co-solvents, identification of phenolic acids (gallic acid, methyl gallate and caffeic acid) was determined by using High-Performance Liquid Chromatography (HPLC). Then, the antioxidant capacity was evaluated by using three different assays: total phenolic content (TPC), ferric reducing/antioxidant power (FRAP) and free radical-scavenging capacity of 2,2-diphenyl-1-picrylhydrazyl (DPPH). SC-CO2 with 70% ethanol-water co-solvent was superior in terms of a higher combination of phenolic compounds extracted and antioxidants capacity. Overall, SC-CO2 with co-solvent 70% ethanol-water technique was efficient in extracting phenolic compounds from L. pumila, and thus the usage of this solvent system should be considered for further optimization studies.
Scaling-up supercritical fluid extraction (SFE) for the extraction of bioactive compounds from herbal plants is challenging, especially with the presence of alcohol-water as co-solvent. Hence, the main objective of this study is to validate the scale-up criteria of SFE process for Phyllanthus niruri (P. niruri), and analyse the extract safety and profitability process at the industrial scale. The study was performed by using supercritical carbon dioxide (SC-CO2) with ethanol-water co-solvent at two operating conditions (L1: 200 bar, 60 °C and L2: 262 bar, 80 °C). The solvent-to-feed ratio (S/F) scale-up validation experiments were conducted at both operating conditions with feed mass capacity of 0.5 kg. The extraction yields and overall extraction curves obtained were almost similar to the predicted ones, with error of 5.13% and 14.2%, respectively. The safety of scale-up extract was evaluated by using a toxicity test against zebrafish embryo (FETT). The extract exhibited a low toxic effect with the LD50 value of 505.71 µg/mL. The economic evaluation using a detailed profitability analysis showed that the SFE of P. niruri was an economically feasible process, as it disclosed the encouraging values of return on investment (ROI) and net present values (NPV) for all scale-up capacities.
In recent years, astaxanthin is claimed to have a 10 times higher antioxidant activity than that of other carotenoids such as lutein, zeaxanthin, canthaxanthin, and β-carotene; the antioxidant activity of astaxanthin is 100 times higher than that of α-tocopherol. Penaeus monodon (tiger shrimp) is the largest commercially available shrimp species and its waste is a rich source of carotenoids such as astaxanthin and its esters. The efficient and environment-friendly recovery of astaxanthins was accomplished by using a supercritical fluid extraction (SFE) technique. The effects of different co-solvents and their concentrations on the yield and composition of the extract were investigated. The following co-solvents were studied prior to the optimization of the SFE technique: ethanol, water, methanol, 50% (v/v) ethanol in water, 50% (v/v) methanol in water, 70% (v/v) ethanol in water, and 70% (v/v) methanol in water. The ethanol extract produced the highest carotenoid yield (84.02 ± 0.8 μg/g) dry weight (DW) with 97.1% recovery. The ethanol extract also produced the highest amount of the extracted astaxanthin complex (58.03 ± 0.1 μg/g DW) and the free astaxanthin content (12.25 ± 0.9 μg/g DW) in the extract. Lutein and β-carotene were the other carotenoids identified. Therefore, ethanol was chosen for further optimization studies.
Oil palm empty fruit bunch (OPEFB) fibre is widely available in Southeast Asian countries and found to have 60% (w/w) sugar components. OPEFB was pretreated using the ammonia fibre expansion (AFEX) method and characterised physically by the Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The results show that there were significant structural changes in OPEFB after the pretreatment step, and the sugar yield after enzymatic hydrolysis using a cocktail of Cellic Ctec2® and Cellic Htec2® increased from 0.15gg(-1) of OPEFB in the raw untreated OPEFB sample to 0.53gg(-1) of OPEFB in AFEX-pretreated OPEFB (i.e. almost a fourfold increase in sugar conversion), which enhances the economic value of OPEFB. A biohydrogen fermentability test of this hydrolysate was carried out using a locally isolated bacterium, Enterobacter sp. KBH6958. The biohydrogen yield after 72h of fermentation was 1.68mol H2 per mol sugar. Butyrate, ethanol, and acetate were the major metabolites.