Siti Mazlina Mustapa Kamal

Subcritical Water Extraction of Bioactive Compounds from Plants and Algae: Applications in Pharmaceutical and Food Ingredients

Plants and algae are the main sources of natural bioactive compounds used in the food and pharmaceutical industries. It is very important to achieve an efficient and safe technique to recover bioactive compounds while maintaining their quality and properties. Subcritical water extraction is the most promising engineering approach that offers an environmentally friendly technique for extracting various compounds from plants and algae. Application of pressurized water and high temperature in subcritical phase is able to modify the dielectric constant and polarity of the solvent which then contributes to a better extraction process. The technique improves the mass transfer rate and preserves the biological potency of the extracts. This article reviews current studies on the extraction of bioactive compounds from various species of plants and algae using the subcritical water technique and discusses its effects and benefits for the food and pharmaceutical industries.

Subcritical Water Technology for Extraction of Phenolic Compounds from Chlorella sp. Microalgae and Assessment on Its Antioxidant Activity

Chlorella sp. microalgae is a potential source of antioxidants and natural bioactive compounds used in the food and pharmaceutical industries. In this study, a subcritical water (SW) technology was applied to determine the phenolic content and antioxidant activity of Chlorella sp. This study focused on maximizing the recovery of Chlorella sp. phenolic content and antioxidant activity measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay as a function of extraction temperature (100–250 °C), time (5–20 min) and microalgae concentration (5–20 wt. %) using response surface methodology. The optimal operating conditions for the extraction process were found to be 5 min at 163 °C with 20 wt. % microalgae concentration, which resulted in products with 58.73 mg gallic acid equivalent (GAE)/g phenolic content and 68.5% inhibition of the DPPH radical. Under optimized conditions, the experimental values were in close agreement with values predicted by the model. The phenolic content was highly correlated (R² = 0.935) with the antioxidant capacity. Results indicated that extraction by SW technology was effective and that Chlorella sp. could be a useful source of natural antioxidants.

Removal of Lactose from Highly Goat’s Milk Concentration through Ultrafiltration Membrane

Concentration of goat milk using cross-flow filtration unit with 10KDa molecular weight cut off (MCWO)-sized ultrafiltration membrane was examined under various operating conditions. The parameters to be optimized are trans-membrane pressure (TMP) and cross-flow velocity. Permeate flux is decreased with time due to fouling of the membrane. The localized membrane fouling may be reduced by increasing the feed flow rate and TMP to mitigate overall membrane fouling. By doing so, the transmission of lactose will also increase. The aim is to produce concentrated goat milk with minimal lactose content and thus high concentration of protein. Spray-drying method is used to convert the concentrated non-lactose milk obtained into milk powder. The milk powder then was characterized in terms of its surface particle, solubility, and nutritional content with the well-commercialized non-lactose milk. This project tackles understanding to minimize the deposition rates of particles on membrane by optimizing the involved parameters and be proved by comparing the yield obtained with well-commercialized non-lactose milk. Keywords: Goat’s milk, lactose intolerance, ultrafiltration, spray dry,membrane, concentration

Microwave-Assisted Pretreatment of Sago Palm Bark

Three types of microwave-assisted diluted solvents were employed using 0.1 N H2SO4 (MSA), 0.1 N NaOH (MSH), and 0.01 N NaHCO3 (MSB). These solvents were evaluated as possible pretreatment routes for sago palm bark (SPB) with their effects on the pretreated substrate. A variety of analyses, consisting of fiber analysis, energy dispersive X-ray spectroscopy (EDX), X-ray fluorescence spectrometer (XRF), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and high-performance liquid chromatography (HPLC), were performed to understand the pretreatment effects on the chemical and physical characteristics of SPB and pretreatment liquor. The thermal analysis has revealed that higher hemicellulose degradation was also found in MSA pretreatment. In the analyses of the pretreatment liquid for the extracted monomeric sugar, a higher amount of glucose was found (9 mg/g) using MSH pretreatment and the highest xylose level was found (4 mg/g) using MSA pretreatment. The analysis of the formation of inhibitors has shown that acetic acid was only found in the MSH pretreatment.

The effects of satay marination on three beef muscle types.

The effects of marination on the weight gain, cooking loss and Warner-Bratzler shear force of three beef muscle types, i.e. blade roast (BR), biceps femoris (BF) and semitendinosus (ST) were investigated by treating them in distilled water (as control), brine solution, tamarind juice, tamarind juice plus salt and satay marinade for 180 minutes. The weight gain of ST muscles were significantly higher (P < 0.01) than the BR muscles in brine solution, tamarind juice plus salt and satay marinade, while ST and BF muscles did not differ significantly (P > 0.01) in all the five treatments. For cooking loss, muscle types did not show a significant difference (P > 0.01) in all marinating treatments except for BR and ST muscles in tamarind juice (P = 0.00023). The presence of salt in tamarind juice gave better results in tenderising ST muscles than using tamarind juice alone.