Synthesis of Adipate Esters Using Candida Rugosa Lipase Immobilized Onto Layered Double Hydroxides

The increasing demand for specially formulated adipate esters make it necessary to develop highly specific catalysts. For this reason, the application of immobilized enzyme as industrial biocatalyst for the synthesis of adipate ester via environmental benign process is undergoing a rapid development. Because of the unique and reproducible properties, layered double hydroxides (LDHs) were used as supports for enzyme immobilization. In this study, layered double hydroxides (LDHs) of Mg/Al-NO3-, Zn/Al-NO3- and Ni/Al-NO3- of molar ratio of M2+/M3+ (4:1) was prepared by co-precipitation method through continuous agitation. Their structures and characteristics were determined using X-ray Diffractometer (XRD), Accelerated of Surface Area and Porosimeter (ASAP), Fourier Transform Infra-red (FTIR) and Scanning Electron Microscopy (SEM). From the analysis results, the supports were found to be successfully synthesized. Lipase from Candida rugosa was immobilized onto these newly synthesized supports by a simple and inexpensive method of physical adsorption. Immobilization of lipase onto these support was confirmed using Energy Dispersion X-ray (EDX). EDX spectra of immobilized LDHs-lipase proved that immobilization process occurred based on the presence of both the metal compounds of the supports and protein components. The percentages of protein loading on LDHs were from 58 - 71%, due to the larger surface area (24.0 – 52.6 m2g-1), porosity (8.7 x 10-3 – 22.8 x 10-3 cm3g-1) and basal spacing (8.2 – 9.3 Ǻ) of the supports. The synthesis of dimethyl adipate (DMA) and dibutyl adipate (DBA) esters catalyzed by immobilized lipases were carried out via esterification of adipic acid and methanol as well as butanol as substrates and hexane as reaction medium. The effects of various reaction parameters such as reaction time, temperature, organic solvent, water activity and mole ratio of substrates were studied to determine optimal conditions for the production of adipate esters. The optimal conditions for both DMA and DBA esters syntheses using immobilized lipases were obtained at reaction time; 2.5 hours, temperature; 50 oC and molar ratio of substrates; 2. High yields (>65%) of the products were obtained in hexane (log P = 3.5) as the reaction medium and optimal percent conversion (up to 85%) was found to be dependant on the water activity (Aw) of 0.53 for DMA and 0.75 for DBA. The stability studies on the effects of thermal stability, leaching study, stability in organic solvent, storage study and reusability were investigated for their influence on the enzymatic esterification for production of adipates. The immobilized lipases retained high catalytic activity and showed increased stability compared to the native lipase in all cases. In thermal stability study, immobilized lipases were less affected and showed high activity even upon incubation at 70°C. When stored at different temperatures for 60 days, all immobilized lipases performed much better in activity. Furthermore, the commercial immobilized lipases and the LDHs-lipases showed an efficient reuse which makes this system attractive and applicable to various reactions

Biochemical production of fatty acid sugar-based biosurfactant (FASB) via green enzymatic route as potential application in pharmaceutical

Enzymatic processes offer an alternative for the synthesis of bio-surfactants through the employment of biocatalysts, which allow for a mild reaction condition and high selectivity. Fatty acid sugar esters, a group of biosurfactants, are produced by the esterification of sugars with fatty acids. They are odorless, non-toxic and non-irritant to the skin, making them suitable not only as emulsifiers for foods, but also in pharmaceuticals and cosmetics. Moreover, due to their high biodegradability and varied range of hydrophilic-lipophilic balance (HLB) values, the study and production of sugar esters have attracted keen attention from many researchers. A biochemical approach has been implemented through the use of lipase immobilized on an inexpensive carrier of mica clay as biocatalyst. The synthesis of fatty acid sugar esters or fatty acid sugar-based biosurfactants was optimized via various reaction parameters before conducting product characterization and validation. High enzyme stability and productivity were successfully performed through biocatalytic system. Furthermore, an optimized reaction parameters studied was achieved for the synthesis of fatty acid sugar sugar-based biosurfactants. The synthesized biosurfactant (or specifically lactose caprate, with molecular formula C22H40O12) was characterized to examine their efficacy for industrial application. This study showed that the biosurfactant derived from lactose and capric acid had an HLB value of 14.88, which is suitable for the preparation of oil-in-water emulsions. In addition, this non-ionic biosurfactant was found to behave like a water-soluble surfactant and an oil-in-water emulsifier which potentially used for food products, pharmaceuticals and detergent industries

Optimization of Nigella sativa oil-based ferulate ester synthesis using response surface methodology

Nigella sativa L. seed, also recognized as black cumin is a medicinal plant that possesses miraculous power of healing due to the abilities to cure various ailments. Owing to the oily properties of plant oil, the oil ester is more preferable exhibiting special features such as non-toxic, outstanding moisturizing action and most importantly the absence of oily texture. In this study, Nigella sativa oil-based ferulate ester was synthesized via transesterification of Nigella sativa oil (NSO) and ethyl ferulate (EF) in the presence of immobilized lipase, Lipozyme RM IM from Rhizomucor miehei. A five-level-four-factor central composite rotatable design (CCRD) from response surface methodology (RSM) was applied to study the influence of synthesis parameters: lipase dosage (50-80 mg), temperature (40-60°C), substrate ratio of NSO:EF (2.5:1-5.5:1 w/w) and time (3-7 hr) aiming for the maximum percentage yield of ester. The optimized synthesis conditions were lipase dosage of 67 mg, temperature of 56°C, substrate ratio (NSO:EF) of 4.4:1 w/w and time of 4 hr. The maximum production of ester obtained was 49.87% which is acceptable with the predicted value of 48.82%

Quality assessment of steviol glycosides in commercial stevia extracts from local market in Malaysia

Extracts from leaves of Stevia rebaudiana Bertoni, steviol glycosides are used to sweeten food and beverages. It has been approved as sweeteners in many countries all over the world. The majority findings show there is no toxicity in steviol glycosides. However, the complex purification process on commercial stevia has caused its authenticity to be challenged and discussed. Furthermore, the safety of commercial stevia extract in Malaysia has been in query. Therefore, the aim of the present study was to screen and determine the quality of commercial stevia extract from local market in Malaysia, in comparison to the standard solution of steviol glycosides obtained from the leaves of Stevia rebaudiana. The present study analysed and compared three independent commercial stevia samples by using High Liquid Performance Chromatography (HPLC), Liquid Chromatography-Mass Spectrometry (LC-MS) and Fourier Transform Infrared Spectroscopy (FTIR). The results showed that the commercial stevia extracts have different qualities of steviol glycosides; in terms of the steviol glycosides content and composition. It is of a remarkable fact that all three analytical methods showed no steviol glycosides were able to be detected in commercial stevia Sample 1. Sample 2 was found to contain the highest concentration of steviol glycosides according to HPLC analysis, while Sample 3 showed the most identical compounds to the standard steviol glycosides according to FTIR analysis. The present study shows the different composition and quality of steviol glycosides in commercial stevia extracts, which warrants further investigation

Development of nanoemulsion incorporated with Hibiscus sabdariffa for cosmeceutical application

Hibiscus sabdariffa (HS) has been reported to possess a crucial content of bioactive compounds, such as phenolic acids and flavonoids, therefore, HS was recognized as a source of antioxidants. Due to that, the development of nanoemulsion incorporated with HS appears promising for cosmeceutical application. This study is focused on the formulation of oil-inwater (O/W) nanoemulsions of HS to enhance the bioaccessibility of its active compounds. The influences of hydrophiliclipophilic balance (HLB) value of surfactant and grapeseed oil (GSO) to olive oil (OO) ratio on the droplet size, zeta potential, PDI and stability of the nanoemulsions were investigated. The results showed that the smallest particle size was obtained at 145.9 nm with PDI = 0.388 and zeta-potential = -41.1 mV in the systems prepared using HLB value of 12 and 2:1 ratio of GSO to OO. Then the selected nanoemulsion which based on the lowest particle size (NE-F6, GSO:OO = 2:1, and HLB = 12) showed good stability over time and temperature without no phase separation, creaming or cracking was spotted. The pH value of the NE-F6 was obtained at 5.2

Development of nanoemulsion incorporated with Hibiscus sabdariffa for cosmeceutical application

Hibiscus sabdariffa (HS) has been reported to possess a crucial content of bioactive compounds, such as phenolic acids and flavonoids, therefore, HS was recognized as a source of antioxidants. Due to that, the development of nanoemulsion incorporated with HS appears promising for cosmeceutical application. This study is focused on the formulation of oil-inwater (O/W) nanoemulsions of HS to enhance the bioaccessibility of its active compounds. The influences of hydrophiliclipophilic balance (HLB) value of surfactant and grapeseed oil (GSO) to olive oil (OO) ratio on the droplet size, zeta potential, PDI and stability of the nanoemulsions were investigated. The results showed that the smallest particle size was obtained at 145.9 nm with PDI = 0.388 and zeta-potential = -41.1 mV in the systems prepared using HLB value of 12 and 2:1 ratio of GSO to OO. Then the selected nanoemulsion which based on the lowest particle size (NE-F6, GSO:OO = 2:1, and HLB = 12) showed good stability over time and temperature without no phase separation, creaming or cracking was spotted. The pH value of the NE-F6 was obtained at 5.2

Optimization of antioxidant extraction in hylocereus polyrhizus seed using response surface methodology

Seeds of red pitaya fruit (Hylocereus polyrhizus) are commonly left underutilized in the food industry. Thus, the objective of this present study was to optimize the extraction condition for the maximum DPPH radical scavenging activity of red pitaya fruit seed extract using response surface methodology (RSM). A Central Composite design was employed to determine the effects of the selected variables, comprising extraction time (30-90 min), extraction temperature (40-80 ℃) and ethanol concentration (60-80 %) on the DPPH scavenging activities. Data were analyzed by using Design Expert (version 10.0.1, Stat-Ease, Inc., Minneapolis, MN, USA) statistical analysis software. The optimal extraction conditions for the highest antioxidant capacity were derived at 45 mins of extraction time, 70℃ extraction temperature and 80 % ethanol concentration that resulted in 92.89 % of scavenging activity. The optimized model developed was verified by comparing the predicted and experimental value of response. The result of measured response agreed well with the predicted values, demonstrating that the model can be used for optimizing the conditions of RSP extract that ensure high recovery of DPPH radical scavenging activity

Comparative study of the biological activities of different commercial Stevia extracts from local market in Malaysia

An increased awareness on consuming healthy food and beverages worldwide has led to an upsurge of interest in functional food, which includes the use of natural sweetener, the Stevia rebaudiana Bertoni extract. Nevertheless, limited data has been available on the biological activities of commercial Stevia extract available in Malaysia. Hence, the present study aims to evaluate the biological activities of commercial Stevia extract from local market in Malaysia, by evaluating its total phenolic (TPC) and total flavonoid content (TFC), as well as its antioxidant and anti-diabetic activities. Three independent Stevia extracts (Samples A, B and C) sourced from local market in Malaysia were evaluated, in comparison to the freshly prepared Stevia extract. The results showed a significantly lower amount of TPC in commercial Stevia extracts when compared to the freshly prepared Stevia extract (7.077 mg GAE/100 g), with sample A containing the highest TPC (6.359 mg GAE/100 g), followed by sample C (1.496 mg GAE/100 g) and sample B (0.624 mg GAE/100 g). Similar trend was observed with TFC, with sample A containing 0.937 mg QE/100 g, followed by sample C (0.264 mg QE/100 g) and sample B (0.029 mg QE/ 100 g) as compared to the freshly prepared Stevia extract (1.684 mg QE/100 g). Sample A showed the highest antioxidant activity (DPPH: 48.84%, FRAP: 2.589 μmole Fe2+/g, ABTS: 28.48%), albeit lower to the freshly prepared Stevia extract. The commercial samples showed a higher α-amylase inhibition activity compared to the freshly prepared Stevia extract, but no inhibition was observed in the α-glucosidase activity. Fundamentally, the results highlight the biological activities of Stevia extract for functional food applications, but caution has to be exercised as all three commercial extracts have significantly different biological activities

Nutraceutical evaluation and antioxidant potential of red kidney bean (Phaseolus vulgaris) and chickpea (Cicer arietenum) seed coats

Legumes have become increasingly in demand due to the rich nutrient compositions and phytochemicals of pulses. However, the seed coats of some legume food products were removed prior consumption causing the food loss its nutritional value. The red kidney bean, RKB (Phaseolus vulgaris) and chickpea, CP (Cicer arietenum) which are the common beans among population were investigated in this study. Seed coats of these beans were analysed for the nutritional composition, phenolic compound and antioxidant properties. Carbohydrate was the major macronutrient in both seed coats. RKB and CP seed coats showed statistically significant composition of moisture, fat, protein and fibre. The caloric value of RKB seed coat (2.63 kcal/g) is higher than CP seed coat (2.29 kcal/g). Nevertheless, CP seed coat is a better source of fibre (27%) than RKB seed coat. Total phenolic content (TPC) of RKB seed coat was 12.14 mg GAE/g, which is much higher than in CP seed coat (0.25 mg GAE/g). Interestingly, the seed coat of RKB has strong antioxidant potency with DPPH assay (IC50 = 105.18 µg/ml) comparable to standard Trolox (IC50 = 96.42 µg/ml), which is much lower than the seed coat of CP (IC50 = 606.12 µg/ml). In addition, the antioxidant activity was highly correlated with TPC content of both seed coats. These properties make the seed coat of both beans are excellent candidates of potent nutraceutical

Microbial synthesis of zinc oxide nanoparticles and their potential application as an antimicrobial agent and a feed supplement in animal industry: a review

In recent years, zinc oxide nanoparticles (ZnO NPs) have gained tremendous attention attributed to their unique properties. Notably, evidence has shown that zinc is an important nutrient in living organisms. As such, both prokaryotes and eukaryotes including bacteria, fungi and yeast are exploited for the synthesis of ZnO NPs by using microbial cells or enzyme, protein and other biomolecules compounds in either an intracellular or extracellular route. ZnO NPs exhibit antimicrobial properties, however, the properties of nanoparticles (NPs) are depended upon on their size and shape, which make them specific for various applications. Nevertheless, the desired size and shape of NPs can be obtained through the optimization process of microbes mediated synthesis by manipulating their reaction conditions. It should be noted that ZnO NPs are synthesized by various chemical and physical methods. Nonetheless, these methods are expensive and not environmentally friendly. On that account, the microbes mediated synthesis of ZnO NPs have rapidly evolved recently where the microbes are cleaner, eco-friendly, non-toxic and biocompatible as the alternatives to chemical and physical practices. Moreover, zinc in the form of NPs is more effective than their bulk counterparts and thus, they have been explored for many potential applications including in animals industry. Notably, with the advent of multi-drug resistant strains, ZnO NPs have emerged as the potential antimicrobial agents. This is mainly due to their superior properties in combating a broad spectrum of pathogens. Moreover, zinc is known as an essential trace element for most of the biological function in the animal’s body. As such, the applications of ZnO NPs have been reported to significantly enhance the health and production of the farm animals. Thus, this paper reviews the biological synthesis of ZnO NPs by the microbes, the mechanisms of the biological synthesis, parameters for the optimization process and their potential application as an antimicrobial agent and feed supplement in the animal industry as well as their toxicological hazards on animals