Category Archives: In Press

MACROSCOPIC CHARACTERISTICS OF PALM OIL AND PALM OIL METHYL ESTER USING DIMENSIONLESS ANALYSIS

The spray characteristics of fuels greatly influence the emissions from diesel engines. Spray development plays a vital role in improving the combustion and emission characteristics of fuels because it directly affects the air-fuel mixture formation. The spray characteristics of fuels depend mainly on the fuel injection process, fuel density, fuel viscosity, ambient pressure, and temperature. Among these, the effect of fuel injection pressure and fuel viscosity is a very important parameter directly affecting spray structures. This study investigates the effects of viscosity of fuel on pre-heating. The spray characteristics such as spray angle and spray tip penetration in a constant volume chamber under non-evaporating conditions are carried out by Mie scattering techniques and using Image J software. The Weber number, Reynolds number, and air to fluid density ratio dimensionless numbers were used to capture the primary forces including the inertia, surface tension, and aerodynamics. The experiments were carried out for different pre-heat temperatures. For the fuels and temperature-pressure conditions evaluated, the Weber number varies from 3000 to 120 000, the Reynolds number varies from 10 000 to 63 000. The result of the macro analysis shows that an increase in the fuel temperature leads to a decrease in viscosity and density, thereby increasing the spray tip penetration.

TOTAL PHENOLIC CONTENTS AND ANTIOXIDANT ACTIVITY OF PALM OILS AND PALM KERNEL OILS AT VARIOUS REFINING PROCESSES

Oil palm is one of the richest sources of antioxidants such as carotenoids, tocopherols, tocotrienols and phenolic compounds. This study quantified the amount of total phenolic content (TPC) and the antioxidant activity of crude to refined palm oil and palm kernel oil products obtained from palm oil mills. The TPC of the oil extracts was determined using Folin-Ciocalteau method expressed as gallic acid equivalent (GAE). Aqueous oil extraction with methanolic solvent was efficient and extract from crude palm oil (CPO) had the highest concentration of TPC. A reduction in trend was observed along the various stages of the refining steps probably due to losses through absorption of bleaching earth, volatilisation and degradation during the refining processes. The antioxidant activity was determined using 2,2-diphenyl-1-picrylhdrazyl (DPPH) assays. Results showed that the effect of antioxidants on DPPH radical scavenging activity decreases in the order of oil extracts CPO > CPKO > RPO > RPKO > RPOo > PKOo. Overall, it was found that CPO extract exhibited the highest antioxidant activity due to high TPC compared to other extracted oil samples.

FORMULATION OF A LOW GLYCEMIC BINDER FORTIFIED WITH PALM VITAMIN E (tocotrienol-rich fraction) FOR FUNCTIONAL GRANOLA BARS

A granola bar is the combination of dry ingredients and a wet binder compressed into a bar form and is an excellent vehicle for delivering bioactive compounds to consumers. Sugar is one of the main components in granola bar binder, and it provides the sticky property and flavour to the granola bar. However, high sugar consumption can cause complications and health problems. This study focuses on the use of low glycemic natural sweeteners in the formulation of a granola bar binder and palm vitamin E (tocotrienol-rich fraction, TRF) as a potential fortifier to enhance the functionality of the granola bar while promoting health benefits, including cardioprotection, neuroprotection, as well as hypocholesterolemic, anti-cancer and antioxidant properties. An augmented simplex lattice design was used to develop the granola binder with natural low glycemic sweeteners (in response to °Brix), namely honey, date paste and coconut sugar. The desired °Brix was 80 to 85. The optimal range of sweeteners blend with the desired °Brix was 31.18% to 38.4% of honey, 7.25% to 9.43% of date paste and 24.65% to 32.63% of coconut sugar. Granola bars were prepared using three different sweetener formulations. Palm TRF was added to the selected binder formulation to enrich the vitamin E content in the finished product (granola bar). Honey and coconut sugar were responsible for the effect on °Brix of the binder, while date paste was the limiting factor that constrained °Brix. Granola bar with 15.22% honey, 4.71% date paste and 16.31% coconut sugar received sensory scoring which was significantly higher than for a commercial bar. The formulated granola bar which was enriched with 3.23 mg g-1 vitamin E had a proximate composition and caloric value comparable to that of the commercial granola bar.

OXIDATIVE CHANGES IN REPEATEDLY HEATED VEGETABLE OILS

Thermal oxidation of vegetable oils due to repeat heating is known to exert adverse effects on human health. The oxidative stability of vegetable oils is one of the important factors in determining suitable types of cooking oils and cooking methods. Therefore, the oxidative changes in several types of commonly used vegetable oils, namely: palm olein (POo), soyabean oil (SBO) and corn oil (CNO) were studied. The oil samples were heated repeatedly at 150°C for five rounds. The oxidation level of the oils was assessed by determining their respective changes in fatty acid composition, peroxide value (PV), free fatty acid (FFA) value and p-anisidine value (AV). SBO and CNO contained significantly higher amount of unsaturated fatty acids (84.1% and 86.2%, respectively) compared to POo (56.8%). Consequently, PV, FFA and AV value of the oil samples increased according to their unsaturation level: POo < SBO < CNO. Therefore, POo was shown to have the greatest oxidative stability against thermal oxidation, followed by CNO and SBO.

OPTIMISATION OF ENZYMATIC DIRECTED INTERESTERIFICATION OF PALM OIL FOR HIGH YIELD OF TRIUNSATURATED TRIACYLGLYCEROL USING RESPONSE SURFACE METHODOLOGY

Unsaturated fatty acids (USAFA), especially monounsaturated fatty acids (MUFA), has been shown to provide substantial health benefits. This study attempted to increase the triunsaturated (U3 ) triacylglycerols (TAG) content in palm oil (PO) via lipase-catalysed directed interesterification (EDIE), to enable the production of a liquid fraction that is high in USAFA, especially MUFA. A response surface methodology with three factors and five levels in a central composite design was employed for optimisation of the EDIE conditions for the U3 TAG production. The effects of reaction temperature (20°C-50°C), reaction time (12-28 hr) and enzyme load (2%-18%) on the U3 TAG and by-products yields were investigated. Well-fitted quadratic and linear models were successfully established for both responses. All processing conditions affected significantly (p<0.05) U3 TAG yield. By-products yield was affected by reaction time and temperature. Although increasing reaction temperature and enzyme load, and extending the reaction time resulted in a higher U3 TAG yield, a higher amount of by-products were formed as well. The optimised processing conditions were a reaction temperature of 30°C and reaction time of 18 hr, when immobilised lipase enzyme load was set at 10% (w/w), and resulted in yields of about 27% of U3 TAG and 23% of by-products.

OPTIMISATION OF PROCESS CONDITIONS FOR ETHANOL PRODUCTION FROM ENZYMATICALLY SACCHARIFIED EMPTY FRUIT BUNCH USING RESPONSE SURFACE METHODOLOGY (RSM)

Oil palm empty fruit bunch (EFB), being one of the lignocellulosic biomass forms generated from the palm oil milling process, has high contents of cellulose and hemicelluloses for bioethanol production. However, the conversion routes so far remain challenging and optimisation is necessary. This article aims at optimising the fermentable process variables in the production of bioethanol from EFB using response surface methodology (RSM). The EFB was firstly pre-treated with mild NaOH, then hydrolysed using diluted H2SO4 to extract mainly xylose and subjected to enzymatic saccharification for glucose recovery prior to fermenting the sugars with Saccharomyces cerevisiae. A Central Composite Design (CCD) was used to optimise the three independent variables involved i.e. pH, temperature and agitation rate. The RSM data subjected to analysis of variance (ANOVA) and a second-order polynomial model revealed the optimised conditions: pH 4, 30°C, 150 rpm and 72 hr in batch fermentation. The validation experiment under these conditions gave a maximum bioethanol yield of 0.66 g g-1 glucose, which was very close to the predicted value (0.56 g g-1). These results confirmed that the model was adequate and reliable to optimise bioethanol production from the enzymatically hydrolysed EFB.

ENZYMATIC INTERESTERIFICATION OF PALM FRACTIONS FOR THE PRODUCTION OF COCOA BUTTER ALTERNATIVES

Cocoa butter is the most preferable confectionery fat. In spite of this, cocoa butter alternatives (CBA) are also highly sought-after confectionery fats due to low supply and higher cost of cocoa butter. In the pursuit to produce palm-based CBA, various technological modification techniques have been employed. These include fractionation, blending, hydrogenation, interesterification (chemical and interesterification) or combination of these processes. Enzymatic interesterification (EIE) of lipids has received a lot of attention for the production of palm-based CBA especially cocoa butter equivalent. This review article, therefore, intends to offer an overview of EIE studies for the production of palm-based CBA. In this review, technological modification techniques are discussed in brief while publication related to EIE are discussed in depth based on its reactions categories (i.e. acidolysis, ester-ester exchange and alcoholysis). Reaction condition (i.e. subtrate, enzyme and optimum condition) and outcome of the EIE process are outlaid in this article.

EFFECT OF FLOW RATE AND CONCENTRATION OF CARBAMIDE ON THE REDUCING NOx EMISSIONS IN PALM BIODIESEL FUELED RESEARCH ENGINE

This study examines the consequences of concentration and flow rate of carbamide (urea) to reduce NOx emissions from a diesel engine propelled with biodiesel. Taguchi-Grey relational-based multi-response optimisation method was employed for test-plan. Results revealed that carbamide flow rate and its concentration have a positive impact on NOx emissions reduction in unmodified diesel engine. The obtained results are also justified with results attained from ANOVA. It is also confirmed that the results obtained in the experimentations are in line with the calculated values obtained Taguchi technique. Hence, the usage of carbamide in tailpipe is an effective way in reducing NOx emissions from diesel engine.