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Sterilisation in palm oil mills is considered a pre-treatment process as it affects stripping efficiency and oil quality. Although sterilisation technology has been well-established in the palm oil milling industry, the roles and principles of sterilisation, particularly related to the chemical changes in fruits and stalks occurring during the process, have been rarely reported. The review begins with the background literature on the biochemical properties of the FFBs, such as the compositions of binding carbohydrates and the phenomena of natural fruit detachment. Followed by the harvesting practice to understand the type of FFBs supplied to the industry. In addition, a comparison of the well-established conventional and alternative sterilisation technologies and sterilisation functions is critically reviewed and assessed. Establishing the current sterilisation process initiatives to address the natural fruit’s separation more efficiently in palm oil mills is important. Particularly visualise sterilisation as a breakup of specific binding carbohydrates that leads to strippability. It will provide a further understanding of the sterilisation mechanism, which would benefit the palm oil miller in optimising the processing of fresh fruit bunches. The information provided in this review is necessary to mitigate the percentage of unstripped bunches and reduce the oil losses and ultimately enhance the oil extraction rate.

The physico-chemical properties of solvent-extracted oil from the seeds of noni (Morinda citrifolia L.), spinach (Spinacia oleracea L.), lady’s finger (Abelmoschus esculentus (L.) Moench), bitter gourd (Momordica charantia L.), mustard (Brassica nigra (L.) Koch), and the dried kernel (copra) of coconut (Cocos nucifera L.) were characterized. Among these sources, spinach seed had the lowest oil content (4.5 ± 0.4%) while coconut kernel had the highest oil content (63.1 ± 2.8%). Palmitic, oleic, and linoleic acids were the major fatty acids for spinach, lady’s finger and noni seed oils, while erucic, eleostearic, and lauric acids were the major fatty acids for mustard seed oil, bitter gourd seed oil, and coconut kernel oil, respectively. All of the oils possessed at least three major peaks in their triacylglycerol profiles except for bitter gourd seed oil which had only one major peak (1-stearoyl, 2,3-dieleostearoyl). The last endothermic peaks were –12.4, –6.0, 6.8, 57.7, 2.7, and 24.3oC for noni, spinach,...

For the first time 5-hydroxymethyl-2-furaldehyde (HMF) was separated from crude palm oil (CPO), and its authenticity was determined using an RP-HPLC method. Separation was accomplished with isocratic elution of a mobile phase comprising water and methanol (92:8 v/v) on a Purospher Star RP-18e column (250 mm × 4.6 mm, 5.0 μm). The flow rate was adjusted to 1 ml/min and detection was performed at 284 nm. The method was validated, and results obtained exhibit a good recovery (95.58% to 98.39%). Assessment of precision showed that the relative standard deviations (RSD%) of retention times and peak areas of spiked samples were less than 0.59% and 2.66%, respectively. Further, the limit of detection (LOD) and LOQ were 0.02, 0.05 mg/kg, respectively, and the response was linear across the applied ranges. The crude palm oil samples analysed exhibited HMF content less than 2.27 mg/kg.

Multipurpose margarine (MPM) or water-in-oil (w/o) emulsion systems were prepared using palm oil (PO)/palm stearin (PS) blends as continuous phases and stabilized by monoacylglycerol (90% monoester) as emulsifier. Experimental analyses of three out of six models of MPM showed that MPM1, MPM2 and MPM3 had low workability force and weaker network structure. As results the solid fat content (SFC) at 28 °C, consistency, storage modulus ( G ′) and softness were 25%, 15.5 × 10 2 kPa, 2.62 × 10 2 kPa and 30 mm ease of cone penetration, respectively. Furthermore, examination microscopy of the images concerning MPM1, MPM2 and MPM3 revealed the presence of symmetrical crystals after 60 days of storage, whereas the MPM4, MPM5 and MPM6 models exhibited asymmetrical crystals during same incubation time. These results indicated that the diminution of PS versus PO contents induced the retardation of phase transition from less stable beta-prime (β′) crystals to the more stable beta (β) crystals during storage.

Two types of pitaya (Hylocereus cacti) seeds (Hylocereus undatus and Hylocereus polyrhizus) were investigated in this study. The fatty acid, phenolic, tocopherol, and sterol contents of the extracted seed oil were analysed. The results showed that the pitaya seeds contained a high amount of oil (18.33–28.37%). The three major fatty acids in the H. undatus seed oil (WFSO) and H. polyrhizus seed oil (RFSO) were linoleic, oleic, and palmitic acids. The total tocopherol contents in the WFSO and RFSO were 36.70 and 43.50 mg/100 g, respectively. The phytosterol compounds identified in the WFSO and RFSO were cholesterol, campesterol, stigmasterol, and β-sitosterol. Seven phenolic acid compounds were identified in the WFSO and RFSO, namely, gallic, vanillic, syringic, protocatechuic, p-hydroxybenzoic, p-coumaric, and caffeic acids. WFSO and RFSO can be differentiated by their Toff and Ton values in the DSC thermal curves. This study reveals that pitaya seed oil has a high level of functional lipids and can be used as a new source of essential oil.

Processing of vegetative material containing pentoses has been shown to result in the formation of furfural. Furfural exhibits a spectrophotometric absorption peak at 518 nm when complexed with aniline acetate. Headspace solid-phase microextraction (HS-SPME) method has been successfully used to confirm the presence of furfural in crude palm oil (CPO). Solid phase microextraction (SPME) fiber composed of divinylbenzene/Carboxen/polydimethylsiloxane (DVB/PDMS/CAR) was used to absorb the volatiles in the headspace of the oil. The isolated compounds from the fiber was desorbed and separated on a capillary polar column of a gas chromatograph. Response surface methodology (RSM) was used to optimize the SPME fiber condition for maximum absorption of furfural from CPO. The optimized temperature and time for furfural extraction onto the SPME fiber are 70 °C for 40 min. Oils obtained from the mill were found to contain between 2 and 13% furfural.

Although blending polyunsaturated oil with more saturated or monounsaturated oils has been studied extensively, there is no similar information regarding the partial replacement of palm olein with olive oil (OO). Therefore the main objective of this study was to investigate the effects of OO partial replacement (0, 25, 50, 75, 90 and 100% w/w) on the chemical stability of palm olein oil (POO). The physicochemical properties of oil samples namely iodine value, peroxide value (PV), anisidine value, TOTOX value (total oxidation value, TV), free fatty acid (FFA), cloud point, color and viscosity were considered as response variables. Significant differences among the oil blend properties were determined at the significance level of P < 0.05. Apart from FFA, all the response variables were significantly influenced by type and concentration of oils. The oil blend containing 10% POO and 90% OO showed the highest TV (6.10); whereas the blend containing 90% POO and 10% OO exhibited the least TV (2.41). This study indicated that the chemical stability of oil blend significantly (P < 0.05) increased with increasing the proportion of polyunsaturated/monounsaturated fatty acid.

The influence of partial replacement of palm olein (POo) with olive oil (Oo), (25 and 50%, w/w) was investigated during five consecutive days of frying. The results indicated that frying performance of POo was significantly (P < 0.05) influenced by partial replacement with olive oil. The highest change in peroxide value (PV), anisidine value (AV), totox value (TV), total polar compound (TPC), viscosity and melting point was shown by the control sample; whereas the replacement of 50% (w/w) palm olein with 50% (w/w) olive oil exhibited the least changes in PV, AV, TV, TPC, viscosity and melting point during the frying process. This study suggests that the partial replacement of palm olein containing a high proportion of saturated fatty acids (i.e., palmitic acid) with olive oil containing a high content of monounsaturated fatty acid (i.e., oleic acid) can provide oil blends with higher chemical stability against oxidation. On the other hand, the prepared oil blend remained liquid at ambient temperature, thereby enhancing the physical stability induced by partial replacement with olive oil.

Hylocereus undatus and Hylocereus polyrhizus are two varieties of the commonly called pitaya fruits. The seeds were separated and the oil was extracted and analysed. Essential fatty acids, namely, linoleic acid and linolenic acid form a significant percentage of the unsaturated fatty acids of the seed oil extract. Both pitaya varieties exhibit two oleic acid isomers. Essential fatty acids are important acids that are necessary substrates in animal metabolism and cannot be synthesised in vivo. Both pitaya varieties contain about 50% essential fatty acids (C18:2 (48%) and C18:3 (1.5%)). This paper details the process of recovering the pitaya seeds and determining the composition of the oil extracted from the seeds.

Response surface methodology was applied to optimize the pre-treatment of oil palm (Elaeis guineensis) fruit spikelets before oil extraction. The treatment applied was drying at different times and temperatures. The dried spikelets were then subjected to mechanical processes and crude oil was extracted. A central composite design was employed to study the responses, namely percentage of free fatty acids (FFA) and oil yield, and the optimum conditions for minimum FFA and maximum oil yield were identified from their respective contour plots. It was concluded that the pre-treatment should be carried out for 12.8 h at 66.8 °C. Under the optimum conditions, the corresponding response values for FFA and oil yield were 1% and 33.6%, respectively. Some of the physicochemical properties of the extracted oil were then determined. The low free fatty acid crude palm oil exhibited good physicochemical properties and could be useful for industrial applications.

There is scarce information on the phenolics of oil palm fruits (Elaeis guineensis). In this study, phenolics were extracted from oil palm fruits and analysed using spectrophotometry for information on the different types of palm phenolics and their antioxidative activities. Analyses of the total phenolic content (TPC), total flavonoid content (TFC), o-diphenols index, hydroxycinnamic acid index, flavonols index and phenol index showed ranges between 5.64 and 83.97 g L -1 gallic acid equivalent (GAE), 0.31-7.53 g L -1 catechin equivalent, 4.90-93.20 g L -1 GAE, 23.74-77.46 g L -1 ferulic acid equivalent, 3.62-95.33 g L -1 rutin equivalent and 15.90-247.22 g L -1 GAE, respectively. The antioxidant assay, 2,2-diphenyl-2-picrylhydrazyl radical scavenging assay, showed antioxidative activities in all the extracts with results ranging from 4.41 to 61.98 g L -1 trolox equivalent. The high antioxidant activities of the oil palm fruit phenolics were also found to increase with increasing TPC and TFC.

5-Hydroxymethylfurfural (HMF) is formed during heat treatment of carbohydrate-containing foods, especially in a deep-fat frying process. This study aimed to investigate the effect of amino acids on the formation and reduction of HMF from glucose, fructose and sucrose at frying temperature in model systems containing binary mixtures of an amino acid and a sugar in equal concentrations (0.3M). The results revealed that the formation of HMF from sugars accelerated in the presence of acidic amino acids (i.e. glutamic and aspartic acids). Conversely, the presence of basic amino acids (i.e. lysine, arginine and histidine) led to reduced concentrations of HMF to non-detectable levels in model systems. The results showed that both pH and heating time significantly affected the formation of HMF from fructose in the presence of glutamic acid. In this regard, a higher amount of HMF was formed at lower pH.

The main goal of the present work was to assess the mechanism of crystallisation, more precisely the dominant component responsible for primary crystal formations and fat agglomerations. Therefore, DSC results exhibited significant effect on temperature transition; peak sharpness and enthalpy at palm stearin (PS) levels more than 40 wt.%. HPLC data demonstrated slight reduction in the content of POO/OPO at PS levels less than 40 wt.%, while the excessive addition of PS more than 40 wt.% increased significantly PPO/POP content. The pNMR results showed significant drop in SFC for blends containing PS less than 40 wt.%, resulting in low SFC less than 15% at body temperature (37 °C). Moreover, the values of viscosity (η) and shear stress (τ) at PS levels over 40 wt.% expressed excellent internal friction of the admixtures. All the data reported indicate that PPO/POP was the major component of primary nucleus developed. In part, the levels of PS should be less than 40 wt.%, if these blends are designed to be used for margarine production.

A modified steam distillation method was developed to extract furfural from crude palm oil (CPO). The collected distillates were analysed using high performance liquid chromatography (HPLC) coupled with an ultraviolet diode detector at 284 nm. The HPLC method allowed identification and quantification of furfural in CPO. The unique thermal extraction of CPO whereby the fresh fruit bunches (FFB) are first subjected to steam treatment, distinguishes itself from other solvent-extracted or cold-pressed vegetable oils. The presence of furfural was also determined in the fresh palm oil from FFB (without undergoing the normal extraction process), palm olein, palm stearin, olive oil, coconut oil, sunflower oil, soya oil and corn oil. The chromatograms of the extracts were compared to that of standard furfural. Furfural was only detected in CPO. The CPO consignments obtained from four mills were shown to contain 7.54 to 20.60 mg/kg furfural.