A study on monitoring of frying performance and oxidative stability of cottonseed and palm oil blends in comparison with original oils

Blending polyunsaturated oils with highly saturated or monounsaturated oils has been studied extensively; however, in literature there is negligible information available on the blending of refined cottonseed oil with palm olein oil. Blending could enhance the stability and quality of cottonseed oil during the frying process. In the present study, the effects of frying conditions on physicochemical properties of the palm olein-cottonseed oil blends (1:0, 3:2, 1:1, 2:3, and 0:1, w/w) were determined and compared to the pure oils. The frying process of frozen French fries was performed in duplicate at 170 ± 5°C for 10 h without interruption. The oil degradations were characterized during deep-frying applications; peroxide, free fatty acid, and iodine value by standardized methods, fatty acid profile by using a gas chromatography-flame ionization detector, polar and polymeric compounds by using the high-performance size exclusion chromatography/evaporative light scattering detector technique. The present study clearly indicated that the oxidative and frying performances of pure palm olein oil and cottonseed oil significantly improved by blending application. Results clearly indicated that the frying performance of cottonseed oil significantly improved by the blending with palm olein oil. Except that free fatty acid content, all the physicochemical variables were significantly influenced by type of pure and blend oils. By increasing the proportion of palm olein oil in cottonseed oil, the levels of polyunsaturated fatty acids decreased, while saturated fatty acid content increased. The progression of oxidation was basically followed by detecting polar and polymeric compounds. The fastest increments for polar and polymeric compounds were found as 6.30% level in pure cottonseed oil and as 7.07% level in 40% cottonseed oil:60% palm olein oil blend. The least increments were detected as 5.40% level in 40% cottonseed oil:60% palm olein oil blend and 2.27% level in 50% cottonseed oil:50% palm olein oil blend. These levels were considerably below the acceptable levels recommended by the official codex. Therefore, the present study suggested that blending of cottonseed oil with palm olein oil provided the oil blends (50% cottonseed oil:50% palm olein oil and 40% cottonseed oil:60% palm olein oil, w/w) with more desirable properties for human nutrition.     

Evaluation of shortenings based on various palm oil products

Several formulations based on blends of hydrogenated palm oil (MP 41·5°C) and palm stearin (IV 44) with other liquid oils, on direct blends of palm stearin with other liquid oils, and on 100% inter-esterified palm olein, were used as feedstocks in shortening production. The shortenings were stored at 20°C over a period of one month. Physicochemical characteristics, creaming properties and baking performance of the shortenings were evaluated and compared with the best shortening on the market. Slip melting point of the shortenings ranged from 41·5 to 46·4°C. Palm-cottonseed oil shortenings had higher solid fat contents at all temperatures than palm-soya bean or palm-low erucic acid rapeseed oil shortenings. The shortenings were rich in C₅₀, C₅₂and C₅₄ glycerides. Creaming power after 12 min of beating ranged from 1·55 to 1·77 cm³ g^?1. Palm stearin-cottonseed (3:2) oil shortening showed the best creaming performance. The specific volume of cakes ranged, for the experimental shortening, from 90% to 101% from the control, with low erucic acid-palm blends showing the best performance. In applications for both aerated cream and cakes, inter-esterified palm olein was excellent.     

棕榈液油在调和油中应用研究

将熔点18℃棕榈液油分别与大豆油、菜籽油、玉米油和葵花籽油进行调配,得出不同季节条件下最佳调配比例;结果表明,棕榈液油作为一种调和油原料油,在春、夏、秋季均能应用于食用调和油。     

Production of trans‐free margarine stock by enzymatic interesterification of rice bran oil,palm stearin and coconut oil

BACKGROUND: Trans‐free interesterified fat was produced for possible usage as a spreadable margarine stock. Rice bran oil, palm stearin and coconut oil were used as substrates for lipase‐catalyzed reaction. RESULTS: After interesterification, 137–150 g kg^?1 medium‐chain fatty acid was incorporated into the triacylglycerol (TAG) of the interesterified fats. Solid fat contents at 25 °C were 15.5–34.2%, and slip melting point ranged from 27.5 to 34.3 °C. POP and PPP (β‐tending TAG) in palm stearin decreased after interesterification. X‐ray diffraction analysis demonstrated that the interesterified fats contained mostly β′ polymorphic forms, which is a desirable property for margarines. CONCLUSIONS: The interesterified fats showed desirable physical properties and suitable crystal form (β′ polymorph) for possible use as a spreadable margarine stock. Therefore, our result suggested that the interesterified fat without trans fatty acid could be used as an alternative to partially hydrogenated fat. Copyright © 2010 Society of Chemical Industry     

Discrimination of palm olein oil and palm stearin oil mixtures using a mass spectrometry based electronic nose

To discriminate mixing ratios for mixtures of palm olein oil and palm stearin oil, an electronic nose based on mass spectrometer (MS-electronic nose) and GC were used. The intensities of each fragment from the palm olein oil and palm stearin oil by the MS-electronic nose were used for discriminant function analysis (DFA). When palm olein oil is mixed with palm stearin oil, more than 3% of stearin oil can be estimated by DFA. The obtained data were used for DFA. DFA plot indicated a significant separation of pure palm olein oil and palm stearin oil. The added concentration of palm stearin oil to palm olein oil was highly correlated with the first discriminant function score (DF1). When palm stearin oil was added to palm olein oil, it was possible to predict the following equation; DF1= −0.112×(conc. of palm stearin oil)+0.416 (r²=0.95). When palm stearin oil was added to palm olein oil, peak area of GC was correlated to DF1 by MS-electronic nose with ratio of palm olein oil vs palm stearin oil. The MS-electronic nose system could be used as an efficient method for the authentication of oil.     

Characterisation of Crystals in Palm Olein

The composition of the crystals obtained during the storage of palm olein between 28 and 10°C were analysed by gas–liquid and high-performance liquid chromatography. The crystals were of the β form, and consisted of a high-melting component and a low-melting component. The high-melting component melts at 65°C and consist of a high concentration of diglycerides, mainly the 1,3-dipalmitin. The low-melting component is probably the palm olein liquid entrapped between the crystals. The high tripalmitin and dipalmitin content in the crystals suggest that these glycerides need to be removed if the olein were to remain clear under fluctuating temperature conditions.     

Development of chemically interesterified healthy coconut oil blends

Edible vegetable oil blends, such as coconut:linseed; coconut:safflower; coconut:sunflower; coconut:rice‐bran oils; in the ratio of 70:30 and 60:40 v/v and pure coconut oil (CNO) were interesterified using sodium methoxide 0.5% and subsequently refined to prepare nutritionally superior flowable CNO blends which remained liquid even at sub‐zero temperatures. The slip melting point of chemically interesterified fats could not be determined as they are liquified just after removing from freezing chamber in comparison with the slip melting point of 21.5–26.5 °C for their uninteresterified counterparts. These interesterified fats were liquid and flowable at 6 °C for more than 4 h in a cooling chamber and their solidification temperature ranged between ?2.0 and ?5.5 °C. Free fatty acids showed an increasing trend from 0.35% to 2.0% resulting in decrease in triglycerides After refining these oil blends showed values similar to their controls. However, iodine value of interesterified and uninteresterified oils were close to each other. Differential scanning calorimetry showed the onset of crystallisation at lower temperatures and lower solid fat content for interesterified fats. A nutritionally superior combination of CNO blend which is flowable at low temperature could be prepared.     

Physicochemical characteristics of palm oil and sunflower oil blends fractionated at different temperatures

This research was carried out to determine the effect of fractionation temperature on the physicochemical characteristics of refined, bleached and deodorized (RBD) palm oil and sunflower oil blends fractionated at different temperatures. Blends of 20% and 40% sunflower oil with 80% and 60% RBD palm oil, respectively, were fractionated at three different temperatures (15, 18 and 21 °C). The results showed that olein with higher iodine value was obtained at lower fractionation temperature. This was because, at lower fractionation temperature, more of the polyunsaturated fatty acid, namely linoleic acid (C18:2), went into the liquid fraction. On the other hand, more of the saturated fatty acid, namely palmitic acid (C16:0), went into the liquid fraction at higher fractionation temperature. Blending reduced the triacylglycerol composition, namely POP, POS, SOO and PLP, while OLO, PLL, OLL and LLL/LLnO increased. Lower fractionation temperature decreased the composition of monosaturated triacylglycerol and increased the composition of di- and polyunsaturated triacylglycerols. Lower fractionation temperature produced a liquid fraction with lower solid fat content and lower cloud point than did higher fractionation temperature.     

Application of hydrogenated palm kernel oil and palm stearin in whipping cream

Non-dairy creams made from hydrogenated palm kernel oil (HPKO) are generally more stable than dairy creams. However, in summer the emulsion tends to separate. This paper outlines some steps that were taken to modify the HPKO with the intention of increasing the stability without affecting whipping performance. This was achieved by blending HPKO with palm stearin (POs). Interesterification was employed to eliminate the increase in solid fat content at 37°C and 40°C. Results of the experiment showed that an interesterified HPKO: POs 66:34 blend proved to have satisfactory whipping performance when compared to creams made with HPKO alone.     

Characterisation of zero‐trans margarine fats produced from camellia seed oil,palm stearin and coconut oil using enzymatic interesterification strategy

Zero‐trans interesterified fats were produced from camellia seed oil (CSO), palm stearin (PS) and coconut oil (CO) with three weight ratios (CSO/PS/CO, 50:50:10, 40:60:10 and 30:70:10) using Lipozyme TL IM. Results showed that the interesterified products contained palmitic acid (34.28–42.96%), stearic acid (3.96–4.72%), oleic acid (38.73–47.95%), linoleic acid (5.92–6.36%) and total medium‐chain fatty acids (MCFA)s (∑MCFAs, 5.03–5.50%). Compared with physical blends, triacylglycerols of OOO and PPP were decreased and formed new peaks of equivalent carbon number (ECN) 44 in the interesterified products. The product CPC3′ showed a slip melting point of 36.8 °C and a wide plastic range of solid fat content (SFC) (45.8–0.4%) at 20–40 °C. Also, the major β′ form was determined. These data indicated that the zero‐trans interesterified fats would have a potential functionality for margarine fats. Subsequently, the antioxidative stabilities of interesterified products with the addition of α‐tocopherol (α‐TOH) and ascorbyl palmitate (AP) were investigated. The results indicated that AP had a dose‐dependent effect at concentrations of 100, 200 and 400 ppm.     

RECOVERY OF PALM CAROTENE FROM PALM OIL AND HYDROLYZED PALM OIL BY ADSORPTION COLUMN CHROMATOGRAPHY

Crude palm oil and crude palm olein were hydrolyzed with lipase from Candida rugosa to produce a free fatty acid (FFA) rich oil. The percentages of FFA produced and carotene degradation after the hydrolysis process were determined. The palm oil and hydrolyzed palm oil were subsequently subjected to column chromatography. Diaion HP-20 adsorbent was used for reverse phase column chromatography at 50C. Isopropanol or ethanol, and n-hexane were used as the first and second eluting solvents, respectively. The objective of hydrolyzing the palm oil was to produce more polar FFA-rich oil in order to enhance the nonpolar carotene bind to the nonpolar HP-20 adsorbent in the column chromatography process. Hydrolyzing palm oil with lipase from Candida rugosa gave 30- and 60-fold, respectively, of FFA in the crude palm oil and crude palm olein in 24 h at 50C. Approximately, 15.56 and 17.48% of carotene degraded in crude palm oil and crude palm olein, respectively. For column chromatography, using isopropanol or ethanol as the first eluting solvent, unhydrolyzed oil and hydrolyzed oil showed the carotene recovery infraction two (carotene-rich fraction) of about 36–37 and 90–96%, respectively. Over 90% of carotene recovery was obtained from     

An investigation on the physicochemical characterization of interesterified blends of fully hydrogenated palm olein and soybean oil

In this study, the effect of interesterification (using sodium methoxide) on physicochemical characteristics of fully hydrogenated palm olein (FHPO)/soybean oil blends (10 ratios) was investigated. Interesterification changed free fatty acid content, decreased oil stability index, solid fat content (SFC) and slip melting point (SMP), and does not affected the peroxide value. With the increase of FHPO ratio, oil stability index, SFC and SMP increased in both the interesterified and non-interesterified blends. Fats with higher FHPO ratio had narrower plastic range, as well. Compared to the initial blends, interesterified fats had wider plastic ranges at lower temperatures. Both the non-interesterified and interesterified blends showed monotectic behavior. The Gompertz function could describe SFC curve (as a function of temperature, saturated fatty acid (SFA) content or both) and SMP (as a function of SFA) of the interesterified fats with high R² and low mean absolute error.     

Lipase-catalyzed acidolysis of palm olein and caprylic acid in a continuous bench-scale packed bed bioreactor

Enzymatic acidolysis of refined, bleached and deodorized (RBD) palm olein with caprylic acid was carried out in a continuous packed bed bioreactor to produce structured lipid (SL) that can confer metabolic benefits when consumed. Lipozyme^® IM 60 from Rhizomucor miehei, a 1,3-specific lipase, was used as the biocatalyst in this study. After 24 h of reaction, 30.5% of the total fatty acid content of the modified oil was found to be caprylic acid, indicating its incorporation into the palm olein. The triacylglycerols (TAGs) of palm olein after acidolysis were separated and were characterized by seven clusters of TAG species with equivalent carbon number (ECN), C28, C30, C32, C34, C36, C38 and C40. Caprylic–oleic–caprylic TAGs were predicted in cluster C32, which recorded the highest amount, with 35.3% of the total TAG. Fatty acid composition at the sn-2 position was determined, by pancreatic lipolysis, as C8:0, 9.2%; C12:0, 2.3%; C14:0, 1.8%; C16:0, 21.3%; C18:0, 4.7%; C18:1, 60.7%. Iodine value (IV), slip melting point (SMP) and differential scanning calorimetric (DSC) analyses of SL were also performed. In IV analysis, SL recorded a drop of value from 60.4 to 48.2 while SMP was reduced from 13 to 4.2 °C, in comparison to RBD palm olein. DSC analysis of SL gave a melting profile with two low melting peaks of −15.97 and −11.78 °C and onset temperatures of −18.43 and −14.03 °C, respectively.     

A high performance liquid chromatography method for determination of furfural in crude palm oil

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.     

Interactions between tocopherols,tocotrienols and carotenoids during autoxidation of mixed palm olein and fish oil

Electron spin resonance (ESR) and spin trapping detection of radical formation showed that the oxidative stability of palm olein/fish oil mixtures increased with the amount of palm olein. Mixtures with red palm olein were less stable than were mixtures with yellow palm olein. Addition of ascorbyl palmitate and citric acid gave further reduction of radical formation, whereas no effect was observed by adding lecithins. Storage of palm olein/fish oil mixtures (4:1) at 30 °C confirmed that red palm olein mixtures were less stable than were yellow palm olein mixtures. Ascorbyl palmitate together with citric acid improved the stability in both cases. The concentrations of α-tocopherol and α-tocotrienol decreased during storage, whereas β-, γ-, and δ-tocotrienols were unaffected. Ascorbyl palmitate reduced the losses of α-tocopherol and α-tocotrienol. The rate of loss of carotenoids was independent of the presence of fish oil and, except for an initial fast drop, also of the presence of ascorbyl palmitate.     

Short-Chain Fatty Acid Formation during Thermoxidation and Frying

Formation and evolution of the short-chain fatty acids originated by oxidation and remaining bound to the parent triglyceride, specifically heptanoate and octanoate, were studied during thermoxidation of palm olein, conventional sunflower oil and high-oleic sunflower oil at 180°C, as well as in real used frying oils of unknown history collected by Food Inspection Services. Fatty acids were quantified by gas–liquid chromatography following transesterification of samples and using methyl nonanoate and methyl heptadecanoate as internal standards. Alteration level was determined through analyses of polar compounds and polar fatty acids. Results showed high correlation coefficients between short-chain fatty acids and polar compounds or polar fatty acids, thus suggesting that quantification of short-chain fatty acids is a good indication of the total alteration level in used frying oils.     

Non-thermal dielectric barrier discharge plasma hydrogenation for production of margarine with low trans-fatty acid formation

A novel technique for palm oil hydrogenation with very low trans-fatty acid formation using non-thermal dielectric barrier discharge (DBD) plasma with parallel-plate configuration has been successfully demonstrated. This green technique does not require catalyst and is highly environmental-friendly. With 15% H₂: 85% He mixed carrier gas concentration ratio and initial 31 °C (rising to 50 °C due to plasma), after 4 h of plasma hydrogenation, iodine value (IV) was reduced from 60.89 to 48.39 and detected trans-fat was 1.44%. This represents trans-fat generation rate of only 0.07% per % decrease in IV, which is about 6.12 times lower than a conventional method relying on high temperature, high pressure and catalyst. About 8 h was required to produce margarine with texture closest to commercial margarines. Acid value (AV) reduced from 0.47 to 0.27%, or 43% reduction, after 12–20 h of treatment, significantly indicating that plasma hydrogenation can also help extend shelf life of oil or margarine. Large portion of DBD plasma hydrogenated palm oil can, thus, be mixed with palm olein and interesterified palm oil to produce margarine with overall trans-fatty acid content no higher than regulatory requirement. Continuous production scheme was presented. This novel plasma hydrogenation technique offers promising possibility for commercial utilization by edible oils industry.     

Crystallization properties of palm oil by dry fractionation

The crystallization, thermal, physical, chemical and morphological properties of palm oil were investigated using differential scanning calorimetry, polarized microscopy, pulsed nuclear magnetic resonance (NMR) and gas chromatography (GC). The palm oil was fractionated into various stearin and olein (with iodine values (IV)>63) fractions by means of a dry fractionation process. During the cooling sequence, samples were taken at regular intervals from the crystallizer and analyzed for their iodine values, chemical compositions and physical behaviour. The physical properties of olein and stearin fractions, such as cloud point, slip melting point and solid fat content, were dependent on the crystallization temperatures. The iodine values of the olein and stearin fractions increased as the crystallization temperature decreased and both fractions started to cloud at lower temperatures. The palmitic acid content of stearin and olein fractions was also affected by the crystallization temperatures.     

Comparison of the stability of palm olein and a palm olein/canola oil blend during deep‐fat frying of chicken nuggets and French fries

Stability of palm olein (PO) and a blend 50% palm olein/50% canola oil (POC) during deep‐fat frying at 180 °C of French fries (FF) or chicken nuggets (CN) was studied through the determination of physical and chemical parameters in the fresh and used oils. Degradation at the end of the study resulted in total polar compounds of 12–13.5% for PO and 11.5–14.5% for POC and viscosity of 65–123.3 cP for PO and 63–72.8 cP for POC. Lower peroxide values (5.33–6.32) were obtained for the blend (PO had 5.21–8.55). Food type affected colour parameters and p‐anisidine value of the oils. For CN, the lowest fat content and higher hardness were obtained when they were fried in PO. CN caused a faster deterioration in the oils, in comparison with FF, especially in POC. Gas chromatography allowed to observe differences in fatty acids composition for both used oils.     

Thermal behavior of concentrated oil-in-water emulsions based on soybean oil and palm kernel olein blends

Droplet size distribution and thermal behavior of concentrated oil-in-water emulsions based on soybean oil (SBO)/palm kernel olein (PKO) blends were investigated. The emulsions were prepared using 70% (wt./wt.) oil blends of SBO/PKO as dispersed phases and stabilized by egg yolk. An increase in PKO level (0–40% wt./wt.) in the oil dispersed phase volume fraction caused significant increases (p < 0.05) in volume-weighted mean diameter (d_4,3). The DSC data suggested that crystallization of the emulsions was induced by a ‘template effect’ of yolk constituents via a surface heterogeneous nucleation. Emulsions with 0–20% (wt./wt.) PKO levels in the dispersed phase demonstrated a good cool–heat stability even after three successive thermal cycles (from 50 °C to ?70 °C at 10 min/°C). After the first thermal cycle, emulsions with 30% and 40% PKO levels in the oil dispersed phase were destabilized due to strong coalescence and crystallized via volume-surface heterogeneous nucleation. The unstable emulsions were attributable to high level of saturated triacylglycerols from PKO, with high droplet size characteristic, causing them to be more prone to partial coalescence.