Production of low trans-fat margarine by partial hydrogenation of palm oil using nature-friendly and catalyst-free microwave plasma technique

A 2.45 GHz microwave (MW) plasma furnished with a negative high voltage has been successfully utilized for partial hydrogenation of palm olein to produce low trans-fat margarine at low temperature and low pressure in the absence of a catalyst. The effects of various parameters: H₂ flow rate, microwave power, reaction temperature, negative high voltage and reaction duration on the iodine value (IV) and culinary characteristics of the hydrogenated oil were investigated. The results showed the optimal parameters of 4 L-min⁻¹ H₂ flow rate, 600 W MW power, 32 °C (due to self-heating of the plasma), 60 kV negative high voltage and 4 h reaction duration, reducing the iodine value from 57.7 to 32.5 with good texture and slip melting point (SMP). The trans-fatty acid was detected by GC–MS to be 4.23%, being lower than conventional catalytic hydrogenation. This catalyst-free MW plasma hydrogenation of vegetable oil under benign conditions is a green alternative for the production of low trans-fat margarine.     

SEMI-SOLID FAT BY INTERESTERIFICATION OF RED PALM OIL WITH OTHER VEGETABLE OILS

Interesterification of appropriate blends of vegetable oils offers an alternative method for obtaining semi-solid fats without hydrogenation. Random interesterification was carried out on blends of different oils, namely palm oil and sunflower oil (8:2, 7:3 and 6:4 w/w), palm oil and rice bran oil (8:2 and 7:3 w/w), palm oil and coconut oil (9:1 and 6:4 w/w), as well as palm oil and soybean oil (7:3 w/w), in the presence of sodium methoxide as a catalyst (0.2% w/v). The melting characteristic of the interesterified fat obtained from a blend of refined red palm oil and sunflower oil blend, in the ratio of 4:1 (w/w; slip melting point 41C) indicated that this combination could be an ideal margarine fat base.     

Pd/碳纳米管催化转移氢化大豆油工艺优化及动力学分析

为降低油脂氢化过程中反式脂肪酸的含量,本实验以自制的Pd/碳纳米管（Pd/carbon nanotubes,Pd/CNTs）为催化剂,在催化转移氢化体系中氢化大豆油,通过响应面试验以大豆油碘值为响应值摸索最优工艺条件,同时对催化转移氢化大豆油进行动力学分析。结果表明：最佳工艺条件为氢化温度84 ℃、催化剂添加量0.20%（以体系质量计）、甲酸铵供体浓度0.33 mol/50 mL、氢化时间90 min,产品的三烯酸、二烯酸和单烯酸反应速率常数分别为4.9×10－2、8.7×10－3和8.31×10－4,氢化亚麻酸和亚油酸的选择性高达5.63和10.47,氢化后大豆油碘值为95.3 g/100 g,反式脂肪酸相对含量仅为10.2%。采用催化转移氢化的方式进行油脂氢化,对制备低反式氢化油脂具有一定的研究意义和应用前景,也可为油脂氢化工业的发展提供一定的理论依据。     

<Emphasis Type="Italic">Trans</Emphasis>-free margarine fat produced using enzymatic interesterification of rice bran oil and hard palm stearin

Trans-free interesterified fats were prepared from blends of hard palm stearin (hPS) and rice bran oil (RBO) at 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, and 80:20 weight % using immobilized Mucor miehei lipase at 60°C for 6 h with a mixing speed of 300 rpm. Physical properties and crystallization and melting behaviors of interesterified blends were investigated and compared with commercial margarine fats. Lipase-catalyzed interesterification modified triacylglycerol compositions and physical and thermal properties of hPS:RBO blends. Slip melting point and solid fat contents (SFC) of all blends decreased after interesterification. Small, mostly β′ form, needle-shaped crystals, desirable for margarines were observed in interesterified fats. Interesterified blend 40:60 exhibited an SFC profile and crystallization and melting characteristics most similar to commercial margarine fats and also had small needle-like β′ crystals. Interesterified blend 40:60 was suitable for use as a transfree margarine fat.     

Influence of lipid composition, crystallization behavior and microstructure on hardness of palm oil-based margarines

Two typical commercial palm oil-based margarines, denoted A (complained as with over-hardness) and B (commercially considered as with acceptable hardness), respectively, were compared in terms of hardness, solid fat content (SFC), lipid composition [fatty acid and triacylglycerol (TAG) composition], crystallization behavior and microstructure. On the basis of these results, the reason of over-hardness in margarine A was discussed. Margarine A showed higher hardness than margarine B with the differences increasing along with rise in temperature in the typical range from 15 to 30 °C. While margarine B has good quality and appropriate hardness, it showed SFCs higher than margarine A. Lipid composition analyses showed that margarine B has small amounts of medium chain fatty acids and higher content of monounsaturated TAGs [1,3-dipalmitoyl-2-oleoyl-glycerol (POP), 1,3-dipalmitoyl-2-linoleoyl-glycerol (PLP), 1-palmitoyl-2-oleoyl-3-stearoyl-glycerol (POS)]. X-ray diffraction analysis revealed that both margarines have β′ and β polymorphs with the β form being dominant in margarine B. Isothermal crystallization kinetics of both margarines under 15, 20, 25, and 30 °C, respectively, fitted using the Avrami model indicates that margarine B hardly crystallizes at temperatures ≥25 °C. Morphologic observations of the microstructure of both margarines by polarized light microscope and scanning electron microscopy showed that formation of large spherulites have an important influence on margarine texture. Occurrence of large spherulites in margarine B is considered to decrease the numbers of crystals and lessen mutual attraction with temperature increasing, which leads to weakened strength of the total network, even if margarine B has a higher SFC value.     

VISCOELASTIC PROPERTIES OF TABLE MARGARINE PREPARED FROM LIPASE-CATALYZED TRANSESTERIFIED MIXTURES OF PALM STEARIN AND PALM KERNEL OLEIN

A controlled-stress rheometer was used to evaluate dynamic viscoelastic (VE) performance of an experimental table margarine prepared from a transesterified palm stearin (PS):palm kernel olein (PKO) mixture (40:60 ratio) using Rhizomucor miehei lipase as the biocatalyst. Comparison was made using a commercial table margarine made of palm oil and palm kernel oil. The experiments were carried out over a period of three months with the margarines kept at 20 and     

Catalyst activation by cold plasma technology and its effect on isomerization of safflower seed oil

High voltage atmospheric cold plasma (HVACP) is a novel catalyst modification technology. In this study, a ruthenium/multi-walled carbon nanotubes (Ru/MWCNTs) catalyst was activated by HVACP instead of the thermal reduction method. The results showed that HVACP activation under the conditions of 180 s discharge time, 150 W discharge power, and 2.5 cm electrode spacing at 25 °C could effectively decrease the activation temperature and time. At this time, the Ru dispersion was 20.1% and the conjugated linoleic acid (CLA) yield was 43.0%. Catalyst characterization proved that the HVACP-treated catalyst did not aggregate and had a good activation effect. The catalyst was applied to the isomerization reaction of safflower seed oil to obtain CLA-rich safflower seed oil. The total CLA content was 43.02%, the trans-oleic acid content was 1.34%, the iodine value (IV) was 133.50 gI₂/100 g, and after reusing five times, the relative activity of the catalyst remained at 77%, which provided the conditions for the preparation of functional oil.     

Frying oils with lower levels of saturated fatty acids induce less heterocyclic amine formation in meat floss (boiled,shredded and fried pork)

Heterocyclic amines (HAs) as potent mutagens are formed in meat floss which is a boiled, shredded and fried traditional meat product. In this study, effects of frying oils (lard, soybean oil and palm oil) on the formation of HAs in meat floss during frying have been investigated. The results showed that the contents of Norharman, Harman, AαC and MeAαC in meat floss that treated with lard and palm oil were higher than soybean oil which contained less saturated fatty acids (P < 0.05). The contents of total HAs in meat floss that treated with palm oil at 150 °C and 180 °C were significantly higher than that treated with soybean oil and lard (P < 0.05). In conclusion, meat floss treated with soybean oil at 120 °C, 150 °C and 180 °C contained lowest levels of HAs and soybean oil could be used as lard substitution to produce healthy meat floss.     

高熔点脂肪对凝胶油基人造奶油品质的影响

以全氢化棕榈油作为高熔点脂肪源,将0.5%～2.5%的全氢化棕榈油与葵花油混合作为基料油,制备凝胶油基人造奶油。探究高熔点脂肪对凝胶油基人造奶油的脂肪酸组成、稳定性、熔点、质构、流变性质、微观结构和晶型的影响。结果表明,当高熔点脂肪添加量低于1.5%时,人造奶油的熔点过低、可塑性较差;而添加量高于1.5%时,人造奶油的不稳定指数值大于1.5,体系劣变严重;添加量为1.5%时,硬度、可塑性和黏度均更接近于市售人造奶油,综合表现最佳。     

Flow properties of table margarine prepared from lipase-catalysed transesterified palm stearin:palm kernel olein feedstock

The flow properties of an experimental table margarine prepared from Rhizomucor miehei lipase-catalysed transesterified palm stearin:palm kernel olein (PS:PKO) blend at 40:60 was stored for 3 months at test temperatures of 20 and 30°C and determined using a controlled-rate rheometer. A commercial table margarine was used as a comparison. The shear stress-shear rate data was represented well by the Herschel–Bulkley model (r > 0.99). The mean yield stress values during storage were the highest for the experimental table margarine. However, the effect of storage on the mean yield stress was insignificant (p > 0.001). The Power Law model with a yield stress also represented the margarine flow well (r > 0.99) and the Power Law intercepts and slopes were also the highest for the experimental margarines, indicating a higher degree of firmness in the experimental samples. Storage effect was also insignificant (p > 0.05).     

Characteristics of palm mid-fractions produced from different fractionation paths and their potential usages

Three palm mid-fraction (PMF) groups produced from different fractionation paths were analyzed in terms of the fat, triacylglycerol and sn-2 fatty acid compositions, thermal properties (melting and crystallization behaviors, and solid fat contents (SFCs)), micronutrient levels and oxidative stability indexes (OSIs) to achieve their sufficient utilization. PMF-A (iodine value (IV), 48.4 g/100 g) fractionated from palm olein contained 43.8% 1,3-dipalmitoyl-2-oleoyl-glycerol (POP) and 16.7% 1-palmitoyl-2,3-dioleoyl-glycerol, showing soften properties (slip melting point (SMP), 27.6°C; SFC at 30°C, 2.2%) at hot weather. PMF-B (IV, 42.3 g/100g) obtained from palm stearin showed similar fat and triacylglycerol compositions as PMF-A, but the high 1,2,3-tripalmitoyl-glycerol level (6.2%) improves its thermal behaviors (SMP, 34.9°C; SFC at 30°C, 13.8%). The SFC profiles of PMF-A and PMF-B were comparable to those found in frozen and puff margarine shortenings. Furthermore, both of the PMF groups exhibited excellent OSIs (13.2 and 11.2 h, respectively) because of their high micronutrient levels (especially γ-tocopherol and campesterol). In general, γ-tocopherol and campesterol contribute to preventing lipids from oxidation under frying conditions. Therefore, PMF-A and PMF-B are recommended for manufacturing margarine shortenings and frying fasts. PMF-C (IV, 33.0 g/100g) produced from the additional fractionation of PMF-A or PMF-B contained the highest POP percentage (67.1%) and showed heat-resistant property (SMP, 31.8°C; SFC at 30°C, 22.4%). Its steep SFC profile was superior to that of cocoa butter, suggesting the fat is preferred in producing hard chocolate fats.     

Improving fatty acid methyl ester production yield in a lipase-catalyzed process using waste frying oils as feedstock

The application of waste frying oil (WFO) mixed with rapeseed oil as a feedstock for the effective production of fatty acid methyl esters (FAME) in a lipase-catalyzed process was investigated. The response surface methodology (RSM) was used to optimize the interaction of four variables: the percentage of WFO in the mixed feedstock, the methanol-to-oil ratio, the dosage of Novozym 435 as a catalyst and the temperature. Furthermore, the addition of methanol to the reaction mixture in a second step after 8 h was shown to effectively diminish enzyme inhibition. Using this technique, the model predicted the optimal conditions that would reach 100% FAME, including a methanol-to-oil molar ratio of 3.8:1, 100% (wt) WFO, 15% (wt) Novozym 435 and incubation at 44.5 °C for 12 h with agitation at 200 rpm, and verification experiments confirmed the validity of the model. According to the model, the addition of WFO increased FAME production yield, which is largely due to its higher contents of monoacylglycerols, diacylglycerols and free fatty acids (in comparison to rapeseed oil), which are more available substrates for the enzymatic catalysis. Therefore, the replacement of rapeseed oil with WFO in Novozym 435-catalyzed processes could diminish biodiesel production costs since it is a less expensive feedstock that increases the production yield and could be a potential alternative for FAME production on an industrial scale.     

Directed interesterification of a brazilian palm oil and analysis of the original and interesterified oil and its fractions

A commercial sample of the Brazilian palm oil from the north eastern State of Bahia after neutralisation, washing and drying was interesterified in the presence of sodium-potassium alloy (NaK) at 30°C in a nitrogen atmosphere. The catalyst was destroyed by addition of water in a carbon dioxide atmosphere and the interesterified oil was crystallised from light petroleum, yielding an olein and stearin fraction. The fatty acid and triacylglycerol composition of the neutralised oil was determined by gas chromatography (g.c.) and high-performance liquid chromatography (h.p.l.c.) respectively and was shown to be similar to that of Malaysian and African palm oil. The compositions of the interesterified Brazilian oil and its liquid and solid fractions were also determined. The physicochemical characteristics of the olein obtained by interesterification with NaK, such as iodine value (96.8) and its softening point (below ?8°C) indicated its suitability for the use as salad oil.     

Enzymatic production of natural sweetener trilobatin from citrus flavanone naringin using immobilised α‐l‐rhamnosidase as the catalyst

An efficient and cost‐effective enzymatic production method for preparation of a high‐valued natural sweetener (dihydrochalcone glucoside trilobatin) was developed by the combination of hydrogenation and enzymatic hydrolysis reactions with α‐l ‐rhamnosidase as the catalyst in aqueous medium. This technology is adopting the cheap and largely available citrus flavanone naringin as the starting material for trilobatin synthesis, and the present enzymatic technology is possibly utilised by commercial for scale‐up production. The production is a straightforward two‐step process, in which naringin was hydrogenated into naringin dihydrochalcone and followed by removal of the rhamnosyl group of naringin dihydrochalcone by enzymatic hydrolysis using immobilised α‐l ‐rhamnosidase as the catalyst. Under optimised conditions, an overall yield of 96% was achieved with a very low loading of α‐l ‐rhamnosidase catalyst at 60 °C in a neutral aqueous buffer solution within 2 h. The immobilised α‐l ‐rhamnosidase catalyst can be recycled for 10 reactions (90% yield retained).     

Enzymatic interesterification of palm and coconut stearin blends

Hard fractions of palm oil and coconut oil, blended in the ratios of 90:10, 85:15, 80:20 and 75:25, were interesterified for 8 h using Lipozyme TL IM. Major fatty acids in the blends were palmitic acid (41.7–48.4%) and oleic acid (26.2–30.8%). Medium‐chain fatty acids accounted for 4.5–13.1% of the blends. After interesterification (IE), slip melting point was found to decrease from 44.8–46.8 °C to 28.5–34.0 °C owing to reduction in solids content at all temperatures. At 37.5 °C, the blends containing 25% coconut stearins had 17.4–19% solids, which reduced to 0.4–1.5% on IE, and the slip melting point (28.6 and 28.8 °C) indicated their suitability as margarine base. The reduction in solid fat index of the interesterified fats is attributed to the decrease in high‐melting triacylglycerols in palm oil (GS₃ and GS₂U type) and increase in triolein (GU₃) content from 1 to 9.2%. Retention of tocopherols and β‐carotene during IE was 76 and 60.1%, respectively, in 75:25 palm stearin and coconut stearin blend.     

Storage stability of cod liver oil organogels formed with beeswax and carnauba wax

In this study, organogels of cod liver oil (CLO) with beeswax (BW) and carnauba wax (CW) were prepared, and compared with a commercial margarine (CM). Oil binding capacities (OBC) of BW organogels were over 99%, while CW had a maximum OBC value of 91.28%. Crystal formation time of BW was shorter. Although the highest solid fat content (SFC) was in the 10% CW containing sample (8.69%), it was 28.99% in the CM sample at 20 °C. The peak melting temperature of CM was 43.70 °C, and BW organogel at 3% addition had the closest values (45.42 °C). Firmness and stickiness values of the organogels were lower than that of CM sample. No significant change in the texture parameters during storage was detected, indicating good stability. There was no hurdle against oxidation by organogelation during storage. This study has shown that CLO organogels can be suitable spreadable products.     

高温气相色谱法分析油脂随机酯交换反应程度研究

以大豆油和极度氢化棕榈油为原料进行酯交换反应,利用高温气相色谱法分析反应前后各种三酰甘油组成的变化,研究了不同催化剂催化酯交换反应的酯交换率,从而评判催化剂催化效果。采用此方法,利用单因素试验对Lipozyme 435脂肪酶催化大豆油与极度氢化棕榈油酯交换的参数进行了研究,得到适合的反应条件为:反应温度90℃、反应时间4 h、加酶量4%(占油脂总质量)、大豆油与氢化棕榈油质量比4∶3。在此条件下反应随机酯交换率为98.3%。     

Quality assessment of refined oil blends during repeated deep frying monitored by SPME–GC–EIMS,GC and chemometrics

The aim of this study was to investigate the effect of the refined palm oil addition (20%) on the fatty acid and sterol compositions of refined olive oil or refined soya bean oil and also to investigate the formation of total polar compounds and volatile compounds in these oil blends during fifty successive deep‐frying sessions of potato fries at 180 °C. The blend of refined olive oil and refined palm oil exhibited a higher chemical stability during the frying process than that of refined soya bean oil and refined palm oil. Indeed, the total polar compounds and volatile compounds formed, especially 2,4‐decadienal, were found to be relatively increased in the refined soya bean oil/refined palm oil blend reaching 36.50% and 46.70%, respectively, after fifty deep‐frying sessions. Moreover, the degradation of linoleic acid and β‐sitosterol was significantly (P < 0.05) observed for the refined soya bean oil/refined palm oil blend. The results have proven that the proper blending of monounsaturated refined olive oil with refined palm oil increases its stability and hence improves the quality of such olive oil during frying process.     

Comparing impacts of dielectric barrier discharge plasma and electron beam irradiation processing on characteristics of Tartary buckwheat whole flour

Dielectric barrier discharge (DBD) plasma, lower and higher dose electron beam irradiation (EBI) are used widely in food processing. In this research, impacts of DBD plasma and EBI processing on characteristics of Tartary buckwheat whole flour were investigated in the range of parameters used most often in food industry. Cross section, small granule and reaggregation of fragments appeared after processing as well as higher values of L*, a* and WI. DBD plasma processing altered the short range crystal structure and hydrogen-containing groups, increasing oil/water absorption and freeze-thaw stability. DBD plasma and EBI processing had a mostly positive effect on hydration properties at 50 to 70 °C, with contrast to a reduction effect at higher temperature. DBD plasma and EBI processing will not affect the nutrients content indeed. TPC, TFC and antioxidant activity increased significantly after EBI processing (≤ 10 kGy) with few free radicals generated.Industrial relevanceDBD plasma and EBI processing are widely used for flour in food industry, with limited focus on physicochemical properties promotion and antioxidant activity protection. This research indicates that DBD plasma processing can affect the properties of Tartary buckwheat whole flour (TBF) significantly, but it shows negative damage to bioactive compounds and antioxidant activity. EBI processing (≤ 10 kGy) can improve physicochemical properties of TBF, which is given slightly higher TPC, TFC and antioxidant activity simultaneously. Both of DBD plasma and EBI processing are safe methods that can improve processing characteristics of the flour, while lower dose EBI processing is more suitable for development of Tartary buckwheat and functional food industry with protection to bioactive compounds and antioxidant activity.