Influence of dietary oils and protein level on pork quality. 2. Effects on properties of fat and processing characteristics of bacon and frankfurter-style sausages

Palm kernel oil (PKO) and palm oil (PO) are used in tropical countries as cheaper substitutes for conventional feed sources such as soya bean oil (SBO) but little is known about their effects on meat quality. This study, therefore, evaluated the effects of these three dietary oils on the fatty acid composition (FA) of pork fat and the qualities of belly bacon and frankfurter sausage. The 3×2 factorial design also included high and low dietary protein. Total cooking loss, water loss and fat losses were determined in frankfurter sausages at chopping temperatures from 2 to 24°C. PKO resulted in a poor P:S ratio (0.34) and a relatively hard fat (slip point 32.8°C), but resulted in bacon with a higher tensile cohesive force and more high quality slices, judged subjectively. PO had a fatty acid composition closer to the SBO control, a better P:S ratio than PKO (0.48) and softer fat. There was a trend for total cooking losses and fat losses to be higher in PKO compared with PO and SBO at all chopping temperatures, suggesting that the firmest, most saturated fat (PKO) was least suitable for frankfurter production. The low protein diet increased the concentration of saturated fatty acids and increased fat firmness but its effect on fatty acid composition and other properties were less marked than those of oil type.     

Influence of dietary oils and protein level on pork quality. 1. Effects on muscle fatty acid composition, carcass, meat and eating quality

This study evaluated the effects of three dietary oils - palm kernel (PKO), palm (PO) and soyabean (SBO) - and two protein levels - high (HP) and low (LP) in a 3×2 factorial design involving 60 pigs on growth performance, muscle fatty acid composition and content, carcass, meat and eating qualities. Oil type did not have a significant effect on growth and carcass quality. PKO significantly reduced the polyunsaturated (PUFA) to saturated (SFA) fatty acid (P:S) ratio in longissimus muscle (P<0.001). PKO increased the concentrations of lauric (12:0), myristic (14:0), palmitic (16:0) and stearic (18:0) fatty acids and decreased linoleic acid (18:2). The LP diet increased intramuscular fat (IMF) from 1.7g/100g muscle in HP to 2.9g/100g (P<0.001), increased tenderness by 0.6 units (P<0.01) and juiciness by 0.5 units (P<0.01) on the 1-8 scale, but at the expense of lower daily weight gain (P<0.01), lower feed conversion efficiency (P<0.01), reduced P:S ratio (P<0.001) and increased lipid oxidation (P<0.01). The results suggest that PKO and PO could be used in tropical developing countries as cheaper alternatives to SBO for the production of good quality and healthy pork, but their limits of inclusion need to be determined.     

OXIDATIVE STABILITY OF A LIPASE-CATALYZED TRANSESTERIFIED PALM STEARIN AND PALM KERNEL OLEIN BLEND

A palm stearin (PS) and palm kernel olein (PKO) blend at ratio 1:1 (by weight) was enzymatically transesterified. The oxidative stability of the blend, its control (without transesterification) as well as the PS and PKO were evaluated in a conventional oven at 60C for two weeks. Samples were withdrawn at 2 day intervals and analyzed for their peroxide value, iodine value, content of conjugated diene and fatty acid (FA) composition. The transesterified blend was found to be more susceptible than the control to oxidation during storage. PS exhibited the largest change in oxidative parameters employed, mainly due to its high level of unsaturated FA.     

Optimization of the enzyme-catalyzed synthesis of amino acid-based surfactants from palm oil fractions

The feasibility of using palm oil fractions as cheap and abundant sources of raw material for the synthesis of amino acid surfactants was investigated. Of a number of enzymes screened, the best results were obtained with the immobilized enzyme, Lipozyme. The effects of temperature, solvent, incubation period, fatty substrate/amino acid molar ratio, enzyme amount, and water removal on the reactions were analyzed and compared to those on reactions with free fatty acids and pure triglycerides as fatty substrates. All reactions were most efficient when carried out at high temperatures (70-80 degrees C) in hexane as a solvent. However, while reactions with free fatty acids proceeded better when a slight excess of the free fatty acids over the amino acids was used, reactions with triglycerides and palm oil fractions were best performed at equimolar ratios. Also, the addition of molecular sieves slightly enhanced reactions with free fatty acids but adversely affected reactions with triglycerides and palm oil fractions. Although reactions with palm oil fractions took longer (6 d) to reach equilibrium compared to reactions with free fatty acids (4 d) and pure triglycerides (4 d), better yields were obtained. Such lipase-catalyzed transacylation of palm oil fractions with amino acids is potentially useful in the production of mixed medium- to long-chain surfactants for specific applications.     

Interpretation of triacylglycerol profiles of palm oil,palm kernel oil and their binary blends

The effects of lipase-catalyzed interesterification (IE) on changes in the chemical composition of palm oil (PO), palm kernel oil (PKO) and their binary blends at 3:1, 1:1 and 1:3 (w/w) ratios, using both 1,3 specific Rhizomucor miehei, (Lipozyme™) and non-specific Pseudomonas sp. lipases were evaluated. IE of the native PO and PKO showed very distinct chemical composition changes. Catalysis of PO, using both lipases, caused synthesis of more medium and long chain triacylglycerols (TAG), with MMM/OLL, MMP, OOO and PPP (M, myristic acid; O, oleic acid; L, linoleic acid; P, palmitic acid) increasing in concentration. In contrast, IE of PKO resulted in the formation of more short and medium chain TAG, with LaLaO and LaMO (La, lauric acid; C, capric acid) experiencing noteworthy increments. Both Rhizomucor miehei and Pseudomonas sp. lipases showed high affinity in hydrolyzing PO fatty acids, resulting in high TAG losses and formation of high percentages of partial glycerides while these lipases were found to enhance the synthesis process in IE of PKO. Catalysis of the three binary blends caused similar TAG compositional changes where the synthesis process focussed on the medium chain TAG, while hydrolysis was observed in the short and long chain TAG that showed corresponding decreases. Catalysis of the three blends was influenced by the major fraction of these blends. Among these blends, PO: PKO at a 1:1 ratio exhibited the highest degree of IE. The diversity and quantity of available TAG are postulated to be the main causes of the different catalytic activities in these binary blends with Pseudomonas sp. lipase showing a higher degree and rate of IE than R. miehei.     

Changes in lipid composition and fatty acid profile of Nham,a Thai fermented pork sausage,during fermentation

Changes in lipid composition and fatty acid profile of Nham during fermentation were investigated. Total lipids of Nham were in the range 2–3%. The extracted lipid of initial Nham mix consisted mainly of triglycerides (TG), accounting for more than 75% of the total lipid, followed by phospholipids (PL) and a trace amount of diglycerides (DG) and free fatty acid (FFA). During fermentation, TG, DG and PL decreased with a concomitant increase in FFA, indicating lipolysis of Nham lipids during fermentation. Changes in fatty acids of the total lipids, non-polar and polar lipid fractions were observed during fermentation. In both total and non-polar lipid fractions, the major fatty acids found in a descending order were oleic (C18:1), linoleic (C18:2) and palmitic (C16:0) acids, which together accounted for 90% of the total fatty acids. Increases in fatty acid contents in both total and non-polar lipid fractions, were observed with a corresponding decrease in the quantity of fatty acids of phospholipids. As the fermentation proceeded, peroxide value generally increased while TBARS values decreased. Overall, lipid oxidation in Nham occurred during fermentation but did not cause the objectionable odour and taste in any Nham tested.     

Comparison of nutrient composition in kernel of tenera and clonal materials of oil palm (Elaeis guineensis Jacq.)

Nutritive information about oil palm kernel is scarce, especially on the composition of sugars and water-soluble vitamins. This study aims to evaluate both tenera and clonal materials for their proximate composition, fatty acid profile, amino acid composition, sugar, mineral and water-soluble vitamin contents. The tenera material had a higher moisture, fat and fibre content as compared to the clonal material, whereas protein, carbohydrate and ash content were higher in the clonal material. The major fatty acid constituents in palm kernel oil were lauric acid, myristic acid and oleic acid. The palm kernel proteins were deficient in lysine and tryptophan but rich in glutamic acid, arginine and aspartic acid. Sucrose was the most abundant sugar in palm kernel. The mineral analysis of the samples showed high levels of potassium, phosphorus, magnesium, calcium and manganese, while niacin was the water-soluble vitamin present at the highest concentrations in palm kernel.     

棕榈油与猪油在组成结构和功能特性上的比较

比较了3种棕榈油和6种猪油产品在理化指标、营养与功能特性指标以及脂肪酸组成及其在甘油三酯Sn-2位上的分布情况,以判断棕榈油对猪油的可替代性.结果表明,棕榈油和猪油的熔点、碘值、酸值、过氧化值等理化指标很接近;棕榈油不含胆固醇,具有比猪油较高的V_E含量和氧化稳定性;在可塑性方面,精炼棕榈油与猪板油相当,而且好于猪杂油和猪膘油,棕榈硬脂与猪骨油相当,棕榈液油与猪皮油相当;虽然棕榈油和猪油的脂肪酸组成具有相似性,猪油的不饱和脂肪酸含量略高于棕榈油的不饱和脂肪酸含量,但是棕榈油的Sn-2位上主要分布不饱和脂肪酸,而猪油的Sn-2位上主要分布饱和脂肪酸,使棕榈油比猪油更加容易消化吸收.     

Physico-chemical properties of various palm-based diacylglycerol oils in comparison with their corresponding palm-based oils

Palm-based diacylglycerol (P-DAG) oils were produced through enzymatic glycerolysis of palm kernel oil (PKO), palm oil (PO), palm olein (POL), palm mid fraction (PMF) and palm stearin (PS). High purity DAG (83–90%, w/w) was obtained and compared to palm-based oils (P-oil) had significantly (P < 0.05) different fatty acid composition (FAC), iodine value (IV) and slip melting point (SMP). Solid fat content (SFC) profiles of P-DAG oils as compared to P-oils had less steep curves with lower SFC at low temperature range (5–10 °C) and the higher complete melting temperatures. Also, P-DAG oils in contrast with P-oils showed endothermic as well as exothermic peaks with higher transition temperatures and significantly (P < 0.05) higher crystallisation onsets, heats of fusion, and heats of crystallisation. Crystal forms for P-DAG oils were mostly in the β form.     

Nutrient composition of Nigerian palm kernel from the dura and tenera varieties of the oil palm (Elaeis guineensis)

The dura and tenera varieties of the oil palm from Calaro Oil Palm Estate, Akamkpa in Cross River State, Nigeria and NIFOR Experimental Oil Palm Station, Abak in Akwa Ibom State, Nigeria were studied to evaluate their proximate, mineral, toxicant and fatty acid compositions. These parameters were determined for both undefatted and defatted samples. The defatted samples had higher nutrient levels than the undefatted ones. The dura variety had a higher moisture content than the tenera in both locations. Antinutrients, such as hydrocyanic acid and total oxalate, were also higher in the dura variety than the tenera. The mineral analysis of the samples showed high levels of magnesium, manganese, iron, copper, zinc, phosphorus, sodium and potassium. The tenera variety showed higher values of most of these minerals than the dura in both of the locations. Palm kernel therefore appears to be a good source of these mineral elements. Phytate and lead were not detected in any of the samples. The fatty acid profile indicated lauric (C 12:0), oleic (C 18:1) and palmitic (C 16:0) to be the major constituent fatty acids of the palm kernel oil samples. There were no significant differences in fatty acid composition between the varieties or locations.     

Physicochemical characteristics of soybean oil, palm kernel olein, and their binary blends

Soybean oil (SBO), palm kernel olein (PKO) and their binary blends (containing 5–40% PKO) were studied for their physicochemical characteristics. Decreases in band absorbencies of the resultant Fourier transform infrared spectra were observed in regions attributable to vibrations of the functional groups of unsaturated fatty acids, mainly the =C–H cis stretching at 3009 cm⁻¹and –C=C cis stretching at 1657 cm⁻¹. The solid fat content was measurable in the blends containing 15–40% PKO at 5 and 10 °C, ranging within 4–20% and 2–13%, respectively. The differential scanning calorimetry melting curve for SBO exhibited more complex transition peaks, suggesting a     polymorphic transformation when compared with PKO with a simpler     . Blending of SBO with PKO reduced the complexity caused by the polymorphic transformation, featuring the endotherms that only related to the β' fat crystals.     

Triglyceride Content of Supercritical Carbon Dioxide Extracted Fractions of Beef Fat

Beef fat was fractionated using supercritical carbon dioxide at 40°C and pressures from 10.3–27.6 MPa. Extractions followed by one or two stage separation were collected at atmospheric pressure and ambient temperature. Triglyceride analysis of extracts using HPLC and evaporative light scattering detection resolved 15 major peaks. Triglyceride content (mg/g extract) was influenced by extraction conditions. Extraction at 27.6 MPa and separation at 20.7 MPa resulted in highest triglyceride concentration, while 13.8 MPa resulted in the lowest. Saturated and monounsaturated triglycerides were selectively extracted based on solvent density and molecular weight. Little selectivity of polyunsaturated triglycerides was observed for fractionating beef fat.     

Lipid content and fatty acid composition of green algae Scenedesmus obliquus grown in a constant cell density apparatus

The lipids of alga Scenedesmus obliquus grown under controlled conditions were separated and fractionated by column and thin-layer chromatography, and fatty acid composition of each lipid component was studied by gas-liquid chromatography (GLC). Total lipids were 11.17%, and neutral lipid, glycolipid and phospholipid fractions were 7.24%, 2.45% and 1.48% on a dry weight basis, respectively. The major neutral lipids were diglycerides, triglycerides, free sterols, hydrocarbons and sterol esters. The glycolipids were: monogalactosyl diglyceride, digalactosyl diglyceride, esterified sterol glycoside, and sterol glycoside. The phospholipids included: phosphatidyl choline, phosphatidyl glycerol and phosphatidyl ethanolamine. Fourteen fatty acids were identified in the four lipid fractions by GLC. The main fatty acids were C18:2, C16:0, C18:3(alpha), C18:1, C16:3, C16:1, and C16:4. Total unsaturated fatty acid and essential fatty acid compositions of the total algal lipids were 80% and 38%, respectively.     

Fatty Acid Content of Supercritical Carbon Dioxide Extracted Fractions of Beef Fat

Utilization of beef fat might be improved via production of fractions with specific functional properties. Beef fat was fractionated using supercritical carbon dioxide at 40°C and pressures from 10.3–27.6 MPa. Extractions followed by one or two stage separation were collected into glass vials at atmospheric pressure and temperature. Resultant extracts were analyzed for fatty acid content by gas chromatography (GC). A significant difference in concentration due to extraction pressure for 16 straight chain fatty acids, 6 branched chain fatty acids, and 7 unknowns was found. Total fatty acids (mg/g extract) increased as pressure increased. Monounsaturated and polyunsaturated fatty acids increased with increasing pressure and solvent density as shown by the saturate/ unsaturate, saturate/monounsaturate, and saturate/polyunsaturate ratios.     

Metabolic fate of long-chain unsaturated fatty acids and their effects on palmitic acid metabolism and gluconeogenesis in bovine hepatocytes

The objectives were to determine the metabolic fate of different long-chain fatty acids, and their effects on palmitic acid metabolism and gluconeogenesis in bovine hepatocytes. Hepatocytes were isolated from four ruminating calves and exposed in suspension for 3 h to one of the following treatments: 1 mM palmitic acid (1C16), 2 mM palmitic acid (2C16), or 1 mM palmitic acid plus either 1 mM oleic (C18:1), linoleic (C18:2), linolenic (C18:3), eicosapentaenoic (C20:5), or docosahexaenoic acid (C22:6). Oxidation of [1-(14)C]palmitic acid or one of the [1-(14)C]-labeled treatment fatty acids to CO2 or incorporation into cellular triglycerides (TG), phospholipids, cholesterol, and cholesterol esters were measured. Rates of oxidation to CO2 were 3- to 4-fold higher for C22:6 than for other fatty acids, with the exception of C20:5, which had intermediate rates of oxidation to CO2. In general, treatments 2C16 and C18:1 yielded the highest rates of incorporation into most cellular lipids, whereas the polyunsaturated fatty acids were poor substrates for incorporation into cellular lipids. The most pronounced change was a large reduction of polyunsaturated fatty acid incorporation into cellular TG compared to 1C16, 2C16, and C18:1. The unsaturated fatty acids also influenced palmitic acid metabolism. The addition of C20:5 yielded the highest rates of palmitic acid oxidation to CO2 followed by addition of C18:1 and C22:6. Treatments containing polyunsaturated fatty acids decreased palmitic acid metabolism to TG and total cellular lipids compared with treatments 2C16 and C18:1. Rates of gluconeogenesis from propionate were significantly higher for the treatment containing C18:1. Long-chain fatty acids vary in their routes of metabolism and influence palmitic acid metabolism and gluconeogenesis in bovine hepatocytes.     

Stability and rheology of concentrated O/W emulsions based on soybean oil/palm kernel olein blends

Droplet size distribution and rheological properties of egg yolk-stabilized emulsions were studied before and after storage (25 °C, 30 days). The dispersed phase (70%) of the emulsions was based on soybean oil (SBO) and 10–40% palm kernel olein (PKO) replacements of SBO. Replacement of PKO resulted in a significant increase in droplet mean diameters and a decrease in rheological properties of the emulsions. All emulsion exhibited a gel-like characteristic with storage modulus higher than loss modulus and tan δ greater than 0.3. Significant increase (p < 0.05) was found for droplet mean diameters and rheological properties of the emulsions after storage. Emulsion with fully SBO and the highest PKO replacement (40%) were found to be the most unstable, which was ascribed to a strong flocculation. With 10–30% PKO replacements, the emulsions displayed a better stability after storage, most probably promoted by significant content of short-medium chain fatty acids in PKO.     

Diet and the lipid composition of adipose tissue in the young lamb

The changes in the lipid composition of the perirenal adipose tissue obtained from groups of lambs receiving either ewes' milk or a reconstituted low-fat milk powder have been studied during the first 8 days after birth. The triglycerides were further analysed by a stereospecific analytical procedure to obtain the intramolecular distribution of the fatty acids between the hydroxyl groups of the glycerol moeity. The percentage composition of the major lipid fractions in the perirenal adipose tissue from the naturally fed lambs remained similar to that of the adipose tissue obtained from the lambs at birth, but in the lambs receiving the artificial diet the relative concentration of the triglycerides was considerably reduced and that of the unesterified fatty acid and phospholipid fractions increased. At birth 18 :1 was the major fatty acid present in the triglyceride, unesterified fatty add and phospholipid fractions. Any polyunsaturated fatty acids were confined to the phospholipid fraction. Although there were negligible concentrations of the C18 polyunsaturated fatty acids, the C20 and C22 polyunsaturated fatty acids comprised some 20% of the fatty acids of the phospholipids. In the naturally fed lambs the concentration of 18: 2ω6 increased considerably during the 8 days after birth and there was a decrease in the concentration of 20 : 3ω9. In the artificially fed lambs the concentration of 20 : 3ω9 remained similar to that found at birth and there was no accumulation of 18 : 2ω6. In the triglycerides at birth 70–80% of 18 : 1-cis was in the 2-position and the saturated fatty acids were located mainly in the 1-and 3-positions. In both groups of lambs the concentration of 18 : 1-cis decreased and the concentration of 18 : 0 increased after birth. In the naturally fed lambs the increase in 18 : 0 occurred mainly in positions 1-and 3-but in the artificially fed lambs the concentration of 18 : 0 also markedly increased in position 2. The changes in concentration of 16 : 0 paralleled that of 18 : 0. In the naturally fed lambs the concentrations of 14:0, 18: 1-trans and 18 : 2ω6 which were probably of dietary origin increased considerably. 14 : 0 and 18 : 1 trans were concentrated largely in positions 1 and 3 whilst 18 : 2ω6 was concentrated mainly in position 2.     

气相色谱-质谱法分析棕榈果脂肪酸组成

采用索氏抽提法分别提取棕榈果肉和棕榈果仁中的油脂,以氢氧化钾—甲醇溶液对油脂进行甲酯化处理,用气相色谱-质谱(GC-MS)法分析。从棕榈果肉和棕榈仁的油脂中均分离并鉴定了9种脂肪酸,其中棕榈果肉中饱和脂肪酸质量分数为49.5%,主要有棕榈酸和硬脂酸,不饱和脂肪酸主要有油酸、亚油酸以及少量的亚麻酸和13,16-二十二碳二烯酸。棕榈仁中饱和脂肪酸80%以上,其中月桂酸质量分数达到41.5%,肉豆蔻酸和棕榈酸含量也较高,此外还含有少量的己酸、辛酸、癸酸和硬脂酸,不饱和脂肪酸有油酸和亚油酸。     

光山县长林系列油茶良种茶籽脂肪含量和脂肪酸组成分析

从河南省林木品种审定委员会认定的适宜在本地区推广的长林系列品种中选出具有代表性的主栽油茶品种长林18号、40号、53号和配栽油茶品种长林166号,采用气相色谱-质谱法(GC-MS)对4个油茶品种茶籽仁中脂肪酸组成和含量进行分析,检验了其干籽出仁率和脂肪含量,并对脂肪含量及脂肪酸组分进行了相关性分析。结果表明:3个主栽品种与1个配栽品种干籽出仁率的差异达到了显著水平(p0.05),但不同品种茶籽脂肪含量差异不大;共检测到了17种脂肪酸组分,其中,茶籽仁中常量组分顺-油酸的含量26.25%～30.82%、棕榈酸的含量2.86%～3.22%、亚油酸的含量3.25%～3.86%。长林40号茶籽中饱和脂肪酸、单不饱和脂肪酸、多不饱和脂肪酸比值为1:6.08:1.05,最接近国际营养学家提出油脂中三类脂肪酸的最佳供能比1:6:1。相关性分析显示,脂肪含量与棕榈酸有一定的相关性,相关系数达到了0.64。结合河南省林木品种审定委员会的研究结论可得,长林40号油茶良种不仅产量高、抗性强,而且干籽出仁率高、含油量高,茶籽脂肪酸组成合理,综合性状优于其他三个品种。     

RHEOLOGICAL PROPERTIES OF ICE CREAM EMULSION PREPARED FROM LIPASE-CATALYZED TRANSESTERIFIED PALM KERNEL OLEIN:ANHYDROUS MILK FAT MIXTURE

The effect of different fat sources used in the preparation of ice cream emulsions was investigated. Anhydrous milk fat (AMF), a mixture of unmodified palm kernel olein (PKO) and AMF (70:30, w/w) and enzyme-transesterified PKO:AMF (70:30, w/w) mixture were used in the preparation of the emulsions. Transesterification was catalyzed by mycelium-bound lipase from Rhizomucor miehei . Rheological and viscoelastic properties measured were the creep compliance, controlled-stress steady state flow and frequency sweep profiles. Results indicate that emulsion prepared using transesterified PKO:AMF (TE-PKO:AMF) exhibited a different rheological behavior from that of AMF alone, and the unmodified PKO:AMF (70:30) blend. Frequency sweep profiles showed that the G = values of both AMF and TE-PKO:AMF emulsions were higher than their G at values, indicating that these emulsions were dominated by the elastic