Antioxidant Enzyme System Modulation by Dietary Palm Oils, Palm Kernel Oil and Soybean Oil in Laying Hens.

Palm-based oils (palm oil and kernel oil) and soybean oil have unique fatty acid and antioxidant profiles based on the compounds present in them. Hence, this study elucidated the antioxidant properties of crude palm oil (CPO), red palm oil (RPO), refined palm oil (RBD), palm kernel oil (PKO) and soybean oil (SBO) and the influence of dietary oils on blood lipid profiles, tissue fatty acid deposition and the expression of hepatic lipid and lipoprotein metabolism genes in laying hens. The oils were analyzed for color, beta-carotene, free fatty acid and acid value, phenolic content and lipid peroxidation. In an in vivo trial, 150 laying hens were allotted into five groups and supplemented with either CPO, RPO, RBD, PKO or SBO for 16 weeks. High antioxidant compounds present in palm oils help reduce the oxidation of oils. Dietary supplementation with palm oils, particularly CPO and RPO, contributed to the lower liver, serum and jejunal mucosal antioxidant enzyme activities. The antioxidant enzyme genes in the jejunal mucosa were downregulated in palm oils and PKO, but there was no difference between oils in antioxidant enzyme genes in the liver. In conclusion, dietary supplementation with oils with high antioxidant content contributed to protection against oxidation and was associated with a lower requirement for producing antioxidant enzymes.

Blood lipid profiles, fatty acid deposition and expression of hepatic lipid and lipoprotein metabolism genes in laying hens fed palm oils, palm kernel oil, and soybean oil.

The palm oil, palm kernel oil and soybean oil have unique and distinctive fatty acid chain length and saturation profiles, and how they affect lipid peroxidation, fatty acid intake and metabolism is worth exploring in poultry. This study elucidated the influence the dietary oils on lipid peroxidation, blood lipid profiles, fatty acid deposition of liver, serum and yolk and the expression of liver genes related to lipid and lipoprotein metabolism in laying hens. About 150 Hisex brown laying hens were fed diets containing crude palm oil (CPO), red palm oil (RPO), refined palm oil (RBD), palm kernel oil (PKO) or soybean oil (SBO) for 16 weeks. Serum, liver and yolk lipid peroxidation were not different between dietary oils. The PKO increased liver, serum and yolk medium-chain fatty acids (MCFA). There was no difference in liver saturated fatty acids (SFA). The CPO and RPO reduced serum SFA, but the PKO increased yolk SFA. The SBO increased polyunsaturated fatty acids (PUFA) in liver serum and yolk. No difference in liver elaidic acid (C18:1-trans), but SBO lowered elaidic acid (C18:1-trans) in serum. Higher very-low density lipoprotein (VLDL) in CPO than RPO and SBO and greater serum lipase in CPO, RBD and PKO than SBO. There was no difference in sterol regulatory element-binding protein 2 (SREBP-II) between oils. Apolipoprotein VLDL-II (APOVLDL2) was upregulated in palm oils and apolipoprotein B-100 (APOB) in RBD. Downregulation in peroxisome proliferator-activated receptor-alpha (PPAR-α), peroxisome proliferator-activated receptor gamma (PPAR-γ) and low-density lipoprotein receptor (LDLR) was observed in palm oils and PKO. In conclusion, different dietary oils greatly influence several aspects of fatty acid metabolism, deposition and lipoprotein profiles but have no influence on reducing lipid peroxidation.

Influence of Dietary Palm Oils, Palm Kernel Oil and Soybean Oil in Laying Hens on Production Performance, Egg Quality, Serum Biochemicals and Hepatic Expression of Beta-Carotene, Retinol and Alpha-Tocopherol Genes.

Despite being used for many decades, there is a lack of poultry research investigating the effects of dietary palmitic, carotenoid and vitamin E-rich palm oils and medium-chain fatty acid-rich PKO. The current study aimed to elucidate the influence of different dietary oils in layers on production performance, egg quality, serum biochemicals and expression of genes related to ß-carotene, retinol and α-tocopherol in the liver. A total of 150 Hisex brown laying hens were fed diets containing CPO, RPO, RBD, PKO or SBO at a similar level for 16 weeks. Different oils did not affect egg production performance and egg quality. CPO improved the freshness of eggs. CPO and RPO enhanced egg yolk color. There was no influence of different oils on serum biochemicals except greater serum ALP in PKO and SBO. CPO and RPO contributed to greater ß-carotene in feed, liver and yolk. There was no difference in retinol and α-tocopherol of serum, liver and yolk. However, the liver RBP4A gene was upregulated in CPO and PKO, and the CYP26A1 gene was downregulated in palm oils and PKO. In conclusion, palmitic-rich saturated fatty acids in palm oils and MCFA-rich PKO did not negatively affect egg production performance and quality compared to oil with high unsaturated fatty acids.

Effect of Heating on Compositional Characteristics and Oxidative Stability of Crude and Refined Rice Bran Oil.

The compositional characteristics and oxidative stability of rice bran oil were determined by observing the formation of oxidative products and alteration in chemical composition of oils during microwave or oven heating. The values of oxidative indicators such as free acidity, peroxide, p-anisidine, total oxidation, thiobarbituric acid and color values, increased faster in refined oils compared to crude ones during heating. In gas chromatography analysis, the percentages of total saturated, monounsaturated and polyunsaturated fatty acids in the studied oils such as lab extracted crude rice bran oil, lab extracted and refined rice bran oil, crude rice bran oil from commercial mill and refined rice bran oil from commercial mill were: 23.07 to 23.56, 41.15 to 42.38 and 34.38 to 35.88, respectively. The heating caused the reduction of polyunsaturated fatty acids content with increasing saturated fatty acids content, and these changes were greater in refined rice bran oil indicating extensive lipid oxidation occurred in refined oil. The change in triacylglycerol species content as determined by High-performance liquid chromatography, was lower in crude oil; the higher stability of these species in crude oil could have contribution to reduce oxidation. During thermal treatment, the generation of hydroperoxides, their degradation and formation of secondary oxidative products evaluated by Fourier-transform infrared spectroscopy, were lower in crude oils. However, the rate of formation of oxidative products in lab prepared samples was lower compared to that in the samples collected from commercial mill. Under extreme thermal condition, the order of oxidative stability: lab extracted crude rice bran oil > crude rice bran oil from commercial mill>lab extracted and refined rice bran oil > refined rice bran oil from commercial mill. The present results will be useful to oil seed processing mills in refining of rice bran oil for economic feasibility and better marketability.

Effect of rice bran oil addition on the oxidative degradation and fatty acid composition of soybean oil during heating.

BACKGROUND: Rice bran oil (RBO) contains significant amounts of micronutrients (oryzanol, tocotrienol, tocopherol, phytosterols etc.) that impart a high resistance to thermal oxidation of the oil. The high oxidative stability of RBO can make it a preferred oil to improve the oxidative and flavor stabilities of other oils rich in PUFAs. In this study, the changes in the oxidative status and fatty acid composition in soybean oil (SO) blended with RBO under extreme thermal conditions were evaluated. METHODS: The blends were prepared in a volume ratio of 10:90, 20:80, 40:60, and 60:40 (RBO:SO). The changes in the oxidative parameters and fatty acid composition of the samples during heating at frying temperature (170°C) were determined using analytical and instrumental methods. Oxidative alteration was also monitored by recording FTIR spectra of oil samples. RESULTS: The increase in oxidative parameters (free fatty acid, color, specific extinctions, peroxide value, p-anisidine value, and thiobarbituric acid value) was greater in pure SO as compared to RBO or blend oils during heating. This indicates that the SO samples incorporated with RBO have the least degradation, while pure SO has the highest. Blending resulted in a lower level of polyunsaturated fatty acids (PUFA)  with       a higher level of saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA). During heating, the relative content of PUFA decreased and that of SFA increased. However, the presence of RBO in SO slowed down the oxidative deterioration of PUFA. In FTIR, the peak intensities in SO were markedly changed in comparison with blend oils during heating. The reduction in the formation of oxidative products in SO during thermal treatment increased as the concentration of the RBO in SO increased; however, the levels of the protective effect of RBO did not increase steadily with an increase in its concentration. CONCLUSIONS: During thermal treatment, the generation of hydroperoxides, their degradation and formation of secondary oxidative products as evaluated by oxidative indices, fatty acids and IR absorbances were lower in blend oils compared to pure SO. In conclusion, RBO can significantly retard the process of lipid peroxidation in SO during heating at frying temperature.

The Effect of Microwave Roasting Over the Thermooxidative Degradation of Perah Seed Oil During Heating.

The impact of microwave roasting on the thermooxidative degradation of perah seed oil (PSO) was evaluated during heating at a frying temperature (170°C). The roasting resulted significantly lower increment of the values of oxidative indices such as free acidity, peroxide value, p-anisidine, total oxidation (TOTOX), specific extinctions and thiobarbituric acid in oils during heating. The colour L* (lightness) value dropped gradually as the heating time increased up to 12 h, whereas a*(redness) and b* (yellowness) tended to increase. The viscosity and total polar compound in roasted PSO was lower as compared to that in unroasted one at each heating times. The tocol retention was also high in roasted samples throughout the heating period. The relative contents of polyunsaturated fatty acids (PUFAs) were decreased to 94.42% and saturated fatty acids (SFAs) were increased to 110.20% in unroasted sample, after 12 h of heating. On the other hand, in 3 min roasted samples, the relative contents of PUFAs were decreased to 98.08% and of SFAs were increased to 103.41% after 12 h of heating. Outcome from analyses showed that microwave roasting reduced the oxidative deteriorations of PSO during heating.

Effect of heating on oxidation stability and fatty acid composition of microwave roasted groundnut seed oil.

The oxidative stability and fatty acid composition of groundnut seed oil (GSO) exposed to microwaves were evaluated during heating at 170 °C. During heating, the oxidative indices such as free fatty acid, peroxide value, p-anisidine value, TOTOX, thiobarbituric acid value, specific extinctions, and color value were increased. The increments were found to be higher in unroasted seed oils compared to roasted ones indicating lower release of lipid oxidation products in roasted GSO. After 9 h heating, the relative content of polyunsaturated fatty acid (PUFA) decreased to 89.53% and that of saturated fatty acid (SFA) increased to 117.46% in unroasted sample. The relative content of PUFA decreased to 92.05% and that of SFA increased to 105.76% in 7.5 min roasted sample after 9 h of heating. However, the roasting process slowed down the oxidative deterioration of PUFA. With increased heating times, an appreciable loss was more apparent in the triacylglycerol species OLL and OOL in unroasted samples compared to roasted ones. In FTIR, the peak intensities in unroasted samples were markedly changed in comparison with roasted samples during heating. The roasting of groundnut seed prior to the oil extraction reduced the oxidative degradation of oil samples; thereby increasing heat stability.

Stability of Silica- and Enzyme-Treated Palm Oil Under Deep Frying Conditions.

The oxidative and thermal stability of low diglycerides palm oil produced via silica treatment (sPO) and enzymatic treatment (ePO) compared with standard quality palm oil (SQ) and premium quality palm oil (PQ) was investigated. Both of the oils displayed better oxidative stability compared with SQ as well as significantly higher (P < 0.05) thermal resistance and oxidative strength than SQ and PQ due to lower amounts of partial glycerides. Although the initial induction periods (IPs) of sPO and ePO were significantly lower compared with SQ and PQ, both the oils showed slower drops in their IP values. The darkening effect after frying was significantly (P < 0.05) slower in sPO compared with SQ, PQ, and ePO. Besides, there is no difference p > 0.05 in the rate of FFA formation between sPO and PQ. The anisidine value and peroxide values were lowest in sPO, followed by ePO, PQ, and SQ.