The study investigates the antioxidant potential of commonly used vegetable oils viz., coconut (CNO), sunflower (SFO), rice bran (RBO), groundnut (GNO), sesame (SESO) and mustard oil (MO), where the oils were extracted with methanol; and these methanolic extracts were used for the antioxidant studies. Fatty acid composition by gas chromatography, physicochemical parameters such as specific gravity, refractive index, acid value, iodine value and peroxide value were also analysed. Total phenolic content (TPC) and antioxidant activities of the oils (DPPH, ABTS, superoxide and nitric oxide radical scavenging assays) were evaluated. Phenolic compounds were identified by high-pressure liquid chromatography (HPLC). Percentage TPC was highest in groundnut oil with 3.09 mg/100 g oil followed by coconut oil, rice bran oil, mustard oil, sunflower oil and sesame oil with 1.8, 0.89, 0.56, 0.49 and 0.33 mg/100 g oil, respectively. The methanolic extracts of oils showed potential antioxidant activity in terms of super oxide and nitric oxide radical scavenging activity.
PRACTICAL APPLICATIONSThe present study indicated that vegetable oils can contribute to the dietary intake of antioxidants, depending on the processing condition. This is the first study of its kind to investigate and compare the phenolic content by HPLC and also the radical scavenging activity (DPPH, ABTS, superoxide and nitric oxide) of different oils. It was observed that the unrefined oils posses better antioxidant activity than the refined oils, which imply the importance of optimizing and/or modifying the existing steps in the vegetable oil processing to retain the polyphenolic content in vegetable oil without compromising other physicochemical parameters. The study has brought out the importance of polyphenolic compounds in vegetable oil as radical scavenging agents that could be beneficial in the management of many degenerative diseases. This may provide vegetable oils a new dimension in health management other than its traditional uses.
Sesame cake, the byproduct obtained after the removal of oil is presently used as cattle field. Present study evaluates the a-glucosidase, a-amylase inhibition and antioxidant properties of black sesame cake extracts. For that purpose, defatted seeds were sequentially extracted with ethyl acetate, methanol, methanol-water 70:30 (v/v) and water. Among the extracts tested, methanol extract demonstrated better antioxidant activities (2,2-diphenyl-1-picrylhydrazyl, hydroxyl and superoxide radical) and total phenol content. But the total flavonoid content and the total reducing power was high for methanol-water. Most active methanol extract was further screened for a-glucosidase and a-amylase inhibition. The extract showed strong a-glucosidase inhibitory potential and mild a-amylase inhibition. The study indicated that the extraction yield and the antioxidant activities were strongly dependent on the solvent, antioxidant assays and extract concentration. These results demonstrated that sesame meal can be exploited as source of protein and bioactive for the development of functional food.
PRACTICAL APPLICATIONSesame seed is one of the most important oil seed crops in the world. Defatted sesame meal, the byproduct obtained after the removal of oil is mainly used as a cattle feed aside from being a good source of protein and antioxidants. This study conducted using sesame meal extracts has revealed the inhibitory potential of the extracts against two carbohydrate digestive enzymes: a-glucosidase and a-amylase. The meal extract showed the presence of phenolics and flavonoids and also showed antioxidant activities. This study thus provides the biochemical rationale for further in vivo studies and utilization of this byproduct for development of functional food for the management of diabetes.
Demand for non-centrifugal sugars (NCS) is hampered by bottlenecks such as improper flow and unhygienic production practices. In this review, we discuss various advances and strategies required for the resurgence of NCS in the global market.
Ghee, a major Indian dairy product, has unique pleasing flavour and granular texture. Ten samples of commercial ghee were analysed for grainy texture, fatty acid composition and melting and crystallisation behaviour. These were compared with laboratory ghee and its blends with high melting fraction (HMF) or low melting fraction (LMF). Grain size and quantity of commercial ghee ranged from 0.200 to 0.330 mm and 1 to 40%, respectively, when incubated at 29°C for 24 h. Laboratory ghee samples showed a grain size and quantity of 0.241 mm and 42%, respectively. Commercial samples with poor granularity had a lower level of saturated fatty acids, while those with bigger grains had a higher level of palmitic acid (>35%). The ratio of unsaturated to saturated fatty acids showed significant variation in these samples. Differential scanning calorimetric analysis of the samples also showed variation in melting and crystallisation behaviour. In general, the characteristics of commercial ghee with poor granularity resembled those of laboratory ghee blended with LMF while commercial ghee with bigger grains compared well with the ghee blended with HMF.
RESUMENSeparación de isómeros cis/trans de ácidos grasos mediante cromatografía de gases, comparación con el método Ag-TLC.El presente estudio investiga la separación de isómeros cis/trans de ácidos grasos mediante cromatografía de gases (GC) utilizando una columna de SP2560 de 75 m y diferentes condiciones que incluyen un programa isotérmico y una programación temperatura-tiempo. La programación temperatura-tiempo mostró una mejor separación de isómeros cis / trans de los ácidos grasos C 14:1 , C 16:1 , C 18:1 , C 18:2 y C 18:3 con los ácidos grasos de cadena corta en comparación con el programa isotermo. La separación de los isómeros trans/trans de los ácidos grasos C 18:1 incluyendo ácido elaídico (C 18:1 Δ9t) y ácido vaccénico (C 18:1 Δ11t) fué difícil mediante programación temperatura-tiempo. La cromatografía en capa fina impregnada con nitrato de plata (Ag-TLC) se realizó para separar fracciones cis/trans y el análisis de la fracciones se llevó a cabo mediante GC. El análisis GC mostró co-elución de los isómeros trans del ácido graso C 18:1 . Así, el estudio muestra que una programación temperatura-tiempo en GC con columna de cianopropilo altamente polar es suficiente para resolver los ácidos grasos trans, junto con los ácidos grasos de cadena corta cuando un gran número de muestras tiene que ser analizado.
PALABRAS CLAVE: Ácidos grasos trans -Cromatografía de gases -Fraccionamiento Ag-TLC -Resolución
SUMMARY
Separation of cis/trans fatty acids isomers on gas chromatography compared to the Ag-TLC methodThe present study investigates the separation of the cis/ trans isomers of fatty acids on the 75 m SP2560 column under different gas chromatographic (GC) conditions including an isothermal program and a time-temperature program. The time-temperature program showed improved separation of cis/trans isomers of C 14:1 , C 16:1 , C 18:1 , C 18:2 and C 18:3 fatty acids along with short chain fatty acids compared to the isothermal program. The separation of trans/trans isomers of C 18:1 fatty acids including elaidic acid (C 18:1 Δ9t) and vaccenic acid (C 18:1 Δ11t) was difficult with the time-temperature program. The thin layer chromatography impregnated with silver nitrate (Ag-TLC) method was performed to separate cis/trans fractions and GC analysis was carried out with the trans fraction. But GC analysis showed a co-elution of trans isomers of C 18:1 fatty acid. Thus the study shows that a time-temperature programmed GC method with the highly polar cyanopropyl column is sufficient to resolve trans fatty acids along with short chain fatty acids when a large number of samples has to be analyzed.
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