Quantification of Rice Bran Oil in Oil Blends
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GRASAS Y ACEITES, 63 (1), ENERO-MARZO, 53-60, 2012, ISSN: 0017-3495 DOI: 10.3989/gya.033311 Quantification of rice bran oil in oil blends By R. Mishra*, H.K. Sharma and G. Sengar Food Engineering and Technology Department. Sant Longowal Institute of Engineering & Technology (Deemed to be University) Longowal – 148 106. Sangrur (PUNJAB). INDIA *Corresponding author: [email protected] RESUMEN ultrasonic velocity and methods based on physico-chemical parameters. The physicochemical parameters such as Cuantificación de aceite de salvado de arroz en mez- ultrasonic velocity, relative association and acoustic clas de aceites. impedance at 2 MHz, iodine value, palmitic acid content and oryzanol content reflected significant changes with Se analizaron diversos parámetros físico-químicos pa- increased proportions of PRBO in the blended oils. These ra la evaluación de mezclas de aceites en diferentes pro- parameters were selected as dependent parameters and % porciones que incluyen: aceite de salvado de arroz físíca- PRBO proportion was selected as independent parameters. mente refinado (PRBO): aceite de girasol (SNF) y las The study revealed that regression equations based on mezclas PRBO: aceite de cártamo (SAF) en diferentes pro- the oryzanol content, palmitic acid composition, ultrasonic porciones. La cuantificación de la presencia del aceite de velocity, relative association, acoustic impedance, and salvado de arroz en las mezclas se llevó a cabo por dife- iodine value can be used for the quantification of rice bran rentes métodos, como cromatografía de gases (GC), cro- oil in blended oils. The rice bran oil can easily be quantified matografía líquida (HPLC), ultrasonidos y métodos basa- in the blended oils based on the oryzanol content by HPLC dos en otros parámetros físico-químicos. Los parámetros even at a 1% level. The palmitic acid content in blended físico-químicos como la velocidad de ultrasonidos, la aso- oils can also be used as an indicator to quantify rice bran ciación y la impedancia acústica a 2 MHz, el índice de yo- oil at or above the 20% level in blended oils whereas the do, el contenido en ácido palmítico y el contenido de oriza- method based on ultrasonic velocity, acoustic impedance nol reflejan cambios significativos con el aumento de la and relative association showed initial promise in the proporción de PRBO en las mezclas de aceites. Estos pa- quantification of rice bran oil. rámetros fueron seleccionados como parámetros depen- dientes y las proporciones de PRBO fue seleccionado co- KEY-WORDS: HPLC – Oryzanol – Rice bran oil mo parámetro independiente. El estudio reveló que las quantification – Ultrasonic velocity. ecuaciones de regresión basadas en el contenido de oriza- nol, la composición de ácido palmítico, la velocidad de ul- trasonidos, la asociación relativa, la impedancia acústica, y 1. INTRODUCTION el índice de yodo pueden ser utilizados para la cuantifica- ción de aceite de salvado de arroz en las mezclas de acei- There are varieties of oils which are refined tes. El aceite de salvado de arroz puede ser cuantificado worldwide and some of the oils are being blended en las mezclas de aceites mediante el contenido orizanol due to the current trends in globalization and determinado por HPLC, incluso a nivel de 1%. El contenido de ácido palmítico en los aceites de mezcla también se demand for nutritional enrichment. Blended oils puede utilizar como un indicador para cuantificar el aceite are gaining popularity worldwide due to the de salvado de arroz en 20% o más nivel en los aceites de advantages they offer such as improved thermal mezcla, donde el método basado en la velocidad ultrasóni- stability, oxidative stability, nutritional benefits ca, la impedancia acústica y de asociación relativa parecía (Sharma et al., 1996) and an ability fulfill specific prometer inicialmente en la cuantificación de arroz aceite desired properties. Indian food regulations do de salvado. not permit the addition to vegetable oils of PALABRAS CLAVE: Cuantificación de aceite de salvado health-promoting components (e.g. oryzanol, de arroz – HPLC – Orizanol – Velocidad ultrasonidos. tocotrienols and lignan antioxidants) in the form of concentrates and isolates. However, vegetable oils containing such components can be blended SUMMARY with those that do not have such health promoting components. Different branches of Quantification of rice bran oil in oil blends. the food processing industry have diverse requirements for blended oils and fat products. Blends consisting of physically refined rice bran oil Frankel and Huang (1994) reported that mixing (PRBO): sunflower oil (SnF) and PRBO: safflower oil (SAF) in different proportions were analyzed for various different proportions of high-oleic sunflower oil physicochemical parameters. The quantification of pure (HOSO) with polyunsaturated vegetable oils rice bran oil in the blended oils was carried out using provides a simple method for preparing more different methods including gas chromatographic, HPLC, stable edible oils with a wide range of desired 53 R. MISHRA, H.K. SHARMA AND G. SENGAR fatty acid compositions. The fatty acid absorption 2.2. Preparation of samples of a sunflower and canola blend at 7:3, 5:5 was found to be superior to that of unblended oils A pure rice bran oil sample was blended with (Crick et al., 1988). Blended oils have been pure safflower and sunflower oil in different ratios reported to have better thermal stability; Handoo i.e. 1, 3, 4, 5, 10 and 20% using a high speed et al., (1992) reported that groundnut oil and homogenized mixer. cotton seed oil blends of 50:50 are more stable than pure cotton seed oil. Lower peroxide values 2.3. Analysis of the samples were reported in stored food items which were fried in rapeseed-cottonseed blends compared Iodine value (IV) [Cd 1-25], saponificataion to those fried in groundnut-cottonseed and value (SV) [Cd 3-25], refractive index (RI) [Cc 7-25] groundnut-rapeseed oil blends (Mehta et al., and specific gravity [Cc 10a-25] were determined 1986). Comparative studies on the physical using standard methods (AOCS 2004). Oryzanol properties of vegetables oils and their blends value (IICT 2008) was measured with a after frying indicated a reduction in peroxide Spectrophotometer (UV-1700, SHIMAZDU). The value when using blended oils (Susheelamma et oryzanol content of each sample was determined al., 2002). by measuring the optical density of the sample at Several researchers have worked on the 315 nm in n-Heptane in a 1 cm cell using a stability of rice bran oil and its blend with other spectrophotometer. oils like groundnut oil, sunflower oil, mustard oil The fatty acids of triglycerides were analyzed by etc. which concluded that oil blends showed good preparing methyl esters according to a conventional stability (Shiela et al., 2004, Sharma et al., 2006). procedure consisting of saponification followed Various methods have been reported for the by acidification and finally methylation using detection of oil. Ambadi oil was detected in diazomethane according to the reported method various common edible oils like groundnut, (Orthoefer and Smith., 1996). A gas chromatographic cottonseed, mustard, sunflower, safflower, palm (GC) analysis of fatty acid methyl esters was and coconut oil by means of color reaction and carried out using a NUCON SERIES 5700 of data spectrophotometry (Adhikari and Adhikari, 1992). station in the range of 0-2.5 mV with a 1.5s A simple TLC method was reported to detect the response rate. A 2m 3 2 mm stainless steel 10% presence of watermelon seed oil in groundnut Silar 7C column packed with 60-120 mesh Gas and sesame oils. Data (1981) has detected some Chrom Q was used. The injector and detector admixtures such as rapeseed in mustard oil by temperatures were maintained at 240 °C. The using critical solution temperature. Seetharamaiah column temperature was set at 160 °C for 5 min and Prabhakar (1986) also detected the rice bran and then increased at a rate of 5 °C per min to a oil content in other edible vegetable oils by the final temperature of 220 °C and kept there for 20 isolation of oryzanol in rice through TLC. In blends min. The total time for analysis was 37 min. Fatty of groundnut-palm and coconut-groundnut oil, acids were tentatively identified by comparison quantification of individual oils was achieved on with the retention times of authentic reference the basis of a computed linear regression samples. equation based on Bellier temperature, cloud point and the fatty acid composition of triglycerides 2.4. Measurement of ultrasonic velocity, (Sharma et al., 1999). Crude rice bran has been relative association acoustic impedance, successfully identified and isolated using reverse- and compressibility in blended oils phase HPLC by Xu and Godber, 1999. The various advantages of blended oils and The densities of all oil samples were measured their increased market demand have also raised using a single capillary pycnometer. The measured the need for a rapid and simple technique for densities were reproducible within 0.2 kg m–3. quantifying the proportion of a specific oil in a blend. The ultrasonic velocities were measured at room Therefore, the present study deals with the temperature (26 1 °C) using a single crystal quantification of pure rice bran oil in the blended variable-path interferometer at 1 and 2 MHz with oils using different methods. an accuracy of 0.05%. The criteria of purities of chemicals and accuracies were checked by comparing the experimental values with a distilled 2. MATERIALS AND METHODS water sample. The isotropic compressibility, relative association, acoustic impedance and 2.1. Materials adiabatic compressibility were calculated using equations 1, 2, 3 and 4 respectively (Mehra and The oils used in the present investigation Israni., 1999). (physically refined rice bran oil, sunflower oil and safflower oil) were obtained from A. P. Organics Ks 5 u–2ρ–1 (1) Pvt. Ltd.