Utilization of unsaponifiable matter from rice bran oil fatty acid distillate for preparing an antioxidant-rich oleogel and evaluation of its properties

D. K. Bhattacharyya,M. Ghosh,S. Sahu

doi:10.3989/gya.0938182

Abstract

Rice bran oil fatty acid distillate (RBOFAD) is an important by-product obtained from the physical refining process. This fatty acid distillate contains high a amount of Unsaponifiable Matter (γ-oryzanol 3.27 gm/100gm UM; total tocopherol 10.93 mg/100 g UM; total phytosterol 21.81 g/100g UM; squalene 1.15 g/100 g UM and total fatty alcohol 73.34 g/100 g UM) and free fatty acids. Antioxidant-rich Oleogels were obtained from rice bran wax (RBW), rice bran oil fatty acid distillate (RBOFAD) and refined rice bran oil. The main objective of this study was to utilize the antioxidant-rich unsaponifiable matter of RBOFAD (UMRBOFAD) as an organogelator along with rice bran wax, which also acts as a good organogelator. Antioxidant-rich oleogel was prepared using UMRBFAD, ethylcellulose (EC) and RBW at 2%, 2%, 3% on weight basis, respectively, in refined rice bran oil and this antioxidant-rich oleogel was compared with rice bran oil oleogel using RBW at 7% on weight basis of rice bran oil. These oleogels were evaluated using a combination of techniques such as differential scanning calorimetry (DSC), polarized light microscopy (PLM), Viscosity, synchrotron radiation X-ray diffraction (SR-XRD) and FTIR Spectroscopy. The differential scanning calorimetry (DSC) measured the thermal properties of rice bran oil oleogel and high antioxidant-rich oleogel. Polarized light microscopy images revealed needle-like crystals for RBW. SR-XRD measurements were used for clarification of the crystal structures of the building blocks of these oleogels. The antioxidant activities of oleogels were evaluated involving DPPH and ABTS assays.

Highlights

Rice bran oil (RBO), a healthy vegetable oil, is a good source of various antioxidants such as oryzanol, tocopherol, tocotrienol, squalene and phytosterol and has greater oxidative stability and longer shelflife than other vegetable oils
Rice bran oil fatty acid distillate (RBOFAD) is a by-product which is produced in the physical refining plants for the de-acidification of RBO and this by-product is mainly utilized in soap manufacturing processes
Refined RBO was purchased from a local grocery store, ethyl cellulose (HIMEDIA, CAS no. 9004-57-3, RM 1610-500) was purchased from a reagent supplier and total unsaponifiable matter was isolated from RBOFAD following the standard AOAC method (AOAC 972.28)

Summary

Introduction

Rice bran oil (RBO), a healthy vegetable oil, is a good source of various antioxidants such as oryzanol, tocopherol, tocotrienol, squalene and phytosterol and has greater oxidative stability and longer shelflife than other vegetable oils. Rice bran oil is a rich source of monounsaturated fatty acids (n-9 MUFA), n-6 PUFA and sterols, and it has been proven to reduce LDL (bad cholesterol) This healthy vegetable oil with a balanced fatty acid profile is more effective for preventing heart disease, skin disease, and cancer and it improves the immune system activity and neurological function (Ahmad Nayik et al, 2015). Fatty alcohols are mainly derived from various vegetable oils and serve as raw material for making oleogel, which is recently gaining importance in bakery applications, various household products and surfactants (Dassanayake et al, 2011; Troni et al, 2013) These constituents are useful for the utilization of functional foods for human health

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