The Production of Edible Rice Bran Oil

Abstract

The sources of oil bearing materials are either of animal or vegetable kingdom. The oil bearing seeds pass through three different stages to get the end product, firstly pretreatment of oil bearing seed either by expellers or by solvent extraction process, thirdly the refining, bleaching, hydrogenation and deodorization of an oil either to produce vanaspati ghee or to utilize the oil as such and make it fit for edible purposes. The edibles oils can be produced from oil bearing seeds, fruits and waste materials like rice bran, mango stone kernels, tobacco seeds etc. The presented report is concerned with the edible rice bran oil. Pakistan is spending more then ten billion rupees on the import of edible oils to meet the requirement of the country. It is a burden on the economy of Pakistan. The locally available oil producing materials must be exploited for the production of edible oils. Rice bran as a byproduct of rice processing industry is available in abundant which can be utilized for the production of edible oil. Among the agro industrial waste materials, rice bran, procured as a by-product of rice processing industry, is one of the major resources for the production of rice processing industry, is one of the major resources for the production of edible oil in Pakistan. The rice bran contains (18.7%) oil on laboratory scale but (15%) oil yield has been taken into account on commercial scale. The refined oil 51,718 tonnes can be produced out of 4,16,716 tonnes of rice bran. The production of edible rice bran oil demands specific process technology and methodology due to presence of lipolytic enzymes in the bran. The lipolytic enzymes hydrolyze the oil present in the bran very quickly and as a result the triglycerides commonly known as an oil are converted into free fatty acids which are not recommended for edible purposes. However, the inactivation of rice bran is carried out by extrusion stabilizer under the name of pretreatment od rice bran. The different processes involved for the production of edible rice bran oil are as given below: i. The stabilization of rice bran, ii. The extraction of Oil, iii. Refining, Bleaching and Deodorization of rice bran oil. The rice is one of the major crops and its production in Pakistan is increasing steadily. Pakistan has become a rice exporting country. During the processing of rice paddy, first of all the rice paddy is dried and then the unwanted material is removed prior to the process of dehusking and polishing of rice to get husk and bran, respectively. Mostly the rice paddy consist of three parts namely rice husk, rice bran and polished rice. The thick outside layer named husk mostly contains silica and cellulosic material, is removed prior to the brown rice. The brown rice after the removal of husk is polished to remove thin layer on the rice to get rice bran as a fine powder which contains oil and other products. No doubt, the brown rice is preferable to white rice as a diet from the nutritional point of view. But such brown rice is not liked in the international market and as a result creates problems to earn the foreign exchange. Pakistan exports rice and bran as a by-product of paddy processing industry which can be utilized for the production of edible oil like Japan where 0.1 million tonnes of edible grade rice bran oil per year is produced. The processing of paddy rice is carried out by machines called hullers and shellers. The major difference between hullers and shellers is that pure rice bran is obtained on accomplishing the process of rice polishing whereas hullers produce a mixture of rice husk and of rice bran. The hullers are not recommended of we have to get the oil from bran and the proper utilization of meal. However, oil can be obtained from the mixed bran of hullers after sieving. The Punjab and Sindh in Pakistan are the traditional rice growing areas. The rice paddy processing units by the names of hullers and shellers are installed in the said provinces of Pakistan. In addition to conventional type of hullers and shellers, some automatic rice processing units have been installed in those provinces and their capacity is reported to be 70 tonnes per day. The capacity and location of these automatic units is given in (Table-I)