rancidity fat and oil
Tittle : Rancidity Measurement in Fats and Oils.
Introduction :
Vegetable oil is an important and widely used lipid source for our everyday food products. Its application is increasing day by day for food purposes and for the manufacturing of a number of toiletry products. However, some vegetable oils are not up to standards to meet consumer satisfaction in terms of their physico-chemical properties or for the texture and stability of the food products (Reyes- Hernandez et al., 2007). Recently, palm oil has become the second most consumed oil all over the world with a competitive price compared to other edible oils.
However, due to its high melting point, it is not gaining due status in spite of being rich in natural antioxidants, vitamins, high oxidative stability and having a long self life (Edem, 2002). Palm oil is also rich in β-carotene which helps to prevent liver and lung cancer (Murakoshi et al., 1992). The food value of the edible lipids also depends on chemical properties like iodine value, peroxide value, p-anisidine value, acidity etc, as well as on some physical properties like solidification temperature, color, appearance etc.
Lipid oxidation is an important deteriorative reaction, which has significant implications in terms of the quality and value of fats and oils, specifically in relation to the off-flavours that develop as a result of autoxidation. Rancidity is caused by hydrolysis and oxidation. Heat, moisture and exposure to light will increase these chemical reactions and thus increase the likelihood of the onset of rancidity.During the initial stages of the oxidation process, hydroperoxides accumulate as primary oxidation products, subsequently breaking down to form low molecular weight oxygenated constituents, such as alcohols, aldehydes, free fatty acids, and ketones, ultimately leading to rancidity. The accumulation of hydroperoxides is commonly monitored using the measurement of peroxide value (PV). The PV, along with acid
Introduction :
Vegetable oil is an important and widely used lipid source for our everyday food products. Its application is increasing day by day for food purposes and for the manufacturing of a number of toiletry products. However, some vegetable oils are not up to standards to meet consumer satisfaction in terms of their physico-chemical properties or for the texture and stability of the food products (Reyes- Hernandez et al., 2007). Recently, palm oil has become the second most consumed oil all over the world with a competitive price compared to other edible oils.
However, due to its high melting point, it is not gaining due status in spite of being rich in natural antioxidants, vitamins, high oxidative stability and having a long self life (Edem, 2002). Palm oil is also rich in β-carotene which helps to prevent liver and lung cancer (Murakoshi et al., 1992). The food value of the edible lipids also depends on chemical properties like iodine value, peroxide value, p-anisidine value, acidity etc, as well as on some physical properties like solidification temperature, color, appearance etc.
Lipid oxidation is an important deteriorative reaction, which has significant implications in terms of the quality and value of fats and oils, specifically in relation to the off-flavours that develop as a result of autoxidation. Rancidity is caused by hydrolysis and oxidation. Heat, moisture and exposure to light will increase these chemical reactions and thus increase the likelihood of the onset of rancidity.During the initial stages of the oxidation process, hydroperoxides accumulate as primary oxidation products, subsequently breaking down to form low molecular weight oxygenated constituents, such as alcohols, aldehydes, free fatty acids, and ketones, ultimately leading to rancidity. The accumulation of hydroperoxides is commonly monitored using the measurement of peroxide value (PV). The PV, along with acid
References: : 1. John C. Allen, R. J. Hamilton (1994). Rancidity in Foods 24th .ed. Springer, 2. Edem DO. 2002. Palm oil: Biochemical, physiological,nutritional, hematological and toxicological aspects: A review. Plant Foods for Human Nutrition (Formerly Qualitas Plantarum) 57, 319-341. 3. Murakoshi M, Nishino H, Satomi Y, Takayasu J, Hasegawa T, Tokuda H, Iwashima A Okuzumi J, Okabe H, Kitano H, et al. 1992. Potent Preventive Action of {alpha}- Carotene against Carcinogenesis: Spontaneous Liver Carcinogenesis and Promoting Stage of Lung and Skin Carcinogenesis in Mice Are Suppressed More Effectively by {alpha}-Carotene Than by beta Carotene.Cancer Res. 52, 6583-6587. 4. Reyes-Hernandez J, Dibildox-Alvarado E, Charo-Alonso M, Toro-Vazquez J. 2007. Physicochemical and Rheological Properties of Crystallized Blends Containing trans -free and Partially Hydrogenated Soybean Oil. J. Am. Oil Chem. Soc. 84, 1081-1093.