Extraction, characterization and thermal and oxidative stability of the bullfrog (Rana catesbeiana Shaw) oil
Bullfrog oil; Natural products; Fatty acids; Physicochemical properties; Oxidative stability; Thermal stability
The physicochemical, chemical, physical and nutritional quality of the oils are the most important parameter for development of new oily based products. Evaluation of their stability is a key factor for their application in pharmaceutical, cosmetics and food industries. Growing interest in the discovery of new sources of natural oils is due to the different compositions and properties of these oils, and the problems that are attributed to many synthetic products for both human health and for the environment. Changes in the values of conjugated dienes and trienes, acid, peroxides, oxidation induction time (IT) and changes in the infrared spectrum bands were evaluated. The physicochemical properties of the bullfrog oil was quite similar to other fish derived oils. Its peroxide, acid, iodine and saponification value were respectively 1.92 meq O2/Kg, 2.95 KOH/g oil, 104.2 g I/ 100 g oil and 171.2 mg KOH/g oil. The bullfrog oil was composed mainly by oleic acid (30%), eicosapentaenoic acid (17.5%) and docosahexaenoic acid (0.77%). The results of our study show that the bullfrog oil has good thermal stability, but a gradual increase of oil oxidation occurred with increasing time of exposure to heat. However, with the addition of BHT, the oxidative stability of the oil was increased, making it more stable during storage. According to these results, the bullfrog oil has physicochemical properties, fatty acids composition and thermal characteristics that makes it suitable for applications in several segments of industries.