Influence of Chemical Refining Processes On the Total Phenolics and Antioxidant Activity of Sunflower Oil - Influence of Chemical Refining Processes On the Total Phenolics and Antioxidant Activity of Sunflower Oil - Open Access Pub

The raw sunflower oil (SFO) has an undesirable flavour and odour. Therefore, to make it suitable for human consumption, the oil has to undergo a number of refining processes such as degumming, neutralization, bleaching and deodorization. During these refining processes, some of the phytochemicals present in SFO is lost. The aim of this study is to evaluate the loss in total phenolic, flavonoid and non-flavonoid contents and the antioxidant properties of the oil at the different chemical refining stages. The crude SFO oil has the highest total phenolic, flavonoid and non-flavonoid contents. The amount of phenolic compounds decreases as the oil undergoes different chemical refining processes. Results of this study indicated that the highest percentage loss of the phenolic compounds occurred during the deodorizing step.The statistical loss of the deodorized oil was 41.7, 63.9 and 27.6 % for total phenolic, flavonoid and non-flavonoid contents respectively. The free scavenging activity of sunflower oil was determined using DPPH and ABTS assays. The percentage scavenging activity ranged from 55.64 to 35.87 % for the DPPH assay while for ABTS assay the activity ranged from 59.46 to 31.43 % in a 50 mg/ml of SFO sample. This showed a decrease in antioxidant activity from crude to DNW to bleached and deodorized oil. The crude oil having the highest phenolic contents showed the highest antioxidant activity in both DPPH and ABTS assays. DOI 10.14302/issn.2379-7835.ijn-14-590 Free radicals are involved in various physiological reactions, causing serious cellular damage resulting in the complete inactivation of biomolecules (proteins, lipids and DNA) and cells, leading to a number of degenerative diseases 1. Antioxidants scavenge the free radicals thus helping in reducing the free-radical induced damage to the cells. Oils contribute a major fraction of the human diet and are lipid materials derived from plants. Sunflower (Helianthus annuus L.) is one of the most important oilseed crop grown in the world and it contains unsaturated fats, protein, fiber and other important phytochemicals including phenolic compounds 2. SFO is widely used in nutrition and is a good source of polyphenols that can scavenge the free radicals produced in our body 3, 4. Crude SFO contains many unwanted compounds such as free fatty acids, odouriferous materials and others which are removed during chemical processing to yield an edible product 5. Chemical refining includes degumming, neutralizing, washing, bleaching, winterizing and deodorizing stages 6, 7. However, during these chemical