2. ROZILA BT MOHAMAD 151887 MASTURA BT KHAIRUDDIN 151886 NUR ERZA FAREEHA BT SARBRI 152590 HANIS NABILLAH BT MIZAN 155032 Noor FAZRIEYANA BT HAMIDON 152268

3. Questions 3)Use oleate and linoleate as starting compounds, write the chemical equations for autoxidation of oil and fat via Singlet Oxygen Mechanism. Show clearly the isomers formed for each of the compounds used. 4) How to minimize deterioration of oil and fats due to singlet oxygen.

4.  This reaction of singlet oxygen proceeds by a different mechanism than free radical autoxidation.  Singlet oxygen is highly electrophilic and reacts rapidly with olefinic bond  Singlet oxygen reacts directly with olefinic bonds by concerted addition, the so-called "ene" reaction.  Oxygen is thus inserted at either end carbon of a double bond, which is shifted to yield an allylic hydroperoxide in the trans configuration Olefinic bond allylic hydroperoxide

5. Oleate(C₁₇H₃₃COO⁻ ) is an ester or salt of oleic acid Structure of olleic acid

6. Reaction of singlet oxygen with oleate Olefinic bond allylic hydroperoxide

7. Structure of linoleic acid linolate Molecular Formula: C 18 H 31 OO -

8. Reaction of singlet oxygen with linolate

9. How to minimize deterioration of oil and fats due to singlet oxygen.  Deterioration of unsaturated vegetable oils by singlet oxygen can be effectively reduced by removal of natural photosensitizers during refining and bleaching.  Refining and bleaching also remove singlet oxygen quenchers such as the carotenoids. The restoration of carotenoids may effectively protect lipids against singlet oxygen deterioration if the resulting yellow coloration of the oil is not objectionable to the consumer.

10.  Another obvious approach is the use of suitable packaging or a container that is absorbent to the light energy necessary for photosensitization or that prevents such light from reaching the oil.