Sami Ghnimi

The New Paradigm for Lipid Oxidation and Insights to Microencapsulation of Omega-3 Fatty Acids

The consumption of omega-3 fatty acids provides a wide range of health benefits. However, the incorporation of these fatty acids in foods is limited because of their high oxidative instability. A new paradigm has emerged to better explain the oxidation mechanism of polyunsaturated fatty acids, which will be discussed here with reference to bulk lipids considered a special case of water in oil microemulsion. This paradigm suggests that lipid oxidation reactions are initiated by heterogeneous catalysis by metal oxides followed by the formation of micelles containing initial hydroperoxides, water, and other amphiphilic compounds. The induction period comes to the end when the formed micelles reach a critical micelle concentration and start to decompose opening the way to intense free radical reactions. Antioxidants and synergists extend the induction period not only by scavenging free radicals but also by stabilizing the micelles. With better understanding of the lipid oxidation mechanism, a tailored choice of antioxidants and synergistic combinations, and efficient encapsulation methods may be optimized to provide stable encapsulates containing highly n-3 polyunsaturated fatty acids. Smart processing and encapsulation technologies utilizing properly stabilized oils as well as optimized packaging parameters aiming to enhance n-3 fatty acid stability by smart selection/design of antioxidants, control of the interfacial physics and chemistry, and elimination of surface oil are needed for this purpose.

Quality evaluation of coffee-like beverage from date seeds (Phoenix dactylifera, L.).

Quality characteristics of coffee-like beverage from roasted date seeds (Phoenix dactylifera, L.) were determined and compared with those of traditional Arabic coffee. The date seed beverage was found to have lower amount of total phenolic compounds and to be a less powerful antioxidant than Arabic coffee. Phytochemical screening showed that date seed extracts contained steroids, tannins, and coumarins, while caffeine, terponoids, saponins, alkaloids, anthraquinones, and anthocyanins were not detected. The levels of trace elements in the date seed extracts were within the ranges reported for Arabic coffee with the exception of cadmium (0.16-0.42 compared to <0.1 in Arabic coffee). The sensory evaluation revealed that the date seed extracts were acceptable but were slightly lower in quality compared to Arabic coffee. The date seed extracts were lighter in color, less cloudy, less bitter, and have less coffee flavor compared to the reference Arabic coffee. Before roasted date seed extracts will be approved for human consumption, their possible estrogenic effects need to be evaluated.