A novel emulsifier from spinach with appetite regulation abilities

Chloroplast thylakoid membranes inhibit pancreatic lipase/colipase activity in vitro and, when included in food, induce satiety signals. This effect is due to their ability to reduce the rate of lipolysis through the inhibition of the lipase-colipase complex. They have a strong affinity to oil which both prevents the lipolytic enzymes from in close contact with its substrate and at the same time protects the thylakoids form proteolytic enzymes present in gastric juices form digesting the thylakoids as quickly. This affinity also imparts thylakoids interesting emulsification properties. The objective of this study was to characterize thylakoids’ ability to stabilize oil-in-water emulsions, and to study their interfacial properties in light of their capacity to inhibit pancreatic lipase-co lipase activity in vitro. As lipolysis is an inherently interfacial process it is important to quantify their interfacial properties and to maximize the oil-water interfacial area covered by the thylakoids in future food formulations. Thylakoids isolated from spinach were used for emulsification studies using a lab-scale high shear homogenizer. The oil-in-water emulsions produced had varying amounts of thylakoids and resulting emulsions were characterized by creaming phase volume, microscopy and light scattering to determine microstructure and droplet size distributions as well as surface load. Electron micrographs showed thylakoids adsorbed as loosely bunched vesicles on the drop surfaces approximately 1 micron in size, and were found to effectively stabilize the oil water interface, but with large droplet size (20 to 200 micron range) and relatively high surface loads (2 to 10 mg/m2).