Stability of bioactive compounds in liposomes after pasteurisation and storage of functional chocolate milk

Abstract

In the present study, liposomes with bioactive compounds (BC), vitamin E (VE) and vitamin C (VC), were characterised after pasteurisation and storage in chocolate milk. Liposomes were obtained using soy phosphatidylcholine (SPC), SPC with stearic acid (SA) or calcium stearate (CaS). Oxidative stability, size, shape and membrane packing were studied after pasteurisation and storage for 28 days at 4 °C. Oxidative stability was also studied after pasteurisation in extreme conditions: 6 months, 25 °C and light. The oxidative level determined in liposomes is much under the permitted limits, generating good quality food. SPC maintained stability in size, shape and membrane packing for 28 days at 4 °C. SPC:SA and SPC:CaS evidenced a decrease in liposomal aggregation and a higher membrane packing for 28 days at 4 °C, which favoured stability. These results were optimum because commercial functional milk must have a shelf life of 7 days at 4 °C. Pasteurised liposomes were incorporated in chocolate milk to study the sensory (after storage for 7 days at 4 °C) and microbiological stability. None of the liposomes contributed to the microbial load. SPC:SA presented high sensorial stability in the milk, being a potentially suitable medium to incorporate BC generating functional food.