Microencapsulation is a promising method for the stabilization of sensitive ingredients and their application as food additives. The protective effect of encapsulation increases the viability of probiotics starting from storage of the product until the probiotics reach the intestine. The positive aspects of encapsulation are based on the created barrier protecting the ingredients from detrimental conditions like low pH values and oxygen.A novel encapsulation mechanism was developed whereby the barrier is formed during spray drying by the gelation of milk proteins. Thereby the principle of the classical rennet-gelation is utilized. Within this process the rennet induced gelation is splitted into two steps. The first step includes the hydrolysis of skim milk concentrate at low temperatures. In the second step during spray drying the temperature induces the initial gelling. After the drying step the probiotics are enclosed in the capsule powder. By rehydration of this capsule powder at temperatures over 30 °C the final gelation starts. Unlike former spray drying encapsulation methods, depending on the rehydration conditions this technology leads to water-insoluble microcapsules. Besides the temperature the composition of the rehydration medium has a determining role for the capsule stability. In this context the gelation properties of the capsule powder was studied by rheological measurements. The difference in the formed barriere between capsule powder and capsules was analysed with low resolution 1H-NMR spectroscopy. The results show that by specific selection of the process parameters the capsule stability can be positively influenced. Also spray drying of enzymatic treated skim milk concentrate was shown to be a suitable possibility for the stabilization of probiotic microorganism.
PrincipalSupervisor: Prof. Ulrich Kulozik ulrich.kulozik@tum.de
