Encapsulation of a low melting fraction of milk fat in sugar matrices

HERRERA, MARTINI, CERDEIRA

Peoria, Illinois, USA

Congreso; 36th Annual Great Lakes Regional Meeting (The American Chemical Society); 2004

The American Chemical Society

Encapsulation of powders with different components is becoming increasingly important in foods especially to protect labile biomolecules. The rate of oxidation in dried fat containing food materials is related to structural changes in the matrix. The low melting fraction of milk fat has a great amount of unsaturated fatty acid which can be easily oxidized. Retention of a low melting fraction of milk fat (Mettler dropping point 16.7°C) in a trehalose, trehalose/lactose or trehalose/sucrose matrix was studied during storage of samples at several water activities (aw). A mixed of 50 wt% of the palmitic sucrose ester P-1670 (HLB = 16) and the palmitic sucrose ester P-170 (HLB = 1) was used as emulsifier agent. The emulsions were freeze-dried and stored at 20°c at aw of 0.11, 0.33, 0.44, 0.54 and 0.76 during 3 months. Surface lipids were determined by washing aliquots with hexane. Encapsulated lipids were determined by dispersing the remaining powder with water and ethanol and extracting with sulfuric eter. Lipid weight was determined after solvent evaporation. Differential scanning calorimetry (DSC) was used to determine heats of fusion of surface and encapsulated lipids. A light scattering technique was used to determine particle size. Surface morphology of the powder was study by enviromental scanning electron microscopy (ESEM). The initial efficiency of encapsulation was 82.8 wt%, 89.5 wt% and 42.5 wt% for the trehalose, trehalose/sucrose and trehalose/lactose matrices, respectively. Although the percentage of the crystalline phase was higher for the trehalose matrix than for the two sugar blends matrices, trehalose was the most effective matrix to retain the low melting fat especially at longer times of storage. The loss of retention was in agreement with the increase of particles size. Retention was also related with the stability of initial emulsions and with changes in surface morphology of the powders.