Fifteen grams of the filtered one-layer microcapsules (Whatman No. 4, filter paper; Fisher Scientific, Loughborough, UK) was added to 100 mL of 0.5% (w/v) alginate solution (pH 5.5) and stirred at an initial speed of 500 rpm to disperse the beads for 20 min before filtration, then the beads were collected and resuspended into 75 g of oil containing 5 g L 1, Tween 80 and 65.5 mM of CaCl2 for 20 min to initiate the external Ca2+ cross-linking of the peripheral alginate layer and formation the sodium alginate gel.