Alginate liquid core capsule formation using the simple extrusion dripping method

Abstract

Liquid core capsules have been widely used in various biotechnological applications. The capsules could be formed by the simple extrusion dripping method. However, the method requires strict control of several process variables in order to form spherical capsules. The aim of this study was to systematically investigate the influence of process variables of the method on the capsule size and shape. The results showed that the capsules diameter was decreased when the concentration of alginate solution was increased. The capsule diameter was increased when the gelation time and dripping tip diameter were increased. The membrane thickness of the capsules was significantly increased by the concentration of calcium chloride, gelation time and dripping tip diameter. However, the concentration of alginate gave the opposite trend on the membrane thickness of the capsules. As a recommendation, uniform and spherical alginate liquid core capsules could be formed when concentration of calcium chloride was > 10 g/l, the concentration of alginate solution was > 5 g/l and < 20 g/l, gelation solution height in between 1.7 cm and 3.2 cm, and stirring rate of the gelation bath was in the range of 400-500 rpm.

Shape Tuning and Size Prediction of Millimeter-Scale Calcium-Alginate Capsules with Aqueous Core

“…The diameter of the mm-CaSA-Caps no longer changed. Taking the average D of row data in Table 2 and plotting it against the viscosity of the CaCl2/CMC solution produced the curve shown in Figure 12b, demonstrating that no apparent trend was observed when the CaCl2/CMC concentration increased, as reported by others [11,35], the reason being that the concentration of Ca 2+ was not changed in the CaCl2/CMC solution, further evidence that the diameter of the mm-CaSA-Caps was mainly controlled by the Ca 2+ diffusion. The effects of surface tension of the coagulation bath (SA/poloxamer 407) on the size of mm-CaSA-Caps were investigated.…”

“…The mm-CaSA-Caps were prepared at 20-25 • C by an extrusion dripping device [11] as shown in Figure 1a. In detail, a solution containing 1 wt.% CMC and 1.5 wt.% CaCl 2 was loaded into a 20 mL plastic syringe, pumped dropwise with the flow rate of 0.5 mL/min by a dripping nozzle into a gelation bath containing 200 mL 0.5 wt.% SA solution.…”

“…No apparent trends of capsule membrane thickness were observed when the CMC concentration was increased [11]. Therefore, the effect of SF on the mechanical and diffusion properties of the capsules was investigated with the CMC concentration increased.…”

An investigation of operational parameters of jet cutting method on the size of Ca‐alginate beads

“…The production of Ca‐alginate beads by the simple dripping system has been thoroughly developed and described in the literature (Chan, ; Chan et al, ; Bhujbal et al, ; Goh et al, ; Kamaruddin, Yuso, & Aziz, ; Lee, Ibrahim, Chu, Zulkifli, & Ravindra, ). The prediction of the range of the bead size can be obtained through modeling equations.…”

“…In addition to the physicochemical properties of sodium alginate solution, the operational parameters of the experimental system are strongly associated with the size and shape of the bead. For the simple dripping process, some of these parameters have already been studied, including the distance between the nozzle and the cross‐linking solution, the hardening time, the temperature and concentration of the cross‐linking solution, the concentration and the type of gel forming ions, and the size and shape of the nozzle through which the solution is dripped (Bhujbal et al, ; Chan et al, ; Darrabie, Kendall, & Opara, ; Lee, Ravindra, & Chan, ; Lee et al, ).…”