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

Abstract

A rarely used option for reduction the size of Ca‐alginate beads is the jet cutter, a rotating disk coupled to the output of the nozzle, and responsible for cutting the jet in smaller sizes. There are few systematic studies in the literature about this apparatus and its operational effects on the bead size. Therefore, this work aimed to investigate some operational parameters on the size of Ca‐alginate beads produced by dripping and jet cutting methods. First, physicochemical properties of different concentrations of sodium alginate solutions were determined, and the viscosity of 0.92 Pa s, corresponding to 2% (wt/wt), was found to be optimum for bead formation. For the dripping process, the highest flow rate of the alginate solution (49 mL/min) caused a limited reduction of bead size to 2 mm. This study on drop formation demonstrated that models developed for size prediction cannot be used as a tool for determination of size, due to the possible influences of the viscous forces. The jet cutter, adapted to a continuous jet regime, allowed to reduce from 5.2 mm to less than 1 mm in size with the increase of the rotation speed from 200 to 900 rpm. However, this increase resulted in higher tangential velocity of the beads, requiring larger collect recipients. This study developed the basis for broadening the application of the jet cutter to different biopolymers and ensures a better performance of this system. Practical applications The technology of microencapsulation consists in the incorporation of a compound within a matrix, and it has been often used in the food industry by solving several limitations, allowing the immobilization, protection, controlled release of some ingredients, and changing of product properties. The use of biopolymers, such as sodium alginate, associated with the dripping method, enable the preservation even thermolabile compounds, such as drugs, organisms, proteins, and fragrances, since mild conditions are used. However, large beads are produced, which can limit their application. A rarely used and cost‐effective option for size reduction is the jet cutter, a cutting tool that, during its rotation, breaks the jet in smaller sizes, producing very small beads. The results of this study showed that the use of jet cutter was effective in the reduction of bead size and developed some basis for broadening its application for encapsulation using different materials.

Diffusion of polyphenols from alginate, alginate/chitosan, and alginate/inulin particles

“…After falling down to this solution, alginate droplets formed insoluble particles with encapsulated thyme extract due to ion exchange (sodium ions from sodium alginate with calcium ions from crosslinking solution). When the process of particle formation was completed, the voltage generator was turned off and particles were left to harden for 2 hr (Paulo, Ramos, & Prata, ).…”

Natural Polymers in Micro- and Nanoencapsulation for Therapeutic and Diagnostic Applications: Part I: Lipids and Fabrication Techniques

“…A maximum flow rate of 49 mL/ minute yielded beads of about 2 mm size. Increasing the rotational speed of the cutter decreased the bead size by 50% though increased the tangential velocity of the droplets leading to a larger space requirement for product collection [62]. Other parameters such as gravitational force, surface tension, viscosity and flow rate were also noted.…”

“…The drops generated are generally in the size range of 120 μm to 3 mm. Paulo and colleagues [62] recently x-rayed the process parameters requisite for the generation of optimally suited calcium alginate beads using the jet cutter. A maximum flow rate of 49 mL/ minute yielded beads of about 2 mm size.…”

The prediction model of nozzle height in liquid jet‐drop method to produce Ca‐alginate beads under microencapsulation process

“…The use of Equation 14for the prediction of optimum nozzle height is not convenient because the information of Oh number or droplet diameter is unknown. Paulo et al (2017) found that the current models for prediction of bead size could not be used in dripping process. For the case of liquid jet breaking up, the Equation (19) has been proposed for prediction of droplets size…”

“…In the dripping process, Paulo et al (2017) described the trials and errors to get spherical beads applicable for 2% alginate solution with liquid flow rate 49 mL/min (using nozzle size 1 mm which is equivalent to liquid jet velocity 1.04 m/s and formed a liquid jet before dripping) at nozzle height of 16-30 cm. The bead size was approximately 2.4 mm which is equivalent to about 2.8 mm of droplet sizes by using average shrinkage value 0.845 (Chan et al, 2009).…”