Microchannel device, and high-oil-load microcapsule and method for preparing the same using the microchannel device

1. A method of preparing an oil-loading microcapsule using a microchannel device, the microchannel device comprising:

a homogenization chamber; and

a microchannel reaction chamber;

wherein the homogenization chamber comprises an aqueous phase feed pipe, an oil phase feed pipe, a first high-pressure acceleration pipe, a second high-pressure acceleration pipe, and a mixing pipe; an inlet end of the first high-pressure acceleration pipe is connected to the aqueous phase feed pipe, and an outlet end of the first high-pressure acceleration pipe is connected to the mixing pipe; an inlet end of the second high-pressure acceleration pipe is connected to the oil phase feed pipe, and an outlet end of the second high-pressure acceleration pipe is connected to the mixing pipe; an inner diameter of the first high-pressure acceleration pipe is smaller than that of the aqueous phase feed pipe, and an inner diameter of the second high-pressure acceleration pipe is smaller than that of the oil phase feed pipe;

the microchannel reaction chamber comprises at least one reaction flow channel; the at least one reaction flow channel each comprises at least two microchannels communicated in sequence; each of the at least two microchannels comprises an inner tube and an outer tube; and a space between the inner tube and the outer tube is configured for fluid flowing; and

the method comprises:

(S1) mixing an alcohol-soluble protein and a hydrocolloid followed by dispersion, alkalinity regulation, and centrifugal filtration to obtain an aqueous phase mixture; and preparing an oil phase;

(S2) feeding the aqueous phase mixture into the homogenization chamber through the aqueous phase feed pipe, and feeding the oil phase into the homogenization chamber through the oil phase feed pipe; dispersing the aqueous phase mixture through the first high-pressure acceleration pipe, and dispersing the oil phase through the second high-pressure acceleration pipe and mixing the aqueous phase mixture and the oil phase in the mixing pipe to form a first emulsion;

(S3) cooling the first emulsion;

(S4) adjusting the first emulsion to pH 6.5-7.5 with dilute hydrochloric acid; allowing the first emulsion to flow into the microchannel reaction chamber to undergo dispersion and mixing such that the alcohol-soluble protein in the aqueous phase mixture undergoes interfacial coacervation to embed the oil phase, thereby obtaining a second emulsion with a core-shell structure;

(S5) removing Na + and Cl − from the second emulsion; and

(S6) drying the second emulsion to obtain the oil-loading microcapsule in a powder form.

2. The method of claim 1 , wherein in step (S1), the alcohol-soluble protein is selected from the group consisting of gliadin, zein, kafirin, and a combination thereof;

the hydrocolloid is selected from the group consisting of gum arabic, carrageenan, guar gum, maltodextrin, alpha-cyclodextrin, beta-cyclodextrin, octenyl succinic anhydride-modified (OSA)-modified starch, and a combination thereof;

the oil phase is selected from the group consisting of camellia oil, linseed oil, peony seed oil, grape seed oil, and a combination thereof;

the alkalinity regulation is performed to adjust a mixture of the alcohol-soluble protein and the hydrocolloid to pH 10.5-12; and

the centrifugal filtration is performed at 3000-6000 rpm for 5-20 min.

3. The method of claim 1 , wherein in step (S3), the first emulsion is cooled through steps of:

feeding the first emulsion to a deceleration-cooling channel, and feeding cooling water into a cooling water circulating device, wherein the deceleration-cooling channel is configured as spiral-shaped to cool the first emulsion and reduce a flow rate of the first emulsion;

in step (S4), the dilute hydrochloric acid is continuously fed through an acidity regulation channel, and a pH of the first emulsion is monitored and fed back through a pH detection probe;

in step (S5), the Na + and Cl − are removed from the second emulsion through steps of:

feeding the second emulsion to an ultrafiltration desalination chamber equipped with a hollow fiber ultrafiltration inner chamber such that the second emulsion passes through the hollow fiber ultrafiltration inner chamber to remove the Na + and Cl − ; and

in step (S6), the drying is performed in a spray dryer.

4. The method of claim 1 , wherein an inner diameter of each of the at least two microchannels is 0.4-1 mm;

in step (S4), the dilute hydrochloric acid has a concentration of 2 mol/L; and

in step (S6), a particle size of the oil-loading microcapsule is 4-40 μm.