Functional emulsion composition for coating rice cake surfaces and manufacturing method thereof

Coating technology to prevent hardening and spoilage of rice cakes using an emulsion of mung bean starch, guar gum, and grapefruit seed extract

This technology is a method for manufacturing a functional emulsion composition for coating the surface of rice cakes, created by mixing mung bean starch solution and guar gum solution, then sequentially adding glycerin, sunflower seed oil, and grapefruit seed extract. Dipping the rice cake briefly into the finished emulsion and drying it forms a thin, edible, moisture-resistant coating layer on the surface.

While the market for rice cakes is expanding into areas like rice cake cakes and cafe-style specialty shops, they have faced challenges in distribution due to short shelf lives caused by retrogradation—where they harden within days of production—and spoilage from mold and microorganisms. Although research has been conducted to maintain quality during storage and distribution, effective methods to simultaneously prevent both hardening and spoilage have been lacking.

In this technology, mung bean starch and guar gum form the structural framework of the film, while glycerin provides flexibility, sunflower seed oil acts as a moisture barrier, and the natural antimicrobial agent, grapefruit seed extract, inhibits microbial growth. The sunflower seed oil is evenly dispersed using a homogenizer, and air bubbles are removed via vacuum degassing to ensure a uniform coating layer. This coating reduces hardness increase and moisture loss while adding antimicrobial properties. It can be applied to the distribution of traditional rice cakes like baekseolgi and injeolmi, the improvement of storage for rice cake cakes and desserts, and as a pre-packaging treatment for convenience store and export products, allowing rice cakes to maintain their soft texture longer and extending shelf life to broaden sales reach.

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Key Features:

• Step of preparing a mung bean starch solution by mixing, stirring, and heating mung bean starch with water, and preparing a guar gum solution by mixing guar gum with water
• Step of mixing and stirring the mung bean starch solution and guar gum solution, then adding and stirring in glycerin
• Step of adding sunflower seed oil to the glycerin-mixed solution, stirring with a homogenizer, and degassing in a vacuum oven
• Step of adding and stirring grapefruit seed extract into the degassed solution to obtain the functional emulsion composition for rice cake surface coating

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This invention was developed with support from the Ministry of Science and ICT for the development of edible coating and texture restoration technology for starchy foods.

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