This technology features an edible film composition and its manufacturing method, created by blending sweet potato starch acetylated with acetic anhydride with glycerol, pectin, and calcium in specific ratios. It consists of 2.5–3.5 wt% acetylated starch, 1–2 wt% glycerol, 0.5–1 wt% pectin, and 0.1–0.2 wt% calcium.
While edible, biodegradable films have gained attention due to plastic pollution, they have traditionally relied on protein sources like gelatin, corn protein, wheat gluten, soy protein, and casein. Although starch accounts for 50–80% of the dry weight of sweet potatoes, up to 15% of the annual harvest is discarded due to processing and storage challenges. Furthermore, sweet potato starch is difficult to use as a primary material for edible films because it does not dissolve well in room-temperature water.
This technology involves adding 0.1–2 parts by weight of acetic anhydride to 100 parts by weight of a sweet potato starch aqueous solution to acetylate the starch. This is then mixed with 94–95 wt% distilled water, glycerol, pectin, and calcium, and stirred at 85–95°C to gelatinize. Impurities and air bubbles are removed before drying to produce the film. The resulting film shows significantly improved tensile strength, elongation, moisture barrier properties, and water solubility. It can be used for individual packaging of produce like strawberries, edible coatings for tablets and capsules, and water-soluble pouches for instant food, allowing discarded sweet potatoes to be repurposed into plastic-free, edible, or water-soluble packaging.
This invention was developed with support from the Rural Development Administration’s project for the mass production and utilization of beneficial sweet potato components.
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