Functional Comparison of Edible Coatings Derived from Purple Cabbage and Calmansi Extracts

Leng, Myan Seng (2025) Functional Comparison of Edible Coatings Derived from Purple Cabbage and Calmansi Extracts. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Edible films are thin materials used to preserve perishable food products. This study aims to compare the effectiveness of various additives– namely ascorbic acid, cabbage and calamansi extract– in cornstarch-based edible films by evaluating their physicochemical and functional properties. It also explores whether natural plant extracts derived from food waste could serve as viable alternatives to commercially available synthetic antioxidants, such as ascorbic acid. The tested formulation consisted of cornstarch-based film (10g/100mL water) plasticized with glycerol (0.25g/100mL) and sucrose (1g/100mL) incorporating 1% (w/v) or 1% (v/v) of active ingredient. Physicochemical analyses included measurements of moisture content, water holding capacity (WHC), and water-vapour permeation rate. Functional properties were assessed based on total antioxidant content [total phenolic content (TPC), total flavonoid content (TFC)], antioxidant activity (% inhibition using 2,2-diphenyl-1-picrylhydrazyl assay) and instrumental colour parameters (L*, a*, b*, C*). Results indicated that moisture content ranged from 7.5% to 10.4%, with films containing ascorbic acid exhibiting the highest. The average WHC was approximately 143% across all samples, with no significant differences observed between treatments. In terms of antioxidant content, the film containing ascorbic acid showed the lowest and most variable TPC results with samples being below the limit of detection (0.19 ± 0.15 mg GAE/g dry film), whereas films fortified with plant extracts demonstrated higher, more consistent results (0.204-0.209 ± 0.002 mg GAE/g). Antioxidant activity, as measured by the DPPH assay, was higher in the ascorbic acid control than in the plant-extract samples. Although colour values showed numerical differences between treatments; no significant variation was found (p > 0.05). In conclusion, natural plant extracts show potential as replacements for synthetic additives in edible film applications by exhibiting superior antioxidant activity and content while maintaining the desirable physical properties of starch-based films.