Citrus Waste Upcycling toward Pectin Moisturizer Films Plasticized with Glycerol and Polyethylene Glycol

Abstract

Citrus waste from Japanese Haruka's peel was upcycled for pectin moisturizer films. Pectin was extracted with aqueous acetic acid and dissolved at a concentration of 3% w/v in distilled water. Two types of plasticizers, glycerol (GLY) and poly(ethylene glycol) (PEG), were added in various weight ratios of 10:0, 7:3, 5:5, 3:7, and 0:10, respectively. The mixture was then dried at 50 °C to form pectin films. The addition of GLY and PEG influenced the films' transparency, revealing changes in their crystallinity. Pectin films at a GLY:PEG ratio of 3:7 exhibited optimal characteristics, including high transparency, significant crystallinity, and moderate sturdiness, displaying better tensile strength and elongation at the breaking point compared to those of the others. Especially, the GLY plasticized film showed higher water accessibility, and the inclusion of plasticizers improved solubility in water. Moreover, the GLY plasticized film exhibited favorable cell affinity with mouse fibroblast cells. When applied to human skin, it enhanced moisture retention similarly to skin covered by the plasticizer film. These results highlight the potential of pectinbased films for enhancing moisture in skincare products.