Extraction of pectin from powdered citrus peels using various acids: An analysis contrasting orange with lime

• Both Orange and lime peels contain high levels of pectin, with lime achieving the highest grade. • The most economical and efficient way to extract pectin is through acid extraction. • Citric acid extraction results in a larger yield and better-quality pectin. Pectin, a vital hydrocolloid, is widely utilized in food, medicine, and cosmetics for its gelling, thickening, and stabilizing properties. Although citrus peels are used for pectin production, there is a need to enhance extraction efficiency and identify the optimal methods for commercial use. This study aimed to optimize pectin extraction from orange peel powder (OPP) and lime peel powder (LPP) using different acids (0.05M HCl, H₂SO₄, HNO₃, and citric acid) under controlled conditions (80°C, pH 2.0) for 60 and 90 min. The highest pectin yield was achieved at 90 min, with sulfuric acid yielding 21.63% from OPP and citric acid producing 32.53% from LPP, confirmed by principal component analysis (PCA). The extracted pectin was analyzed for several key characteristics, including moisture content, ash content, equivalent weight, methoxyl content, anhydrouronic acid (AUA) content, and solubility in hot and cold water, and hot and cold alkali. Pectin from OPP exhibited higher moisture and ash levels than that from LPP. Specifically, OPP-derived pectin demonstrated 61.65% esterification, 7.29% methoxyl content, 67.19% AUA content, and an equivalent weight of 683.41 mg/mL. In contrast, pectin extracted from LPP showed 66.39% esterification, 7.73% methoxyl content, 66.09% AUA content, and a higher equivalent weight of 792.57 mg/mL. Both OPP and LPP yielded high-methoxyl pectin suitable for gelling applications. PCA revealed that pectin extracted from LPP had superior values for equivalent weight, methoxyl content, and esterification degree compared to OPP. Interestingly, AUA content negatively correlated with these properties, while other parameters were positively correlated. These findings indicate that using citric acid to extract pectin from lime peels could outperform current commercial methods, yielding high-methoxyl pectin with excellent gelling properties. This makes it especially valuable for industrial applications in the food, pharmaceutical, and cosmetic sectors.