Enhancing Functional Food Applications With Carambola Peel and Pulp Dietary Fiber: Effects of Sustainable Drying Methods (Oven and Freeze) on Nutritional Value and Hydration Properties

Abstract

This study explores the extraction and characterization of dietary fiber (DF) from carambola fruits, focusing on both peel and pulp fractions. After pretreatment with 96% ethanol to mitigate enzymatic activity, DF was extracted using both hot-air oven-drying and freeze-drying methods. Physicochemical properties, functional attributes, and nutritional composition of the extracted fractions were analyzed. Notably, DF derived from the peel exhibited superior functional, antioxidant, hydration, and physicochemical properties compared to DF from the pulp. The peel fraction of freeze-dried (FE) showed exceptional attributes, boasting the highest levels of DPPH assay (68.73%), total flavonoid content (14.98 mg QE/100 g DM), total phenolic content (156.6 mg GAE/100 g DM), ferric-reducing antioxidant power (458.3 mg AAC/g DM), vitamin C (52.12 mg ascorbic acid/100 g DM), and vitamin A (140.2 μg β-carotene/100 g DM). Additionally, it demonstrated a remarkable oil holding capacity (2.591 g oil/g DM). Furthermore, employing freeze drying as the extraction method proved advantageous, yielding DF with superior physicochemical, nutritional, antioxidant, and hydration properties compared to oven drying. Notably, freeze drying also demonstrated environmental benefits by minimizing energy consumption and CO₂ emissions, aligning with green extraction practices.