Development of Advanced Processing Techniques for Pigeon Pea Dal to Enhance In vitro Protein Digestibility

Pigeon pea (Cajanus cajan) is a nutritionally significant legume, rich in protein (18–25%), carbohydrates (57.6%), and essential micronutrients such as ascorbic acid, folic acid, niacin, and pantothenic acid. However, the presence of antinutritional factors such as polyphenols, phytic acid, and enzyme inhibitors adversely impacts protein digestibility and bioavailability. This study was conducted to develop advanced, energy-efficient thermal processing methods, including hydrothermal treatment, autoclaving, and infrared heating, to enhance the in vitro protein digestibility (IVPD) and reduce the polyphenol content of pigeon pea dals. Each treatment was applied at varying intensities, followed by different drying durations, and evaluated for moisture content, IVPD, and polyphenol levels. The moisture content across treatments ranged from 8.45% to 16.78%, with the lowest levels achieved under extended drying durations (5 hours for hydrothermal and infrared heating, and 8 hours for autoclaving). IVPD significantly increased with thermal exposure, reaching 82.81% in hydrothermal (HT30+DT5), 85.72% in autoclaving (AC60+DT8), and 85.12% in infrared heating (IRH30+DT5). Polyphenol content exhibited a decreasing trend with increasing duration of thermal treatment. This reduction is attributed to thermal degradation of polyphenols during treatment. Thermal processing disrupted protein matrices and degraded polyphenols, contributing to improved digestibility.