Physicochemical and functional characteristics of residual pulp of potato

Abstract

Starch-rich liquid effluent is generated after peeling, cutting and washing of tubers during the fries processing. After sedimentation of this effluent is recovered a wet residual pulp, and after drying is obtained dry residual pulp or simply named in this study residual pulp of potato (RPP). In order to convert the effluent into a material easy to store for long periods (such as the potato starch), which would make it suitable for various applications. The aim of this study was to evaluate the effect of the drying conditions, specifically variables temperature and air flow on the drying time and water activity, pH, titratable acidity, instrumental colour parameters, water absorption index, water solubility index and oil absorption capacity of dry RPP. Central Composite Design was used, with temperature levels from 50.0 to 70.0 °C and air flow from 0.06 to 0.092 m3 m–2 s–1. Temperature and airflow affected the study characteristics, except for lightness (L*), water solubility index and oil absorption capacity. It was concluded that milder conditions (lower temperatures) and intermediate air flow resulted in higher-quality final products (lighter, less acidic), although requiring higher drying time. Therefore, depending on the product application, different drying conditions can be used.