Studies on Moisture Adsorption Isotherm of Ighu from Different Cassava Varieties and Accelerated Shelf Life Storage in Different Packaging Materials

Moisture sorption isotherm characteristics and shelf life of Ighu, a traditional food product derived from three cassava varieties processed using two indigenous methods in Isuochi (Umunneochi LGA, Abia State) and Udi (Enugu State), Nigeria was studied. The equilibrium moisture content (EMC) was determined using the static gravimetric method across water activity (aw) levels of 0.08 to 0.1 at different temperatures. Experimental data were fitted to four standard sorption models: Brunauer–Emmett–Teller (BET), Guggenheim–Anderson–de Boer (GAB), Oswin, and Halsey. The water vapour transmission rate (WVTR) and permeability coefficients of three packaging materials—low-density polyethylene (LDPE), high-density polyethylene (HDPE), and laminated nylon were also assessed at 30°C and relative humidity (RH) levels from 20.16% to 90.70%, using saturated salt solutions. Results showed a direct correlation between EMC and aw, with sorption curves displaying Type II sigmoid behaviour. The BET model exhibited the best fit for the adsorption data, while laminated nylon presented the best barrier properties to moisture migration, with the lowest WVTR values (0.048–2.250 g H₂O/day/m²) compared to HDPE (0.240–2.391 g H₂O/day/m²) and LDPE (1.201–4.011 g H₂O/day/m²). Ighu stored in laminated nylon at 20–33% RH maintained a projected shelf life of up to 10 years compared to those from LDPE and HDPE. These findings underscore the significance of packaging material and environmental conditions in enhancing the storage stability of Ighu, supporting its long-term preservation and commercial viability