OPTIMIZATION OF ROASTING TEMPERATURE AND DURATION FOR FENUGREEK FLOUR FUNCTIONALITY AND LOCALLY MADE STEWS (HULBAT) ACCEPTABILITY

Abstract

This study aimed to optimize the roasting temperature and roasting time of fenugreek seed (Bishoftu) to produce good quality flour that is used to produce traditional hulbat food. The rotatable Central Composite Design (RCCD) was used to determine how temperature (130-150°C) and time (2-10 min) affected the following variables: proximate (moisture content, ash, crude fat, crude protein, crude fiber, carbohydrate, energy), minerals (Na, K, Ca, Mg, Fe and Zn), Functional (water absorption capacity, oil absorption capacity, water absorption index, water solubility index, swelling index, swelling power and bulk density), sensory attribute of stew prepared from roasted flour (colour, texture, taste, aroma, flavour and overall acceptability). The findings showed increased ash, protein, Na, K, Ca, Mg, and Fe contents. As the roasting temperature increased and time prolonged, the MC, crude fat, carbohydrate, energy, crude fiber, Zn, WAC, OAC, WAI, WSI, SI, SP, BD, colour, texture, taste, flavour, and overall acceptability were declined. The impacts of the independent factors on the dependent variables' MC, crude protein, Ca, Mg, and Fe; oil absorption capacity; water solubility index; swelling power; bulk density; and overall acceptability were all statistically significant (p≤0.0001). The water absorption index, swelling index, aroma, taste, and flavour showed substantial (p≤0.0001) changes as a result of linear and interaction effects of temperature and time. However, ash, water absorption capacity and colour contents were significantly (p≤0.0001) affected by the linear effects of temperature and time combination. The Design-Expert used for optimization gave two possible optimum conditions with the desirability of 0.87 and 0.89. The best desirability (0.89) was achieved at roasting temperature and roasting time of 150℃ and 4.13 min, respectively. At these conditions, MC was 5.24%, crude fat 8.05%, crude fiber 7.51%, crude protein 27.01%, carbohydrate 58.03%, energy 399.90 kcal, colour 4.89, aroma 4.76, taste 4.98, flavour 4.62 and overall acceptability 4.66. The quantity and quality of nutrients and functional properties of flour from fenugreek seed significantly depend on the temperature at which the fenugreek is roasted and the roasting time.