Effect of heat treatment on selected macronutrients in the wild harvested edible ground cricket, Henicus whellani Chopard

Abstract

Globally, edible insects are increasingly being recognised as an alternative to animal protein source. However, the effect of heat-processing methods on the insects’ nutritional value has not been extensively studied for most edible insects. The effect of thermal processing on proximate and dietary fibre composition of the edible ground cricket, Henicus whellani Chopard, was investigated at different exposure periods for roasting and wet-heating (0, 15, 30 and 60 min); and for microwaving (2 and 5 min). Moisture, ash, crude fat and crude protein were determined using standard proximate analysis methods whilst dietary fibre fractions were determined using the enzymatic gravimetric method. Highest crude protein content (67.6%) was observed after microwaving for 5 min. Crude fat was highest (10.7%) after wet-heating at 95 °C for 60 min. The highest ash content (5.1%) was attained after wet-heating at 95 °C for 30 min. All thermal processes resulted in significant increase in soluble dietary fibre fractions. The highest soluble dietary fibre (5.78 g/100 g) was obtained after roasting for 60 min at 60 °C. Roasting at a lower temperature for shorter time (60 °C for 15 min) resulted in higher insoluble dietary fibre (8.70 g/100 g) than at a higher temperature and longer time (80 °C for 30 min)(3.72 g/100 g). The highest total dietary fibre (13.81 g/100 g) was obtained after roasting for 60 min at 60 °C while the lowest fibre level (4.66 g/100 g) was obtained after roasting for 30 min at 80 °C. Microwaving (for 5 min), wet-heating (95 °C for 60 min), wet-heating (95 °C for 30 min) and roasting (60 °C for 60 min) resulted in the highest retention of protein, fat, ash and total dietary fibre; respectively. The evaluated time-temperature combinations are recommended for insect processing to achieve protein, fat, ash and dietary fibre fractions suitable for human consumption.