The impact of composition and techno-functional properties of edible insect (Macrotermes subhyalinus, Gonimbrasia belina and Hermetia illucens) flours on the nutritional and sensorial profile of biscuits

Abstract

In response to a growing demand for protein, the food industry is exploring alternative protein sources for human consumption. The aim of this research was to explore the potential use of insect flour as a protein-rich ingredient for biscuits and monitor the sensorial acceptability of the product for human consumption. Macrotermes subhyalinus (Madzhulu), Gonimbrasia belina (Mashonzha) and Hermetia illucens (black soldier fly), were ground. Analyses were conducted to determine the three edible insect flours' nutritional, physicochemical, technological and antioxidant properties. A relatively high protein was obtained for the edible insect flours ranging from 34.90 to 52.74%. A significant difference (p < 0.05) was observed for the fat within the edible insect flours. The three edible insect flours showed no significant difference (p > 0.05) in their carbohydrate content and ranged from 22.33 to 28.10%, respectively. There was a significant difference (p < 0.05) in the lightness of the edible insect flours, with G. belina (57.95) being the lighter in colour. In the comparison of the redness of the three edible insect flours, there was no significant difference (p > 0.05); however, M. subhyalinus (5.72) was redder compared to G. belina (3.92) and H. illucens (4.46), respectively. The foam capacity (FC) and foam stability (FS) of all three edible insect flours were not significantly different (p > 0.05). Moreover, H. illucens (3.63%) displayed low antioxidant activity against the DPPH radical, while M. subhyalinus (55.37%) displayed the highest activity. Principal component analysis was applied to the edible insect flours' technofunctional properties and antioxidant indices. Principal component 1 (PC1) accounted for 51.39% of the total variability, while component 2 accounted for 24.71%. Regarding PC1, the FS, Oil binding capacity (OBC) and FC were responsible for the major differences in the edible insect flours. The findings revealed that edible insect flours are a good source of antioxidants and can be used as an alternative protein source and a potential novel food additive due to their techno-functional qualities. Due to their valuable nutritional value, edible insect flours were a good choice for traditional food supplementation. Composite flour and biscuits were made by partially substituting wheat flour with 5%, 10%, 15% and 20% (w/w) edible insect (M.subhyalinus, G. belina and H. illucens) flour. Wheat biscuit (100%) was used as a control. An acceptability study of the biscuit sample was conducted among fifty (n=50) untrained using a five-point facial hedonic scale. The evaluation of the biscuits among the panellist was based on the following parameters: appearance, colour, aroma, taste, texture, and overall liking on a 5-point hedonic scale, with one (1) representing the least score (dislike very much) and five (5) the highest score (like very much). The results revealed that all the biscuits formulated with insect flours might be labelled as “high in protein” products following Regulation no. 1924/2006, ranging from 12.13 to 20.63%. With regards to optical properties, all of the biscuits were placed in the first quadrant of the chromatic diagram, but the biscuits with insect flour showed a significantly lower value of the b* coordinate 27.91 to 29.83 than the control (31.27 ± 1.09), which led to a darkening of the samples regardless the concentration used. As a result, the colour difference for biscuits was not significantly different (p > 0.05) . Textural quality revealed that hardness decreased as the concentration of edible insect addition increased. Based on the data obtained, for sensory it was concluded that the enriched of biscuit to up to 10% was preferable as there were no significant differences ( p > 0.05) in these samples and the control. Moreover, most panellists perceived the biscuits containing insects as too dark at 20%. Furthermore, studies should be carried out to analyse the influence of different structural components and flavourings, such as chocolate, in the formulation of biscuits with insect powders to improve their sensory attributes. The use of M. subhyalinus, G. belina and H. illucens flour might offer a new opportunity for reformulating bakery products, such as biscuits and improving their properties