Effect of Blanching Plus Fermentation on Selected Functional Properties of Mealworm (Tenebrio molitor) Powders

Abstract

The aim of this study was to determine the effect of blanching followed by fermentation of mealworms (Tenebrio molitor) with commercial meat starter cultures on the functional properties of powders produced from the larvae. Full fat and defatted powder samples were prepared from non-fermented and fermented mealworm pastes. Then the crude protein, crude fat, and dry matter contents, pH, bulk density, colour, water and oil binding capacity, foaming capacity and stability, emulsion capacity and stability, protein solubility, quantity of free amino groups, and protein composition of the powders were evaluated. Regardless of the starter culture used, the blanching plus fermentation process reduced the crude and soluble protein contents of the full fat powders and in general impaired their water and oil binding, foaming, and emulsifying properties. Defatting of the powders improved most functional properties studied. The o-phthaldialdehyde assay revealed that the amount of free amino groups was higher in the fermented powders while sodium dodecyl sulfate polyacrylamide gel electrophoresis demonstrated that the soluble proteins of the fermented powders were composed of molecules of lower molecular mass compared to non-fermented powders. As molecular sizes of the soluble proteins decreased, it was clear that the protein structure was also modified by the fermentation process, which in turn led to changes in functional properties. In general, it was concluded that fermentation of mealworms with blanching as a pre-treatment does not contribute to the functional properties studied in this work. Nevertheless, the results confirmed that the properties of non-fermented powders are comparable to other food protein sources.

Effects of Hexane on Protein Profile, Solubility and Foaming Properties of Defatted Proteins Extracted from Tenebrio molitor Larvae

“…Interestingly, the same authors reported maximal edible insect protein solubility at alkaline pH values ranging from 7 to 12, depending on the fraction [ 37 , 47 ]. Borremans et al (2020) observed that the solubility of hexane-defatted T. molitor meals (i.e., TMD) decreased compared to full-fat meals (i.e., TMI) at pH values above 8 [ 9 , 22 ], as obtained in our study ( Figure 3 ). However, the same tendency was not repeatable for soluble protein extracts, since the pH increase did not affect the protein solubility of NDSP compared to HDSP.…”

“…Yi et al (2013), Zielińska et al (2018), and Stone et al (2019) reported that non-defatted T. molitor had poor foaming properties, which was confirmed by our results for TMI and NDSP ( Figure 4 ) [ 7 , 8 , 24 ]. Borremans et al (2020) evaluated the foaming properties of hexane-defatted T. molitor meal and showed increased foam capacity from 94% in the control sample to 540% for the defatted mealworms, which is similar to what is observed for TMD [ 22 ]. Lastly, foaming capacity of HDSP (629%) happened to be higher than the one of egg albumen (575%) which is commonly used as a foaming agent in food formulation.…”

“…These authors determined that hexane-defatted protein fractions had better amino acid composition, protein solubility and functional properties compared to the same fractions defatted with methanol and ethanol [ 20 ]. Borremans et al (2020) compared the functional properties of full-fat and hexane-defatted T. molitor meals and demonstrated that the defatted meal’s foaming capacity was equivalent to that of egg albumen, indicating its potential as alternative foaming agents in food formulation [ 22 ]. However, the detailed effects of hexane-defatting on the protein profile of T. molitor meals and protein extracts, their solubility and foaming properties were never evaluated.…”

Possibilities of the Development of Edible Insect-Based Foods in Europe

“…This is due to the shorter breeding period, lower costs of obtaining the particular insect form and the greater amount of the material obtained. T. molitor larvae are very nutritious and are characterized by good flavor, digestibility and functionality [ 70 , 71 ]. These insects are easy to breed and exhibit a rather constant protein content.…”

Effects of Enzymatic Hydrolysis on the Functional Properties, Antioxidant Activity and Protein Structure of Black Soldier Fly (Hermetia illucens) Protein

“…The most important hurdle to the use of insects as food in Western countries is consumer acceptance. Studies have indicated that in developed countries, insects may be accepted by consumers when they are fragmented and included in a food as a protein powder or ingredient [ 10 ]. By applying enzymatic hydrolysis technology for protein recovery, a broad spectrum of food and feed ingredients might be produced with improved and upgraded functional properties and protein nutritional value [ 11 ].…”