Carme Güell

The effectiveness of high pressure-assisted extraction (HPAE) in improving insect protein extraction and functionality was studied. Defatted insect powders of Tenebrio molitor and Alphitobius diaperinus were pressure treated at 100–300 MPa for 5 min at 25 °C. Protein content, molecular weight distribution (MWD) of protein fractions, emulsifying activity (EA), and modifications in the secondary structure of the proteins were assessed for the different fractions. In comparison to control, HPAE at 100, 250, and 300 MPa enhanced protein extraction by approximately 18% for both insect species. A 22% increase in protein extraction was observed for A. diaperinus at 200 MPa compared to the control. A clear decrease in EA was noted for both T. molitor and A. diaperinus proteins extracted at 150, 200, 250, and 300 MPa. The MWD analysis indicated that HPEA increased the intensity of protein bands between 10–20 kDa and around 37 kDa for both insect species. This study demonstrates the potential of high pressure to not only enhance protein extraction by up to 22% but also to modify the emulsifying activity of insect proteins.

The main objective of this research was to evaluate the performance of portable FT-MIR (4000 to 630 cm ⁻¹ ) and handheld FT-NIR (7400 to 4000 cm ⁻¹ ) spectrometers, combined with partial least squares regression (PLSR) multivariate analysis. This method was used to predict the percentage of insect lipids added to mixtures of vegetable and seed oils, as well as to profile the fatty acid composition in the lipid fractions of Locusta migratoria and Acheta domesticus mixed with these oils. Insect lipids from L. migratoria and A. domesticus were extracted from their powdered forms using organic solvent extraction and then mixed with five edible oils (olive, sunflower, avocado, almond, and linseed) at concentration ratios ranging from 0 to 100% (n = 140). The fatty acid (FA) profile of the samples was determined using the fatty acid methyl ester (FAME) method. PLSR was used to develop algorithms for predicting insect lipid content in mixtures and FA composition. The PLSR model for predicting the percentage of insect lipids in mixtures with vegetable and seed oils demonstrated good linearity, with high correlation ( R _CV = 0.99), low standard errors of cross-validation (SE _CV ≤ 2.21%) and prediction (SE _P ≤ 2.32%), and high predictive performance as indicated by the ratio of prediction to deviation (RPD ≥ 9.23). The percentage of myristic, palmitic, stearic, oleic, linoleic, and α-linolenic fatty acid as well as the content of saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) were accurately predicted with values of SE _CV ≤ 4.64% and an R _CV ≥ 0.88. However, the FT-MIR spectrometer tested showed superior performance in predicting fatty acids and SFA, MUFA, PUFA reaching values of 0.99 in coefficient of correlation (RP) and 0.66% in standard error in prediction (SE _P ).

The objective of the study was to evaluate infrared (IR) spectroscopy in combination with pattern recognition analysis as a rapid technique to quantify the percentage of insect lipid added into the chickpea-based dough as well as the dough’s fatty acid profile. Several chickpea-based doughs were prepared with a variable amount of Tenebrio molitor, Alphitobius diaperinus, and Acheta domesticus lipid fraction (0, 2.9%, 5.8%, 8.7%, and 11.6%) replacing the same amount of olive and sunflower oil. The raw dough was analyzed using portable Fourier transform mid-infrared (FT-MIR) and handheld FT near (FT-NIR) spectrometers. The fatty acid profile was determined by using fatty acid methyl esters (FAME) methods. Partial least squares regression (PLSR) with cross-validation (leave-one-out) was used to build up a model to predict the percentage of insect lipid added showing a low standard error of cross-validation (SE_CV ≤ 0.71%), strong correlation (R _CV ≥ 0.85), and great predictive ability (RPD, 5.21–5.53) with the external validation set. The saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids as well as the content of palmitic, oleic, and linoleic were correctly predicted with values of SE_CV ≤ 5.64% and an R _CV ≥ 0.88. Nonetheless, the FT-MIR device tested showed higher performance to predict SFA, MUFA, PUFA, and fatty acids reaching values of 0.97 in coefficient of correlation (R _P) and 2.81% in standard error in prediction (SE_P).

Mealworm, TM (Tenebrio molitor), and black soldier fly, BSF (Hermetia illucens) are of special interest for food and feed applications due to their environmental benefits such as low water and land requirements, low greenhouse gas emissions, and high feed-conversion efficiency. This study assesses the use of ultrafiltration (UF) to fractionate protein concentrates from TM and BSF (TMPC, BSFPC) in order to enhance emulsifying and foaming properties. A 30 kDa regenerated cellulose acetate membrane enabled the separation of concentrate and permeate fractions for both insect proteins from two different initial feed concentrations (10 and 7.5 g/L). Permeate flux and protein transmission behave differently depending on the insect type and the initial concentration; while for TMPC permeate flux increases with a decrease in the initial protein concentration, it is not affected for BSFPC. The existing membrane cleaning protocols are suitable for recovering water flux after UF of insect proteins, enabling membrane re-use. Emulsifying activity is maintained for all the TMPC fractions, but it is significantly lower for the permeate fractions of BSFPC. Foaming properties are maintained for all the UF fractions of BSFPC and the ones from 7.5 g/L TMPC. Acidic solubilization leads to a fraction with enhanced emulsifying capacity and one with higher foaming capacity than the original for BSFPC. This study opens the door to membrane technology for insect protein fractionation, which has not been studied so far and has already provided useful solutions for other animal and plant proteins.

Water-in-oil-in-water (W₁/O/W₂) emulsions are complex delivery systems for polyphenols amongst other bio-actives. To stabilize the oil–water interphase, dairy proteins are commonly employed, which are ideally replaced by other, more sustainable sources, such as insect proteins. In this study, lesser mealworm (Alphitobius diaperinus) protein concentrate (LMPC) is assessed and compared to whey protein (WPI) and pea protein (PPI), to stabilize W₁/O/W₂ emulsions and encapsulate a commercial polyphenol. The results show that LMPC is able to stabilize W₁/O/W₂ emulsions comparably to whey protein and pea protein when using a low-energy membrane emulsification system. The final droplet size (d_4,3) is 7.4 μm and encapsulation efficiency is between 72 and 74%, regardless of the protein used. Under acidic conditions, the LMPC shows a similar performance to whey protein and outperforms pea protein. Under alkaline conditions, the three proteins perform similarly, while the LMPC-stabilized emulsions are less able to withstand osmotic pressure differences. The LMPC stabilized emulsions are also more prone to droplet coalescence after a freeze–thaw cycle than the WPI-stabilized ones, but they are the most stable when exposed to the highest temperatures tested (90 °C). The results show LMPC’s ability to stabilize multiple emulsions and encapsulate a polyphenol, which opens the door for application in foods.

In a preliminary study, commercial insect powders were successfully identified using infrared spectroscopy combined with multivariate analysis. Nonetheless, it is necessary to check if this technology is capable of discriminating, predicting, and quantifying insect species once they are used as an ingredient in food products. The objective of this research was to study the potential of using attenuated total reflection Fourier transform mid-infrared spectroscopy (ATR-FTMIR) combined with multivariate analysis to discriminate doughs and 3D-printed baked snacks, enriched with Alphitobius diaperinus and Locusta migratoria powders. Several doughs were made with a variable amount of insect powder (0–13.9%) replacing the same amount of chickpea flour (46–32%). The spectral data were analyzed using soft independent modeling of class analogy (SIMCA) and partial least squares regression (PLSR) algorithms. SIMCA models successfully discriminated the insect species used to prepare the doughs and snacks. Discrimination was mainly associated with lipids, proteins, and chitin. PLSR models predicted the percentage of insect powder added to the dough and the snacks, with determination coefficients of 0.972, 0.979, and 0.994 and a standard error of prediction of 1.24, 1.08, and 1.90%, respectively. ATR-FTMIR combined with multivariate analysis has a high potential as a new tool in insect product authentication.

There is a pressing need to extend the knowledge on the properties of insect protein fractions to boost their use in the food industry. In this study several techno-functional properties of a black soldier fly (Hermetia illucens) protein concentrate (BSFPC) obtained by solubilization and precipitation at pH 4.0–4.3 were investigated and compared with whey protein isolate (WPI), a conventional dairy protein used to stabilize food emulsions. The extraction method applied resulted in a BSFPC with a protein content of 62.44% (Kp factor 5.36) that exhibited comparable or higher values of emulsifying activity and foamability than WPI for the same concentrations, hence, showing the potential for emulsion and foam stabilization. As for the emulsifying properties, the BSFPC (1% and 2%) showed the capacity to stabilize sunflower and lemon oil-in-water emulsions (20%, 30%, and 40% oil fraction) produced by dynamic membranes of tunable pore size (DMTS). It was proved that BSFPC stabilizes sunflower oil-in-water emulsions similarly to WPI, but with a slightly wider droplet size distribution. As for time stability of the sunflower oil emulsions at 25 °C, it was seen that droplet size distribution was maintained for 1% WPI and 2% BSFPC, while for 1% BSFPC there was a slight increase. For lemon oil emulsions, BSFPC showed better emulsifying performance than WPI, which required to be prepared with a pH 7 buffer for lemon oil fractions of 40%, to balance the decrease in the pH caused by the lemon oil water soluble components. The stability of the emulsions was improved when maintained under refrigeration (4 °C) for both BSFPC and WPI. The results of this work point out the feasibility of using BSFPC to stabilize O/W emulsions using a low energy system.