Optimizing the Rheological and Textural Properties of Chapatti Enriched with House Crickets (Acheta domesticus) Flour Using Hydrocolloids by an I-Optimal Design.

The fortification of food with edible insect flour can improve its nutrition profile, but also affect its techno-functional characteristics. In this study, an I-optimal design was applied to improve the rheological and textural properties of wheat flour chapatti containing 10% cricket (Acheta domesticus) flour. More specifically, the impact and optimal addition of hydrocolloids (carboxymethyl cellulose, hydroxypropyl methylcellulose, guar gum and xanthan gum) and water content were studied. For all the responses, the model and model terms were highly significant and showed the different impact of the hydrocolloids on the rheological properties. To evaluate the predictive power of the models, two sets of optimal process settings were chosen: one based on dough properties, and another on baked chapatti. For both sets, the actual responses were in the range of predicted responses for almost all properties. In addition, it was shown that using the settings based on dough properties, the actual responses were not significantly different from the control chapatti, whereas for the settings based on baked chapatti, there were differences in terms of the extensibility of both dough and chapatti. Thus, the I-optimal design is suitable to optimize the dough properties and the baked chapatti when enriching chapatti with cricket flour.

On the nitrogen content and a robust nitrogen-to-protein conversion factor of black soldier fly larvae (Hermetia illucens).

Currently, a broad discussion exists in the literature regarding insect protein analysis. At its core, main difficulties and uncertainties are the inconsistent use of analysis methods and nitrogen-to-protein conversion (kP) factors. While the Kjeldahl and Dumas methods are both used in the literature, their result represents inherently different nitrogen fractions. Thus far, no correlation between them is established for insect matrices, which is a major uncertainty. Although much effort has been made towards more accurate kP factors, calculation of these was based on merely one sample while the chemical composition varies depending on rearing conditions. Using a broad variation in black soldier fly (BSF) larvae samples in the present study, a correlation between Kjeldahl and Dumas and a robust kP factor have been established. Moreover, the nitrogen distribution of BSF samples was also assessed after accurate chitin analyses. A highly significant linear correlation existed between the results of Kjeldahl and Dumas (slope, 1.009; intercept, - 0.008; R2, 0.9997). Consequently, both methods were deemed interchangeable for BSF larvae. Using amino acid data, a practical, more accurate and robust kP factor of 4.43 was obtained. Concerning the chitin content, the average of all BSF larvae samples was 5.95 ± 0.86 g N-acetylglucosamine/100 g dry matter and no correlation with the kP factor was observed. Regarding the nitrogen distribution of the samples, it was found that the contribution of nitrogenous compounds other than protein and chitin is not only high but also prone to variation (12-30% of the total nitrogen content).

Enhancing the specificity of chitin determinations through glucosamine analysis via ultra-performance LC-MS.

As chitin is gaining an increased attention as feedstock for industry, quantification thereof is becoming increasingly important. While gravimetric procedures are long, not specific and highly labour-intensive, acidic hydrolysis of chitin into glucosamine followed by quantification of the latter is more performant. Even though several quantification procedures for the determination of chitin can be found in the literature, they give inconsistent results and their accuracy was not assessed due to the lack of certified analytical standards. Therefore, in the present study, commercially available chitin from practical grade was characterised in detail, allowing the assessment of method accuracy. The procedure for the hydrolysis of chitin into glucosamine and subsequent quantification via UPLC-MS was investigated in detail as well. Using 9-fluorenylmethyl chloroformate (FMOC-Cl) as derivatisation reagent, glucosamine was quantified using reversed-phase chromatography. For the chitin hydrolysis, the highest glucosamine recovery was obtained with 8.0 M HCl for 2 h at 100 °C. The entire procedure for chitin quantification, including the hydrolysis, was characterised by high interday and intraday precision and accuracy. The specificity of the procedure was assessed as well by analysing different mixtures of cellulose and chitin. Chitin recoveries from these analyses ranged from 98.8 to 105.8% while no signal was observed for 100% cellulose, indicating the high specificity of the procedure. It was also concluded that the procedure is much faster and less labour-intensive compared to the gravimetric procedure.

Fermentation Versus Meat Preservatives to Extend the Shelf Life of Mealworm (Tenebrio molitor) Paste for Feed and Food Applications.

Freshly prepared pastes from blanched mealworms (Tenebrio molitor) are highly perishable and prone to microbial and chemical changes upon storage due to their high water activity, near-neutral pH, and their rich nutrient profile. Their shelf life is short unless preservation methods are used. In this study, the effects of preservatives (sodium nitrite and sodium lactate) and lactic acid fermentation (with the starter cultures Bactoferm® F-LC and Lactobacillus farciminis) on the microbiological and the chemical stability of mealworm pastes stored at 4°C were compared. During the storage experiment, the pH, water activity, color, microbial counts, and fat oxidation were monitored. In addition, the prevalence of the pathogens Bacillus cereus, Salmonella spp., and Listeria monocytogenes were studied. Microbial quality evaluation of the mealworm pastes showed that the addition of preservatives did not inhibit microbial growth during refrigerated storage, reaching the upper limits for consumption between seven and 14 days. By contrast, the acid medium (pH < 4.50) created by fermentation stabilized all microbial populations investigated, indicating that these pastes could be consumed up to (at least) 8 weeks of refrigerated storage. L. monocytogenes, Salmonella, and B. cereus were not detected in any of the samples and lipid oxidation of the samples was minimal. Altogether, this study shows that lactic acid fermentation can be used successfully to inhibit microbial growth, to maintain chemical quality, and to extend the shelf life of mealworm pastes stored at 4°C.

Effect of heat processing on the nutrient composition, colour, and volatile odour compounds of the long-horned grasshopper Ruspolia differens serville.

Heat processing is commonly used to prepare edible insects for consumption. This study aimed at determining the effect of boiling and subsequent oven roasting on Ruspolia differens' nutrient composition, colour and odor compounds. Boiling leads to: a significant increase in protein and decrease in fat content on a dry matter basis; a minimal influence on its amino and fatty acids profile; a significant reduction in its ash content due to leaching of phosphorus, potassium and sodium; a significant increase in iron, zinc, copper, manganese and calcium content; and a fivefold reduction in the amount of vitamin B12. Roasting leads to a relative increase in the amount of calcium and trace mineral elements but doesn't affect other nutrients. Roasting results into a more uniform colour intensity when green and brown polymorphs are roasted together. Lipid oxidation is responsible for the colour and aroma of heat processed R. differens.

Nutrient composition of the long-horned grasshopper Ruspolia differens Serville: Effect of swarming season and sourcing geographical area.

This research investigates the effect of swarming season and sourcing geographical area on the nutrient composition of R. differens. On a dry matter basis, protein (34.2-45.8%) and fat (42.2-54.3%) are the major macro-nutrients. Leucine (80. 9-88.5), lysine (54.0-69.8) and valine (59.2-61.8) are the most abundant essential amino acids (EAA) (mg/g protein). Tryptophan is the most limiting EAA. Its EAA composition is like the children and adults' reference protein. Its fat is highly unsaturated (63.5-64.7). Oleic (38.4-42.7), linoleic (19.0-23.0) and palmitic (26.6-27.8) fatty acids (FA) (g/100 g total FA) are the most abundant. Geographical area significantly influences its mineral content within seasons. Season significantly influences its fat, protein, ash and mineral content but not its AAs' and FAs' content. Both factors significantly influence its vitamin B12 content (0.73-1.35 µg/100 g).