Quality of Tenebrio molitor Powders: Effects of Four Processes on Microbiological Quality and Physicochemical Factors.

Tenebrio molitor, the first edible insect approved as a novel food in the EU, is a promising candidate for alternative protein sources, implementing circular and sustainable production systems. This study aims to determine the microbiological quality and physicochemical properties of mealworm powders obtained by four different processing pathways. Contents of dry matter, protein, fat, ash, water activity (aw) and a range of microbial counts were measured and analyzed by one-way ANOVA with Tukey's test. Results showed small differences in the proximate composition of the powder samples (protein 55.62-57.90% and fat 23.63-28.21% of dry matter, DM), except for the one that underwent a defatting step (protein 70.04% and fat 16.84%), p < 0.05. A level of water activity of less than 0.2 was reached for all pathways. Fresh mealworm samples had high total aerobic counts (8.4 log CFU/g) but were free of foodborne pathogens. Heat treatments applied during transformation were sufficient to kill vegetative cells (reduction of 2.8-5.1 log CFU/g) rather than bacterial endospores (reduction of 0.3-1.8 log CFU/g). Results were confirmed by predictive microbiology. This study validated the efficacy of a boiling step as critical control points (CCPs) of insect powder processing, providing primary data for the implementation of HACCP plans.

Study of structural changes of gluten proteins during bread dough mixing by Raman spectroscopy.

The aim of the present study was to evaluate Raman spectroscopy in determining changes that occur in the structure of gluten proteins induced during bread dough mixing. Raman spectra were measured directly within the dough. Three particular phases of mixing were studied: under-mixing, optimum mixing and over-mixing. A thiol blocking reagent, Tris(2-carboxyethyl)phosphine (TCEP) was then used to reduce disulphide bonds within proteins to confirm the important role of disulphide bridges in gluten network formation. For the control dough, the most important changes occurred during the optimum mixing phase when an increase in intermolecular disulphide bonds, anti-parallel ß-sheet and α-helix structures was observed, combined with the hydrophobic burial of tryptophan and tyrosine residues. The addition of TCEP appeared to effectively reduce the formation of intermolecular disulphide bonds, anti-parallel ß-sheet and α-helix structures and lead to a more disordered secondary protein structure.

Effect of long-term storage conditions on wheat flour and bread baking properties.

This paper presents a study on the effect of storage conditions on wheat flour quality for 30 months. Such study may be of interest for research projects conducted over long periods. Wheat flours were stored in two types of packaging (permeable paper bags and watertight containers) and at two temperatures (ambient temperature and a cold storage room). Selected qualities parameters were evaluated regularly such as chemical stability, consistency, extensibility, resistance, water absorption, Solvent Retention Capacity and Gluten Index Performance. In addition, Near-Infrared Spectroscopy was used to monitor the flour's evolution and models were employed to predict certain parameters. The results showed that storage at ambient temperature led to significant modifications of flour parameters and baking performances, whereas storage at low temperature preserved the initial quality of the flour. A practical recommendation is to favour storage at low temperature in a sealed container to prevent interaction with oxygen and moisture uptake.

Optimization of dynamic headspace extraction of the edible red algae Palmaria palmata and identification of the volatile components.

A new extraction method was applied to the volatile compounds of Palmaria palmata. Dynamic headspace was optimized according to an experimental design, and descriptive sensory analysis and intensity and similarity tests were performed for each extract to assess their respective representativeness. Results showed that extract obtained with crushed algae after a 30 min purge was the most representative. GC-MS analysis was then performed on this extract to identify the volatile components. Seven halogenated compounds, seven aldehydes, two ketones, three alcohols, and four miscellaneous compounds were identified. Among them, halogenated compounds were the most characteristic of red algae, and more particularly, iodoethane and iodopentane, which had yet been found in other seaweeds.