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Nutritional value and microbiological aspects of dried yellow mealworm (Tenebrio molitor L.) larvae pretreated with a pulsed electric field
Complete protein, which includes all the essential amino acids, and bioactive compounds needed in human nutrition, can be found in edible insects. Bioactive compounds play a crucial role in protecting cells from the damage caused by free radicals. Therefore, in this study, fat extraction yield, protein content, amino acid profile, total polyphenol content, antioxidant properties, crustacean and mollusk content, and microbiological quality have been assessed to evaluate the influence of the drying method and pulsed electric field (PEF) pretreatment. To this end, the sample was processed by the PEF at varied specific energy intakes (5, 20, and 40 kJ/kg) and dried by means of two methods: convective (CD) and infrared-convective (IR-CD). A comparable protein content (47.5–48.7 g/100 g d.m.) was determined for most of the samples tested. A significantly higher lysine and methionine content was detected in the CD insects, especially for samples treated by the PEF at 40 kJ/kg. The IR-CD samples exhibited a significantly higher content of polyphenols as compared to those obtained by means of the CD method, whereas the PEF apparently had a significant impact to the extent of increasing their content. Taking into account allergenicity, the crustacean content was approximately 10 times higher than the mollusk content. The study has shown that the PEF treatment prior to infrared-convective drying resulted in the assurance of the microbiological quality of dried insects for food use. Furthermore, a dose of the PEF at 20 and 40 kJ/kg demonstrated the antimicrobial effect. The results have proven that, in this case, a high temperature during the CD method did not cause the undesirable changes that had been expected. Therefore, PEF-assisted convective drying may conceivably be considered to obtain highly nutritionally valuable insects; however, it is crucial to utilize appropriate parameters in the course of the PEF processing.
The Impact of Drying Methods on the Quality of Blanched Yellow Mealworm (Tenebrio molitor L.) Larvae
The growing world population necessitates the implementation of appropriate processing technologies for edible insects. The objective of this study was to examine the impact of distinct drying techniques, including convective drying at 70 °C (70CD) and 90 °C (90CD) and freeze-drying (FD), on the drying kinetics, physical characteristics (water activity, color), chemical characteristics (chemical composition, amino acid profile, oil properties, total polyphenol content and antioxidant activity, mineral composition, FTIR), and presence of hazards (allergens, microorganisms) of blanched yellow mealworm larvae. The freeze-drying process results in greater lightness and reduced moisture content and water activity. The study demonstrated that the freeze-dried insects exhibited lower contents of protein and essential amino acids as compared to the convective-dried insects. The lowest content of total polyphenols was found in the freeze-dried yellow mealworm larvae; however, the highest antioxidant activity was determined for those insects. Although the oil isolated from the freeze-dried insects exhibited the lowest acid and peroxide values, it proved to have the lowest PUFA content and oxidative stability. All the samples met the microbiological criteria for dried insects. The results of the study demonstrate that a high temperature during the CD method does not result in the anticipated undesirable changes. It appears that freeze-drying is not the optimal method for preserving the nutritional value of insects, particularly with regard to the quality of protein and oil.
Effect of Cricket Powder Incorporation on the Profile of Volatile Organic Compounds, Free Amino Acids and Sensory Properties of Gluten-Free Bread
Comparison of technological and physicochemical properties of cricket powders of different origin
Despite the widely described high nutritional value of insects, many authors suggest significant differences in the nutrient content depending on the breeding conditions, preparation methods, or even geographical origin. To date, there is no reports on the technological and physical properties of cricket powder (CP). This article describes the properties of 3 CPs of various geographic origins. The oil-absorption, water-binding, foaming capacities and foam stability were analysed. Thermal changes by DSC, water behaviour by LF-NMR and FTIR analysis were performed as well. On the obtained results, it was found that all analysed cricket powders were characterized by a high content of protein and fat. The geographical origin did not affect oil absorption, while the differences were recorded for water-binding. No foaming properties were observed in any of CPs. Thermal analysis showed the beginning of protein degradation at temperatures above 110 °C. Despite the differences in the water behaviour of dry CPs, no significant changes in hydrated CPs were observed. On the basis of the obtained results, it was found that the geographic origin of cricket powder will not affect the differences in technological properties, and thus the application of CP as an additive increasing the nutritional value can be widely used.
Field Cricket (Gryllus bimaculatus) and Spirulina (Arthrospira platensis) Powders as Environmentally Friendly Protein Enrichment Ingredients in Corn Snacks
Unconventional protein sources are currently extensively studied as food ingredients. This study aimed to evaluate the effect of 1.5% and 3% field cricket powder (GB) and 2–8% of its mixture (1:1) with spirulina powder (S) on the nutritional value, physicochemical properties, and sensory characteristics of corn extrudates. Additionally, 2% baking powder (BP) was added to assess its impact on the properties of the enriched extrudates. The results showed that both GB and GB + S improved nutritional value, with protein content increasing by up to 46% and higher levels of essential amino acids, particularly leucine and valine. However, these ingredients decreased the expansion ratio (by up to 15%), colour lightness (by up to 30%), and yellowness (by up to 47%) and increased the hardness (by up to 25%) of the corn extrudates. The S addition positively influenced product storage stability but decreased its sensory acceptance, especially aroma and taste. The BP addition mitigated the negative effects of higher GB and GB + S concentrations, particularly on sensory characteristics. In conclusion, incorporating up to 6% of the GB + S mixture provides a higher protein content with only minor changes to the product’s characteristics compared to GB. Ratings exceeding 4.2 points indicate the good acceptability of these snacks.