Valorization of biological waste from insect-based food industry: Assessment of chitin and chitosan potential

Edible mealworms can be farmed to produce high-quality nutrients and proteins, useful as ingredients in human and animal foods. During this process biological waste is produced. This work explores the usage of the biological waste as source to produce chitin and chitosan with different potential applications. Different waste fractions were processed, and the feasibility of chitin isolation was assessed. Chitosan was derived, and films were fabricated and tested for intended uses. Data indicate that biopolymers with different properties can be obtained from multiple biological waste fractions. All samples show antibacterial activity, while chitosan films derived from molt show interesting properties for packaging purposes. Films also trigger the expression of anti-inflammatory phenotype markers in macrophage cells, which may be useful for tissue engineering implantation purposes. Altogether, biological waste from insect farming can be used to extract chitin and chitosan with different properties, and therefore, suitable for different applications.

Impact of the Addition of Tenebrio molitor and Hermetia illucens on the Physicochemical and Sensory Quality of Cooked Meat Products

The use of proteins from insects, plants, microalgae, fungi or bacteria as an alternative to proteins of animal origin such as meat, fish, eggs or milk can meet the worldwide protein demand in the future. As the consumption of whole insects might be problematic or unacceptable for many consumers, especially in European countries, the use of homogenized insects or protein extracts from insects for the production of products might be a possibility to overcome general acceptability problems. However, the quality criteria of these products have to be comparable with consumers' expectations with regard to known products. Therefore, in the present study, we produced a meat product, replaced 10% and 20% of the pork with homogenized larvae of Tenebrio molitor and Hermetia illucens, and determined different physicochemical and sensory parameters at production and during modified atmosphere storage for 21 days. Additionally, the alteration of different bacteria species during this storage was analyzed in challenge tests. After production, the addition of insects resulted in higher cooking losses and pH values in the products with 20% insects, higher pH and yellowness, lower lightness, protein and hardness results in the Hermetia products, as well as higher yellowness and lower protein and hardness values in the cooked meat products with Tenebrio molitor. During modified atmosphere storage, the color differences principally remained, whereas the concentrations of inoculated Bacillus cereus, Listeria monocytogenes and Escherichia coli were not influenced by the addition of insects to the cooked meat products. The sensory results of the insect products, especially at higher concentrations and with Hermetia illucens, worsened during modified atmosphere storage. The addition of homogenized insect larvae, especially at higher concentrations and particularly of Hermetia illucens, influences different physicochemical and sensory parameters of the cooked meat products.

ELECTROPHORETIC DETERMINATION OF CHITIN IN INSECTS

An electrophoretic method (on-line coupled capillary isotachophoresis with capillary zone electrophoresis with conductometric detection (cITP-CZE-COND)) for the determination of chitin in insects based on the analysis of glucosamine after acidic hydrolysis of the sample is described. Chitin is deacetylated and hydrolyzed to glucosamine by acidic hydrolysis (6 M sulfuric acid, 110 °C, 6 h). Under optimized electrophoresis conditions, glucosamine (GlcN) is separated from other sample components in cationic mode and detected with a conductometer within 15 min. The performance method characteristics of the GlcN assay, i.e., linearity (0.2-20 μmol), accuracy (103 ± 5%), repeatability (1.9%), reproducibility (3.4%), limits of detection (0.06 μmol/L) and quantification (0.2 μmol/L), were evaluated. On a series of 28 insect samples, it was proven that cITP-CZE-COND provides results of chitin content in insects comparable to the literature data. The important features of the developed cITP-CZE-COND method are easy sample treatment, high sensitivity and selectivity, and low running costs. It is clear from the above that the cITP-CZE-COND method is suitable for analysis of insect samples for chitin content.

Insect exuviae as soil amendment affect flower reflectance and increase flower production and plant volatile emission

Soil composition and herbivory are two environmental factors that can affect plant traits including flower traits, thus potentially affecting plant-pollinator interactions. Importantly, soil composition and herbivory may interact in these effects, with consequences for plant fitness. We assessed the main effects of aboveground insect herbivory and soil amendment with exuviae of three different insect species on visual and olfactory traits of Brassica nigra plants, including interactive effects. We combined various methodological approaches including gas chromatography/mass spectrometry, spectroscopy and machine learning to evaluate changes in flower morphology, colour and the emission of volatile organic compounds (VOCs). Soil amended with insect exuviae increased the total number of flowers per plant and VOC emission, whereas herbivory reduced petal area and VOC emission. Soil amendment and herbivory interacted in their effect on the floral reflectance spectrum of the base part of petals and the emission of 10 VOCs. These findings demonstrate the effects of insect exuviae as soil amendment on plant traits involved in reproduction, with a potential for enhanced reproductive success by increasing the strength of signals attracting pollinators and by mitigating the negative effects of herbivory.

A rapid acid hydrolysis method for the determination of chitin in fish feed supplemented with black soldier fly (Hermetia illucens) larvae

Insects are a natural source of feed for fish and have received more attention as a potential source of sustainable high-quality protein. However, contrasting results in different feeding trials have been ascribed to the chitin contained in the exoskeleton of insects and highlighted the importance of developing reliable methods for the quantification of chitin to draw meaningful conclusions about its effect on fish health. A rapid method based on the hydrolysis of chitin into glucosamine and further quantification by liquid chromatography tandem mass spectrometry is evaluated. The method offers good selectivity, linearity, limit of detection (1.08 × 10⁻⁵ % w/v or 5.38 × 10⁻⁴ % w/w), limit of quantification (3.26 × 10⁻⁵ % w/v or 1.63 × 10⁻³ % w/w), trueness (88.39–109.29 %) and precision (2.24–10.72 %). The quantitative method was successfully applied to real samples of fish feed supplemented with chitin from black soldier fly (Hermetia illucens) larvae.