Several species of insects have been indicated as suitable and alternative sources of nutrients for humans and animals. A crucial aspect is that their nutritional composition and development time can be influenced by the substrate used for rearing. The main objective of this study is to evaluate how the fatty acid composition ofTenebrio molitor (Coleoptera: Tenebrionidae) larvae changes with different rearing substrates. For this purpose, a standard diet (51.8% wheat bran + 40.7% soybean meal) was alternatively supplemented with addition of 7.5% (w/w) sunflower, linseed or fish oil. Dry matter, percentage of proteins and lipids, ash and fibre of larvae and substrates, as well as insect development time were determined, highlighting slower growth for insects raised on oil-enriched diets, compared to the control. Gas-chromatography was used to evaluate the fatty acid profile of larvae and substrates. A total of 15 fatty acids was identified and quantified. Palmitic, oleic and linoleic acids were always the most abundant fatty acids detected in larvae, suggesting the presence of physiological regulation mechanisms inT. molitor. The larval content of palmitoleic, oleic, alpha-linolenic and eicosapentaenoic acids was correlated with their content in the rearing diets, indicating strict dependence on diet mainly for PUFA n-3. The n-6/n-3 ratio was influenced by the substrate as well, showing a similar trend between insects and diets but with less variability in larvae. Principal component analysis conducted on the fatty acids profile of larvae displayed several clusters based on the different growing media. This study highlights the importance of the diet in determining the final fatty acid profile of mealworm larvae, although fatty acid enrichment could be dampened by physiological processes of the insects.

The current food system is placing significant strain on limited available resources. Novel protein sources have been suggested as a potential solution for ensuring further growth without compromising the natural balance of the planet. In this direction, edible insects appear to be crucial players. Consumers may not always prefer the direct use of insects as human food, indicating that the indirect use of insects as animal feed might be more suitable. Insects are characterised by high nutritional value and similar digestibility compared to more traditional feed such as soybean meal and fishmeal. However, effective introduction of edible insects in animal diets requires one or more processing operations. Processing is paramount for ensuring high microbiological safety while improving the quality, digestibility and palatability of the insect. Additionally, feed processing could allow a combination of insect-based ingredients with other traditional feed ingredients, obtaining a uniform and stable mixture, which can easily and conveniently be provided to the farmed animals. In this review, an overview of the most common processing methods (blanching, grinding, drying, mixing, extrusion) applied to edible insects with the aim of delivering high-quality insect-based feed is presented. Each processing step is carefully evaluated, the pros and cons of each operation are considered and important recommendations are provided. Barriers and opportunities for advancing the use of insects within the feed sector are finally illustrated. A strong emphasis is placed on the need of evaluating the effect of any processing step on the quality and safety of insect-derived products, particularly considering the possibility of replacing traditional feed ingredients with insect-derived materials.

The proper assessment of the nutritional value of insects requires an accurate estimation of their chitin content. Conventional methods are based on recovery and gravimetric determination of chitin; despite its common use, however, this approach fails to provide a reliable approximation of the actual chitin content. Indeed, structural and physicochemical characterization of the extracted chitin usually reveals the presence of impurities, resulting in e.g. a C/N ratio significantly different from that of pure chitin (6.86) or a degree of deacetylation >100 %. Alternative analytical methods to estimate insect chitin include indirect measurement via estimation of the fiber content and spectrometric methods for the estimation of D-glucosamine. The present review aims to provide a critical discussion of these methods while discussing their advantages and limitations. A comprehensive evaluation of these methods was performed based on their selectivity, accuracy, requirements in time and lab infrastructure and applicability to a variety of insect species and insect-based products. Spectrometric methods, which exhibit high accuracy and selectivity were selected as the most appropriate, with chromatography improving their accuracy. Indirect methods based on the estimation of fibers and acetate were discouraged as they exhibit lower selectivity, although their lab requirements are significantly lower.

Black soldier fly larvae can conveniently convert anaerobically digested aquaculture waste, recovering nutrients to valorise in the food and feed sectors.

This study aimed to evaluate the ability of fluorescence spectroscopy to predict the shelf life of fresh-cut apples. Changes in fluorescence spectra, colour, and nutritional quality were monitored during the storage at 4, 10, and 15 °C. Kinetic models employing pseudo-zero and first-order equations were developed to describe the quality change over time, and activation energy was obtained using the Arrhenius model. The results showed that the browning index (BI) was the most reliable indicator for predicting the shelf life of fresh-cut apples and was correlated with the fluorescence index computed from the PARAFAC-resolved fluorescence components (r > 0.90). A fluorescence value of 1.79, corresponding to a shelf life of approximately 5 days, was determined as the critical value for discriminating between high- and low-quality products. In conclusion, fluorescence was suggested as a suitable technology for rapid, accurate and non-destructive shelf life monitoring of fresh-cut apples.