Black soldier fly (BSF) larvae may play a role in a circular economy by upcycling low-value organic streams into high value biomass. In this paper, the capacity of BSF larvae to process 12 organic side-streams (mono-streams) and two standard substrates (chicken start mash and Gainesville diet) was investigated. Survival, larval mass, feed conversion ratio, and waste reduction were evaluated in relation to the proximate composition of the side-streams used. Survival rates larger than 80% were observed for 10 of the organic mono-streams and the two standard substrates. Maximum mean larval weight ranged from 38.3 mg up to 176.4 mg regardless of high survival and was highly correlated with substrate crude protein content. Feed conversion ratio (range 1.58–8.90) and waste reduction (range 17.0–58.9%) were similar to values reported in other studies in the literature. On low protein substrates (e.g., apple pulp), survival rates remained high, however, possibly due to protein deficiency, limited larval growth was observed. It is concluded that several low value organic side-streams can successfully be processed by BSF larvae, thereby opening the possibility of lowering the costs of BSF farming. Potentially mixing nutritionally distinct mono-streams into a mixed substrate might improve BSF performance. However, more research is needed for optimizing diets to guarantee production of BSF larvae of constant yield and quality.

Due to increasing welfare and population, the demand for alternative protein sources, obtained with minimal use of natural resources, is rising in today’s society. Insects have the potential to be used as an alternative protein source since they are considered to be able to convert low-value biomass into high-value components, resulting in opportunities for valorisation of organic side streams. Moreover, insects are suggested to be a sustainable protein source, referring to the efficient “feed to body” mass conversion potential. The aim of this review was to explore the potential to rear the yellow mealworm (Tenebrio molitor), the house cricket (Acheta domesticus) and the migratory locust (Locusta migratoria) on low or not yet valorised organic side streams within the food supply chain. This was performed by collecting research information focusing on the rearing of the insects in scope on organic biomass. In addition, the nutritional composition of the produced insects as well as their dietary requirements will be reviewed. Finally, the availability of side streams in the EU will be discussed as well as their potential to be used as insects feed.

The increasing cultivation of microalgae in photobioreactors warrants efficient and non-invasive methods to quantify biomass density in real time. Nephelometric turbidity assessment, a method that measures light scatter by particles in suspension, was introduced already several decades ago but was only recently validated as a high-throughput tool to monitor microalgae biomass. The light scatter depends on the density of the suspended particles as well as on their physical properties, but so far there are hardly any accounts on how nephelometric assessment relates to classic methods such as dry weight and spectrophotometric measurement across a broad biomass density range for different microalgae species. Here, we monitored biomass density online and in real time during the semi-continuous cultivation of three commercial microalgae species Chloromonas typhlos, Microchloropsis gaditana and Porphyridium purpureum in pilot-scale photobioreactors, and relate nephelometric turbidity to dry weight and optical density. The results confirm a relatively strong (R2 = 0.87–0.93) and nonlinear relationship between turbidity and biomass density that differs among the three species. Overall, we demonstrate how nephelometry can be used to monitor microalgal biomass in photobioreactors, and provide the necessary means to estimate the biomass density of the studied species from turbidity data to facilitate automated biomass monitoring.

Due to its potential as a sustainable protein source, the industrial relevance of Tenebrio molitor, known as yellow mealworm, is set to increase substantially. Given the novelty of its application in the food industry, knowledge is lacking regarding the nutritional quality of commercially farmed mealworms. This study investigated the nutritional composition of larvae from four different rearing facilities in Belgium and specifically investigated whether their nutritional profiles adhered to defined European nutrition claims (Regulation (EC) No. 1924/2006). In particular, the European nutrition claims “high in protein”, “high unsaturated fat”, “high in fibre” and “rich in P, Mg, K, Zn and Mn” were applicable for all mealworm samples on a dry matter basis. On a fresh matter basis, yellow mealworms were found to be “high in protein”, “high unsaturated fat” and “low in sugar”.

Insects are receiving a lot of attention as an alternative protein source, especially the black soldier fly, Hermetia illucens. This insect is of particular interest due to its potential as a waste converter as it can be grown on low-value organic substrates, such as agricultural side-streams, manure and decomposing materials. It’s capacity to turn low-value biomass into high-quality protein provide new opportunities in organic waste management. Unfortunately, rearing of black soldier fly larvae (BSFL) does not run efficiently on most substrates. Several parameters influence the rearing efficiency of BSFL. One of the parameters that is often overlooked is the moisture content of the substrate and the physical properties, such as water release/holding, associated with it. In this study the water release properties of 3 BSFL feeds, each at a dry matter content ranging from 10 to 90%, were investigated using 4 different methods, being water release by (1) filtration, (2) sedimentation, (3) syneresis and (4) centrifugation. Rearing of BSFL on the substrates with different dry matter content showed that water release influences larval performance and survival. Moreover, correlating survival to water release indicated that when substrates are hydrated to the minimum dry matter content, at which no water release is measured by the sedimentation method, the highest BSFL survival can be achieved for that substrate. In addition, a standardised method for determining the most optimal dry matter content of substrates based on substrate water holding capacity was developed.