Inclusion of Hermetia Illucens larvae or prepupae in an experimental extruded feed: process optimisation and impact on in vitro digestibility

Review: Insects as a novel feed ingredient: processing technologies, quality and safety considerations

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 Effects of Slaughter Methods and Drying Temperatures on the Protein Hydrolysis of Black Soldier Fly Larvae Meal

In recent years, the potential of insects as a sustainable protein alternative to feed the growing world population has been explored. Differences in the ways insects are processed can affect their proximate composition and digestibility. This work studied the effects of the combination of different types of slaughter methods and drying temperatures on the proximate composition, organic matter digestibility (OMd), hydrolysis degree (DH/NH2 and DH/100 g DM), total hydrolysis (TH), and hygienic and sanitary characteristics of BSFL (black soldier fly larvae) meal. Four types of slaughter methods were used including freezing (F), blanching + freezing (B), Melacide® + freezing (M), and liquid nitrogen slaughter (N). Each of these was used with three drying temperatures (50, 70, and 90 °C). A negative correlation between the acid detergent fiber (ADF) and protein digestibility parameters was obtained. The most suitable drying temperature was 70 °C, as it produced higher values of protein digestibility (DH and TH), resulting in hygienic and sanitary conditions suitable for food use. Slaughtering with liquid nitrogen and blanching was more conducive to achieving high protein digestibility results than traditional freezing or the use of Melacide®.

Evaluation of In Vitro Protein Hydrolysis in Seven Insects Approved by the EU for Use as a Protein Alternative in Aquaculture

Rapid population growth is leading to an increase in the demand for high-quality protein such as fish, which has led to a large increase in aquaculture. However, fish feed is dependent on fishmeal. It is necessary to explore more sustainable protein alternatives that can meet the needs of fish. Insects, due to their high protein content and good amino acid profiles, could be a successful alternative to fishmeal and soybean meal traditionally used in sectors such as aquaculture. In this work, seven species of insects (Hermetia illucens, Tenebrio molitor, Acheta domestica, Alphitobius diaperinus, Gryllodes sigillatus, Gryllus assimilis, and Musca domestica) approved by the European Union (UE) for use as feed for farmed animals (aquaculture, poultry, and pigs) were studied. Their proximate composition, hydrolysis of organic matter (OMd), hydrolysis of crude protein (CPd), degree of hydrolysis (DH/NH2 and DH/100 g DM), and total hydrolysis (TH) were analyzed. The results showed that Tenebrio molitor had digestibility similar to that of fishmeal, while Acheta domestica and Hermetia illucens provided similar digestibility to that of soybean meal. The acid detergent fiber (ADF) data were negatively correlated with all protein digestibility variables. The differences in the degree of hydrolysis (DH) results and the similarity in total hydrolysis (TH) results could indicate the slowing effects of ADF on protein digestibility. Further in vivo studies are needed.

Effect of black soldier fly larvae as substitutes for fishmeal in broiler diet

This study investigated the effect of processed forms (defatted or hydrolyzed) of black soldier fly larvae (Hermetia illucens L., BSFL) as a protein substitute on broilers. Experiment 1 was a feeding experiment, and Experiment 2 was a metabolism experiment. In Experiment 1, a total of 120 day-old Arbor Acres broilers (initial body weight 39.52 ± 0.24 g) were used for 28 days. There were 8 replicate pens, and 5 broilers were assigned to each pen. In Experiment 2, a total of 36 day-old broilers (initial body weight 39.49 ± 0.21 g) were used for the metabolism trial. There were 2 broilers in a metabolism cage and six replicate cages per treatment. The dietary treatments were as follows: a basal diet (CON), a basal diet without fishmeal and substitute with defatted BSFL (T1), a basal diet without fishmeal and a substitute with hydrolyzed BSFL (T2). In Experiment 1, during the entire experimental period, the T2 group significantly increased (p < 0.05) body weight gain and feed intake compared to the CON and T1 groups. The feed conversion ratio showed a lower tendency (p = 0.057) in the T2 group than in the CON and T1 groups. At 2 weeks, the CON and T2 groups were significantly higher (p < 0.05) crude protein (CP) digestibility than the T1 group. At 4 weeks, the total protein level significantly increased (p < 0.05) in the CON and T2 groups compared to the T1 group. In Experiment 2, the CP digestibility significantly increased (p < 0.05) in the T2 group compared to the CON and T1 group at weeks 2 and 4. At week 4 amino acid digestibility, the T2 group significantly increased (p < 0.05) lysine, methionine, tryptophan, and glycine digestibility compared to the T1 group. There was no difference in fecal microbiota among the treatment groups. In conclusion, feeding hydrolyzed BSFL as a fishmeal substitute in broiler diets improved growth performance, CP digestibility, and specific amino acid digestibility. Therefore, it is considered that hydrolyzed BSFL in broiler diets can be sufficiently used as a new protein source.

Evaluation of the Physical Characteristics and Chemical Properties of Black Soldier Fly (Hermetia illucens) Larvae as a Potential Protein Source for Poultry Feed

The aim of this study was to investigate and compare the effects of different drying methods on the physical and chemical properties of black soldier fly larvae (BSFL) to determine their potential as an alternative protein source in animal feed. The experimental design was a 2 × 3 factorial arrangement in a completely randomized design (BSFL type × drying method), with five replications. The influence of post-harvest procedures was studied, including the different BSFL types (non-defatted and defatted) and drying methods (parabola dome, hot air oven, and microwave). The results showed that the types of BSFL, drying methods, and their interaction significantly (p < 0.001) influenced the feed's physical properties; these included the brightness of color (L* 29.74-54.07; a* 0.40-5.95; b* 9.04-25.57), medium bulk density (381.54-494.58 g/L), free flow with an angle of repose (41.30-45.40°), and small particle size. They significantly (p < 0.001) influenced the nutritive value of BSFL, which contained 42-59% crude protein, 7-14% crude fiber, 9-30% ether extract, and 5035-5861 kcal/kg of energy. Overall, both BSFL types and all the drying methods resulted in a slight variation in the proximate composition. However, a microwave and a hot-air oven were considered the most suitable methods for producing BSFL powder because of the high levels of nutrients retained and the improved physical parameters when compared to a parabola dome. This characterization of the physical and chemical composition of BSFL represents a preliminary methodology that could be used to initially preprocess larvae for use as an alternative protein source in animal feed and for other applications.

Investigating the Potential of Full-Fat Soy as an Alternative Ingredient in the Manufacture of Low- and High-Moisture Meat Analogs

The increase in meat consumption could adversely affect the environment. Thus, there is growing interest in meat analogs. Soy protein isolate is the most common primary material to produce low- and high-moisture meat analogs (LMMA and HMMA), and full-fat soy (FFS) is another promising ingredient for LMMA and HMMA. Therefore, in this study, LMMA and HMMA with FFS were manufactured, and then their physicochemical properties were investigated. The water holding capacity, springiness, and cohesiveness of LMMA decreased with increasing FFS contents, whereas the integrity index, chewiness, cutting strength, degree of texturization, DPPH free radical scavenging activity, and total phenolic content of LMMA increased when FFS contents increased. While the physical properties of HMMA decreased with the increasing FFS content, its DPPH free radical scavenging activity and total phenolic contents increased. In conclusion, when full-fat soy content increased from 0% to 30%, there was a positive influence on the fibrous structure of LMMA. On the other hand, the HMMA process requires additional research to improve the fibrous structure with FFS.

In Vitro Crude Protein Digestibility of Insects: A Review

The high protein content of insects has been widely studied. They can be a good food alternative, and therefore it is important to study the effect of digestion on their protein. This review examines the different in vitro protein digestibility methodologies used in the study of different edible insects in articles published up to 2021. The most important variables to be taken into account in in vitro hydrolysis are the following: phases (oral, gastric and intestinal), enzymes, incubation time and temperature, method of quantification of protein hydrolysis and sample preprocessing. Insects have high digestibility data, which can increase or decrease depending on the processing of the insect prior to digestion, so it is important to investigate which processing methods improve digestibility. The most commonly used methods are gut extraction, different methods of slaughtering (freezing or blanching), obtaining protein isolates, defatting, thermal processing (drying or cooking) and extrusion. Some limitations have been encountered in discussing the results due to the diversity of methodologies used for digestion and digestibility calculation. In addition, articles evaluating the effect of insect processing are very limited. It is concluded that there is a need for the standardisation of in vitro hydrolysis protocols and their quantification to facilitate comparisons in future research.

An Enhanced Water Solubility and Stability of Anthocyanins in Mulberry Processed with Hot Melt Extrusion

Mulberry fruits are rich sources of anthocyanins that exhibit beneficial biological activity. These anthocyanins become instable in an aqueous media, leading to their low bioavailability. In this study, a colloidal dispersion was produced by processing mulberry samples with hot-melt extrusion. In this process, hydrophilic polymer matrices were used to disperse the compound in an aqueous media. Mulberry samples were processed with hot-melt extrusion and in the presence of an ionization agent and sodium alginate to form mulberry-extrudate solid formulations. The particle size of mulberry-extrudate solid formulations decreased, while the total phenol content, the total anthocyanin content, and solubility increased. Fourier transform infrared spectroscopy (FT-IR) revealed that mulberry-extrudate solid formulations now contained new functional groups, such as -COOH group. We investigated whether mulberry-extrudate solid formulations had a positive impact on the stability of anthocyanins. The non-extrudate mulberry sample and mulberry-extrudate solid formulations were incubated with a simulated gastric fluid system and an intestinal fluid system. The number of released anthocyanins was determined with HPLC. We found that anthocyanins were released rapidly from non-extrudate mulberry extract. Mulberry-extrudate solid formulations contained a large number of available anthocyanins even after being incubated for 180 min in the intestinal fluid system. Thus, hot-melt extrusion enhanced water solubility and stability of anthocyanins with the prolonged release.

Benefits and Challenges in the Incorporation of Insects in Food Products

Edible insects are being accepted by a growing number of consumers in recent years not only as a snack but also as a side dish or an ingredient to produce other foods. Most of the edible insects belong to one of these groups of insects such as caterpillars, butterflies, moths, wasps, beetles, crickets, grasshoppers, bees, and ants. Insect properties are analyzed and reported in the articles reviewed here, and one common feature is nutrimental content, which is one of the most important characteristics mentioned, especially proteins, lipids, fiber, and minerals. On the other hand, insects can be used as a substitute for flour of cereals for the enrichment of snacks because of their high content of proteins, lipids, and fiber. Technological properties are not altered when these insects-derived ingredients are added and sensorial analysis is satisfactory, and only in some cases, change in color takes place. Insects can be used as substitute ingredients in meat products; the products obtained have higher mineral content than traditional ones, and some texture properties (like elasticity) can be improved. In extruded products, insects are an alternative source of proteins to feed livestock, showing desirable characteristics. Isolates of proteins of insects have demonstrated bioactive activity, and these can be used to improve food formulations. Bioactive compounds, as antioxidant agents, insulin regulators, and anti-inflammatory peptides, are high-value products that can be obtained from insects. Fatty acids that play a significant role in human health and lipids from insects have showed positive impacts on coronary disease, inflammation, and cancer. Insects can be a vector for foodborne microbial contamination, but the application of good manufacturing practices and effective preservation techniques jointly with the development of appropriate safety regulations will decrease the appearance of such risks. However, allergens presented in some insects are a hazard that must be analyzed and taken into account. Despite all the favorable health-promoting characteristics present in insects and insects-derived ingredients, willingness to consume them has yet to be generalized.

Black soldier fly larvae meal and fat can completely replace soybean cake and oil in diets for laying hens

Currently, there is a great interest in finding alternative protein and energy sources to replace soybean-based feeds in poultry diets. The main objective of the present study was to completely replace soybean in layer diets with defatted meal and fat from black soldier fly larvae without adverse effects. For this purpose, 5 × 10 Lohmann Brown Classic hens were fed either a soybean-based diet or diets based on defatted black soldier fly larvae meal and fat from 2 producers (1 commercial, 1 small-scale) operating with different rearing substrates, temperatures, and larvae processing methods (10 hens/diet). The data obtained included nutrient composition of larvae meals and diets, amino acid digestibility (6 hens/diet), and metabolizability, performance and egg quality (all 10 hens/diet). In addition, the acceptance of the 4 larvae-based diets was tested against the soybean-based diet in a 6-day choice feeding situation (10 hens/treatment). The nutritional value of the larvae-based diets was equivalent to the soybean-based diet in hens with a laying performance of 98%. Although average feed intake was not significantly different over the 7 experimental weeks, the diets based on larvae feeds from the small-scale production appeared to be slightly less accepted in a choice situation than the soy-based diet and those with larvae from commercial origin. This was more likely the effect of the larvae fat rather than that of the larvae protein meal. In addition, the commercial larvae material was superior to that from the small-scale production concerning supply with digestible sulfur-containing amino acids (548 vs. 511 mg/day) and lysine (792 vs. 693 mg/day), egg weight (67 vs. 63 g), daily egg mass (66 vs. 61 g/day) and, in tendency, feed efficiency. The results indicate that soybean-based feeds can be replaced completely by black soldier fly meal and fat in diets of high-performing layers. However, because of nutritional differences between the larvae materials of different origin the quality of the larvae has to be closely monitored before being used.

Impact of Agro-industrial Byproducts on Bioconversion, Chemical Composition, in vitro Digestibility, and Microbiota of the Black Soldier Fly (Diptera: Stratiomyidae) Larvae

The interest in using byproducts from agro-food industries as a rearing substrate for insects is increasing rapidly. We investigated the influence of byproducts of vegetal origin (okara-a byproduct of soy milk production, maize distillers with solubles, brewer's grains), used as rearing diet for black soldier fly larvae (BSFL), on the following parameters: biomass production, substrate reduction (SR), nutritional profile and in vitro digestibility, and larval gut microbiota. Hen diet was used as a control substrate. The highest larval biomass was collected on maize distillers, whereas the highest SR was observed on okara. The rearing substrate affected ash, ether extract, and chitin larval content. The BSFL reared on okara were characterized by a lower lauric acid content (17.6% of total fatty acids). Diets also influenced in vitro crude protein digestibility (%) for monogastrics, with the highest values for BSFL reared on maize distillers (87.8), intermediate for brewer's grains and okara BSFL, and the lowest for hen BSFL (82.7). The nutritive value for ruminants showed a lower Net Energy for lactation for BSFL reared on hen diet than okara and dried maize distillers BSFL. The different byproducts showed an influence on the larval gut microbiota, with a major bacterial complexity observed on larvae fed with the hen diet. The neutral detergent fiber concentration of dietary substrate was negatively correlated with Firmicutes and Actinobacteria relative abundance. Insects valorized byproducts converting them into high-value larval biomass to be used for feed production. The results evidenced the effects of the tested byproducts on the measured parameters, underling the chemical composition importance on the final insect meal quality.

Mineral Composition of Cereal and Cereal-Free Dry Dog Foods versus Nutritional Guidelines

The aims of the present work are to estimate the nutritional value and to evaluate and compare the levels of macroelements (Ca, P, K, Na, Mg), microelements (Fe, Zn, Mn, Cu), heavy metals (Co, Cd, Pb, Mo, Cr, Ni), and their ratios in extruded complete foods for adult dogs, their compatibility with nutritional guidelines, as well as food profile similarity. Basic composition was determined according to Association of Official Analytical Chemists (AOAC). Analyses for elements were performed using an atomic absorption spectrometer. All the evaluated dry dog foods met the minimum recommended levels for protein and fat. Eighteen tested dog foods (60%) did not meet at least one recommendation of nutritional guidelines. Four dog foods exceeded the legal limit of Fe and five foods exceeded the legal limit of Zn; in one of them, Zn level was almost twice higher. Dog foods with insect protein exceeded the legal limit for Mn content. Eight dog foods had an inappropriate Ca:P ratio. Heavy metals were below detection limit in all analyzed dog foods. The results seem to show the need for regular feed analyses of the elemental composition in raw materials before introducing supplementation and for the monitoring of the mineral composition of finished pet food.

Extrusion texturization of cricket flour and soy protein isolate: Influence of insect content, extrusion temperature, and moisture-level variation on textural properties

Due to the increasing global population and unsustainable meat production, the future supply of animal-derived protein is predicted to be insufficient. Currently, edible insects are considered as a potential and "novel" source of protein in the development of palatable meat analogues. This research used high moisture extrusion cooking (HMEC), at a screw speed of 150 rpm, to produce meat analogues using full- or low-fat cricket flours (CF) and soy protein isolate (SPI). Effects of water flow rate (WFR), cooking temperature (9 and 10 ml/min; 120, 140, and 160°C, respectively), and CF inclusions levels of 0, 15, 30, and 45% were analyzed. Cooking temperature and CF inclusion had a significant effect (p < .05) on both tensile stress in parallel and perpendicular directions, while WFR had no significant effect (p = .3357 and 0.7700), respectively. The tensile stress increased with temperature but decreased with CF inclusion at both WFRs. Comparatively, the tensile stress was stronger at WFR of 9 ml/min than at 10 ml/min; however, the tensile stress in parallel was mostly greater than tensile stress in perpendicular directions. Fibrous meat analogues with high anisotropic indices (AIs) of up to 2.80 were obtained, particularly at WFR of 10 ml/min and at inclusions of 30% low-fat CF. By controlling HMEC conditions, full-/low-fat cricket flours at 15% and 30% inclusions can offer an opportunity to partially substitute SPI in manufacturing of fibrous meat analogues.

Black soldier fly defatted meal as a dietary protein source for broiler chickens: effects on carcass traits, breast meat quality and safety

Finding insect meals as alternative sources of poultry feedstuffs is a recent research topic; therefore, the present study aimed to evaluate the effects of defatted black soldier fly (Hermetia illucens L., HI) larvae meal in broiler chicken diets on the carcass characteristics and meat quality parameters, proximate composition, fatty acid profile and the heavy metal content of the breast meat. Four dietary treatments were designed: a control diet (HI0) and three experimental diets (HI5, HI10 and HI15), corresponding to 50, 100 and 150 g/kg HI inclusion levels, respectively. The inclusion of 50, 100 and 150 g HI meal per kg feed supply 16.56%, 33.01% and 49.63% of required crude protein. The broilers were slaughtered at day 35, the carcasses were weighed and the breast muscles were excised from 16 birds per each feeding group (two birds per replicate pens) and used for meat quality evaluation. Linear and quadratic responses were observed, for increasing HI meal levels, in the live and carcass weights (maximum for HI10). As far as the colour of the breast meat is concerned, redness (a*) showed a linear response, while yellowness (b*) linearly decreased with increasing HI meal levels (minimum for HI15). As the HI larvae meal increased in the diets, the moisture content linearly decreased and the protein content increased. The total saturated fatty acid and total monounsaturated fatty acid proportions rose to the detriment of the polyunsaturated fatty acid fraction. The HI larvae meal, used in the current study, represents a valuable protein source for broiler chickens when included by up to 100 g/kg in their diets, as an improved slaughtering performance was observed without any detrimental effects on meat quality parameters or heavy metal residues in the meat.

Review: Insects and former foodstuffs for upgrading food waste biomasses/streams to feed ingredients for farm animals

The increasing global need to find alternative protein/energy sources has triggered research in the field of non-conventional feed ingredients, with insects and former foodstuffs being the most promising. Insects contain high level of protein and fat, whereas former foodstuffs contain high energy in the form of carbohydrates and fats; therefore, both should be considered as promising alternative feed ingredients for livestock production. In addition to the nutritional value, they also represent a way by which food waste biomasses/streams can be upgraded to valuable feed ingredients. This review outlines the main nutritional and safety issues of insects and former foodstuffs, and also considers the legal framework involved. The importance of the type of insect metamorphosis and tailored substrates that could lead to the production of a premium feed is also described. This is also the first time that a review discusses the nutritional quality of former foodstuffs. Energy and the main nutrient content of former foodstuff are compared with the composition of common cereals as the principal energy sources in animal feed. For both ingredients a critical review of the safety issues is provided. Based on the current data available, both insects and former foodstuffs have an excellent potential use as alternative feed ingredients for livestock production. When produced in line with the criteria set by major feed/food authorities, they are characterized by high quality and safety standards. This makes them comparable to other feed materials and ingredients currently available on the market, although their full nutritional, functional, safety and sustainability evaluation cannot be considered complete.