Antimicrobial Biomasses from Lactic Acid Fermentation of Black Soldier Fly Prepupae and Related By-Products

Worldwide, thousands of insect species are consumed as food or are used as feed ingredients. Hermetia illucens, ‘black soldier fly’, is one of them, and a large amount of puparia and dead adults flies are accumulated during rearing. These materials represent important wastes but no studies are still present in the literature regarding their functional properties and potential reuse. Lactic acid bacteria (LAB) are a heterogeneous group of bacteria contributing to various industrial applications, ranging from food fermentation, chemicals production to pharmaceuticals manufacturing. A LAB feature of industrial interest is their ability to produce antimicrobial metabolites. Considering the scientific and commercial interest in discovering novel antimicrobials, this work will be direct towards fermentation of insect-derived biomasses: puparia and adults insect at the end of life cycle. To the best of our knowledge, the in vitro antimicrobial activity of fermented insects is tested for the first time. This study aimed also to evaluate differences in the composition between fermented and unfermented insects, and to study whether the fermentation and the type of LAB used played a crucial role in modifying the composition of the substrate. Results firstly highlighted fermentability of this species of insects, showed that fermented black soldier flies puparium possess a high antimicrobial activity against tested pathogens. Moreover, result of chemical composition showed that fermented biomass had a higher percentage of fat and a more complex fatty acids profile

EFFECTS OF PRE-SLAUGHTER DIETS ON THE VITAMIN E AND COLOUR STABILITY OF LAMB MEAT

Multiple factors such as high temperature, light, free oxygen, metals, length of storage etc., can induce dangerous free radicals in products of animal origin, mainly affecting lipids, due to a major susceptibility of PUFAs to oxidation. This oxidative phenomenon is very harmful because it speeds up the quality deterioration of products of animal origin such as meat, altering color and reducing shelf life. In order to reduce oxidative reactions, a balance between pro-oxidants and anti-oxidants is required in determining oxidative stability of lipids (Gravador et al., 2015). High levels of vitamin E in meat reduce oxidative reactions, offsetting endogenous muscle pro-oxidants. The relationship between finishing diets with different vitamin E compositions and the final content of the vitamin found again in the lamb meat was investigated. Thirty male lambs were separated in five groups from six lambs each and, for 54 days pre-slaughter, assigned to either one of four concentrate diets (a barley/maize-based concentrate, a Megalac (saturated fat) containing concentrate, a protected linseed containing concentrate, or a citrus pulp and maize distiller grains-based concentrate) or a pasture based diet. After slaughter, analyses have been effected on the minced Muscle semimembranosus, packed in a high oxygen modified atmosphere (MAP: 80% O2: 20% CO2) with illumination, for up to 14 days. The tied-up Vitamin E content to the stability of storage and color stability of lamb meat were measured after 0 (2 hours after packaging), 3, 7, 10 and 14 days of refrigerated storage with high oxygen levels. The color deteriorated and vitamin E content decreased significantly over time in all samples. Meat redness was significantly affected by diet, along with hue angle, which has been associated with browning in meat. Lower meat redness values and higher hue angle values were identified in meat from lambs fed pasture based diets. The vitamin E final content in meat was also significantly affected by diet. Meat from lambs fed grass diet for all through the experiment, in fact, introduced values of vitamin E clearly superior to those introduced by the meat from lambs fed concentrate diets

Valorization of seasonal agri-food leftovers through insects

Most of the leftovers from agricultural productions and industrial processing of vegetables are currently discarded as waste, augmenting production costs and environmental impacts. Black soldier flies (BSF) are nonpest insects that can grow on various types of organic materials. The larvae initially act as fast and efficient bioconverters, before being further valorized as biomass rich in proteins, fats and chitin. The aim of the present studywas to exploit the potential of BSF prepupae reared on vegetable leftoverswith high seasonality, and to obtain compounds with high added value and further industrial and agronomic uses such as food/feed, soil improver or fuel. The optimization of BSF rearing substrates based on different leftovers combinations was performed through a Mixture Design approach. Initially, a database was built detailing the availability, seasonality and nutrient composition of the vegetable by-products. According to the seasonal availability of the agri-food leftovers, threemain groups were identified: annual, summer and autumnmixtures, in order to promote the exploitation of the highest quantity of leftovers. This approach allowed the obtainment of statistically reliable correlations (R2 N 0.75) between the employed leftovers and the content of lipid and nitrogen compounds (protein and chitin) of the BSF prepupae. In particular, a mixture of vegetable leftovers available in autumn that included legume (25 wt%), cereal (20 wt%) and vegetable (25 wt%) wastes proved to be the best combination in terms of insect growth (−25% development time compared to the control group) and nutritional composition. The chemical composition of the insect biomass allowed the identification of potential applicationswith high added value, such as food ingredients (protein and fats) or nutraceuticals (chitin). The identification of the optimal parameters to ensure the greatest possible efficiency would promote the scale-up of BSF rearing to an industrial level