Food waste and byproducts are generated along the entire food processing and storage chain. The large amount of waste deriving from the whole process represents not only a great economic loss but also an important ethical and environmental issue in terms of failure to recycle potentially reusable materials. New, clear strategies are needed to limit the amount of waste produced and, at the same time, promote its enhancement for further conversion and application to different industrial fields. This review gives an overview of the biological approaches used so far to exploit agri-food wastes and byproducts. The application of solid-state fermentation by different microorganisms (fungi, yeasts, bacteria) to produce several value-added products was analyzed, focusing on the exploitation of lactic acid bacteria as workhorses for the production of flavoring compounds.

Okara is the main soybean by-product resulting from the processing of soy milk and tofu. Despite being a product with a lot of potential and rich in many bioactive compounds such as polyphenols, it presents an unpleasant, rancid aroma. For this reason its use in the food industry is limited. In this study, we have reported the integral use of okara in a solid state fermentation process, conducted with wild strains of lactic acid bacteria, to evaluate the effect of bacterial metabolism on the volatile and polyphenolic profiles. Strains belonging to Lactobacillus acidophilus, Lacticaseibacillus rhamnosus and Pediococcus acidilactici species were used in monoculture and, for the first time, in co-culture. The results showed an improvement in the aromatic fraction showing a decrease in hexanal, responsible for off-flavour, and an increase in ketones with fruity and buttery notes in fermented okara. Polyphenols were also affected, and, in particular, a bioconversion of glucoside isoflavones to the aglycone forms was highlighted in all fermented substrates. In addition, the appearance of both phenyllactic and p-hydroxyphenyllactic acids as well as the increase in indole-3-lactic acid was observed for the first time upon okara fermentation. Overall, the co-culture appears to be the most promising for biovalorization of okara, thereby opening the possibility of its use in the development of functional ingredients.

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.