Cheese manufacturing generates large volumes of whey with high biochemical and chemical oxygen demand, historically treated as waste. Yet, whey is rich in lactose, proteins, and minerals that can be fractionated and upgraded into foods and bio-based products. During cheese production, 80% to 90% of the total volume is discarded as whey, which can cause severe pollution. However, milk by-products can be a natural source of high-value-added compounds and a cost-effective substrate for microbial growth and metabolites production. The current review focuses on cheese whey as a key milk by-product, highlighting its generation and composition, the challenges associated with its production, methods for fractionating whey to recover bioactive compounds, its applications in functional food development, the barriers to its broader use in the food sector, and its potential as a substrate for producing value-added compounds. Particularly, the focus was on the recent solutions to use cheese whey as a primary material for microbial fermentation and enzymatic processes, producing a diverse range of chemicals and products for applications in the pharmaceutical, food, and biotechnology industries. This review contributes to defining a framework for reducing the environmental impacts of whey through its application in designing foods and generating biomaterials.

Apple fruit is among the most consumed fruits in the world, both in fresh and processed forms (e.g., ready-to-eat fresh slices, juice, jam, cider, and dried slices). During apple consumption/processing, a significant amount of apple residue is discarded. These residues can also be interesting materials to exploit, particularly for direct valorization in the design of added-value foods. In fact, apple waste/by-products are rich in essential components, including sugars, proteins, dietary fibers, and phenolic compounds, as they comprise apple peels, seeds, and pulp (solid residue of juice production). In this sense, the current review paper presents an overview of the nutritional composition of apple waste/by-products, and mainly apple pomace, highlighting their application in producing value-added products through microbial biotechnology. If appropriately managed, apple by-products can generate a variety of useful compounds required in food (as well as in feed, pharmaceutics, and bioenergy). Recent strategies for the synergic use of apple waste/by-products and microbial resources such as lactic acid bacteria and yeasts are discussed. This review contributes to defining a reference framework for valorizing apple waste/by-products from a circular economy perspective through the application of bioprocesses (e.g., fermentation), mainly oriented towards designing foods with improved quality attributes.

Fresh plant matrices of food interest host complex microbial communities. Within these microbial ecosystems, biochemical and ecological interactions are relevant in contributing to food quality and safety. In particular, lactic acid bacteria (LAB) play key roles in fermentative processes, bioprotection, and bioactivity. Despite their well-recognised importance in food biotechnology, the ecological dynamics and metabolic versatility of LAB in plant-based environments are still poorly explored. Understanding their diversity and how they adapt to matrix-specific stressors is crucial for identifying new strains with distinctive technological and biofunctional traits. This review summarises a selection of recent studies on LAB associated with fresh plant-derived matrices (i.e., fresh fruits, vegetables, and edible flowers). Particular attention is given to culture-dependent and culture-independent approaches employed for their identification. The main technological and functional aspects are also examined, aiming to assess their properties of interest, including resistance to adverse environmental conditions and mechanisms of microbial interaction. Furthermore, the discussion addresses the main biotechnological applications of selected LAB, including the development of fermented plant-based foods and beverages, the design of probiotic cultures/biocontrol solutions, and the valorisation of plant by-products. To our knowledge, this is the first review to provide an integrated overview of genomic and ecological insights into LAB associated with fresh plant matrices. This approach would help to improve understanding of LAB adaptive dynamics and identify sustainable drivers of innovation in agro-food systems.

The dairy industry is one of the most important sectors in food processing, contributing to the production of daily-needed products. Milk processing also results in the formation of by-products that can worsen the environment if not utilised properly. In this context, several efforts have been undertaken to mitigate their impacts by incorporating them into a novel production process/cycle. Milk by-products can serve as a natural source of high-value, high-impact inputs when introduced into such a process. Milk by-products can be a natural source of high-value-added compounds and a cost-effective substrate for microbial growth and metabolites production. The current review focuses on cheese whey as a key milk by-product, due to its significant production volume and environmental impacts. In fact, from ten litres of milk utilised in cheese production, eight to nine litres of whey are formed, and untreated whey can cause severe pollution due to its high biochemical oxygen demand and chemical oxygen demand. Recently, cheese whey has been widely utilised as a primary material for microbial fermentation and enzymatic processes to produce a diverse range of chemicals and products with applications in the pharmaceutical, food, and biotechnology industries. This review contributes to defining a framework for valorising whey through the application of bioprocesses in designing foods with enhanced qualities and the generation of biomaterials.