Fermentation is a chemical process in which enzymes from certain microorganisms, without oxygen, break down and transform food molecules. 

This process improves the shelf life of products and enriches the aromatic and nutritional profile, creating a unique range of flavors. That makes fermentation an effective technique for giving a second life to waste products from the agri-food supply chain, extracting bioactive compounds and essential nutrients.

Over the centuries, fermentation techniques have been improved through empirical knowledge and growing scientific understanding. In the 19th century, Louis Pasteur revolutionized our knowledge of fermentation, demonstrating that it’s caused by living microorganisms, paving the way for more in-depth studies on the biological processes underlying fermentation.

During the 20th century, the development of microbiology allowed for the isolation and identification of specific microorganisms responsible for various fermentations, improving the control of processes and the quality of fermented products. In the 1970s, with the advent of genetic engineering, it became possible to genetically modify microorganisms further to optimize fermentation processes and the production of desired compounds.

The famous writer and journalist Michael Pollan described fermentation as a "profound transformation of foods for culinary purposes that occurs without the aid of any heat source," comparing it to a "cold fire." This transformation makes foods more digestible and preservable, similar to cooking, but it happens through natural and biological processes.

Modern biotechnologies are further expanding the possibilities offered by fermentation processes, with particular attention to the extraction and purification of bioactive compounds. 

To make it, it is necessary to study and monitor the action and change of lactic acid bacteria populations and other microorganisms during fermentation. These can increase the fraction of nutrients the body can absorb and use from foods, generating new substances with functional properties, and improving the organoleptic and nutritional characteristics of the final product. Moreover, fermentation plays a central role in addressing one of the most pressing and urgent problems of our times: the enormous amount of waste generated daily by agri-food supply chains.

Peels, seeds, stems, and leaves are just some of the by-products of the food industry that are discarded in every production cycle as they are unwanted and unnecessary for obtaining the finished product. However, these plant and fruit elements often contain higher concentrations of bioactive compounds than products on the shelves. For example, citrus peels are rich in phenolic compounds and antioxidants, while asparagus waste and other vegetables contain phytosterols, saponins, and flavonoids. Additionally, they can be transformed into high-value-added products such as nutraceuticals, prebiotics, and probiotics, offering health benefits beyond their basic nutritional value.

Enhancing agro-food waste, Spoke 2 of Onfoods, specializes in researching a circular food system, and studies fermentation through the FERM_WASTE and METRO_FARM projects. One of the most promising approaches for valorizing these wastes is fermentation with bacteria, yeasts, and fungi. For example, by-products from artichoke production, such as outer leaves and stems, can provide excellent yeasts and bacteria for extracting useful nutrients, such as polyphenols and carotenoids, through fermentation. Similarly, fungi in cereal by-products can be used to obtain bioactive compounds.

The FERM_WASTE project focuses on identifying and collecting useful microorganisms for fermenting agro-food by-products: the goal is to develop new fermentation processes that can produce foods enriched with nutrients. For example, the plan is to create at least one type of bread or cereal product enhanced with fermented waste materials, or by using lactic acid bacteria, it’s possible to control the growth of harmful microorganisms, thus improving food safety.

In addition to creating new foods, FERM_WASTE research is defining the best conditions for treating by-products before fermentation to achieve the maximum result. Pre-treating waste speeds up and improves the extraction process and the effect of fermentation on by-products. Increasing the efficiency of these processes is indeed one of the most complex goals that FERM_WASTE must face.

Moreover, isolating and characterizing new microorganisms from food waste is fundamental to analyzing the valorization and creation of new enriched foods. Preliminary results suggest that various food wastes still present many microbes, fungi, and yeasts that can be exploited in fermentation processes and should be studied in depth. The best method is to analyze the genome, and the genetic makeup of various fungal species, understanding the mechanisms by which they act on foods. A better understanding of the characteristics and actions of microorganisms, yeasts, and fungi will help the production of bioactive compounds.

The METRO_FARM project also focuses on transforming waste and agro-food by-products to obtain compounds of industrial interest, such as bioactive molecules, nutrients, and fibers. Unlike FERM_WASTE, METRO_FARM, however, uses enzymatic catalysis procedures in addition to fermentation. This involves exploiting the natural action of enzymes that act as catalysts, speeding up and facilitating chemical reactions. With enzymatic catalysis, specific enzymes can easily break down waste molecules, reducing them into smaller compounds, and releasing vitamins and antioxidants. The compounds thus released are then extracted and used to create supplements or various nutrients. This approach, combined with fermentation activity, allows for improved extraction of soluble dietary fibers, polyphenols, and other molecules, and additionally, reduces antinutritional factors and mycotoxins from agricultural by-products. Antinutritional factors are substances naturally present in many plant foods, produced by the plant to protect it from molds, bacteria, and predator attacks, which reduce nutrient absorption and decrease the food's nutritional value. Mycotoxins are compounds naturally produced by various fungi and are usually found in foods such as cereals, dried fruits, nuts, and spices. The presence of mycotoxins in food can have harmful effects on human health, causing gastrointestinal problems, kidney disorders, and immunodeficiency. Conducting research and adopting new strategies for enzyme application can help manage the health aspects of valorizing by-products.

But there is another complication METRO_FARM must face. One of the main difficulties lies in improving and scaling the enzymatic extraction process of bioactive compounds, increasing production capacity, and reducing environmental impact in favor of greater productivity. A possible solution in this sense is to automate the extraction procedures using immobilized enzymes in chemical reactors, ensuring the quality and safety of the final products. This would bring the valorization process to a large scale while ensuring extraction and purification processes that comply with health regulations.

Given the complexity of the research project, METRO_FARM collaborates with companies such as Sacco and Barilla. Sacco, a leader in food, nutraceutical, and pharmaceutical innovation, focuses on creating new easy-to-consume foods, such as baked goods and meat and fish alternatives, valorizing waste products. The collaboration with Barilla, on the other hand, focuses on reusing waste from sauce production, to effectively separate food waste from glass.

If not properly managed, agroindustrial waste can cause serious environmental and financial problems. This is a global waste of about 1.3 billion tons of products per year, which in India alone amounts to over 234.5 million tons of agro-food circuit waste, representing a significant challenge for management. In the future, this figure could worsen with the increase in the world population and, consequently, the demand for food. However, this waste can become added value thanks to innovative techniques such as fermentation and the use of enzymes. The correct use of agricultural waste can support entire industries, create jobs, develop rural areas, and solve waste management and pollution problems. By adopting sustainable fermentation and extraction techniques, it’s possible to significantly reduce the environmental impact of by-products of the food supply chain. All this is possible thanks to the ever-increasing presence of research projects and investments that seek to shed light on new extraction methods that are easily applicable and functional. Continuous research and innovation on fermentation are fundamental steps for the future, as they allow lifeblood for this food extraction method and preservation, thanks to the renewed scientific and popular interest it enjoys.

Fermentation represents a link between the past and the future, an ancient technique that continues to offer modern solutions for healthier and more sustainable nutrition. With its ability to transform and valorize waste, it thus confirms itself as a sustainable process to look forward to the future of global food production and consumption.