MICROWAVE ASSISTED EXTRACTION OF BIOACTIVE COMPOUNDS IN AVOCADO PEEL BY-PRODUCTS

Fruits and vegetables represent an important component of the diet for human health for all the bio compounds they contain. On one side, humans need to eat these products for the huge amount of bio compounds that can provide for good maintenance; however, on the other side, there is a huge production of waste related to the transformation of the products during the entire food production chain from the industries. The industries related to food processing, in particular, for all that work on fruits and vegetables processing, are the one of the largest generators of waste, that is later put into the environment. The most common kind of waste product from the processing phase is liquid and solid (such as peels, seeds, stones, and unused flesh). All of that is responsible for the main causes of the environmental pollution problem, but only if they are not utilized or disposed of properly. There are several ways in which this waste can be used for its full potential, principally these wastes are used as fertilizers for the soil in agriculture, feed for animals, use it as biomass to produce energy or biofuels. These agri-food waste by-products are rich in a wide range of high-value bioactive components, such as polyphenolic and antioxidants compounds, for which they could be revalorized for other purposes many industries have started to consider these wastes as a possible field of study from which to start research and investments on possible new uses. (Mir-Cerdà et al., 2023). The trend of companies is increasingly moving towards developing methods to reuse bio- compounds extracted from waste as a potential resource due to the number of substances of high value that are possible to extract and reuse from it. The open-mindedness of companies towards this direction could be able to significantly reduce the problems related to possible environmental damage and related disposal costs, but it could also be seen as an additional strength for all those industries that could generate greater profits. (Gowe, 2015). The open-mindedness of companies in this direction could significantly reduce the problems related to possible environmental damage and related disposal costs, but it could also be seen as an additional strength for all those industries that could generate greater profits. The potential for the use of these by-products would be enormous; among the possible applications there is first the isolation and then the creation of functional or enriched foods. The development of new techniques for the transformation of these materials into marketable products could offer a viable solution to this waste problem, while promoting sustainable economic growth from a bioeconomic point of view (Hasan et al., 2024). To reduce the environmental impact of the extraction of phenolic compounds, green options and solvents with the lowest environmental impact are constantly research. In fact, today, the main efforts are focused to research and use of green solvents, such as water, supercritical CO2, and ethanol. In fact, this study focused on the use of ethanol and water solutions as reagents and MAE was used to perform the extractions. Subsequent analyses of the extracted compounds, such as polyphenols for example, were carried out by liquid chromatography due to their chemical-physical characteristics. As for detection, this was carried out by UV/vis analysis, fluorescence or mass spectrometry. Mass spectrometry was used because it allows us to better identify and understand the structure of the extracted compounds; this allows us to obtain information on the antioxidant activity.

La tesi si pone come obiettivo la rivalorizzazione della buccia di avocado attraverso tecnologie emergenti ed il più possibile eco-compatibili. Questo tema è molto attuale nella filiera agroalimentare, dove numerosi sottoprodotti e residui delle diverse lavorazioni vengono quotidianamente smaltiti semplicemente perché considerati privi di valore. Per il recupero dei composti bioattivi ancora presenti in questo caso nella buccia di avocado, è stato applicato un trattamento di estrazione a microonde (MAE), ottimizzando questo processo attraverso l’utilizzo di un disegno sperimentale (CCD). L'estrazione è stata eseguita attraverso l’utilizzo di diverse concentrazioni di etanolo (0-100%), variando la temperatura e il tempo di esposizione del campione. Le condizioni di estrazione ottimali ottenute dal processo con MAE per recuperare i composti fenolici totali sono: una miscela di solventi al 50% di etanolo e acqua, potenza di 800 W, temperatura di 75 °C e un tempo di estrazione di 15 minuti. Successivamente gli estratti sono stati analizzati spettrofotometricamente per determinare: la capacità antiossidante totale con i metodi FRAP e ABTS e i composti fenolici totali con il metodo FOLIN. I singoli composti fenolici sono stati inoltre identificati e quantificati tramite analisi HPLC/MS. Tutti i risultati ottenuti da questo studio, dimostrano che questa tipologia di estrazione offre, rispetto alle tecniche convenzionali, vantaggi significativi, in termini di maggiore efficienza, ridotto impatto ambientale e migliore recupero dei composti bioattivi. Le possibilità di utilizzare i composti bioattivi recuperati sono molteplici, ed in particolare potrebbe risultare decisamente interessante l’integrazione di questi biocomposti in diverse matrici alimentari, con l'obiettivo di creare degli alimenti funzionali e arricchiti. In conclusione, questo studio dimostra che gli scarti della buccia di avocado, possono essere una grande risorsa per l'estrazione sostenibile di composti bioattivi, utilizzando la tecnologia a microonde. Inoltre, questo approccio “circolare” non solo risulta sostenibile a livello ambientale, ma offre anche nuove opportunità economiche per le aziende che iniziano a sfruttare gli scarti di lavorazione come risorsa, trasformando dei residui da smaltire in prodotti di alto valore con benefici per la salute dei consumatori.