LIPASE AS AN INNOVATIVE PREDICTIVE TOOL TO DIRECT DECISION-MAKING STRATEGIES FOR HAZELNUTS INDUSTRIAL STORAGE AND QUALITY ASSESSMENT

Hazelnuts are among the most important raw materials in the confectionery industry, but their quality and shelf life are strongly limited by lipid degradation processes that lead to rancidity. Both oxidative and enzymatic deterioration pathways originate from the hydrolysis of triacylglycerols, a reaction catalyzed by lipases. Recent research identified the hazelnut allergen Cor a 8, a non-specific lipid transfer protein (nsLTP), as a novel lipase responsible for initiating lipid hydrolysis. Building on this discovery, the present PhD project investigated the potential of lipase activity as an innovative biochemical marker to support industrial decision-making for hazelnut storage, quality assessment, and shelf-life prediction. The work was carried out through a collaboration between the University of Turin and Soremartec Italia (Ferrero Group). A key objective was the development of a rapid, robust, and industry-compatible assay for lipase activity measurement at the industrial level. Using this assay, lipase activity was evaluated in multiple industrial batches belonging to different cultivars, demonstrating clear cultivar-dependent lipase activity ranges. Accelerated shelf-life studies were then performed to assess whether initial lipase activity could predict quality evolution during storage. Although lipase activity changed during storage and was influenced by post-harvest conditions, the initial activity could not be used as a direct quantitative predictor of future activity. Nevertheless, it provided valuable information on cultivar-specific stability and storage sensitivity, supporting its use as an early quality indicator. The effects of industrial heat treatments on lipase activity were also investigated. Across all cultivars tested, thermal processing consistently reduced lipase activity and this reduction was maintained throughout storage, suggesting that heat treatment can partially inhibit the enzyme and potentially delay the onset of lipid degradation. Structural investigations performed through Circular Dichroism and NMR further contributed to understanding the behaviour of this unconventional lipase under thermal stress. ABSTRACT _____________________________________________________________________________________ 2 Finally, lipase activity was monitored during hazelnut development, providing insight into its physiological role during fruit maturation. Overall, this work demonstrates that lipase activity represents a promising biochemical marker for hazelnut quality assessment. The industrial assay developed during this project enables rapid screening of raw materials and provides a valuable tool to support storage strategies, process optimization, and shelf-life management within the confectionery industry