Effect of acorn harvesting time on the nutritional profile, polyphenols content, antioxidant activity and volatiles of different acorn flours.

Acorn flour resulted to be a promising alternative to the cereal flour for different applications thanks to its nutritional value, lack of gluten proteins and polyphenols content. The aim of the study was to find possible differences in nutritional value, polyphenols, antioxidant properties and volatile profile of acorn flours obtained by acorns harvested at different times and to promote acorn flour as a rich source of nutrients and bioactive constituents. Indeed, two acorn flours have been studied: one was obtained from acorns harvested at the beginning of November 2023 (Spring 2023) and the other from those harvested in the late November 2023 (Fall 2023). This study received funding from the European Union - Next-GenerationEU - National Recovery and Resilience Plan (NRRP) – MISSION 4 COMPONENT 2, INVESTMENT N. 1.1, CALL PRIN 2022 PNRR D.D. 1409 del 14-09-22 (CUP J53D23018470001). Results from nutritional analysis showed some differences, Flour Fall 2023 resulted to be richer in sugar content (glucose, fructose), total free aminoacids and most of the minerals (calcium, iron, phosphorous and magnesium) with respect to flour Spring 2023. An HPLC-MS/MS method was used for the determination of 38 polyphenols in flour samples (Mustafa et al., 2022) and their concentration resulted to be comparable between samples. However, the antioxidant activity, studied by DPPH free radical assay, Total Phenolic Content (TPC), Total Flavonoids Content (TFC) and Total Tannin Content (TTC), resulted to be different in acorn samples. In particular, TPC, TFC and TTP demonstrated a higher antioxidant activity in flour Spring 2023 with respect to flour Fall 2023. Finally, volatile profile was studied by HS-SPME-GC-MS and furanic compounds were quantified by HS-SPME-GC-MS (Acquaticci et al., 2024). This study demonstrated that acorn is a rich source of carbohydrates (50%), dietary fiber (25%), protein (10%) and macro-microelements such as potassium and calcium. Moreover, it has been assessed that flours obtained by acorns harvested at different times of the year showed differences in nutritional profile, antioxidant activity and volatiles. However, further studies are needed to understand if these differences will be maintained in food products to optimize the use of this flour to have a food product with the best possible properties.