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  • Freeze-Dried Nutritious Chestnut Preparation Enriched With Minerals From Thermal Water
    Publication . Trad, Hiba; Roriz, Custódio Lobo; Heleno, Sandrina A,; Nassri, Rym
    Chestnuts have long been a staple food of rural populations, valued for their high nutritional content, including vitamins such as vitamin C and B6, fiber, minerals and carbohydrates, all while being free of cholesterol. In Portugal, chestnuts are a widely cultivated product, leading to significant waste generation, much of which are often discarded. To address this issue, it is crucial to find sustainable methods for repurposing these by-products into high-value products. In this context, the present work focuses on the valorisation of non- commercial chestnuts to develop a nutritional preparation using the freeze-dried technique. This method involves a dehydration process that removes water from food, preserves the nutritional quality of chestnut, and to extends their shelf life. Additionally, the preparation will be enriched with beneficial minerals derived from the thermal water, further enhancing its nutritional value. This approach aligns with the principals of sustainable food production by reducing waste and contributing to the circular economy. Four Portuguese chestnut varieties (Amarelal, Boa Ventura, Judia and Longal) were characterized regarding their nutritional composition, chemical profile, mineral composition and bioactive properties. Nutritional evaluation was caried out by determining the fat, protein, ash, carbohydrates and energy value. Chemical characterization was performed resorting to different chromatographic techniques, namely High-Performance Liquid Chromatography with refractive index detection (HPLC-RI) for free sugars, High-Performance Liquid Chromatography coupled to fluorescence detection (HPLC-FL) for tocopherols, Ultra-Fast Liquid Chromatography coupled to photodiode array detection (UFLC-PDA) for organic acids, and Gas Chromatography with flame ionization detection (GC-FID) for fatty acid profiling. Mineral composition and bioactive properties, including antimicrobial activity and cytotoxicity, were also evaluated. The results showed that chestnuts presented relevant and functional properties, with carbohydrates representing the major macronutrient and unsaturated fatty acids being predominant in the lipidic fraction. Sucrose was the major free sugar determined, while regarding organic acids, tocopherols and essential minerals presented themselves in considerable amounts. All varieties exhibited moderated to low antimicrobial potential and low cytotoxicity, supporting their potential application in food products. The incorporation of thermal water contributed to the mineral enrichment of the freeze-dried formulation while maintaining their nutritional quality. The final product, rich in vitamins, minerals, and bioactive compounds, demonstrated promising potential as a functional food ingredient for applications such as health drinks, fortified foods, or dietary supplements. Overall, this work highlights the feasibility of valorizing non-commercial chestnuts through sustainable technological approaches, contributing to waste reduction, food innovation, and the development of value-added products with potential industrial applications.
    2026Dissertação de mestrado Acesso aberto Ver mais