Food by-product drying. Effect of temperature, ultrasound and pulsed electric field in drying kinetics and quality
- Autores: Beatriz Llavata Cabrero
- Directores de la Tesis: Juan Andrés Carcel Carrión (dir. tes.)
- Lectura: En la Universitat Politècnica de València ( España ) en 2025
- Idioma: inglés
- Tribunal Calificador de la Tesis: Federico Gómez Galindo (presid.), Isabel Hernando Hernando (secret.), Francesco Marra (voc.)
- Programa de doctorado: Programa de Doctorado en Ciencia, Tecnología y Gestión Alimentaria por la Universitat Politècnica de València
- Materias:
- Enlaces
- Tesis en acceso abierto en: RiuNet
- Resumen
The agri-food sector generates many by-products with economic and environmental impact. Up-cycling them into value-added products promotes a circular economy and sustainability. However, their high moisture content makes them prone to degradation, requiring stabilization through drying. Convective drying is the most widely used in the industry due to its simplicity, while freeze-drying better preserves quality, but both consume significant energy. In this regard, strategies are explored to improve drying processes, such as increasing air temperature, applying pulsed electric fields (PEF) as a pretreatment, or applying ultrasound (US) to accelerate drying while maintaining quality. Increasing air temperature speeds up drying, PEF pretreatment applies electrical pulses that alter cell membranes to facilitate water release and US enhances water transfer, reducing drying time. However, these methods can also affect the final product quality.
This thesis evaluated the stabilization of agri-food by-products through drying, including artichoke by-products, cider apple pomace, kiwifruit surpluses, orange peel, butternut squash and yellow turnip. The effects of air temperature, PEF pretreatment, US application, and their combination were analyzed. Results showed that higher temperatures reduced processing times but impacted on antioxidant properties, functional properties and color. PEF pretreatment had different effects depending on the matrix and slightly accelerated drying processes. Likewise, US application reduced drying times. However, the combination of PEF and US achieved the greatest drying acceleration in both convective and atmospheric freeze-drying. Therefore, the combined application of these technologies could be useful for stabilizing agri-food by-products through drying, but PEF conditions must be tailored to each matrix.
