Grazioso, Angela (2025) Production of algal flours for food purposes: metabolism and process optimization. [Tesi di dottorato]

Documento PDF Grazioso_Angela_38.pdf Visibile a [TBR] Amministratori dell'archivio Download (11MB) | Richiedi una copia

Abstract

Proteins play a crucial role in human nutrition, and the growing demand for sustainable food systems has intensified interest in alternative protein sources. Among these, microalgae represent a promising option due to their high protein content, sustainable production, and minimal land requirements. However, their strong colour and odour limit consumer acceptance and food applications. This PhD thesis investigated the impact of a novel physical bleaching process, based on heat and photosynthetically active radiation (PAR), on the nutritional, functional, and biological properties of selected microalgae. Cyclotella cryptica, Arthrospira sp. (Spirulina), and Chlorella sorokiniana were studied and compared with commercially available white microalgae (white Chlorella). Comprehensive chemical analyses revealed species-specific effects of bleaching, with lipids being the most affected macronutrient, showing increased oxidation and hydrolysis, particularly in Spirulina and C. sorokiniana. Cytotoxicity assays indicated good biocompatibility of bleached and green C. cryptica and Spirulina, while commercial white C. sorokiniana showed dose-dependent cytotoxicity. Techno-functional properties also were investigated in order to assess applicability in food formulations. Green Spirulina showed the highest functional performance, with bleaching causing only a slight reduction, while white C. sorokiniana exhibited the poorest functionality. In vitro digestibility of untreated microalgae ranged between ≈40-60% while bleaching generally reduced digestibility, especially in Spirulina. Simulated intestinal fermentation experiments demonstrated the capacity of microalgal ingredients to modulate gut microbiota and short-chain fatty acids (SCFAs) production. Notably, bleaching did not substantially impaired SCFA generation, with white C. sorokiniana and green Spirulina emerging as the most promising products in this respect. Finally, the application of bleached microalgae in baked products demonstrated their potential as egg powder substitutes, with bleached Spirulina and white Chlorella producing biscuits with textural properties comparable to egg-based formulations. Overall, this work highlights both the potential and limitations of bleached microalgae as sustainable protein-rich food ingredients.

Downloads

Actions (login required)

Modifica documento