Millora de la qualitat sensorial i nutricional de les varietats tradicionals hortícoles: el cas del calçot (allium cepa l.)
- Autores: Sílvia Sans Molins
- Directores de la Tesis: Joan Simó Cruanyes (dir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2019
- Idioma: español
- Tribunal Calificador de la Tesis: Jaime Prohens Tomás (presid.), Anna Gras Moreu (secret.), Pere Muñoz Odina (voc.)
- Programa de doctorado: Programa de Doctorado en Tecnología Agroalimentaria y Biotecnología por la Universidad Politécnica de Catalunya
- Materias:
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- Resumen
Sensory and nutritional quality are key elements for consumers, providing added value to agri-food products. However, there is a general perception that horticultural products have lost their quality, especially their taste.
Landraces have an identity associated with a specific area and historical origin, and are adapted to local conditions, both environmental (soil and climate) and crop management (generally low inputs). Nevertheless, they present a medium-low yield, resulting in a progressive replacement by improved varieties with high yields when cultivated in high-input systems. The landraces that remain in commerce are those which have found a high-quality niche market where consumers’ interests go beyond the price. The survival of landraces depends on their distinctive qualities, as in the case of calçots (the immature floral stems of second-year sprouts of onions (Allium cepa L.)). Calçots are typical of Catalonia, specifically from counties in the province of Tarragona where the European Union has designated them with the Protected Geographical Indication (PGI): Calçot de Valls. The calçot market is in constant evolution and expansion, and its cultivation extended beyond its traditional area many years ago.
The quality attributed to a product should be objective and measurable, in order to make its control a routine. The determination of food sensory and nutritional qualities (the most relevant qualities for consumers) presents some limitations, especially when a large number of samples needs to be tested. This necessitates the search for alternative methodologies to measure food quality in the fastest and most efficient way. For example, NIR (Near Infrared) spectroscopy presents some advantages in comparison with conventional analytical methods: multi-analyte, speed, low cost, no reagents, etc.
The objective of this thesis, structured around four articles, is to develop knowledge and tools to improve and control the nutritional and sensory qualities of calçots, with the aim of providing an identification based on those two characteristics in the Calçot de Valls.
Nutritional properties of calçots are similar to those previously reported in onion bulbs, despite the fact that the part of the plant consumed is different. As happens with other vegetables, the cooking process has an important impact on the calçots’ composition, increasing most of the parameters tested, and decreasing others like total phenols or, more drastically, flavonoids, with an 85% loss.
The environmental influence was found to be higher than genetic influence when only considering accessions from the Blanca Tardana de Lleida onion landrace (the only one authorized by the PGI). This result suggests to prioritize management optimization over plant breeding programs to increase quality. However, when considering three other onion varieties, the genetic variability sharply increases, as do the expected advances in plant breeding introducing new variability via cross-breeds between varieties.
It would be feasible to use NIR spectroscopy to test the nutritional and sensory properties of calçots, while facilitating the management of a large number of samples. The accuracy of models developed to estimate chemical properties was between good and excellent (RPD (Ratio of Performance to Deviation) between 1.99 and 8.07). Although the developed models to estimate sensory attributes are less accurate (RPD between 1.41 and 1.78), NIR spectroscopy can help to detect those samples that differ substantially from the ideotype (high sweetness, low fiber perception and the absence of off-flavors), as a first screening in plant breeding programs or in the elimination of outliers in quality control.
