Tesis doctoral de Mónica Pérez Martínez
Coffee brew begins to change immediately after it has been prepared, losing its characteristic aroma because the volatilization of the responsible chemical compounds, and increasing its acid, bitter and residual tastes, inducing to a very short shelf life of the coffee brew. Furthermore, during the last few years, the antioxidant capacity of coffee has been observed and deeply studied. It is mainly due to the presence of polyphenolic compounds, melanoidins and other maillard reaction products, formed during the roasting process. However, little is known about the chemical causes that lead to the quality loss of the coffee brew along the time, and whether its antioxidant capacity changes. For these reasons, it is very interesting to go deeper in the knowledge of the chemical changes on the coffee brew at the consumer storage conditions, that is real temperature and time, because in some previous studies of other authors, the ageing of coffee brew was simulated and accelerated by an increase of the temperature, which can affect in different way to the chemical compounds of coffee. the aim of this work was to study the influence of the storage conditions (temperature and presence/absence of oxygen), the extraction method (filter, french press, mocha and espresso) and the use of additives on the coffee brew (origin colombia) changes, with the final aim of extend its shelf life. Ph, soluble chemical compounds related to taste and flavour (caffeine, trigonelline, 5-caffeoylquinic, caffeic and ferulic acids, and 4-vinylguaiacol by hplc), volatile compounds related to aroma (by hs-gc-ms), antioxidant capacity (polyphenols by folin ciocalteau, dpph, abts, and fremy¿s salt and tempo by electron spin resonance spectroscopy) and sensorial attributes were analyzed in coffee brews (origin colombia) packaged with or without oxygen, and stored at room (25ºc) and refrigeration (4ºc) temperatures up to 90 days. Moreover, several additives, such as acidity regulators, were added to coffee brew and the same chemical and sensorial parameters were analyzed during storage. as general conclusion of this work could be pointed out, on the one hand, that the storage of coffee brew without oxygen at refrigeration temperature is the optimum preservation condition of this kind of beverages, and that the use of sodium carbonate and, to a lesser extend sodium bicarbonate, offers benefits to consumers because extends its shelf life and hardly modifies its antioxidant capacity. On the other hand, the application of the esr spectroscopy to measure the antioxidant capacity of the coffee brew may contribute to the knowledge of whether the antioxidant capacity is due to the presence of phenolic compounds that can be bioavailable or to the melanoidins or other maillard reaction products, the bioavailability of which is still unclear but which may act as prebiotic compounds.
Datos académicos de la tesis doctoral «Evolución químico-sensorial de bebidas de café, origen colombia, durante su almacenamiento. aplicación de estrategias de alargamiento de su vida útil«
- Título de la tesis: Evolución químico-sensorial de bebidas de café, origen colombia, durante su almacenamiento. aplicación de estrategias de alargamiento de su vida útil
- Autor: Mónica Pérez Martínez
- Universidad: Navarra
- Fecha de lectura de la tesis: 29/04/2010
Dirección y tribunal
- Director de la tesis
- María Concepción Cid Canda
- Tribunal
- Presidente del tribunal: María iciar Astiasaran anchia
- susana isabel Pereira casal vicente (vocal)
- José angel Rufian henares (vocal)
- bettina-maria Cí¤mmerer (vocal)