Physicochemical and microbiological characterization of the dehydration processing of red pepper fruits for paprika production

In order to determine whether changes in pectin fractions facilitate or not the traditional drying of red pepper fruits (Capsicum annuum L.) and the possible consequences of these changes on the dehydration conditions for paprika processing, that have an impact on the evolution of carotenoid content (responsible for colour), this evolution and other parameters were monitored during a traditional drying process in correlation with the temperature–time combinations used. Evolution of microbial flora was followed to analyse their possible contribution, as an exogenous source, to enzymatic polygalacturonase (PG) activity. Our results indicated that the mild temperature–time regime mediated the selection and proliferation of a microbial flora that contributed to enzymatic PG activity modifying the pectic fraction. The enzymatic activity generated rises in the calcium pectate (CaP) fraction, which favoured the drying of fruit with an initial low content of soluble pectins (SP) and CaP. Thus, the changes in texture helped during the transfer of moisture, facilitating the dehydration process, and therefore, a milder temperature–time regime was required. Consequently, bioactive compounds of the fruit, such as capsorubin, capsanthin and provitamin A carotenoids, remained almost unaltered. On the other hand, when the SP fraction increased during dehydration, the process was delayed, and this was also correlated with a higher content in SP and CaP in fresh fruit, indicating that the fruits were harvested at a later stage of ripeness. In this case a more intense temperature–time regime was needed, negatively affecting the carotenoid content by decreasing it significantly.