Title : Differences in furanic and phenolic composition of Ceratonia siliqua L. liquors according to the roasting degree and variety of carob
Carob liqueur is a traditional beverage made from crushed carob pods in different Mediterranean countries such as Portugal. The determination of the phenolic (gallic acid) and furanic (5-hydroxymethyl furfural and furfural) composition in different varietal roasted or unroasted carob liquors was assessed in this work by high performance liquid chromatography coupled with photo-diode array detection (HPLC-PAD). Three Portuguese Ceratonia siliqua L. varieties were used for the experiments, AIDA, Mulata and Galhosa, and these unroasted or roasted (at 120 °C and 150 °C) raw materials were macerated in fig spirit to produce the corresponding liquors. Gallic acid was the main phenolic compound found in samples and was in greater amount in the unroasted AIDA liquor. In the case of Galhosa and Mulata liquors, the roasting step was necessary in order to obtain higher quantities of gallic acid. However, the liquors elaborated with carob roasted at 150 °C presented concentrations of 5-hydroxymethylfurfural above the threshold of concern established by the European Food Safety Authority (EFSA). On the other hand, the content of furfural came from both raw materials used, the fig spirit and the carob pulp, mainly from the roasted fruit. Therefore, the present study indicates that different approaches must be taken into account when using different varieties on liquor elaboration. In addition, although the roasting step favors the organoleptic characteristics of the carob fruit, it should be borne in mind that it also increases the concentration of certain compounds that can become harmful to human health.