Research background: The carob tree (Ceratonia siliqua L.) is grown primarily for its seeds that are utilized in the production of the highly prized locust bean gum. The material left after the separation of seeds from the pods is utilized in the production of a range of traditional products including carob syrup, usually in cottage-type industries. The international market penetration of carob syrups is rather limited and, accordingly, scant information exists on their composition and phytochemical properties compared to mainstream syrups. The present study aims to determine key chemical parameters, phenolic profiles and antioxidant properties of carob syrups and benchmark these against those of date and maple syrups.
Experimental approach: Carob syrups were prepared from 19 accessions of the carob, under laboratory conditions, by a similar procedure to those practiced by small-scale producers. The pH, browning index, the content of proteins, minerals, hydroxymethylfurfural, sugar composition, total phenols, antioxidant capacity and phenolic profiles of the produced syrups along with branded samples of date and maple syrups were analyzed.
Results and conclusions: The pH and sugar composition of the carob syrups were comparable to those of date and maple syrups. In general, the carob syrups contained more proteins, minerals, phenolic acids, flavonoids and total phenols, and exhibited higher antioxidant capacity than the date and maple syrups. The carob syrups exhibited excessive browning and contained more, or comparable content of hydroxymethylfurfural, than the date and maple syrups. The data indicate that carob syrups provide more nutrients and possess superior antioxidant potential to date and maple syrups. The high contents of the carcinogenic hydroxymethylfurfural of the carob syrups warrant milder heating regimens in the concentration step during production.
Novelty and scientific contribution: In contrast to studies based on commercial and/or homemade syrups, this work utilized a relatively large number of laboratory-prepared samples for creating a robust database for carob syrup. The results indicated that carob syrups possess superior health promotion and disease prevention effects than the widely traded date and maple syrups. In addition to their potential positive contribution to public health, carob syrups have been shown to be promising candidates for bolstering the economic returns of farmers in carob-producing countries.
Keywords: Ceratonia siliqua L.; antioxidant capacity; hydroxymethylfurfural; nutritional content; phenolic profile; syrup.