Investigating the chemical and microbial characteristics of date syrup during the production stages (from the raw material to the final product)

The purpose of this study is to investigate the chemical and microbial properties of date syrup during different stages of production line from the raw material to the final product. The amounts of total soluble solids, pH, acidity, total and reducing sugars, polyphenolic compounds, antioxidant activity and microbial count were measured and the type of microorganisms was determined based on phenotypic characteristics in different stages of production. The obtained results showed that during the stages of juice clarification and concentration, pH gradually decreased and acidity, total sugar, reducing sugar and total solid matter increased and reached their maximum in the syrup. Comparison of traditional syrup with factory produced syrup showed more pH and acidity, total and reducing sugar, total soluble solid, polyphenolic compounds and lower antioxidant activity for traditional syrup compared to the produced one. In general, the content of polyphenolic compounds and antioxidant activity gradually decreased in different stages of production, so that date syrup (279 mg of gallic acid per 100 grams of sample and 33%) indicated higher content of polyphenolic compounds and antioxidant activity than dates (388 mg of gallic acid per 100 g of sample and 57%). The results of the microbial test showed the lowest microbial load for the produced syrup compared to dates and different syrups. However, the presence of B. licheniformis in the syrup makes the product sour, in this regard finding a suitable solution to increase the shelf life of the product seems necessary. The traditional syrup showed a lower microbial load than the produced syrup, although B. licheniformis was observed in the traditional syrup despite the high heat treatment. Based on the obtained results, the date syrup was free of coliforms, which indicates maintaining the hygienic principles of manufacture during the production line.