Evaluation of physico-chemical parameters and bio-active compounds of date seeds of fifteen Moroccan cultivars

Date production and processing generate a huge amount of seeds that have interesting food, cosmetic, and medicinal properties. However, they are insufficiently valorised. This work aims to investigate physical and physico-chemical parameters and bio-active compounds of date seed powder (DSP) of 15 Moroccan cultivars. The studied parameters were: color parameters (L*, a*, b*, Cab*,and hab), humidity, total soluble solids, water activity (aw), pH, ash, and minerals. The evaluated bio-active compounds included total betalain, betacyanin and indicaxantin pigments, and total polyphenols. The evaluation of antioxidant activity was also carried out. The results have shown that there is a significant difference between the studied cultivars. The DSP has a high dry matter (DM) rate (89.14-91.66%) with predominance of insoluble solids. It is also characterized by a good stability according to aw values (0.41-0.56). In addition, DSP is rich in potassium and it is slightly acidic with a pH value ranging between 4.96 and 5.62. The content of indicaxanthin yellow pigments exceeds that of betacyanin red pigments. DSP also has high polyphenol contents reaching up to 6.99 g gallic acid equivalent 100 g^‑1 DM and an interesting antioxidant activity (1.95-7.63 g ascorbic acid equivalent 100 g^‑1 DM). Furthermore, the principal component analysis confirmed the divergence between the studied cultivars. ‘Najda’ was distinguished by the highest values of antioxidant activity, total betalains, indicaxanthins, betacyanins, ash, a* and Cab*, and the lowest values of pH, lightness L* and hue angle hab. In addition, ‘Bouittob’ was distinguished by low values of humidity, aw and b*. Some cultivars were characterized by potential characteristics such as ‘Ademou’, ‘Black Bousthammi’, ‘Bouslikhene’, ‘Jihel’, ‘Haoua’, and ‘Najda’. This study highlighted that the DSP is an excellent source of nutritional and bio-active compounds, and antioxidant activity. It could therefore be appropriately used as an ingredient in functional foods and cosmetics.