Date Seed: Rich Source of Antioxidant Phenolics Obtained by Hydrothermal Treatments.

The growing interest in natural compounds is helping to improve the management of agro-industrial by-products such as the date seed as sources of such compounds. In this work, the application of a hydrothermal treatment at 160 and 180 °C for 60 min was studied to achieve the solubilization of its phenolic components and sugars in order to obtain biologically active extracts. The percentage of phenols and total sugars in the final extracts were very similar, at 45 and 25% for the 160 and 180 °C treatments, respectively. The treatment at a higher temperature allowed greater solubilization of other components. The antioxidant activity was measured as free-radical scavenging capacity. For the DPPH• method, expressed as EC50, the results were 0.34 and 0.37 mg/L, the TEAC values for the ABTS• method were 6.61 and 3.28 mg/g dried extract, and the values obtained by the ORAC method were 12.82 and 9.91 mmol Trolox/g dried extract, for 160 and 180 °C, respectively. All these values are higher than those of other plant extracts and extracts obtained using the whole date. Therefore, the date seed is a very important source of phenols, and through thermal and chromatographic processes, it is possible to obtain extracts with high antioxidant activity.

New insights into antityrosinase capacity and polyphenols of asparagus during hydrothermal treatments.

An understanding of the antityrosinase capacity and polyphenols changes during hydrothermal treatments was crucial for application of asparagus. Therefore, asparagus extract was treated at a range of 80-160 °C for 30-150 min in a high temperature reactor. The results suggested that tyrosinase inhibition rate of untreated asparagus extract was recorded as 3.26% but significantly increased to 51.22% and 50.80% after heating for 90 min at 140 °C (lnR0 of 7.21) and 160 °C (lnR0 of 8.57), respectively. The generation and degradation of polyphenols followed the pseudo-first-order kinetic model. The coumaric acid content was increased from 35.03 µg/mL to 307.66 µg/mL at lnR0 of 8.16. The degradation of rutin in asparagus extract was far less compared to that of coumaric acid. Compounds formed were determined by UPLC-Q-TOF-MS yielding main fragments at m/z 451 and 601. In conclusion, hydrothermal treatment was a feasible method for increasing the antityrosinase capacity of asparagus.