Developing a bioactive brew is a novel track for revalorization of palm date byproducts. The effect of roasting temperature (160, 180 and 200 °C ) and roasting time (10, 20 and 30 min) on the hardness of the roasted date seeds, moisture content of the defatted roasted date seed powder (DRDSP), bulk density of the DRDSP, color parameters of DRDSP, quality attributes (extraction yield, pH and browning index), the chemical properties (antioxidants and total phenolic content) and the sensory attributes (color, aroma, taste and overall preference) of the brew prepared from DRDSP was studied. The physicochemical, quality, and sensory attributes were found to be significantly influenced by the roasting temperature and time. Additionally, the models proposed could satisfactorily describe the changes in the different properties during the roasting process. The optimum conditions of the roasting process obtained using the superimposed contour plot were 199.9 °C and 21.5 min. In the longer term, the results of this study would be beneficial for the manufacturers of the date seeds powder and brew.

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Dynamic vapor sorption equipment (AQUADVS) was used to determine adsorption and desorption isotherms for powder rich in fiber (PRF) produced from Palm Date flesh of Sifri cultivar (Phoenix dactylifera L.) at temperatures 25, 35 and 45 °C in a wide range of water activity (0.09–0.87). Equilibrium was achieved within 29 and 25 h for the adsorption and desorption process respectively. The obtained data were fitted to ten models (Peleg, GAB, BET, Halsey, Oswin, Smith, Modified Henderson, Adam and Shove, Modified Oswin and Modified Halsey). The results indicated that the PRF followed type III behavior. The empirical Peleg model was found to be the best to represent the experimental data in the water activity range 0.09–0.87. The isosteric heat of sorption and the differential entropy decreased by increasing the moisture content and can be predicted by polynomial functions. Glass transition temperatures (Tg) of PRF were determined. The Tg decreased as the moisture content increased and can be correlated using the Gordon and Taylor model (R2=0.976). The PRF should be stored at moisture less than 9 d.b.% and temperature less than 35 °C.

Full-fat roasted date seeds are considered an excellent source of antioxidants which can treat many diseases. The specific objectives were to investigate the effect of roasting temperature and time on the hardness of whole seeds, moisture content of the roasted date seeds powder, DPPH radical scavenging activity, total phenolic contents, extraction yield, pH, browning index and sensory properties of the brew prepared from the full-fat roasted date seeds and to construct descriptive models that could describe this effect. Date seeds were roasted at three temperatures (160, 180 and 200 °C) for different period of times (10, 20 and 30 min) using a natural conventional oven; then grinded and next brewed. Hardness of whole seeds, moisture content of the seeds powder, DPPH radical scavenging activity and total phenolic contents, extraction yield, pH and browning index and sensory properties of the brew were significantly affected by the roasting conditions. The statistical results indicated that the proposed model could adequately describe the measured properties. Strong correlations have been found among the properties of the brew as well. The producers of the date seeds brew can utilize these results for controlling the roasting process.