Cm 700 minolta spectrophotocolorimeter

The pH of date fruit was determined using a calibrated pH-meter GLP21 (Crison, Barcelona, Spain) on a water suspension (0.5 g sample with 50 mL deionized water blended for 2 min).
The external color of date fruit was measured using a CM-700 Minolta spectrophotocolorimeter (Minolta, Osaka, Japan) in CIELAB mode under CIE Standard Illuminant D65 and observation angle 10°. CIELAB coordinates (lightness (L*), red/green (a*) and yellow/blue (b*)) were obtained from which the psychophysical magnitudes Chroma (C* = (a*² + b*²)^1/2) and Hue (H* = arctg b*/a*) were calculated. Color differences (ΔE* = (ΔL*² + Δa*² + Δb*²)^1/2 between Medjoul and Confitera dates were also calculated.

The pH of the date seed flours with different particle sizes was determined in triplicate by using a GLP21 (Crison, Barcelona, Spain) pH meter with the samples diluted 1:10 in deionized water. The color (CIEL*a*b* coordinates) of the date seed flour was measured in triplicate with a CM-700 Minolta spectro-photocolorimeter (Minolta, Osaka, Japan) equipped with an illuminant D₆₅ and an observation angle of 10°. Lastly, the water activity (aw) of the date seed flours with different particle sizes was determined in triplicate with a Novasina TH-500 (Novasina, Axair Ltd., Pfaeffikon, Switzerland) water activity analyzer at room temperature.