Color flex spectrocolorimeter

The color parameters of crumb cakes (lightness L*, redness a*, and yellowness b*) were determined with a Color Flex spectrocolorimeter (Hunter Associates Laboratory Inc.,) for 10 days of storage at room temperature (Ben Slima et al., 2017 (link)). The determination of color was carried out in triplicate.

The ash and moisture contents were determined according to the Association of Official Analytical Chemists (AOAC) standard methods [22 ]. While the total crude lipid was determined by gravimetric method after the Soxhlet extraction of samples [21 (link)], the crude protein was identified by the factor of 6.25 after multiplying total nitrogen content. The phenol-sulfuric-acid method was used to determine the total carbohydrate content [21 (link)].
The pH analysis of PLS (1%) was evaluated using a digital pH meter (Systronics Instruments, India). The color of PLS was determined using a Color Flex spectrocolorimeter (Hunter Associates Laboratory Inc., Reston, VA, USA) and reported as luminosity (L∗), red-green intensity (a∗), and blue-yellow intensity (b∗).

Color, pH (1% solution at 25 °C), and viscosity at various concentrations of MLWSP in H₂O (0.5, 1, and 1.5 g L⁻¹) were determined. The color was evaluated using a Color Flex spectrocolorimeter (Hunter Associates Laboratory Inc., Reston, VA, USA) and was reported as L*, a*, and b* values, referring to the measuring parameters of lightness, redness, and yellowness, respectively. The sample was filled in a 64 mm glass cup with three readings. The latter was determined in triplicate. The white tile and black glass were used to standardize the equipment. The pH was measured using a digital pH meter (Mettler-Toledo AG, Schwerzenbach, Switzerland). Viscosity was determined at 25 °C by using a digital viscometer (NDJ-1, Japon) at 30 rpm spindle rotation. The moisture and ash content were determined using the AOAC [58 ] method. Total sugars were determined by the phenol-sulfuric acid method [59 (link)]. Crude fat was determined gravimetrically by Soxhlet extraction of dried samples. Crude protein content was estimated by multiplying total nitrogen content by the factor of 6.25.

Color measurement parameters (lightness L*, redness a* and yellowness b*) were carried out using a color flex spectrocolorimeter (Hunter Associates Laboratory Inc., Reston, VA). L* value indicates the lightness, 0–100 representing dark to light, a* value gives the degree of the green–red color, with a higher positive a* value indicating more red. The b* value indicates the degree of the blue–yellow color, with a higher positive b* value indicating more yellow.

The color of the flour samples was determined by Color Flex Spectrocolorimeter (Hunter Lab D-25, Ruston, USA) which was calibrated using a white reference tile. The results were expressed in terms of L* (lightness/brightness), a* (redness/greenness), and b* (yellowness/blueness) values.