Cm 3600d colorimeter

Instrumental measurement of the beetroot juice’s color parameters was performed in the CIE L*a*b* system (L*—lightness; a*—red to green; b*—yellow to blue) using a Konica Minolta CM-3600d colorimeter (Osaka, Japan) [18 (link)]. Determination in fivefold repetition for each sample was made in transmission mode, with the following settings: an illuminant D65, an observation angle of 10°, using a glass cuvette with a layer thickness of 2 mm. The total color difference ΔE* between untreated and HPH-processed juice was calculated by the application of Equation (1).
$${\Delta \mathrm{E}}^{*}=\sqrt{{\left({\Delta \mathrm{L}}^{*}\right)}^2+{\left({\Delta \mathrm{a}}^{*}\right)}^2+{\left({\Delta \mathrm{b}}^{*}\right)}^2}$$

Color parameters of both organic green tea leaves and infusions were measured with a CM-3600d colorimeter (Konica Minolta, Shanghai, China) using the Lab color system. The appearance color of tea samples was measured directly. The tea infusions were prepared according to the national standard (GB/T 23776-2018) [28 ]. Approximately 3.0 g of organic green tea was sampled, 150 mL of boiling distilled water was added, and after 5 min of steeping, the tea infusion was filtered. The color parameters (L*, a*, b*) were then measured after the filtrate cooled to room temperature. L* indicates brightness, with values ranging from 0 to 100, where higher values represent higher brightness. The a* value represents red-green color, with “+” indicating red and “-” indicating green. The b* value represents yellow-blue color, with “+” indicating yellow and “-” indicating blue. ΔE denotes the total color difference [21 (link)]. Measurement of each sample was repeated 9 times.