2.5. Browning Index

The browning index was determined using the procedure described by Ruangchakpet and Sajjaananta [29] with some modifications. Briefly, 1 g of fresh mung bean sprouts was homogenized in 15 mL of 10% trichloroacetic acid. After a 2 h incubation at 35 °C, the samples were centrifuged at 15,000× g at 25 °C for 15 min.

Changes in the color of the mung bean sprouts were measured using a High-Quality Colorimeter (Envisense). The values of L*, a*, b* were measured. The L* value indicates the lightness of the color, which ranges from 0 (dark) to 100 (white). A positive value of a* indicates a red color, while a negative value of a* indicates a green color. A positive value of b* indicates a yellow color, while a negative value of b* indicates a blue color.

The assessment of browning was carried out by calculating the following formula:

where w = (a* + 1.75L*)/(5.645L* + a* − 0.3012b*).