## 3 Results
### Physico-Chemical Parameters of the Tested Rice Drinks
#### 3.2.3 Colour Parameters of the Studied Rice Drinks  
Based on the tests conducted, significant (\(p\) < 0.05) differences were found in all colour parameters in the CIE L*a**b*** colour space of each of the rice drinks tested (Table 4). Comparing the colour parameter L*, describing brightness, it can be seen that all the beverages were characterised by very high brightness, ranging from about 75 to 85. The colour parameters a* relating to red (+a*) and green (-a*) tones differed significantly in the rice beverages tested; nevertheless, all the beverages were characterised by a colour shift towards red tones. The beverages tested in this study also showed positive values for the parameter b*, meaning that a colour shift towards yellow characterized them. There are little data in the available literature on the colour parameters in the CIE L*a**b*** colour space of rice drinks. [PERSON] et al. (2023) [31] showed the brightness of commercial rice drinks at 77.35 \(\pm\) 0.13, which is close to the results obtained in this work. Similar values for this parameter were demonstrated by the same authors for rice drinks based on white rice (from 83.61 \(\pm\) 0.46 to 84.59 \(\pm\) 0.53). In turn, the rice drinks they produced from red rice were characterised by significantly lower values of the L* parameter (from 51.40 \(\pm\) 0.57 to 61.67 \(\pm\) 0.16), while the products based on black rice were significantly the darkest (from 28.11 \(\pm\) 0.23 to 30.19 \(\pm\) 0.58). All rice drinks tested in this study were characterised by positive values of the a* parameter, which ranged from 3.14 \(\pm\) 0.03 to 6.87 \(\pm\) 0.06. According to the literature, com \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Beverage Code** & **L*** & **a*** & **b*** & **White Index** \\  & & & & **(WI)** \\ \hline RB\_1 & 80.29 \(\pm\) 0.02 f & 3.14 \(\pm\) 0.03 a  & 17.46 \(\pm\) 0.49 d  & 82.23 \(\pm\) 0.09 e  \\ RB\_2 & 83.39 \(\pm\) 0.01 h  & 5.89 \(\pm\) 0.01 e  & 13.87 \(\pm\) 0.26 a  & 84.74 \(\pm\) 0.04 f  \\ RB\_3 & 78.41 \(\pm\) 0.06 c  & 5.94 \(\pm\) 0.04 e  & 17.35 \(\pm\) 0.18 d  & 80.53 \(\pm\) 0.09 c  \\ RB\_4 & 75.14 \(\pm\) 0.10 a  & 3.72 \(\pm\) 0.01 b  & 19.89 \(\pm\) 0.12 f  & 77.82 \(\pm\) 0.06 a  \\ RB\_5 & 76.26 \(\pm\) 0.15 b  & 6.34 \(\pm\) 0.04 f  & 19.84 \(\pm\) 0.57 f  & 79.06 \(\pm\) 0.29 b  \\ RB\_6 & 79.79 \(\pm\) 0.20 e  & 3.89 \(\pm\) 0.01 c  & 17.57 \(\pm\) 0.42 d  & 81.80 \(\pm\) 0.29 d  \\ RB\_7 & 78.99 \(\pm\) 0.41 d  & 5.30 \(\pm\) 0.06 d  & 18.58 \(\pm\) 0.47 e  & 81.32 \(\pm\) 0.50 d  \\ RB\_8 & 82.47 \(\pm\) 0.47 s  & 6.25 \(\pm\) 0.09 f  & 15.86 \(\pm\) 0.20 c  & 84.22 \(\pm\) 0.50 f  \\ RB\_9 & 84.87 \(\pm\) 0.12 l  & 3.89 \(\pm\) 0.10 c  & 14.59 \(\pm\) 0.40 b  & 86.20 \(\pm\) 0.18 g  \\ RB\_10 & 78.11 \(\pm\) 0.11 c  & 6.87 \(\pm\) 0.06 s  & 16.06 \(\pm\) 0.09 c  & 80.03 \(\pm\) 0.12 c  \\ \hline \hline \end{tabular} Mean values \(\pm\) standard deviation with different letters (a*) in the same column differ significantly (Duncan’s test, \(p\) < 0.05).  
\end{table} 
Table 4: Colour parameters of the tested beverages and their whiteness index. mercial rice drinks had a much lower value of this parameter (2.09 \(\pm\) 0.20) [31]. Regarding rice drinks made from white rice, [PERSON] et al., 2023 [31] showed negative values (from \(-\)1.44 \(\pm\) 0.03 to \(-\)2.14 \(\pm\) 0.08), indicating a greater colour shift towards shades of green. In turn, drinks obtained by the same authors based on black and red rice were characterised by a more significant colour shift towards shades of red, obtaining a* parameter values ranging from 7.05 \(\pm\) 0.14 to 10.37 \(\pm\) 0.34 and from 12.03 \(\pm\) 0.16 to 13.81 \(\pm\) 0.17, respectively [31]. In the research conducted in this study, rice drinks were characterised by b* parameter values ranging from 13.87 \(\pm\) 0.26 to 19.89 \(\pm\) 0.12, which was confirmed by other studies. For commercial rice drinks, this parameter averaged 16.34 \(\pm\) 0.07.