## 2 Results and Discussion  
### Color Characteristics and Appearance  
Color is a critical sensory attribute in food product development, significantly influencing consumer perception, acceptability, and purchasing behavior [16]. Hydrocolloids, such as seaweed-derived gelling agents, play a pivotal role in modifying food matrix properties, including chromatic characteristics [17; 18]. The results of color characteristics, including lightness (L*), redness (a*), and yellowish (b*) of drinking jelly made with strawberry fruit concentrate and varying concentrations of GF gelling agent, are shown in Figure 1A-C. The L* values of the drinking jelly samples exhibited a continuous increase, and, overall, the increased concentration of gelling agent had effectively increased the L* value in the samples; however, at lower concentrations, no significant differences were observed. The S1 and S2 samples showed L* values around 40 with no significant differences, whereas the S3-S5 samples showed L* values of 50, 65, and 70, respectively. This indicates that adding GF gelling agent to the drinking jelly progressively increases the lightening effect. [PERSON] et al. [19] reported that adding a seaweed-based gelling agent improved the lightness of the jelly by altering the moisture and sugar content. [PERSON] [20] explored that adding a seaweed gelling agent in the jelly enhanced the color characteristics and overall appeal. Similarly, the a* values in the drinking jelly samples were constantly increased with the GF gelling agent's increased concentration. The S1 samples displayed an a* value of 26, while the S2 samples showed slightly higher a* values (27) and, as the concentration increased, the a* values in the S3-S5 samples increased to 27.7, 34.3, and 34.4, respectively. This indicates a significant increase in the a* value in the samples at higher concentrations of GF gelling agents. [PERSON] et al. [21] reported that natural pigment in the seaweed could contribute to the jelly's color. [PERSON] et al. [22] suggested that the increase in color characteristics is the synergistic effect of both the pigment's natural color and the other jelly ingredients. This is in accordance with the present study, where strawberry fruit concentrate and GF gelling agent contribute to red pigments. On the other hand, the b* values in drinking jelly continuously decreased as the GF gelling agent concentration increased. Among the sample variants, the S1 sample had the highest b* value (6.5), followed by the others, and the S5 sample had the lowest b* value (1.9). The other samples ranged from 2.6 to 4.9 (\(p<0.05\)). This indicates that higher concentrations of the GF gelling agent result in a less yellow hue in the drinking jelly. [PERSON] (2007) reported that using different natural pigments affects the color properties of jelly, certain that elevated levels of red pigment in the jelly could adversely reduce the yellowish. Overall, the color characteristics results indicate that the concentration of the GF gelling agent significantly affects the color attributes of drinking jelly. Increased concentrations of the gelling agent lead to a lighter, redder, and less yellow jelly. This is in accordance with the study of [PERSON] et al. (2014) and [PERSON] et al. (2015). Additionally, the change in color characteristics can be attributed to the interaction between the seaweed gelling agent and the strawberry fruit concentrate, which may influence the overall visual appeal of the product. Among the different concentrations, the optimal concentration of GF gelling agent appears to be around 0.8% (S4), where the jelly achieves a desirable balance of lightness and redness, enhancing its aesthetic appeal. Figure 2 shows the appearance of a strawberry-based drinking jelly made using different concentrations of GF gelling agent. The pictorial reference showed that increasing the GF concentration in the drinking jelly composition significantly affected the consistency and homogeneity of the drinking jelly.