# Analysis of Sushi Rice: Preparation Techniques, Physicochemical Properties and Quality Attributes
## 3 Results and Discussion
### Investigating the Sushi Rice Production Process  
3.2.1. Washing and Soaking Sushi Rice  
The weight variation in rice samples subjected to a combination of different washing durations and subsequent soaking times are presented in Table 2. Washing time significantly (\(p<0.05\)) affected rice weight gain, with notable differences observed between W1 and W3, W4, and W6. Increasing washing time from 200 to 260-350 s appears to improve weight gain (1-2%). Although comparisons such as W1 and W2, as well as W3, W4, and W6, showed no significant differences (\(p<0.05\)), the results indicate that washing duration does influence rice weight gain, particularly within certain time intervals. The working hypothesis was that increasing the rinsing time would result in more water being absorbed during the washing process itself, which would reduce the amount of water that could be absorbed during the soaking process. This hypothesis turned out to be incorrect. On the other hand, it was found that with longer washing times (from 4 min 50 s upwards),the rice stuck more in the rice-forming device, which resulted in nigiri balls with a more irregular shape and weight, requiring the machine to be stopped more often in order to clear out the stuck rice. For all washing groups (Table 2), the rice exhibits a gradual rise in weight gain as soaking time extends from 15 to 45 min. However, no significant differences (\(p<0.05\)) were noted beyond 45 min. This pattern implies that rice achieves its peak absorption capacity within 30-45 min of soaking. Prolonged soaking beyond this period may result in minor weight reduction, likely caused by excessive water absorption (overhydration) or the breakdown and release of starches from the grains. Overall, while minor differences exist between washing groups and soaking durations, the data does not show a statistically significant (\(p<0.05\)) or consistent trend in weight gain. For culinary applications such as sushi rice preparation, washing and soaking processes should aim for balanced hydration, avoiding excessive washing or overly long soaking to maintain grain integrity and prevent undesirable textural changes [11]. Therefore, it was found in the study that rice washing for 230 s was enough to reach a good quality product, and increasing this time not only does not benefit rice quality but might even cause problems during the later forming process. Based on the washing time results, we selected a 230 s washing duration for subsequent soaking and shelf-life quality assessment of sushi rice. Since no differences in rice weight gain were observed during the 15-75 min soaking period, we examined how shorter soaking durations (0-15 min) impact water absorption. We selected these specific time intervals to examine how both short and extended soaking durations affect rice hydration. In Figure 2, it is depicted how varying periods of soaking influence water absorption in sushi rice, consequently altering its total weight. During the initial soaking period (0-3 min), the rice showed a rapid increase in weight, suggesting a quick absorption phase. Initial rice weight increased from 0.75 kg to 0.84 kg during the first 3 min of soaking, demonstrating rapid water uptake. In a comparable study conducted by [PERSON] et al. [32] examining the hydration kinetics of rice, it was found that moisture content increased rapidly within the first 5 min in _Taron Mahali_ (a long variety of rice). The researchers suggested this could be attributed to the presence of surface cracks and internal fissures in the grains, which likely formed during the milling process. In a study by [PERSON] et al. [33], water absorption in _Oryza sativa_ L. rice increased significantly during the first 20 min of soaking, with no further notable increase observed after 30 min. During the soaking period of 3 to 6 min, the weight of the rice stabilized, indicating no further significant increase in water absorption.