I discovered that granulated dashi prepared with purified water has less unpleasant odor than tap water.

NEW.

It has been found that using purified water is effective for enjoying the original aroma of dashi.

LIXIL Co., Ltd. (hereinafter referred to as LIXIL) discovered that when preparing granulated dashi with tap water in water purification research, residual chlorine in tap water generates aldehydes, which are said to be the cause of unpleasant odor. On the other hand, granulated dashi prepared with purified water that removes residual chlorine can suppress the unpleasant odor derived from aldehydes and reveal the original aroma of dashi can be enjoyed. The types and amounts of components that increase depending on the type of granulated dashi vary, and in this study using three types of chicken, bonito, and kelp, the usefulness of purified water was most prominent with chicken. Part of this research result was presented at the 71st annual meeting of the Japanese Society of Food Science and Technology (August 29-31, 2024, Aichi Prefecture).

■ Research Background
LIXIL believes that enhancing the value of water leads to improving the quality of life, and as a leading company in water-related products, it is pursuing the potential of water through technologies such as water purification. As part of this, LIXIL is earnestly researching the impact of LIXIL products such as water purification cartridges on food.
In this study, we focused on granulated dashi widely used in households and investigated the influence of residual chlorine on components (fragrant components) related to the aroma of granulated dashi.

■ Research Summary
Granulated dashi prepared from tap water and purified water, using chicken, bonito, and kelp, were comprehensively compared for their fragrant components. As a result, in the case of chicken, tap water detected higher levels of three aldehydes (isobutyraldehyde, 2-methylbutyraldehyde, isovaleraldehyde) and 1-vinylaziridine, which are known to be the cause of unpleasant odor compared to purified water. On the other hand, no differences were observed in the original fragrant components of granulated dashi.

Furthermore, aldehydes were more detected in tap water than in bonito and kelp.

Differences were observed in the substances and detection levels of unpleasant odors in each granulated broth, with chicken broth showing the most significant impact of tap water.

Next, in the case of tap water, we investigated the factors causing the increase in unpleasant odors. As a result, it was revealed that the increase in residual chlorine concentration in the water used led to an increase in the substances causing unpleasant odors in chicken broth, bonito, and kelp, and that residual chlorine in tap water is involved in the generation of substances causing unpleasant odors.

This research revealed that granulated broths prepared with purified water that had removed residual chlorine had less unpleasant odor compared to tap water, demonstrating the usefulness of purified water in enjoying the original aroma of the broth.
LIXIL will leverage the insights gained this time to contribute to the development of water purification technology that further enhances the value of water, and work towards realizing the rich and comfortable living environment that everyone desires.