Relationship the among of folate content, to free amino acid level, and color of toasted nori

Abstract

　It has been reported that folate (a vitamin) is involved in a variety of physiological functions and is an essential component for normal fetal development during pregnancy. The Ministry of Health, Labor, and Welfare has provided regarding the ingestion of folate supplements (recommended to reduce the risk of prophylaxis) to women planning a pregnancy. However, these supplements are taken by women at a later stage of their pregnancy. Therefore, awareness about the importance of folate and how it can be obtained from foods on a daily basis are required. In this context, focusing on toasted nori, which has a high folate content, we conducted a study on the differences in the folate content among samples of toasted nori and the relationship between its taste and color, which is an important factor when purchasing nori. Upon measuring the folate levels from 10 samples of different regions and grades, it was revealed that the differences in their maximum and minimum levels were more than twice. A color difference analysis revealed that the brighter the yellow and green colors of the samples, the lower the folate levels, whereas the darker the sample colors, the higher the folate levels. To analyze the taste of nori, the levels of four types of free amino acids, known as taste-active amino acids, present in the nori were measured. The result showed the strongest correlation between the free aspartic acid and folate levels. Hence, our study suggests that consumers must observe the color of the toasted nori during purchase as it is correlated with the folate levels.