Studies on utilization and food functionalities of Akamoku (Sargassum horneri) collected in Yamaguchi Prefecture
Title
山口県で収穫された褐藻アカモクSargassum horneri の利用と食品機能性に関する研究
Studies on utilization and food functionalities of Akamoku (Sargassum horneri) collected in Yamaguchi Prefecture
Degree
博士（健康福祉学）
Dissertation Number
甲第30号
(2025-03-18)
Degree Grantors
Yamaguchi Prefectural University
Abstract
This study aimed to clarify the food characteristics and functionality of Akamoku from various perspectives based on samples collected in Yamaguchi Prefecture. This study investigated changes in food characteristics and functionalities when Akamoku was processed, as well as the functionality of consuming commercially processed Akamoku products.
In the examination of food characteristics, we focused on the adhesiveness, adhesion, hardness, cohesiveness, and color differences of Akamoku due to differences in boiling conditions, drying methods, and rehydration temperature conditions. The results suggest that, in terms of boiling conditions, long boiling at 90°C for 3 or 5 min is not suitable from the viewpoints of properties and color. In terms of drying methods, viscosity was enhanced by freeze-drying and the green color was remarkably etained, suggesting that freeze-drying is useful for retaining the viscosity and color of Akamoku.
In the examination of changes in functionalities, we focused on changes in the antioxidative activity of Akamoku due to boiling conditions. Total polyphenol content and DPPH radical scavenging ability were determined using two types of Akamoku from different production areas, harvesting periods, and freezing conditions. The results showed that raw Akamoku of both types had higher polyphenol content and DPPH radical scavenging ability than processed Akamoku. Regarding the effect of boiling temperature on antioxidant properties, there was less variation in polyphenol content and antioxidative activity in the case of boiling at 60°C than in the case of boiling at 90°C, indicating that processing at lower temperatures may be effective in retaining antioxidative activity. Furthermore, a positive correlation was observed between the total polyphenol content and DPPH radical scavenging ability, suggesting that polyphenols play an important role in antioxidant properties.
Regarding the functionality of consuming commercial processed Akamoku products, we aimed to explore the effect of incorporating commercially available boiled Akamoku or microwave-boiled Akamoku into breakfast or lunch meals along with rice on postprandial blood glucose dynamics. The experiment included three distinct test meals: a standard meal comprising rice, soup, and seasoning; an Akamoku-enriched meal incorporating commercially available processed Akamoku with standard components; and a microwave-boiled Akamoku meal with standard meal components. The blood glucose dynamics under these three dietary conditions were compared between healthy adult male and female participants. The results suggested that both boiled Akamoku and microwave-boiled Akamoku reduced postprandial maximum blood glucose level, elevated blood glucose level, duration of elevated blood glucose level, and rate of elevated blood glucose level, but did not reduce blood glucose fall time and incremental area under the curve. These findings suggest that ingestion of Akamoku and heated Akamoku had an inhibitory effect on postprandial blood glucose elevation, but did not impede the bodily absorption of sugars or nutrients.
The findings of this study may increase our understanding of the food characteristics and functionality of Akamoku and promote its consumption. Furthermore, if the consumption of Akamoku expands, it is expected to contribute to the revitalization of local fisheries and fishing villages, as well as efforts to promote the sixth industrialization. Based on these results, future applications of Akamoku in the food industry are expected.
In the examination of food characteristics, we focused on the adhesiveness, adhesion, hardness, cohesiveness, and color differences of Akamoku due to differences in boiling conditions, drying methods, and rehydration temperature conditions. The results suggest that, in terms of boiling conditions, long boiling at 90°C for 3 or 5 min is not suitable from the viewpoints of properties and color. In terms of drying methods, viscosity was enhanced by freeze-drying and the green color was remarkably etained, suggesting that freeze-drying is useful for retaining the viscosity and color of Akamoku.
In the examination of changes in functionalities, we focused on changes in the antioxidative activity of Akamoku due to boiling conditions. Total polyphenol content and DPPH radical scavenging ability were determined using two types of Akamoku from different production areas, harvesting periods, and freezing conditions. The results showed that raw Akamoku of both types had higher polyphenol content and DPPH radical scavenging ability than processed Akamoku. Regarding the effect of boiling temperature on antioxidant properties, there was less variation in polyphenol content and antioxidative activity in the case of boiling at 60°C than in the case of boiling at 90°C, indicating that processing at lower temperatures may be effective in retaining antioxidative activity. Furthermore, a positive correlation was observed between the total polyphenol content and DPPH radical scavenging ability, suggesting that polyphenols play an important role in antioxidant properties.
Regarding the functionality of consuming commercial processed Akamoku products, we aimed to explore the effect of incorporating commercially available boiled Akamoku or microwave-boiled Akamoku into breakfast or lunch meals along with rice on postprandial blood glucose dynamics. The experiment included three distinct test meals: a standard meal comprising rice, soup, and seasoning; an Akamoku-enriched meal incorporating commercially available processed Akamoku with standard components; and a microwave-boiled Akamoku meal with standard meal components. The blood glucose dynamics under these three dietary conditions were compared between healthy adult male and female participants. The results suggested that both boiled Akamoku and microwave-boiled Akamoku reduced postprandial maximum blood glucose level, elevated blood glucose level, duration of elevated blood glucose level, and rate of elevated blood glucose level, but did not reduce blood glucose fall time and incremental area under the curve. These findings suggest that ingestion of Akamoku and heated Akamoku had an inhibitory effect on postprandial blood glucose elevation, but did not impede the bodily absorption of sugars or nutrients.
The findings of this study may increase our understanding of the food characteristics and functionality of Akamoku and promote its consumption. Furthermore, if the consumption of Akamoku expands, it is expected to contribute to the revitalization of local fisheries and fishing villages, as well as efforts to promote the sixth industrialization. Based on these results, future applications of Akamoku in the food industry are expected.
Creators
Saito Yoshiyuki
Languages
jpn
Resource Type
doctoral thesis
Publishers
山口県立大学大学院健康福祉学研究科
File Version
Not Applicable (or Unknown)
Access Rights
open access