## 4 Conclusions  
The present work showed that thermo-ultrasonic treatment can improve the nutritional properties and emulsion stability of sea bass fish head broth. Short-term thermo-ultrasonic treatment can primarily increase the rate and amount of extraction of proteins, fats and total sugars. Nutrient concentration of a boiling water bath for 120 min can be achieved by thermal sonication for 30 min. The concentration of hexanal, nonanal, 1-octen-3-ol and 2-pentylfuran in the thermo-ultrasonic treatment groups was higher than the boiling water groups. Further, thermo-ultrasonic treatment can reduce the particle size and improve the storage stability of fish head broth. This is mainly due to the cavitation and mechanical breaking force of an ultrasound on fish head tissue and the fat globules of fish broth. Therefore, we can use thermo-ultrasonic technology to develop ready-to-eat fish broth products with higher nutrient content and superior storage stability. Ready-to-eat fish broth products can provide a richer diet and as a source of nutrition for special groups such as pregnant women and the elderly. As the effects of seasonings such as salt and ginger were not considered in this study, in the future, we will pay more attention to the flavor and taste of ready-to-eat fish broth.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/foods13162498/s1](https://www.mdpi.com/article/10.3390/foods13162498/s1)]([https://www.mdpi.com/article/10.3390/foods13162498/s1](https://www.mdpi.com/article/10.3390/foods13162498/s1)), Figure S1: The \(a^{\star}\) and \(b^{\star}\) values of fish broth by different treatment; Table S1: Free amino acids (FAAs) of the sea bass fish head broth.  
Conceptualization, H.L. and X.L.; methodology, H.L. and X.L.; validation, W.Z. and S.L.; formal analysis, H.L., X.L. and W.Z.; investigation, S.L. and J.L. ([PERSON]); resources, [PERSON] ([PERSON]), X.Z. and Z.H.; data curation, H.L. and X.L.; writing--original draft preparation, H.L. and X.L.; writing--review and editing, [PERSON] ([PERSON]), X.Z. and Z.H.; visualization, [PERSON] ([PERSON]) and Z.H.; supervision, Z.H.; project administration, Z.H.; funding acquisition, [PERSON] ([PERSON]) and Z.H. All authors have read and agreed to the published version of the manuscript.  
The National Natural Science Foundation of China (32372474, 32172348, 31972205), the S&T Project of Yangjiang (SDZX2020012), Key Science and Technology projects of the Xinjiang Uygur Autonomous Regions (2022A02002-4), the 111 Project (B17018), and the Guangdong Provincial Key Laboratory of Intelligent Food Manufacturing (2022B1212010015). China Postdoctoral Science Foundation (2022M721196), and Basic and Applied Basic Research Foundation of Guangdong Province (2022A1515110186).  
Not applicable.  
The original contributions presented in the study are included in the article/Supplementary Materials, further inquiries can be directed to the corresponding author.  
Figure 8: Schematic diagram of the thermo-ultrasonic treatment on fish broth.  
**Acknowledgments:** The authors are grateful to the National Natural Science Foundation of China (32372474, 32172348, 31972205), S&T Project of Yangjiang (SDZX2020012), Key Science and Technology projects of the Xinjiang Uygur Autonomous Regions (2022A02002-4), 111 Project (B17018) and Guangdong Provincial Key Laboratory of Intelligent Food Manufacturing (2022B1212010015), China Postdoctoral Science Foundation (2022M721196), and Basic and Applied Basic Research Foundation of Guangdong Province (2022A1515110186).  
**Conflicts of Interest:** The authors report no conflicts of interest.