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. 2025 Oct 14;14(20):3496.
doi: 10.3390/foods14203496.

Optimized Alkaline Extraction and Functional Characterization of Carrageenan from Eucheuma perplexum Using Response Surface Methodology

Irene P Daet  1   2 , Tai-Yuan Chen  3 , Sharon N Nuñal  1 , Jose P Peralta  1 , Rhoda Mae C Simora  1 , Meng Chou Lee  4 , Jui-Sheng Chang  5 , Rex Ferdinand M Traifalgar  6
Affiliations

Optimized Alkaline Extraction and Functional Characterization of Carrageenan from Eucheuma perplexum Using Response Surface Methodology

Irene P Daet et al. Foods. .

Abstract

Seaweeds are increasingly valued in the food industry for their bioactive compounds, mainly hydrocolloids like carrageenan. This study investigates E. perplexum, a red seaweed, as a unique and sustainable source of carrageenan with promising functional properties. Using response surface methodology (RSM), the extraction process was optimized through alkaline extraction, identifying optimal conditions of 85 °C for 3 h with 2.58 M KOH, which yielded 77.10% carrageenan. The extracted carrageenan exhibited strong emulsifying activity (71.53 ± 2.41) and color properties comparable to commercial carrageenan, highlighting its viability for food applications. Chemical evaluation revealed a higher sulfate content (8.45 ± 0.16) and slightly reduced carbohydrate levels, which may influence its gelling and stabilizing abilities. Structural examination through ATR-FTIR spectroscopy corroborates the presence of key functional groups, including sulfate esters and galactose derivatives, inferring molecular integrity. These results emphasize the importance of RSM in optimizing extraction and underscore the ability of E. perplexum as a promising source of the derived carrageenan, which is a high-performance additive in food systems. Further research on purification, functional enhancement, and safety assessment is recommended to facilitate its integration into commercial food systems.

Keywords: Eucheuma perplexum; alkaline extraction; carrageenan; emulsifying activity; response surface methodology; seaweed hydrocolloids.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Three-dimensional graphic surface optimization of carrageenan yield of E. perplexum versus extraction temperature and KOH concentration.
Figure 2
Figure 2
Emulsifying stability (ESI) and the ability of E. perplexum. CCGN stands for crude E. perplexum carrageenan, and KCGN for commercial carrageenan. Values are expressed as mean ± standard deviation (n = 3). Error bars represent variability among replicates.
Figure 3
Figure 3
Infrared spectra of the crude carrageenan fraction from E. perplexum (a) and commercial carrageenan from (Sigma-Aldrich Co., St. Louis, MO, USA) product (b).
See this image and copyright information in PMC

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