Biological activities of plant polysaccharides currently are of interest because of their benefits to human health. These result in the related products in particular extracts to be in demand for both food and nutritional applications. In the present work, conditions for obtaining maximum values in terms of yield, gel strength, expressible water, and extractant color of polysaccharide extracts from Cladophora sp. (locally called in Thai as ‘Kai') were investigated using response surface methodology (RSM). A Central Composite Design (CCD) with three independent variables: temperature (60–100℃), extraction time (30–118 min) as well as algae concentration (10–60%) was adopted to study those response variables. Data analysis showed that all the variables significantly (p < 0.05) affected the extraction yield, gel strength, expressible water, and b* value, whilst their effects on L* and a* values were statistically insignificant. The optimum parameters obtained by applying a desirability function method were 68℃ extraction temperature, 73 min extraction time, and 31 g Cladophora sp.. Experiments were accordingly conducted using these optimal condition factors, resulting in values of extraction yield, gel strength, expressible water, and b* value of 47.46±0.12%, 554.67±33.94 N, 13.55±0.05%, and 6.24±0.01, respectively. These empirically obtained values were in good agreement with those predicted using the RSM mathematical model. In conclusion, the reported optimal extracting condition technically could be further applied to the extracting processes of Cladophora sp. polysaccharide to obtain maximum yield and high-quality extracts.
Phungam et al. (Sun,) studied this question.