Development of Subcritical Water Extraction for Areca Alkaloids and Its Influence on the Structure of Areca Nut Husk

The optimal process parameters of subcritical water extraction (SWE) for areca alkaloids in areca nut (AN) husk were described: extraction temperature of 110.87 °C, liquid-to-solid ratio of 18.98:1 and extraction time of 50.01 min. It was found that the factors influencing the process in order of significance were extraction time > extraction temperature > liquid-to-solid ratio. Considering practical conditions, the parameters were adjusted to the extraction temperature of 110 °C, the liquid-to-solid ratio of 19:1 and the extraction time of 50 min. The measured extraction rate was 81.7%, which is close to the predicted value, indicating that the extraction process optimized by Response Surface Methodology (RSM) is feasible. Meanwhile, preliminary results from XRD and FT-IR indicated that SWE had a significant influence on the structure of the AN husk, possibly by damaging some of the crystalline regions of cellulose in the AN husk or reducing the concentration of various functional groups. Overall, this study provided valuable insights in the SWE for areca alkaloids and its influence on the structure of areca nut husk, and further exploration for industrialization is still under development in our laboratory.