Effects of temperature and pressure on the vacuum drying characteristics of red seaweed kappaphycus alvarezii

The Philippines is one of the top producers of seaweed products such as carrageenan. The country's seaweed industry is considered as a major economic contributor to the aquaculture industry. However, the current method of sun drying the seaweeds may still be improved in terms of quality and capacity. To further understand the material behavior of seaweeds, this study proposes to characterize the drying behavior of red seaweed (Kappaphycus alvarezii) by means of a vacuum dryer. The study aims to evaluate the effects of the temperature and pressure in drying the red seaweed. Drying experiments were conducted in a vacuum oven at chamber temperatures of 50, 60, and 70 °C, with drying pressures ranging from 10 kPa to 20 kPa. The effects of drying temperature and pressure on the moisture ratio and the drying rate of seaweed samples were illustrated by generating drying curves. The results showed that increasing the drying temperature significantly decreased the drying time of the seaweed samples. However, the vacuum pressure induced in the oven effected insignificantly. The generated drying curves on the said samples demonstrated a gradual decrease in the moisture content with respect to the drying time, until it reached equilibrium like many other drying characteristics on various samples. Statistical analysis verified that only the drying temperature had a significant effect on the vacuum drying process.