CONDUCTIVE HYDRO-DRYING OF RED AND BROWN SEAWEED SOURCES FROM SOUTHERN COASTAL ZONES

Introduction

Conventionally, seaweed is sun- or shade-dried. As a novel drying approach, Conductive Hydro-Drying (CHD), a low-temperature drying technique, is finding several applications in the food industry. This study focused on the use of CHD to dry seaweed (red and brown) sourced from the coastal region of Ramnad, Tamil Nadu, India.

Materials

This study investigates the drying behavior of red and brown seaweed to optimize the drying process and improve product quality. The seaweeds were subjected to three temperature treatments: 50, 70, and 90 °C. Due to these temperature treatments, the impact on the seaweeds was identified by analyzing the key parameters, including the drying time, temperature, moisture content, water activity, and color.

Results and conclusion

The initial moisture content was around 78-82% for both types of seaweed. With high temperatures (90°C), the drying time was significantly more reduced than the other temperatures, and the low moisture content was observed (~10%). The drying rate during the constant rate period was relatively high, which allowed for rapid moisture removal. As the moisture content decreased, the drying rate slowed significantly during the falling rate period, indicating the diffusion-controlled nature of moisture removal at lower moisture contents. However, the final moisture content of dried seaweed is 10-11% in the case of red and 14-17% in the case of brown. Significant differences in terms of color and water activity values were observed for both the seaweeds. The low-temperature (50℃) CHD-dried red and brown seaweed had better color retention than that of the other temperatures. This is the first work reported using CHD to dry seaweeds.