Osmotic dehydration of Kappaphycus alvarezii

The red alga Kappaphycus alvarezii has been reported to be a potential raw material for functional food due to its high content of soluble dietary fibre, mineral, omega-3 fatty acids as well as a substantial amount of essential amino acids. In order to benefit from these excellent nutritional properties, this project aimed to develop a high-value dehydrated snack from K. alvarezii using osmotic dehydration (OD) treatment prior to hot air-drying. A 3?×?3 factorial design with 50°, 60° and 70°Brix sucrose concentration as well as treatment temperatures of 30, 35 and 40 °C were used. In general, an increase in sucrose concentration and temperature promoted mass transfer. OD treatment using 70°Brix sucrose concentration at 40 °C caused case hardening of the seaweed that reduced the solid gain (p?<?0.05). Firmness of the seaweed increased with sucrose concentration and was not altered by temperature (p?<?0.05). The colour of the seaweed was not affected by OD treatment (p?>?0.05), but dehydrated seaweed became darker at high sugar concentration. Interaction effect between sucrose concentration and temperature was found to affect the water loss and solid gain of the OD treatment (p?<?0.05). The best sensory acceptable dehydrated seaweed was successfully identified. The final product contained high dietary fibre and very low Na/K ratio.