Effect of crude sea grape hydrocolloids extract on the rice starch physicochemical and digestibility properties

The combination of starch and hydrocolloids is widely used in food manufacturing as a thickening agent for texture modification, but a comprehensive understanding of the influence of hydrocolloids on starch properties is lacking. Sea grape (Caulerpa lentillifera) is an underutilized edible green macroalga, which is mainly cultivated in closed systems in Thailand. Here, the effects of a crude aqueous extract of sea grape hydrocolloids on thermal properties, pasting properties, gel morphology, and starch digestibility of rice starch were compared with the addition of carrageenan and sodium alginate, which are the seaweed hydrocolloids widely used in the food industry. Results showed that the addition of crude sea grape hydrocolloid extract increased retrogradation enthalpy similar to carrageenan. The seaweed hydrocolloids also impacted peak viscosity and breakdown of pasting properties. Swollen granules identified in gel morphology studies suggested that the addition of seaweed hydrocolloids restricted starch granule disruption and altered starch digestibility by increasing the rapidly digested starch content. The addition of sea grape hydrocolloids to starch produced a similar outcome to carrageenan and sodium alginate as a possible future substitute.