Water sorption isotherms and air drying kinetics modelling of the brown seaweed Bifurcaria bifurcata

Moisture sorption characteristics of probiotic‐fermented sea tangle powder and its thermodynamic properties

“…At all temperatures tested, the X eq increased linearly as the a w increased up to about 0.7, and then increased sharply with further increases in a w . This is typical J‐shaped type III moisture sorption behavior, which was also reported for several other brown and red algae, such as F. vesiculosus (Moreira, Chenlo, Sineiro, Arufe, et al, ), B. bifurcate (Moreira, Chenlo, Sineiro, Sánchez, et al, ), K. alvarezii (Senthil et al, ), Gracilaria (Lemus et al, ), and Gelidium sesquipedale (Mohamed et al, ). The high carbohydrate contents (42.71–65.74%) appear to primarily be responsible for the type III sorption behavior of the sea tangle powders (Brunauer, Deming, Deming, & Teller, ).…”

“…Smaller values of X eq were measured at a higher temperature in the entire a w range (Figure a); this was attributed to the higher temperature providing more kinetic energy to water molecules, which promoted the desorption of water molecules from their binding sites and thus resulted in a less hygroscopic powder (Palipane & Driscoll, ). A similar effect of temperature on moisture sorption was also reported for other brown and red algae, such as B. bifurcate , Gracilaria , and G. sesquipedale , at temperatures between approximately 5 and 55°C (Lemus et al, ; Mohamed et al, ; Moreira, Chenlo, Sineiro, Sánchez, et al, ). However, the opposite effect of temperature was reported for some dried fruits, such as raisin and date, which contain high amounts of sugar, but relatively low amounts of insoluble solids and proteins (Myhara & Sablani, ).…”

“…Within the linear increase region ( a w < 0.7), the X eq was less than about 0.4 g water/g dry matter, but this value dramatically increased to 1.13 g water/g dry matter at 37°C, 1.29 g water/g dry matter at 25°C, and up to 2.40 g water/g dry matter at 4°C as the a w further increased above 0.9 (Figure a). This moisture sorption capacity of the probiotic‐fermented sea tangle powder was higher than that reported for other seaweeds, in which the X eq was generally about 0.1–0.2 g water/g dry matter in the linear increase region ( a w values below about 0.6–0.7) and increased up to about 0.65–1.2 g water/g dry matter as the a w increased further to about 0.9 (Lemus et al, ; Mohamed et al, ; Moreira, Chenlo, Sineiro, Arufe, et al, ; Moreira, Chenlo, Sineiro, Sánchez, et al, ; Senthil et al, ). Due to their high moisture sorption capacity, the sea tangle powders placed at a w > 0.5 developed water bridges between the particles during the initial storage period, and were transformed to rubbery and even liquid states during storage, as shown in the pictures of Figure a.…”

“…Moreira, Chenlo, Sineiro, Arufe, et al () reported that the q st of F. vesiculosus (a brown alga) decreased from 21.24 to 0.01 kJ/mol as the X eq increased from 0.07 to 0.34 g water/g dry matter. Moreira, Chenlo, Sineiro, Sánchez, et al () also reported a decrease in the q st value of B. bifurcate (a brown alga), from 18.67 to 0.04 kJ/mol, as the X eq increased from 0.05 to 0.17 g water/g dry matter. The q st of the probiotic‐fermented sea tangle powder decreased much more slowly as the X eq increased, in comparison to the q st values reported for the other two brown algae.…”

“…Halsey, Guggenheim–Anderson–de Boer (GAB), and modified Brunauer–Emmett–Teller (BET) models have been successfully used to describe the moisture sorption isotherms of the algae. The net isosteric heat of sorption of water ( q st ) values measured for F. vesiculosus , B. bifurcate , and G. sesquipedale revealed a trend toward an exponential decrease as the X eq increased (Mohamed et al, ; Moreira, Chenlo, Sineiro, Arufe, et al, ; Moreira, Chenlo, Sineiro, Sánchez, et al, ). Thermodynamic analyses revealed that moisture sorption was an enthalpy‐driven process for F. vesiculosus and B. bifurcate (Moreira, Chenlo, Sineiro, Arufe, et al, ; Moreira, Chenlo, Sineiro, Sánchez, et al, ).…”