Moisture Sorption Characteristics of Kudzu Starch and Sweet Potato Starch

Abstract

Moisture sorption characteristics of kudzu starch and sweet potato starch were investigated based on the results of moisture sorption isotherms at ll"C, 20°C and 3o"C, thermal analysis, isosteric heat of sorption and entropy of sorption. The water of crystallization in sweet potato starch was strongly retained compared with that in kudzu starch. Differences in amount of moisture sorbed between kudzu starch and sweet potato starch seemed to be attributable to the stability of the microscopic structure. The interaction of moisture-sweet potato starch was stronger than that of moisture-kudzu starch. Amount of moisture sorbed and strength of moisture-starch binding of the starches, preheated to llO"C, decreased compared with those of the starches vacuum-dried at 20°C because of release of water from the amorphous part of the starch granule.

Some Physiochemical Properties of Large, Medium and Small Granule Starches in Fractions of Wheat Grain.

“…The moisture content of starch granules at each relative humidity tended to increase in the order of large, medium and small in the same fractions, as well as from the surface layer to the center, especially at 98% relative humidity. Boki et al (1990) speculated that the difference in water activity for starches can be ascribed to the difference in strength of moisture-starch interaction and the submicroscopic structure of the starch granule. Hence, it may be that the moisture sorption properties at saturated relative humidity are primarily dependent on the surface area, not the internal structure, of the granules.…”

Optimization of the drying of <i>Moringa oleifera</i> leaves by determination of thermophysical parameters

“…The existence of polar sites of great activity in the Moringa oleifera leaves which are covered with water molecules forming the monolayer (Benseddik et al, 2014) could explain this fact. According to other authors (Boki et al, 1990;Salgado et al, 1994), this phenomenon is due to the fact that in a very restricted field of moisture, when the moisture content increases, certain products inflate and favours the opening of new sites of adsorption of strong joining, which increases isosteric heat. In the Table 4, one observes with the increase in the temperature, it occurs a reduction in the moisture content characteristic (X o ).…”

Relationship between monolayer and multilayer water contents, and involvement in gelatinization of baked starch products

“…Caurie (1971) concluded that the condensed water is likely to be water occurring over A w 0.784. For starch powders, the changes in water sorption can be observed at A w 0.6-0.8, indicating a microporous structure (Boki et al, 1990;Boki and Ohno, 1991), and Cadden (1988) reported that the sorbed water changes at around A w 0.7 in the A w -water content relationship. In addition, Fringant et al (1996) reported that water retention increases especially over $A w 0.8, and these results therefore may indicate the existence of a discontinuous water layer over A w 0.7-0.8.…”