No abstract

Chemically modified rices were prepared by treating with propylene oxide and epichlorohydrin. Gelatinization and retrogradation characteristics of these modified rices were investigated by using DSC and amylograph. Hydroxypropylation of rice caused an extreme decrease in gelatinization temperature from 62°C to 50°C and reduced the retrogradation rate of cooked rice. In rice treated by both hydroxypropylation and cross-linking the retrogradation was reduced more than for hydroxypropylated rice.

A branched oligosaccharides (BOS) mixture was prepared from liquefied corn starch using Bacillus lichenifrmis maltogenic amylase (BLMA). A highly concentrated BOS was prepared by removing glucose and maltose through yeast fermentation, which increased the BOS content. Water activity (a~) of bread went from 0.87 to 0.82 when 10% (w/w) or to 0.78 when 20% (w/w) BOS was added. BOS lowered a, more effectively as concentration of BOS increased. The water sorption isotherm of BOS was much higher than that of sucrose at q, 0.1-0.8. BOS also prevented starch retrogradation in bread, probably due to steric hinderance and to the state of water retained by BOS. Relative sweetness of BOS was -17.5% of sucrose. The BOS mixture produced by BLMA might provide a new type humectant for foods that is low in sweetness and retards retrogradation.

Amylography, scanning electron microscopy and storage tests demonstrated that native pea starches were highly resistant to granule disintegration during heating in dilute slurries, resulting in low hot paste viscosity, high retrogradation and syneresis. Cationization at degrees of substitution of 0.02 to 0.05 reduced the pasting and gelatinization temperatures, increased peak viscosities and set‐back on cooling but eliminated syneresis after storage at 4°C and − 15°C. The principal effects of cationization were to promote rapid granule dispersion at low pasting temperatures, yielding a molecular dispersion of amylose and amylopectin on heating to 95°C. On cooling, the gel structures were firm and the cationic groups controlled the realignment of starch chains during low temperature storage.

One strain of osmophilic Trichosporon sp. which produces highest amounts of erythritol, was isolated from honeycomb. This strain produced highest amounts of erythritol with total glucose utilization in fermentation medium at 35°C and a temperature of 30°C results in an insufficient glucose utilization and lower production of erythritol, but higher growth of cell mass as compared with fermentation temperature of 35°C. An efficient fermentation medium for production of erythritol by the strain was mixture of 30% glucose and 4% corn steep liquor, and using this culture medium, the strain produced 141 g/l of erythritol at 35°C after 3 days of fermentation in 5001‐fermentor. It was also found that yield of microbial cells (Yx/S) to yield of erythritol (Ye/S) was 1:1 during phase of yeast growth and the proportion was changes to 1:10 during stationary phase.