Distribution of saccharides and salts on amphoteric ion-exchange resin.

An amphoteric ion-exchange resin hardly shrank in 550 and 300 g/L glucose and sodium chloride solutions, respectively; however, the bed packed with a cation-exchange resin shrank considerably. From the distribution coefficients of some saccharides, the swelling pressure of the amphoteric ion-exchange resin was estimated to be 2.0 MPa at 25 °C. The distribution coefficients of glucose, galactose, fructose, and mannose were independent of their concentration and were about 0.621. On the other hand, the apparent distribution coefficients of NaF, NaCl, NaBr, NaI, LiCl, KCl, and CsCl largely depended on concentration. A model for the distribution of salts on the amphoteric resin was proposed, assuming an interaction between the anion of the salt and the positively charged fixed ions with binding constant B. The B values of the chloride salts were nearly the same (1.69-2.94 L/mol), while the values of the sodium salts were largely different depending on the anion.

Characterization of Spaghetti Prepared Under Different Drying Conditions.

Spaghetti dried at low (max. 50 °C), high (max. 70 °C), and very high (max. 85 °C) temperatures were characterized by their color, surface structure, rupture strength, texture analysis, and sauce retention capacity. The texture and sauce retention capacity were estimated for cooked spaghetti. The color of the spaghetti's methanol extracts, as evaluated through absorbance at 440 and 466 nm, did not depend on the drying temperature. A trend was observed in the surface texture of spaghetti, as estimated by atomic force microscopy and mercury intrusion porosimetry, where the surface was rougher when dried at higher temperatures than at low temperatures. Furthermore, the rupture strength was also higher for the spaghetti dried at higher temperatures. This result can be ascribed to the formation of stronger gluten networks, promoted by denaturation of gluten at the higher temperatures. However, the hardness of cooked spaghetti was not affected by the drying temperature, a result attributable to the action of water sorption to offset any differences in hardness among the spaghettis dried at the 3 different temperatures. The sauce retention capacity of cooked spaghetti was evaluated using a dextran solution as a simulated sauce, and by this method, the capacity of the spaghetti dried at a low temperature was shown to be significantly lower than that of the spaghetti dried at higher temperatures. This can be ascribed to the smoother surface of cooked spaghetti dried at the lower temperature and also to the leakage of amylose onto the surface during cooking.