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This study was conducted to determine the optimal temperature and time for the regiospecific oxidation of primary alcohol groups in corn starch with 2,2,6,6-tetramethyl-1-piperidinyl oxoammonium ion (TEMPO) and sodium hyphochlorite (NaOCl). The study also elucidated the molecular structure of fully oxidized corn starch (FOCS) prepared at optimum temperature and physicochemical properties of the partially (10%, 20%, and 30%) oxidized corn starches (POCS). The reaction time rapidly decreased up to 30 degrees C, and then gradually decreased. Selectivity, yield, and viscosity were drastically reduced at temperatures higher than 35 to 40 degrees C. Optimal oxidation temperature for the production of FOCS was determined as 35 degrees C. Regiospecific oxidation of the primary alcohol group without oxidation of the secondary alcohol group was confirmed in (13)C-NMR and IR spectra. Water-binding capacity, swelling power, solubility power, and transmittance of POCS increased as the degree of oxidation increased. Hardness, gumminess, and chewiness of corn starch gel containing POCS were not significantly different from those of native corn starch gel at 1-d storage, but the values of the starch gel containing POCS were smaller than those of the native starch gel after 1-d storage. However, springiness and cohesiveness did not differ significantly among the samples regardless of storage time.

This study examined the characteristics of the oxidation reaction on the primary alcohol groups in cellulose involving the 2,2,6,6-tetramethyl-1-piperidinyl oxoammonium ion (TEMPO) and determined the optimum conditions for the preparation of oxidized cellulose (OC). The applicability of OC in polysaccharide systems was also investigated. The effects of TEMPO, sodium bromide (NaBr), and temperature on the oxidation reaction time, yield, and selectivity for primary alcohol groups were examined using response surface methodology (RSM). The reaction time decreased with increases in the temperature and the levels of TEMPO and NaBr. The yield increased with the level of NaBr and decreased as the temperature increased. Selectivity increased with the temperature and decreased as the levels of TEMPO and NaBr increased. The optimum levels of TEMPO and NaBr and the optimum temperature for the production of OC were determined as 0.3 mM/100 mM anhydroglucose unit (AGU), 50 mM/100 mM AGU, and 25 degrees C, respectively. The water and oil binding capacity and viscosity of cellulose increased with oxidation. Wheat starch containing OC exhibited a decreased initial pasting temperature and setback, but increased peak viscosity, gelatinization, and retrogradation enthalpy (DeltaH). The hardness of the wheat starch gel decreased significantly upon the addition of OC.

Franubet, a mutant of Nubet, had grains of smaller weight, less starch, but greater protein content than did Nubet. Nubet starch had simple granules with bimodal granule size distribution (diameters of 9–22 and 1.2–4 μm for the A and B granules, respectively), whereas Franubet starch had smaller (diameters of 1–4 μm) and irregular-shaped granules, and some displayed compound starch granules. There were no significant differences in X-ray diffraction pattern and amylose content, but Nubet starch had a greater phosphorous (0.045%) and bound lipid (0.61%) content than Franubet starch (0.026 and 0.47%, respectively). Franubet amylopectin (AP) had similar proportions (4.0%) of chains with DP 6–9 and larger proportions (21.5%) of chains with DP >37 than did Nubet AP (4.2 and 19.7%, respectively). Franubet starch showed lower onset gelatinization temperature (52.8 °C) and smaller enthalpy change in melting of amylose–lipid complex (0.5 J/g) than did Nubet starch (54.6 °C and 1.0 J/g, respectively). Franubet starch displayed a lower pasting temperature, less final and setback viscosity but greater peak and breakdown viscosity, which could be attributed to its lower lipid and phospholipid content.

If a chi-squared analysis were to be performed to determine whether preferences were significant in a paired preference test, the appropriate expected frequencies in the analysis would represent those that would occur should the consumers have no preference. One way of determining these ‘no preference’frequencies, for a particular test situation, would be to note the preference responses obtained when the stimuli were putatively identical. Over 2000 consumers were given paired preference tests in which the stimuli were putatively identical. Response conditions and consumer groups were varied and the proportions of preference and no preference responses were noted. In a preliminary experiment, further research was seen to be justified when for putatively identical stimuli, judges did not exclusively express lack of preference; many expressed a preference for one or other of the stimuli. Further experiments were conducted using a written response condition and putatively identical potato chips (potato crisps) as stimuli. Using a single ‘no preference’option, variation in the placement of this option at either first, second or third place on the response sheet had no significant effect on the response frequencies. The proportion of ‘no preference’responses was approximately 30% in all cases. A previously reported 40-20-40 distribution was not always confirmed. The experiment was repeated with Korean consumers; these had fewer ‘no preference’responses. Deriving preferences from hedonic scales, rather than having judges respond to preference options, increased the proportion of ‘no preference’responses, with American judges still having more than Korean judges. Yet there are logical objections to extracting preference data from hedonic scales. Increasing the number of ‘no preference’options to two or three, had the effect of increasing the number of ‘no preference’responses up to as much as approximately 60%. Extending the results to Koreans, using two ‘no preference’options, it was seen that only the judges in an anonymous response condition had significantly fewer ‘no preference’responses than Americans. The use of these response frequencies as expected frequencies in chi squared analyses was illustrated, after adjustments for counterbalancing.

This is the first report on regulation of the isoamylase1 gene to modify the structure of amylopectin and properties of starch by using antisense technology in plants. The reduction of isoamylase1 protein by about 94% in rice endosperm changed amylopectin into a water-insoluble modified amylopectin and a water-soluble polyglucan (WSP). As compared with wild-type amylopectin, the modified amylopectin had more short chains with a degree of polymerization of 5-12, while their molecular sizes were similar. The WSP, which structurally resembled the phytoglycogen in isoamylase-deficient sugary-1 mutants, accounted for about 16% of the total alpha-polyglucans in antisense endosperm, and it was distributed throughout the whole endosperm unlike in sugary-1 mutant. The reduction of isoamylase activity markedly lowered the gelatinization temperature from 54 to 43 degrees C and the viscosity, and modified X-ray diffraction pattern and the granule morphology of the starch. The activity of pullulanase, the other type of starch debranching enzyme, in the antisense endosperm was similar to that in wild-type, whereas it is deficient in sugary-1 mutants. These results indicate that the isoamylase1 is essential for amylopectin biosynthesis in rice endosperm, and that alteration of the isoamylase activity is an effective means to modify the physicochemical properties and granular structure of starch.

The objectives of this study were to characterize starches isolated from potato, canna, fern, and kudzu, grown in Hangzhou, China, for potential food and nonfood applications and to gain understandings of the structures and properties of tuber and root starches. Potato and canna starches with B-type X-ray patterns had larger proportions of amylopectin (AP) long branch chains (DPor=37) than did fern (C-type) and kudzu (C(A)-type) starches. The analysis of Naegeli dextrins suggested that fern and kudzu starches had more branch points, alpha-(1,6)-D-glycosidic linkages, located within the double-helical crystalline lamella than did the B-type starches. Dispersed molecular densities of the C- and C(A)-type APs (11.6-13.5 g/mol/nm(3)) were significantly larger than those of the B-type APs (1.4-6.1 g/mol/nm(3)) in dilute solutions. The larger proportion of the long AP branch chains in the B-type starch granules resulted in greater gelatinization enthalpy changes (Delta H). Retrograded kudzu starch, which had the shortest average chain length (DP 25.1), melted at a lower temperature (37.9 degrees C) than the others. Higher peak viscosities (550-749 RVU at 8%, dsb) of potato starches were attributed to the greater concentrations of phosphate monoesters, longer branch chains, and larger granule sizes compared with other tuber and root starches.