Pathama Chatakanonda

Relationship of Gelatinization and Recrystallization of Cross-Linked Rice to Glass Transition Temperature

ABSTRACT Nonwaxy rice starch was cross-linked with sodium trimetaphosphate and sodium tripolyphosphate to obtain different degrees of cross-linking (9.2, 26.2, and 29.2%). The objective was to investigate the influence of cross-linking on thermal transitions of rice starch. Starch suspensions (67% moisture) were heated at 2°C/min using differential scanning calorimetry (DSC) to follow melting transition of amylopectin. Biphasic transitions were observed at ≈60–95°C in all samples. Melting endotherms of amylopectin shifted to a higher temperature (≤5°C) with an increasing degree of cross-linking, while there was no dramatic change in enthalpy. Recrystallization during aging for 0–15 days was significantly suppressed by cross-linking. The delayed gelatinization and retrogradation in crosslinked starch were evident due to restricted swelling and reduced hydration in starch granules. Glass transition temperature (Tg) measured from the derivative curve of heat flow was -3 to -4°C. No significant change in Tg w...

The influence of time and conditions of harvest on the functional behaviour of cassava starch: a proton NMR relaxation study

The extent of irrigation of crops in the field not only affects crop yield but also the functionality of the harvested product. This irrigation effect severely affects the processing response of starch harvested from Cassava and leads to industrial quality control problems. In this paper we show how the NMR transverse proton relaxation spectrum is a sensitive probe of the effect of irrigation on cassava starch functionality. The results suggest that increased irrigation results in a looser packing of the amylose and amylopectin chains in the cassava starch granule that facilitates their plasticization and gelatinization.

Effect of calcium ions on ethanol production from molasses by Saccharomyces cerevisiae

One of the most widely used feedstocks for potable or biofuel ethanol fermentation is blackstrap molasses, a byproduct of cane sugar production. Inconsistent quality of molasses frequently found in industrial production, however, makes ethanol production much less efficient and cost-ineffective. Besides fermentable sugars (sucrose, glucose and fructose) present in molasses, calcium is also found in the range of 10–20% of the total carbonated ash (15% by weight). In the sugar process, calcium is usually applied as lime, CaO, during defecation, which sometimes results in over-liming if juice quality is poor. In this study, the role of calcium residues (0–0.72% w/v of Ca2+ in the form of calcium chloride) on fermentation efficiency of yeast was evaluated using model solutions of sucrose, glucose and fructose (20% w/v). The results suggest a detrimental effect of calcium ions on yeast performance which was concentration dependent. A slight decrease in fermentation rates and ethanol yields was evident when calcium was present at 0.18% w/v Ca2+ in all sugar solutions. This effect was more pronounced when calcium ion concentration increased. At 0.72% w/v of Ca2+, the rates of fermentation and ethanol yields of all sugars were considerably decreased (the ethanol yields decreased by 14–25% relative to the control sample, i.e. no calcium ion added). At a very high concentration of Ca2+ (2.16% w/v), yeast fermentation of sucrose was almost absolutely inhibited. This might be, in part, due to the inhibition effect of invertase enzyme for conversion of sucrose to invert sugars, a limiting step in ethanol fermentation of sucrose by yeast. The pretreatment of molasses by acid prior to fermentation was then introduced to remove calcium which improved the fermentation efficiency.

Characterization of Molecular Mobility in Carbohydrate Food Systems by NMR

Pavinee Chinachoti1, Elena Vittadini2, Pathama Chatakanonda3, and Yael Vodovotz4 1Hill’s Pet Nutrition, Inc. and Subsidiaries, Topeka, KS 66617, USA; 2Universita degli Studi di Parma, Dipartimento di Ingegneria Industriale, 43100 Parma, Italy; 3Cassava and Starch Technology Research Unit, Kasetsart Agricultural and Agro-Industrial Product Improvement Institute (KAPI), Kasetsart University, Bangkok 10900, Thailand; and 4Department of Food Science and Technology, The Ohio State University, Columbus, OH 43210, USA

Influence of reaction parameters on carboxymethylation of rice starches with varying amylose contents

The influence of reaction parameters on the carboxymethylation of rice starches with different amylose contents was investigated. Rice starches with varying amylose contents showed various degrees of susceptibility to the reaction conditions. The maximum degree of substitution (DS) for all three rice starches was obtained under similar reaction conditions which involved a reaction medium consisting of isopropanol-water at the ratio of 90:10, a molar ratio of NaOH:AGU at 1.5 and a reaction temperature and time of 40°C and 3 h. Under these conditions, the DS for all rice starches was similar; however, when the reaction was performed under conditions using lower NaOH concentration, the effect of starch types on the DS was observed. The results could be explained in terms of the granular/structural features of the different rice starches, their degrees of granular swelling as influenced by the reaction conditions and the accessibility of the etherifying reagents to starch molecules.

Physical structure behavior to wettability of electrospun poly(lactic acid)/polysaccharide composite nanofibers

Poly(lactic acid) has been electrospun into submicron fibers with embedded cassava starch matrix. The fibers had average fiber diameters between 140 and 680 nm. The starch content varied from 10 to 20% in total solids. Water contact angles were measured on sheets of these fiber materials and correlated with the fiber size and starch content. Water contact angles varied from 80 to 120° which shows that the fiber composition can control the mat properties from hydrophilic to hydrophobic. The results also showed variation in the average fiber diameters alone did not always affect sheet wettability. These results show the importance of the relationship between the electrospun fiber sheet topography and material composition to the wettability of polysaccharide electrospun nanofibers.