RESUMO
Starches from different potato cultivars were characterized as amylose and phosphorus content, crystallinity, thermal and paste properties. Statistical analysis of amylose content showed difference between starches samples and the cultivars Asterix and BRS Clara showed higher contents than others. Phosphorus content ranged from 633 to 966.7 mg kg(-1). The X-ray diffraction analysis showed that the crystallization of potato starches can be classified as B-type X-ray pattern, presenting crystallinity index ranging from 20.02% to 21.59%. Regarding thermal properties, the onset temperature did not show statistical difference between starch samples, in gelatinization and retrogradation analysis. As expected there was a significant decrease in peak temperature and enthalpy after the retrogradation of starches. For the pasting properties results showed significant difference in all cultivars. Pearson correlation coefficients showed that amylose content was negatively correlated to the onset, peak and final temperature of gelatinization, final temperature of retrogradation and pasting temperature. Phosphorus content was positively correlated to crystallinity index, peak viscosity and breakdown. Starches extracted from potato varieties showed different characteristics which can be useful to food and related industries that make use of potato starch, allowing wide options of use in various sectors of industrial application in Brazil.
Assuntos
Solanum tuberosum/química , Amido/química , Amilose/química , Brasil , Varredura Diferencial de Calorimetria , Lipídeos/química , Fósforo/química , Difração de Raios XRESUMO
BACKGROUND: Starch is the major component of potato tubers, amounting approximately to 150-200 g kg (-1) of the tuber weight. Starch is considered to be a major factor for the functionality of the potato in food applications. This study evaluated the physical characteristics of potato starches isolated from tubers of different potato cultivars grown in soil with three levels of phosphorus (P) availability. All potatoes were growing according the same method. The starches were isolated by physical methods and the samples were analyzed for the amylose, P content, paste properties (RVA) and thermal properties of gelatinization and retrogradation (DSC). Experimental data were analyzed considering the potato cultivars and the three soil P availability. RESULTS: For all measured parameters significant impact of cultivar and soil P availability was determined. Phosphorus contents in potato starches ranged from 0.252 to 0.647 g kg(-1) and amylose from 27.18 to 30.8%. Starches from different potato cultivars independent of soil showed a small range of gelatinization temperature. All starches showed low resistance heating and shear stress. CONCLUSION: The results showed the influence of growing conditions (soil P availability) and also of the differences between the potato cultivars on important characteristics of applicability of starches.