Microstructure analysis of high pressure induced gelatinization of maize starch in the presence of hydrocolloids

SCHNEIDER TEIXEIRA, A.; DELADINO, L.; GARCÍA, M.A.; ZARITZKY, N.E.; SANZ, P.D.; MOLINA-GARCÍA, A.D.

FOOD AND BIOPRODUCTS PROCESSING

INST CHEMICAL ENGINEERS

Año: 2018 vol. 112 p. 119 - 130

0960-3085

The effect of high hydrostatic pressure (HHP) treatment on maize starch granules was analyzedtaking into account different operating conditions (time, temperature, high pressuresand starch to water ratio) and the effect of hydrocolloids (-carrageenan, guar and xanthangum). Morphological analysis using different microscopic techniques, mainly SEM and Cryo-SEM, was carried out. This study was complemented with information acquired throughDifferential Scanning Calorimetry (DSC), X-ray diffractometry (XRD) and spectrophotometricdetermination of the amylose and amylopectin concentrations released from the granules.The gelatinization degree obtained by DSC increased accordingly with the intensity (pressurelevel and exposure time) of the HHP treatment, while the gelatinization temperaturewas scarcely affected. The presence of hydrocolloids in the suspension during HHP processingwould ensure water availability. Almost complete gelatinization was observed forthe sample treated at 700 MPa, both by DSC and XRD. At 400 MPa the gelatinization degreewas significantly lower in starch with added xanthan gum (XG) in comparison to the otherhydrocolloids, denoting a possible stabilization effect of XG on the starch granular structureduring gelatinization. Maize starch granules (A-type XRD pattern), when submitted to HHPtreatment, showed characteristic peaks of A and B-type patterns. Signals of V-diffractionpattern, ascribed to amylose?lipid complexes, were detected by XRD in samples submittedto either very high pressure (700 MPa), long treatment times at 400 MPa (120 min) or in presenceof hydrocolloids (at lower pressures and times). The formation of V-crystalline complexwould be favored by hydrocolloids presence under pressure. These results correlated wellwith the lower concentrations of amylose released from granules after these treatments.