Morphometric and crystallinity changes on jicama starch (Pachyrizus erosus) during gelatinization and their relation with in vitro glycemic index

Abstract

de M exico 03940, M exico 5 CNMN, Instituto Polit ecnico Nacional, Luis Enrique Erro, Unidad Profesional Adolfo L opez Mateos, Zacatenco, Ciudad de M exico 07738, M exicoThe effect of gelatinization on the in vitro glycemic index (GI) of starch obtained from jicama tubers was investigated, and the relationships between the starch crystallinity, granule morphology, and the GI were measured. Samples were prepared by heating an aqueous dispersion of starch (1:3 w/v) at different baking process temperatures (60, 65, 70, 75, or 80°C). Native starch granules showed spherical and polyhedral shapes, with a morphometric aspect ratio (AR) of 0.89-1.0 and sizes ranging from 3 to 21 mm. During the thermal process a change in the AR (0.21-0.88) and size (3.0-46 mm) was observed, as well as the formation of agglomerates. Native jicama starch exhibited a C A -type X-ray diffraction pattern, while those thermally treated showed a transition from the C A -type to C B -type, decreasing their crystallinity (20.8-11.5%) at higher temperatures. The gelatinization degree of the starch samples and the glycemic index showed the largest values (97.4% and 98.6% respectively) at the highest temperature (80°C), while the crystallinity percentage followed an inverse correlation to temperature (11.5%, 80°C), indicating that the thermal history affected the behavior of the starch enzymatic digestion. The in vitro glycemic index correlated positively with the gelatinization degree based on aspect ratio (R 2 ¼ 0.977), DSC gelatinization enthalpy (R 2 ¼ 0.969), and crystallinity (R 2 ¼ À0.988). Based on these results a mathematical model is proposed to determine the glycemic index as a function of the aspect ratio. However, more studies are required to validate this information.

Ultrasound-assisted extraction of starch from frozen jicama (P. erosus) roots: Effect on yield, structural characteristics and thermal properties

“…In Figure 6, the diffraction bands of all samples showed a characteristic type C pattern, presenting strong peaks at 17°a nd 23°(2θ) angles and smaller peaks at 5.6°and 15°(2θ) but related to a polymorphism C A type (Cai, Cai, Man, Zhou, & Wei, 2014) as indicated by the presence of a shoulder at 18°(2θ). These results are similar to those reported for jicama native starch by Ramírez-Miranda et al (2017). A statistical analysis showed no significant difference (p > 0.05) between the sonicated samples in the crystallinity percentage, which varied from 26 ± 1.4% to 32 ± 1.7%.…”

“…These values are in the range of those reported by Stevenson et al (2007) and Ramírez-Miranda et al (2017). The differences could be related to small variations in the moisture content of the samples (8-9%), as seen by Cheetham and Tao (1998), who mention that the hydration of the granules can lead to an increase in crystallinity, without changing the original crystal type.…”

“…The images were acquired in RGB color. The jicama tissues were prepared as reported by Ramírez-Miranda et al (2017).…”

“…The starch was spread on double-sided tape and covered with gold film (20 s, 10 -1 mTorr, Denton Vacuum Desk II), as proposed by Ulbrich, Natan, and Flӧter (2014), and then different zones were subsequently observed under various magnifications (100, 500 and 1000×) for each sample. The jicama tissues were prepared as reported by Ramírez-Miranda et al (2017).…”

Effects of ultrasonic and enzymatic treatment on physical and chemical properties of brown rice

“…However, the formation of amylose complex could change the crystalline pattern of starch into V‐type after some treatments such as soaking (Manful, Grimm, Gayin, & Coker, ), drying (Horrungsiwat, Therdthai, & Ratphitagsanti, ), and parboiling (Derycke et al, ), leading to change in starch properties. Thermal properties have been investigated using differential scanning calorimetry (DSC) to determine the gelatinization of rice after treatment which may be related to cooking properties and glycemic response of brown rice (Ramírez‐Miranda et al, ; Zhu, Liu, Wilson, Gu, & Shi, ). Additionally, there was no study on the effect of ultrasonic and ETs on glycemic response which was one of the most concerned parameters for grain selection.…”