Physicochemical, Molecular, and Digestion Characteristics of Annealed and Heat–Moisture Treated Starches Under Acidic, Neutral, or Alkaline pH

Abstract

Cereal Chem. 94(4):770-779Rice, maize, and potato starches were incubated under acidic (2), neutral (7) or alkaline (11) pH conditions, and combined with annealing (ANN) or heat-moisture treatment (HMT), with the aim to evaluate their changes of physicochemical, digestion, and molecular characteristics. The applied treatments produced changes in all starches, showing void zones in the granules, which were more evident in ANN samples. The HMT starches promoted the formation of granular conglomerates that still showed birefringence. Overall, the evaluated conditions promoted changes in granule architecture (revealed by differences in gelatinization enthalpy) and crystallinity, for which an extensive degradation of their characteristics diffraction patterns occurred. These changes were more evident when incubation under acidic conditions was employed. Through principal component analysis, we found that the structural changes in starch granules have a direct influence on slowly digestible starch, resistant starch, and predicted glycemic index values, and this is the result of a higher proportion of organized crystallites, obtained from the acid hydrolysis process. † Corresponding

Physicochemical characterisation andin vitroStarch digestion of Avocado Seed Flour (Persea americana V. Hass) and its starch and fibrous fractions

“…b); that other studies have related with their granular integrity and to influence their functional properties. From this, we observe that the isolation process from the flour promoted a decrease in the intensity in both starch‐related zones (Table S4), and such decrease can result in partial loss of molecular interactions among starch granules and other flour components (De la Rosa‐Millán, ). In the same sense, such molecular rearrangement may influence some functional properties related with water uptake and viscosity (De la Rosa‐Millán, ; Chávez‐Murillo et al ., ).…”

“…Regarding the starch and fibrous fraction, their colour was lighter, probably due to processing conditions that may have removed some pigments from the parental material. However, for a starch to be considered of high quality, its colour should be as close to white as possible (De la Rosa‐Millán, ).…”

“…These differences could reveal molecular interactions with other molecules as fibre and/or proteins ( r = 0.99, P < 0.05), that have been often related with improved thermal stability (Silva et al ., ). In a similar fashion, the fibre‐rich fraction showed lower‐starch transition values (Tp = 61.21 °C, ΔH = 7.24 J g −1 ), from which we could hypothesise that the higher amount of fibres difficulted the water absorption capacity of starch granules; and that stronger molecular interactions occurred among proteins and fibres ( r = 0.97, P < 0.05), as suggested by other authors (Anderson et al ., ; De la Rosa‐Millán, ; Chávez‐Murillo et al ., ).…”

“…After 72 h of storage, the gel dispersions were re‐evaluated, finding significantly lower values when compared with their initial conditions. The greater changes occurred in the avocado flour, followed by the fibre fraction, whilst in the case of starch it presented 65.43% of transmittance, that could be related with the retrogradation of both amylose and amylopectin and their possible interactions with residual fibres (Tester & Morrison, ; De la Rosa‐Millán, ). With the aim to further comprehend the molecular characteristics of the analysed materials, we estimated their linear starch chains length using its complexing characteristics with iodine, that under the evaluated conditions reflected the length of linear molecules of the samples, relating them with their amylose fraction (Table ) (Wang & Copeland, ).…”

“…4000–800 cm −1 ) with a resolution of 4 cm −1 by twenty scans with a half‐band width of 15 cm −1 . All chemical functional groups were identified using published reports (De la Rosa‐Millán, ; Chávez‐Murillo et al ., ).…”