The effect of pH on the chemical and structural interactions between apple polyphenol and starch derived from rice and maize

Abstract

To date, how pH affects starch–polyphenol mixtures has not been thoroughly investigated. This study explored the impact of combining apple polyphenol (AP) with both normal rice starch (NRS) and normal maize starch (NMS) across a range of pH conditions. NRS–AP mixture particle sizes across a pH range of 3–8 varied from 169.9 ± 5.4 to 187.5 ± 6.9 μm, while for NMS–AP particles, these sizes ranged from 161.8 ± 8.0 to 176.0 ± 4.9 μm, indicating that the aggregation of starch–AP was inhibited under low pH condition. The melting enthalpy (△H) values of the NRS–AP mixture across a pH range of 3–8 were 8.50 ± 0.06–9.56 ± 0.12 J/g, while the corresponding value for the NMS–AP mixture was 5.77 ± 0.05–6.21 ± 0.08 J/g. FTIR analyses revealed that the degree of order of these starch–AP mixtures significantly decreased under low pH conditions. XRD analysis further revealed that both NRS–AP and NMS–AP mixtures exhibited V‐type structures, and relative crystallinity levels decreased significantly under low pH conditions. Together, these results indicate that low pH values inhibit the recrystallization of NRS–AP and NMS–AP mixtures. Overall, these findings provide additional evidence regarding the interactions between AP and specific starches under a range of pH conditions.

Donut-Shaped Microparticles Prepared from Different C-Type Starch Sources: Characterization and Encapsulation of Gallic Acid

“…Several authors reported that the main reason for the encapsulation of phenolic compounds with starch is due to the formation of hydrogen bonds (between the hydroxyl and carboxylic groups of GA and oxygen atoms of the glycosidic linkages of starch) and not by an amylose inclusion complex. 1,41 We postulated that the higher number of single helices in the endogenous lipid-amylose complex present in PeS, corroborated by DSC measurement, could positively contribute to the intrachain entrapment of GA.…”

Complexation of starch and phenolic compounds during food processing and impacts on the release of phenolic compounds

“…Phenolic molecules can form inclusion or noninclusion complexes or intermolecular aggregates with starch molecules through hydrophobic interaction (Chou et al., 2020; Zhao, Sun, et al., 2019), hydrogen bonds (Wang, Wang, et al., 2021; Wang et al., 2018), CH–π bonds (Wang et al., 2021b), and/or van der Waals forces (Amoako & Awika, 2019). Phenolic compounds (ligand molecules) can be bound in the cavity of the helix (Sudlapa & Suwannaporn, 2023), between helices in the crystallization regions (Guo et al., 2019), or in the amorphous regions (Zhang et al., 2020; Zhao, Wang, et al., 2019), as shown in Figure 1.…”

“…Typical structures representing the formation of the V‐type inclusion complexes can be characterized using differential scanning calorimetry (DSC), X‐ray diffraction (XRD), or nuclear magnetic resonance (NMR) techniques (Chou et al., 2020; Liu et al., 2019; Zhao, Sun, et al., 2019; Zhao, Wang, et al., 2019). The complexes show melting endotherms at a temperature exceeding 90°C using DSC (Obiro et al., 2012), and the V‐type crystalline peaks at 7.5°, 13°, and 19.9° of 2 θ (Chai et al., 2013) using XRD.…”

“…Considering the thermal instability of phenolics, nonthermal treatments have great potential to form starch-phenolic complexes. However, due to the differences in the structure Liu et al, 2020;Wang et al, 2021a;Wang et al, 2021b;Wang, Zhang, et al, 2021;Wang et al, 2018); V-type inclusion complex driven by hydrophobic interaction (Chou et al, 2020) Heated at 70 through hydrogen bonds at 200 W ultrasonic power, V-type inclusion complex driven by hydrophobic interaction at 400-1000 W ultrasonic power (Zhao, Sun, et al, 2019;Zhao, Wang, et al, 2019) Note: Hydrothermal treatment at 90-120 • C for 20-30 min for blends of starches and phenolics is for the complete gelatinization of starch and induces the noninclusion or inclusion complexes, which depends on the amylose content and phenolic structure. The presence of ethanol solution can improve the starch-phenolic complexation by modulating the degree of swelling or gelatinization of starch and the solubility of phenolics.…”

Phenolic Release during In Vitro Digestion of Cold and Hot Extruded Noodles Supplemented with Starch and Phenolic Extracts

“…XRD is an effective technique to characterize the formation of complexes between starch and phenolics, including non-inclusion complexes [37][38][39] or V-type inclusion complexes [40][41][42]. Compared with native starch with typical peaks of A-type crystallites (Figure 1), XRD patterns of cold extruded starch in the absence and presence of phenolics (CE-S and CE-S-P2) showed typical diffraction peaks of A+V-type crystallites with less pronounced peaks at 12.8 1) [43], indicating that the cold extrusion altered the starch crystalline structure, which is consistent with the results of the cold extruded wheat starch [44].…”