Inhibition of in vitro starch digestion by ascorbyl palmitate and its inclusion complex with starch

Microwave-mediated formation of lotus-seed starch-palmitic acid complexes and their multi-scale structural changes

Recent studies have revealed that starch-lipid complexation can significantly impact gut health via the formation of V-type resistant starch. This study used varying microwave (MW) power levels (600, 700, 800, 900, 1000 W) to prepare V-type lotus-seed starch (LS)-palmitic acid (PA) complexes and investigates their multi-scale structural and thermal properties. The results indicate that MWs promote hydrophobic LS-PA complexation to form a B + V6II-type crystalline structure, with the V-type complexation rate found to positively correlate with MW power. Specifically, a higher MW power is more conducive to guiding the evolution of the disordered structure in the complex system back to the ordered arrangement and enhancing the crystallinity and stability of the system. The evolution of this V-type crystallization process peaks at an MW power of 1000 W MW to afford a complexing index of 55.409 %. Further thermal-property analyses reveal that the V-type complexed starch is mainly arranged as highly thermally stable accumulated single-helix structures that dissociate at 100-105 °C. These findings provide valuable data for regulating V-type complex formation through MW treatment and establish a theoretical foundation for precisely designing healthy starch-based foods.

A comparison of the physicochemical properties, digestibility, and expression patterns of starch-related genes of two supersweet corn hybrids (F1) and their parents

The quality difference of corn largely depends on parental selection. Herein, the structure, digestive characteristics, and expression patterns of starch-related genes of two supersweet maize hybrids and their parents were studied. The structural analysis revealed that the starch of supersweet corn is round or oval, and the particles are smaller compared to those of normal corn. Hybridization changed the grain morphology, crystal, and helical structure of starch. Parents had a significantly different influence on supersweet corn. Notably, hybridization improved the setback value and digestibility of Shantian1500F1 and Shantian2000F1 compared to that of the parents. ZmBEI, ZmPHOH, and ZmAGPL2 genes had a consistent high expression throughout the whole grain formation phase. The results of this study expand our understanding of the breeding of supersweet corn hybrids and the effect of parents on the new strand. These results provide a useful reference for further breeding and studies of supersweet corn for starch production in corn.

Starch-guest complexes interactions: Molecular mechanisms, effects on starch and functionality

Starch is a natural, abundant, renewable and biodegradable plant-based polymer that exhibits a variety of functional properties, including the ability to thicken or gel solutions, form films and coatings, and act as encapsulation and delivery vehicles. In this review, we first describe the structure of starch molecules and discuss the mechanisms of their interactions with guest molecules. Then, the effects of starch-guest complexes on gelatinization, retrogradation, rheology and digestion of starch are discussed. Finally, the potential applications of starch-guest complexes in the food industry are highlighted. Starch-guest complexes are formed due to physical forces, especially hydrophobic interactions between non-polar guest molecules and the hydrophobic interiors of amylose helices, as well as hydrogen bonds between some guest molecules and starch. Gelatinization, retrogradation, rheology and digestion of starch-based materials are influenced by complex formation, which has important implications for the utilization of starch as a functional and nutritional ingredient in food products. Controlling these interactions can be used to create novel starch-based food materials with specific functions, such as texture modifiers, delivery systems, edible coatings and films, fat substitutes and blood glucose modulators.

Comparison of anti-allergic activities of different types of lotus seed resistant starch in OVA-induced mouse model

Currently, evidence from observational studies suggests dietary fiber intake may be associated with decreased risk of food allergy. As a type of dietary fiber, resistant starch was also widely reported to possess anti-allergic properties. However, there is a relative paucity of studies assessing the influence of resistant starch types on their anti-allergic activity and its possible underlying mechanisms. In the current study, the anti-allergic effects of RS3-type (retrograded starch), RS4-type (chemically modified starch, cross-bonded), and RS5-type (starch-palmitic acid complex) of lotus seed resistant starch were evaluated in the OVA (100 mg/kg)-induced food allergic mice model. The results showed that oral administration of RS3 or RS4 lotus seed resistant starch (0.3 g/100 g b.w.) for 25 days significantly improved adverse symptoms of food allergy such as weight loss, increases in allergy symptom score and diarrhea rate; with significant reduction of serum specific antibody IgE, TNF-α, IL-4 levels and improved Th1/Th2 balance being observed. The mechanism may involve the regulation of lotus seed resistant starch on intestinal flora and the metabolites short-chain fatty acids and bile acids. Taken together, the findings may enhance understanding towards ameliorative effects of resistant starch on food allergy, and offer valuable insights for the exploration of novel anti-allergic bioactive compounds.

Preparation of starch-palmitic acid complexes by three different starches: A comparative study using the method of heating treatment and autoclaving treatment

Recent research emphasizes the growing importance of starch-lipid complexes due to their anti-digestibility ability, prompting a need to explore the impact of different starch sources and preparation methods on their properties. In this study, starch-palmitic acid (PA) complexes were prepared by three different starches including Tartary buckwheat starch (TBS), potato starch (PTS), and pea starch (PS) by heating treatment (HT) and autoclaving treatment (AT), respectively, and their physicochemical property and in vitro digestibility were systematically compared. The formation of the starch-PA complex was confirmed through various characterization techniques, including scanning electron microscopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, and X-ray diffraction. Among the complexes, the PTS-PA complex exhibited the highest complexation index over 80 %, while the PS-PA complex had the lowest rapid digestible starch content (56.49-59.42 %). Additionally, the complexes prepared by AT exhibited higher resistant starch content (41.95-32.46 %) than those prepared by HT (31.42-32.49 %), while the complexes prepared by HT held better freeze-thaw stability and hydration ability than those prepared by AT. This study highlights the important role of starch sources in the physicochemical and digestibility properties of starch-lipid complex and the potential application of AT in the preparation of novel resistant starch.

Bioactive delivery systems based on starch and its derivatives: Assembly and application at different structural levels

Starch and modified starch, spanning various structural levels, are comprehensively reviewed, with a special emphasis on the advancement of starch and its derivative-based delivery systems for bioactive substances. The pivotal aspect highlighted is the controlled release of active ingredients by starch-based delivery systems with distinct hierarchical structures. At the molecular level, diverse categories of starch degradation products, such as dextrin and highly branched starch, serve as versatile amphiphilic carriers for encapsulating active ingredients. At the level of helical structure, the distinctive configuration of the starch-guest complex partly determines the mechanism of controlled release for diverse active components. At the crystal and particle structural level, starch assumes the role of a carrier, effectively modulating the release of active substances, and enhances the innate physiological activity of different active components. As a natural polymer molecule, starch can also generate hydrogel materials in polymer form, expanding its utility in the fields of food, materials, and even medicine.

Extrusion as pretreatment for complexation of high-amylose starch with glycerin monostearin: Dependence on the guest molecule

Low-moisture extrusion (LME) can modify starch structures and enrich their functionality. These LME-made starches may efficiently form inclusion complexes (ICs) with hydrophobic guest molecules, which is profoundly impacted by the guest molecule concentration. In this work, the influence of glycerin monostearin (GMS) concentration on the structure and in vitro digestibility of pre-extruded starch-GMS complexes was investigated. The results showed that LME pretreatment increased the complex index of high-amylose starch with GMS by 13 %. The appropriate GMS concentrations produced ICs with high crystallinity and excellent thermostability. The presence of IC retarded amylose retrogradation and dominated bound water in starches. In addition, highly crystallized ICs were resistant to enzymolysis and had a higher proportion of resistant starch. The acquired knowledge would provide a better understanding of the LME-modified starch and GMS concentration-regulated IC formation.

Starch-ascorbyl palmitate inclusion complex, a type 5 resistant starch, reduced in vitro digestibility and improved in vivo glycemic response in mice

The prevalence of type 2 diabetes (T2D) has become a major public health concern worldwide. Slowly digested or indigestible carbohydrates such as resistant starch (RS) are associated with a low glycemic index (GI) and the decreased risk of developing T2D. Recently, starch inclusion complexes (ICs) have raised attention due to their thermally stable structure and high RS content. In this study, starch-ascorbyl palmitate (AP) ICs were produced using two different methods with hydrothermal treatments performed, and their in vitro digestion kinetics and in vivo glycemic response in C57BL/6J mice were investigated to determine their potential as a new type of RS, i.e., RS5. After treatments of annealing followed by acid hydrolysis (ANN-ACH), IC samples produced by both methods retained V-type crystalline structure. Either in their raw or treated conditions, V6h-AP ICs prepared using the "empty" V-type method exhibited a more favorable hydrolysis pattern as compared to its counterpart produced by the DMSO method in terms of a lower hydrolysis rate and equilibrium concentration (C∞) (p < 0.05). From the in vitro results, the ANN-ACH treated V6h-AP IC exhibited an estimated GI (eGI) value of 54.83, falling within the range of low GI foods and was the lowest among all tested samples (p < 0.05). Consistent with the in vitro digestion kinetics, the in vivo results showed that mice fed with ANN-ACH V6h-AP IC exhibited a modest glycemic response as evidenced by the lowest increase in postprandial blood glucose and AUC blood glucose (p < 0.05). In addition, the in vivo GI of the ANN-ACH V6h-AP IC (39.53) was the lowest among all the sample treatments and was even lower than that of the RS2 comparison (56, p < 0.05), indicating its more pronounced effect in modulating the postprandial glycemic response in mice and great potential as a new RS5.

Ultrasonication-mediated formation of V-type lotus seed starch for subsequent complexation with butyric acid

V-type starches comprise single helical structures that can be complexed with other small hydrophobic molecules. The development of the subtypes of these assembled V-conformations is dependent on the helical state of the amylose chains during complexation, which is influenced by the pretreatment employed. In this work, the effect of preultrasonication on the structure and in vitro digestibility of preformed V-type lotus seed starch (VLS) and its potential for complexing with butyric acid (BA), was investigated. The results showed that ultrasound pretreatment did not affect the crystallographic pattern of the V₆-type VLS. The optimal ultrasonic intensities increased the crystallinity and molecular ordering of the VLSs. With an increase in the preultrasonication power, the pores on the VLS gel surface decreased in size and were more densely distributed. The VLSs formed at 360 W were less vulnerable to digestive enzymes than their untreated counterparts. Additionally, their highly porous structures could accommodate numerous BA molecules, and thus generated inclusion complexes via hydrophobic interactions. These findings would provide valuable insights into the ultrasonication-mediated formation of VLSs and suggest their potential application as carriers for the delivery of BA molecules to the gut.

Structural and Physicochemical Properties of Starch from Rejected Chestnut: Hydrothermal and High-Pressure Processing Dependence

The quality standards for the export of chestnuts generate large quantities of rejected fruits, which require novel processing technologies for their safe industrial utilization. This study aimed to investigate the impact of high-pressure processing (HPP) and hydrothermal treatments (HT) on the physicochemical properties of rejected chestnut starch. Chestnuts were treated by HPP at 400, 500, and 600 MPa for 5 min and HT at 50 °C for 45 min. In general, all HPP treatments did not induce starch gelatinization, and their granules preserved the integrity and Maltese-cross. Moreover, starch granules' size and resistant starch content increased with the intensity of pressure. Native and HT chestnut starches were the most susceptible to digestion. HPP treatments did not affect the C-type crystalline pattern of native starch, but the crystalline region was gradually modified to become amorphous. HPP-600 MPa treated starch showed modified pasting properties and exhibited the highest values of peak viscosity. This study demonstrates for the first time that after HPP-600 MPa treatment, a novel chestnut starch gel structure is obtained. Moreover, HPP treatments could increase the slow-digesting starch, which benefits the development of healthier products. HPP can be considered an interesting technology to obtain added-value starch from rejected chestnut fruits.

Structure-digestibility relationship of starch inclusion complex with salicylic acid

Amylose, the linear component of starch, can complex with small molecules to form single helical inclusion complexes of 6, 7, or 8 glucosyl units per helical turn, known as V₆, V₇, and V₈. In this study, starch-salicylic acid (SA) inclusion complexes with different amounts of residual SA were obtained. Their structural characteristics and digestibility profiles were obtained with complementary techniques and an in vitro digestion assay. Upon complexation with excess SA, V₈ type starch inclusion complex was formed. When excess SA crystals were removed, the V₈ polymorphic structure could remain, while further removing intra-helical SA converted the V₈ conformation to V₇. Furthermore, the digestion rate of the resulted V₇ was lowered as indicated by increased resistant starch (RS) content, which could be due to its tight helical structure, whereas the two V₈ complexes were highly digestible. Such findings could have practical implications for novel food product development and nanoencapsulation technology.

Inhibitory Effect of Ascorbic Acid on in vitro Enzymatic Digestion of Raw and Cooked Starches

Ascorbic acid, also known as vitamin C, was previously reported to inhibit the activity of pancreatic α-amylase, the primary digestive enzyme for starch. A major implication of such inhibition is a slowed rate of starch digestion into glucose, which thereby reduces postprandial hyperglycemia. The aim of this study was to explore the inhibitory effects of ascorbic acid at various concentrations on the in vitro digestion of high amylose maize starch (HAMS) and potato starch (PS) in both raw and cooked conditions. Resistant starch (RS) content, defined as the starch that remained after 4 h of simulated in vitro enzymatic digestion, was measured for the starch samples. Upon the addition of ascorbic acid, the RS contents increased in both raw and cooked starches. Cooking significantly reduced the RS contents as compared to raw starches, and less increase in RS was observed with the addition of ascorbic acid. The inhibitory effect of ascorbic acid on the digestion of raw starches showed a dose-dependent trend until it reached the maximum extent of inhibition. At the concentrations of 12.5 and 18.75 mg/mL, ascorbic acid exhibited the most potent inhibitory effect on the in vitro starch digestion in raw and cooked conditions, respectively. Overall, our results strongly indicate that ascorbic acid may function as a glycemic modulatory agent beyond other important functions, and its effects persist upon cooking with certain concentrations applied.