Research advances on the formation mechanism of resistant starch type III: A review

Efficiency of Resistant Starch and Dextrins as Prebiotics: A Review of the Existing Evidence and Clinical Trials

In well-developed countries, people have started to pay additional attention to preserving healthy dietary habits, as it has become common knowledge that neglecting them may easily lead to severe health impairments, namely obesity, malnutrition, several cardiovascular diseases, type-2 diabetes, cancers, hypertensions, and inflammations. Various types of functional foods were developed that are enriched with vitamins, probiotics, prebiotics, and dietary fibers in order to develop a healthy balanced diet and to improve the general health of consumers. Numerous kinds of fiber are easily found in nature, but they often have a noticeable undesired impact on the sensory features of foods or on the digestive system. This led to development of modified dietary fibers, which have little to no impact on taste of foods they are added to. At the same time, they possess all the benefits similar to those of prebiotics, such as regulating gastrointestinal microbiota composition, increasing satiety, and improving the metabolic parameters of a human. In the following review, the evidence supporting prebiotic properties of modified starches, particularly resistant starches and their derivatives, resistant dextrins, was assessed and deliberated, which allowed drawing an interesting conclusion on the subject.

Isolated Pea Resistant Starch Substrates with Different Structural Features Modulate the Production of Short-Chain Fatty Acids and Metabolism of Microbiota in Anaerobic Fermentation In Vitro

Resistant starches (RSs) with different structural features were isolated from both native and pullulanase-debranched and acid-hydrolyzed pea starches. Their microscopic changes, short-chain fatty acids (SCFA) composition, microbiota communities, and structural characteristics of the corresponding fermenta residues by the end of 24 h of the in vitro fermentation period were investigated. The microbial fermentation clearly caused numerous cracks and erosion on the RS granule surface. In comparison to the positive control, significantly higher levels of butyrate, propionate, and total SCFA were produced after 24 h of in vitro fecal fermentation when resistant starches were used as substrates. The RS substrates with different structural characteristics enabled varying growth of Bifidobacterium spp., Eubacterium spp., and Faecalibacterium spp. The discrepancy in microbiota communities associated with the differences in SCFA from the fermentation of RS with different structural features would be critical toward the rational design of foods containing resistant starch with targeted health benefits.

Type III Resistant Starch Prepared from Debranched Starch: Structural Changes under Simulated Saliva, Gastric, and Intestinal Conditions and the Impact on Short-Chain Fatty Acid Production

Type III resistant starch (RS3) has high resistance to enzymatic digestibility and benefits colonic bacteria by producing short-chain fatty acids (SCFAs) via fermentation. Studies have delineated RS preparation and the description of RS fractions with different types of starch, but the digestion process has received little attention. The molecular and crystalline structure changes, thermal properties, and SCFA content of RS3 obtained from debranched starch were investigated in simulated salivary, gastric, and intestinal digestion systems. The average degree of polymerization and the melting enthalpy change of the digested RS3 residues increased; a high molecular order was reflected by the higher relative crystallinity. Fine structural changes suggested that enzyme-resistant starch might form during digestion by the rearrangement of short amylose chains into enzyme-resistant structures with higher relative crystallinity. After fermentation of human feces, RS3 increased the SCFA content, especially of butyric acid, indicating that this recrystallized RS3 could be a new prebiotic product.

Structural rearrangement of native and processed pea starches following simulated digestion in vitro and fermentation characteristics of their resistant starch residues using human fecal inoculum

Pea starches, in both native (NPS) and retrograded-autoclaved forms (RAPS), were subjected to simulated gastrointestinal (GI) digestion in vitro, their multi-scale structural characteristics, morphological features, molecular distribution and thermal properties were characterized. A gradual increase in the short-/long-range crystallinity, melting enthalpy of gelatinization on increasing digestion time was observed for both the native and retrograded-autoclaved pea starch samples based on the X-ray diffraction, Fourier-transform infrared spectra, solid-state 13CNMR and differential scanning calorimetry measurements. It was especially noticed that the growth rate of crystallinity and double helices, as well as the decrease in Mw values were evidently greater for RAPS than for NPS. To investigate how different molecular fine structure of pea starch substrate affects the gut microbiota shifts and dynamic short-chain fatty acid profile, their resistant starch residues obtained from both native and retrograded-autoclaved pea starch after 8 h of simulated GI tract digestion was used as the fermentation substrate. The levels of acetate, propionate and butyrate gradually increased with the increasing fermentation time for NPS and RAPS. In comparison to the blank control (i.e., the group without the addition of carbohydrate), the fermented NPS and RAPS obviously resulted in an increased abundance of Firmicutes and Bacteroidetes, accompanied by a decrease in Proteobacteria, Actinobacteria and Verrucomicrobia. Both NPS and RAPS promoted different shifts in the microbial community at the genus level, with an increase in the abundance of Bacteroides, Megamonas and Bifidobacterium, as well as a reduction in the abundance of Fusobacterium, Faecalibacterium and Lachnoclostridium in comparison to the blank control samples.

A more pronounced effect of type III resistant starch vs. type II resistant starch on ameliorating hyperlipidemia in high fat diet-fed mice is associated with its supramolecular structural characteristics

The anti-obesity effects of two categories of resistant starch (RS) including RS₂ (isolated from untreated lentil starch, URS) and RS₃ (isolated from autoclaved and retrograded lentil starch, ARS) on mice with high-fat (HF) diet-induced obesity and the supramolecular structure-in vivo physiological functionality relationship of RS were investigated. Following 6 consecutive weeks, the obese mice in the two RS administered groups displayed suppression of body/liver weight gain and an improvement in serum glucose/lipid profile, antioxidant status, and gut microbiota structure. Compared with the URS intervention group, the ARS administration resulted in a more pronounced effect in controlling body weight, together with a more prominent reduction in blood glucose and triglyceride concentration, as well as a significant increase in the HDL-c level in obese mice. The ARS group also showed an absolute advantage over URS in suppressing the oxidative stress and regulating the liver function induced by the HF diet. Simultaneously, the administration of URS and ARS efficiently suppressed the HF-diet induced alterations in gut microbial ecology, with an obviously decreased ratio of Firmicutes to Bacteroidetes, especially for the ARS group, suggesting its beneficial role in gastrointestinal tract health. The structural characterization results revealed that ARS and URS differed significantly in their supramolecular structural characteristics, where ARS exhibited a higher proportion of crystallinity and double helix content with an X-ray diffraction pattern of a C_B type crystal polymorph and a low proportion of molecular inhomogeneity. This study suggested that the difference in the anti-obesity effect of resistant starches was a consequence of the diversity in their structural features.

The retrogradation characteristics of pullulanase debranched field pea starch: Effects of storage time and temperature

The structural changes and retrogradation behavior of the processed pea starch stored at 4 °C and 25 °C for different length of time (6, 12, 24, 48, and 72 h) was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), solid-state 13C nuclear magnetic resonance spectroscopy (13CNMR), Fourier transform infrared spectroscopy (FT-IR), and small angle X-ray scattering (SAXS), their corresponded physicochemical properties were studied by rapid visco-analyzer (RVA). A mixture of B- and V-type crystalline polymorph was observed by XRD for all processed and retrograded pea starch. A continuous increase in the following parameters was observed during the initial retrogradation of pea starch for 6-48 h at 4 °C and for 6-24 h at 25 °C, followed by a decreased trend during the subsequent storage time from 48 h to 72 h at 4 °C, and from 24 h to 72 h at 25 °C, including the values of relative crystallinity, degree of order, and degree of double helix measured by XRD, 13CNMR, and FT-IR, respectively. The results of this study would provide useful information for better designing of starch-based food ingredients with improved functional and health benefits.