New insights into starch, lipid, and protein interactions - Colon microbiota fermentation

Starch, lipids, and proteins are essential biological macromolecules that play a crucial role in providing energy and nutrition to our bodies. Interactions between these macromolecules have been shown to impact starch digestibility. Understanding and controlling starch digestibility is a key area of research. Investigating the mechanisms behind the interactions of these three components and their influence on starch digestibility is of significant practical importance. Moreover, these interactions can result in the formation of resistant starch, which can be fermented by gut microbiota in the colon, leading to various health benefits. While current research has predominantly focused on the digestive properties of starch in the small intestine, there is a notable gap in understanding the colonic microbial fermentation phase of resistant starch. The benefits of fermentation of resistant starch in the colon may outweigh its glucose-lowering effect in the small intestine. Thus, it is crucial to study the fermentation behavior of resistant starch in the colon. This paper investigates the impact of interactions among starch, lipids, and proteins on starch digestion, with a specific focus on the fermentation phase of indigestible carbohydrates in the colon. Furthermore, valuable insights are offered for guiding future research endeavors.

Structure, properties, and resistant starch content of modified rice flour prepared using dual hydrothermal treatment

In this study, modified rice flour with high resistant starch (RS) content was prepared by dual hydrothermal treatment, which combined the heat-moisture treatment with the pressure-heat treatment method. The effects of dual hydrothermal treatment on the structure and properties of modified rice flour and their relationship with RS content were further discussed. The results showed that the RS content of modified rice flour was higher than that of rice flour (RF), and dual hydrothermal treatment was more effective than single hydrothermal treatment. Adhesion and aggregation occurred between the particles of modified rice flour. Both crystallinity and short-range ordering were increased in modified rice flour compared to RF. Moreover, the modified rice flour of dual hydrothermal treatment had higher crystallinity and a more ordered short-range structure of starch, which improved RS content to a certain extent. Compared to single hydrothermal treatment, the modified rice flour of dual hydrothermal treatment had a lower viscoelasticity and a better thermal stability. Both RF and modified rice flour gels were composed mainly of free water, with minimal amounts of bound and immobile water. The study may provide a reference for the production and application of modified rice flour.

Effect of different heat-moisture treatment times on the structure, physicochemical properties and in vitro digestibility of japonica starch

Modified starch was prepared from japonica starch (JS) by heat-moisture treatments (HMT). Under the same moisture content and HMT temperature, the effects of various HMT times on the structural, properties of JS and its in vitro digestibility properties were investigated. The results showed that adhesion occurred between the particles of japonica starch after the HMT, and there were depressions on the surface. The size of the JS particles increased, the short-range ordering and relative crystallinity of the HMT-modified starch increased and gradually decreased, reaching a peak of 36.51 % at 6 h, as the HMT time was extended. The pasting indexes of HMT-modified starch decreased and then increased with the increase of the HMT time; compared with JS, the thermal stability of HMT-modified starch increased while the pasting enthalpy decreased. All the HMT-modified starches were weakly gelatinous systems and pseudoplastic fluids. Following HMT, the amount of resistant starch (RS) and slowly digested starch (SDS) grew initially before declining. The amount of RS in HMT-modified starch peaked at 24.28 % when the HMT time was 6 h. The results of this research can serve as a theoretical foundation for the creation of modified japonica starch and its use in the food industry.

A Study on the Structural and Digestive Properties of Rice Starch-Hydrocolloid Complexes Treated with Heat-Moisture Treatment

Rice starch-hydrophilic colloid complexes (SHCs) were prepared by incorporating xanthan gum and locust bean gum into natural rice starch. Subsequently, they underwent hygrothermal treatment (H-SHC) to investigate their structural and digestive properties with varying colloid types and added amounts of H-SHC. The results demonstrated that heat-moisture treatment (HMT) led to an increase in resistant starch (RS) content in rice starch. This effect was more pronounced after the addition of hydrophilic colloid, causing RS content to surge from 8.42 ± 0.39% to 38.36 ± 3.69%. Notably, the addition of locust bean gum had a more significant impact on enhancing RS content, and the RS content increased with the addition of hydrophilic colloids. Enzyme digestion curves indicated that H-SHC displayed a lower equilibrium concentration (C∞), hydrolysis index (HI), and gluconeogenesis index (eGI). Simultaneously, HMT reduced the solubility and swelling power of starch. However, the addition of hydrophilic colloid led to an increase in the solubility and swelling power of the samples. Scanning electron microscopy revealed that hydrophilic colloid encapsulated the starch granules, affording them protection. X-ray diffraction (XRD) showed that HMT resulted in the decreased crystallinity of the starch granules, a trend mitigated by the addition of hydrophilic colloid. Infrared (IR) results demonstrated no formation of new covalent bonds but indicated increased short-range ordering in H-SHC. Rapid viscosity analysis and differential scanning calorimetry indicated that HMT substantially decreased peak viscosity and starch breakdown, while it significantly delayed the onset, peak, and conclusion temperatures. This effect was further amplified by the addition of colloids. Rheological results indicated that H-SHC displayed lower values for G', G″, and static rheological parameters compared to natural starch. In summary, this study offers valuable insights into the development of healthy, low-GI functional foods.

Direct Electrochemistry of Methanobactin Functionalized Gold Nanoparticles on Au Electrode

Mathanobatins (Mb, Mbtins) were immobilized successfully on nanometer-sized gold colloid particles associated with β-mercaptoethylamine. The structures of Mb functionalized gold nanoparticles were characterized and confirmed by UV-vis spectroscopy (UV-vis), FTIR spectra and electrochemical analyses. Direct electron transfer between Mb or copper-loading Mbtins and the modified electrode was investigated without the aid of any electron mediator. The copper-loading Mbtins act as a better electrocatalyst for the reduction of H2O2 than Mb. The copper-loading Mb, with which gold nanoparticles were functionalized, as a model enzyme, was immobilized on gold electrode to construct a novel H2O2 biosensor. In pH 6.4 phosphate buffer solution, the reduction and oxidation peak potentials of Mb functionalized gold nanoparticles modified Au electrode (copper-loading Mbtins) were 0.115 and 0.222 V. On the surface, capacitance per unite area (Cd) of Mb functionalized gold nanoparticles modified electrode were 38 μF cm-2. The immobilized Mb displayed the features of a peroxidase and gave an excellent electrocatalytic response to the reduction of H2O2. The detection limit of Mb functionalized gold nanoparticles (copper-loading) were 09 × 10-5 mA/M (S/N = 3). The Michaelis-Menten constant (Km) was 0.787 mM. Good stability and sensitivity were assessed for the biosensor.

Overexpression of stearoyl-CoA desaturase 1 in bone-marrow mesenchymal stem cells increases osteogenesis

AIM

The goal of this study was to examine the relationship between stearoyl-CoA desaturase 1 (SCD1) and osteogenesis in bone marrow mesenchymal stem cells (BM-MSCs).

METHODS

SCD1 was overexpressed in BM-MSCs using lentiviral transduction. Then, osteogenesis was induced by low glucose DMEM (10% fetal bovine serum). Alkaline phosphatase (ALP) activity assays, Western blot analyses of SCD1 and osteocalcin, and stainings for ALP and alizarin red were done to assess the extent of osteogenesis in BM-MSCs.

RESULTS

ALP activity was markedly higher in the SCD1 overexpressing cells compared with cells transduced with empty vector or control (untransduced) cells at 1 and 2 weeks after osteogenic induction. By contrast, ALP activities were comparable between control cells and cells transduced with empty vector. Western blot analysis demonstrated that osteocalcin levels were higher in the SCD1 overexpressing cells, compared with cells transduced with empty vector or control cells, at 1 and 2 weeks after osteogenic induction. These findings were corroborated by stainings for ALP and alizarin red that demonstrated a more active osteogenesis in the SCD1 overexpressing cells 2 weeks after osteogenic induction.

CONCLUSION

Increased levels of SCD1 enhance osteogenesis in BM-MSCs.

[Posterior stabilized knee arthroplasty: 5-year follow up]

OBJECTIVE

To evaluate the middle-term results of posterior stabilized knee arthroplasty (PSKA).

METHODS

From July 1995 to July 2000, 19 knees of 18 patients were replaced with posterior stabilized prosthesis (Insall-Burstein II). Among the patients, 2 were male, and 16 female. Their average age was 62.5 years (44-78 years). One patient was operated on bilaterally. Preoperative diagnosis revealed osteoarthritis in 16 knees, and rheumatoid arthritis in 3 knees. Four knees demonstrated severe bone deficiency during surgery. Before operation, 15 of the rest knees were varusly deformed, 4 were valgusly deformed, and 8 had flexion contracture. Two patients underwent surgery previously. 17 patients (18 knees) were followed-up for 41-60 months, each of them was evaluated with the Special Surgery Knee Scoring System.

RESULTS

Average preoperative scores increased from 62 preoperatively to 89 postoperatively. The range of motion was significantly improved from 91 degrees preoperatively to 115 degrees postoperatively. Eleven knees were rated as excellent, 5 good, 1 fair, and 1 poor. The excellent and good rate was 88.9%.

CONCLUSIONS

With its design features, PSKA can effectively improve the range of motion and maximum flexion angle without compromising posterior stability. PSKA is suitable for both primary and revision total knee arthroplasty but caution should be taken for patellar complications.