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1.
Carbohydr Polym ; 262: 117968, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33838833

RESUMO

Enzymatically rearranging α-1,4 and α-1,6 glycosidic bonds in starch is a green approach to regulating its digestibility. A two-step modification process successively catalyzed by 1,4-α-glucan branching enzymes (GBEs) from Rhodothermus obamensi STB05 (Ro-GBE) and Geobacillus thermoglucosidans STB02 (Gt-GBE) was investigated as a strategy to reduce the digestibility of corn starch. This dual GBE modification process caused a reduction of 25.8 % in rapidly digestible starch fraction in corn starch, which were more effective than single GBE-catalyzed modification with the same duration. Structural analysis indicated that the dual GBE modified product contained higher branching density, more abundant short branches, and shorter external chains than those in single GBE-modified product. These results demonstrated that a moderate Ro-GBE treatment prior to starch gelatinization caused several suitable alterations in starch molecules, which promoted the transglycosylation efficiency of the following Gt-GBE treatment. This dual GBE-catalyzed modification process offered an efficient strategy for regulating starch digestibility.


Assuntos
Enzima Ramificadora de 1,4-alfa-Glucana/química , Glicosídeos/química , Amido/química , Enzima Ramificadora de 1,4-alfa-Glucana/metabolismo , Amilose/química , Amilose/metabolismo , Bacillaceae/enzimologia , Digestão , Glicosídeos/metabolismo , Espectroscopia de Ressonância Magnética/métodos , Estrutura Molecular , Rhodothermus/enzimologia , Amido/metabolismo
2.
J Agric Food Chem ; 69(1): 354-367, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33350823

RESUMO

Dietary starch is usually associated with elevated postprandial glycemic response. This is a potential risk factor of type 2 diabetes. Here, a 1,4-α-glucan branching enzyme (GBE) was employed to reassemble α-1,4 and α-1,6 glycosidic bonds in starch molecules. Structural characterization showed that GBE-catalyzed molecular reassembly created an innovative short-clustered maltodextrin (SCMD), which showed a dense internal framework along with shortened external chains. Such short-clustered molecules obstructed digestive enzymes attack and displayed dramatically reduced digestibility. Therefore, SCMD was served as a dietary starch substitute to improve postprandial glucose homeostasis. A 22.3% decrease in glycemic peak was therefore detected in ICR mice following SCMD intake (10.7 mmol/L), compared with that in the control (13.8 mmol/L). Moreover, an attenuated insulin response (40.5% lower than that in control) to SCMD intake was regarded suitable for diabetes management. These novel discoveries demonstrate that enzymatically rebuilding starch molecules may be a meaningful strategy for diabetes management.


Assuntos
Diabetes Mellitus Tipo 2/dietoterapia , Polissacarídeos/metabolismo , Animais , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Índice Glicêmico , Homeostase , Humanos , Insulina/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos ICR , Polissacarídeos/química , Período Pós-Prandial , Amido/metabolismo
3.
J Sci Food Agric ; 101(9): 3742-3748, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33301206

RESUMO

BACKGROUND: Designing a high-concentration (50%, w/w) maltodextrin saccharification process is a green method to increase the productivity of maltose syrup. RESULTS: In this study, a temperature-mediated two-step process using ß-amylase and pullulanase was investigated as a strategy to improve the efficiency of saccharification. During the saccharification process, both pullulanase addition time and temperature adjustment greatly impacted the final maltose yield. These results indicated that an appropriate ß-amylolysis in the first stage (the first 8 h) was required to facilitate saccharification process, with the maltose yield of 8.46% greater than that of the single step saccharification. Molecular structure analysis further demonstrated that a relatively low temperature (50 °C), as compared with a normal temperature (60 °C), in the first stage resulted in a greater number of chains polymerized by at least seven glucose units and a less heterogeneity system within the residual substrate. The molecular structure of the residual substrate might be beneficial for the subsequent cooperation between ß-amylase and pullulanase in the following 40 h (second stage). CONCLUSION: Over a 48 h saccharification, the temperature-mediated two-step process dramatically increased the conversion rate of maltodextrin and yielded significantly more maltose and less byproduct, as compared with a constant-temperature process. The two-step saccharification process therefore offered an efficient and green strategy for maltose syrup production in industry. © 2020 Society of Chemical Industry.


Assuntos
Glicosídeo Hidrolases/química , Maltose/análise , Polissacarídeos/química , Biocatálise , Glucose , Hidrólise , Temperatura
4.
J Agric Food Chem ; 68(44): 12400-12412, 2020 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-33084325

RESUMO

Molecular structure of starch in daily diet is closely associated with diabetes management. By enzymatically reassembling α-1,4 and α-1,6 glycosidic bonds in starch molecules, we have synthesized an innovative short-clustered maltodextrin (SCMD) which slowly releases glucose during digestion. Here, we investigated the potential benefits of the SCMD-containing diet using diabetic db/db mice. As compared to a diet with normal starch, this dietary style greatly attenuated hyperglycemia and repaired symptoms associated with diabetes. Additionally, in comparison with acarbose (an α-glucosidase inhibitor) administration, the SCMD-containing diet more effectively accelerated brown adipose activation and improved energy metabolism of db/db mice. Furthermore, the SCMD-containing diet was a more suitable approach to improving the intestinal microflora than acarbose administration, especially the proliferation of Mucispirillum, Akkermansia, and Bifidobacterium. These results reveal a novel strategy for diabetes management based on enzymatically rebuilding starch molecules in the daily diet.


Assuntos
Diabetes Mellitus Tipo 2/dietoterapia , Diabetes Mellitus Tipo 2/metabolismo , Carboidratos da Dieta/metabolismo , Microbioma Gastrointestinal , Polissacarídeos/metabolismo , Animais , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Diabetes Mellitus Tipo 2/microbiologia , Carboidratos da Dieta/análise , Modelos Animais de Doenças , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Polissacarídeos/química , Amido/metabolismo
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