pectins and trimetaphosphoric-acid

In view of the high nutritional values and bioactivities of resistant starch and pectin, it would be a good choice to chemically combine pectin and starch to give a new type of chemically modified resistant starch.. A new type of chemically modified resistant starch has been prepared by cross-linking starch and pectin using sodium trimetaphosphate. Starch-pectin conjugates can well prevent the hydrolysis catalysed by different enzymes, such as α-amylase, amyloglucosidase, pancreatin as well as β-amylase and glucosidase. Although the conjugates do not change the crystal type of starch, they increase the degree of crystallinity. Moreover, thermal stability and structural homogeneity of the conjugates are positively correlated with double-helical order in the crystalline region.. This study gives a new method for the preparation of resistant starch-pectin conjugates which can be widely used as a new type of food additive in the industry.

Topics: alpha-Amylases; beta-Amylase; Chemical Phenomena; Cross-Linking Reagents; Crystallization; Drug Stability; Food Additives; Glucan 1,4-alpha-Glucosidase; Glucosidases; Hot Temperature; Hydrolysis; Pancreatin; Pectins; Polyphosphates; Starch

Polymers mixtures as well as cross-linking reactions are approaches that have been used successfully to modulate the polymers characteristics in order to improve the control over drug release rate. High amylose and pectin are polysaccharides frequently used to prepare drug delivery systems. Since the drying technique can strongly influence the properties of such systems, the aim of this work was to characterize high amylose/pectin mixtures cross-linked with sodium trimetaphosphate and dried by different techniques - oven and lyophilization. The results showed that samples dried by lyophilization presented reduced particle size, higher porosity and higher swelling ability than the samples dried in oven. Besides, lower thermal stability and different diffraction patterns showed by the former particles should reflect the structural changes as a function of drying technique.

Topics: Amylose; Cross-Linking Reagents; Drug Compounding; Particle Size; Pectins; Polymers; Polyphosphates

Pectin-high amylose starch mixtures (1:4; 1:1; 4:1) were cross-linked at different degrees and characterized by rheological, thermal, X-ray diffraction and NMR analyses. For comparison, samples without cross-linker addition were also prepared and characterized. Although all samples behaved as gels, the results evidenced that the phosphorylation reaction promotes the network strengthening, resulting in covalent gels (highest critical stress, G' and recovery %). Likewise, cross-linked samples presented the highest thermal stability. However, alkaline treatment without cross-linker allowed a structural reorganization of samples, as they also behaved as covalent gels, but weaker than those gels from cross-linked samples, and presented higher thermal stability than the physical mixtures. X-ray diffractograms also evidenced the occurrence of physical and chemical modifications due to the cross-linking process and indicated that samples without cross-linker underwent some structural reorganization, resulting in a decrease of crystallinity. The chemical shift of resonance signals corroborates the occurrence of structural modifications by both alkaline treatment and cross-linking reaction.

Topics: Amylose; Chemistry, Pharmaceutical; Cross-Linking Reagents; Crystallization; Delayed-Action Preparations; Drug Carriers; Drug Compounding; Gels; Hot Temperature; Hydrogen-Ion Concentration; Magnetic Resonance Spectroscopy; Molecular Structure; Pectins; Phosphorylation; Polyphosphates; Rheology; Technology, Pharmaceutical; Thermogravimetry; X-Ray Diffraction

High amylose and pectin were mixed at 1:1 mass ratio and cross-linked with sodium trimetaphosphate (STMP) in alkaline medium. Films were prepared from aqueous dispersions of these cross-linked polymer blend at three different concentrations (3, 4 and 5%), by solvent casting method. Characterization of the films included thickness, surface morphology, water uptake, water vapor permeability (WVP), tensile strength measurements and enzymatic digestion. The cross-linking allowed to obtain films with improved mechanical properties and reduced WVP. The high resistance to enzymatic digestion exhibited by these films represents a promising approach to their application in the development of colon drug delivery systems.

Topics: Amylose; Colon; Cross-Linking Reagents; Drug Carriers; Drug Compounding; Drug Stability; Hydrophobic and Hydrophilic Interactions; Microscopy, Electron, Scanning; Pancreatin; Pectins; Polyphosphates; Stress, Mechanical; Surface Properties; Tensile Strength; Thermodynamics