Polysaccharide-based nanosystems: a review.

Polysaccharide-based nanosystem is an umbrella term for many areas within research and technology dealing with polysaccharides that have at least one of their dimensions in the realm of a few hundreds of nanometers. Nanoparticles, nanocrystals, nanofibers, nanofilms, and nanonetworks can be fabricated from many different polysaccharide resources. Abundance in nature, cellulose, starch, chitosan, and pectin of different molecular structures are widely used to fabricate nanosystems for versatile industrial applications. This review presents the dissolution and modification of polysaccharides, which are influenced by their different molecular structures and applications. The dissolution ways include conventional organic solvents, ionic liquids, inorganic strong alkali and acids, enzymes, and hydrothermal treatment. Rheological properties of polysaccharide-based nano slurries are tailored for the purpose functions of the final products, e.g., imparting electrostatic functions of nanofibers to reduce viscosity by using lithium chloride and octenyl succinic acid to increase the hydrophobicity. Nowadays, synergistic effects of polysaccharide blends are increasingly highlighted. In particular, the reinforcing effect of nanoparticles, nanocrystals, nanowhiskers, and nanofibers to hydrogels, aerogels, and scaffolds, and the double network hydrogels of a rigid skeleton and a ductile substance have been developed for many emerging issues.

Effect of Amylose and Crystallinity Pattern on the Gelatinization Behavior of Cross-Linked Starches.

Starches from normal maize (NM), normal potato (NP), waxy maize (WM), and waxy potato (WP) were cross-linked with seven different concentrations (0.01, 0.05, 0.1, 0.5, 1, 5, 10%) of sodium trimetaphosphate and sodium tripolyphosphate. The use of low-amylose WM and WP as well as A-crystalline maize and B-crystalline potato starches can determine the influence of the amylose content and crystallinity pattern on the cross-linking of starches. The results showed that the viscosity of the cross-linked starch (CLs) first increased and then deceased, and finally no viscosity was detected; WM showed no viscosity at 5% and NP at 1%. In addition, the viscosity of NM first increased and then became undetectable at 0.5%. Strikingly, the WP developed viscosity even at a 10% reagent level (RL), and it developed the highest viscosity of all samples at 1%. The starch-iodine method was a facile and high-performance method for the characterization of the cross-linking degree (CL%), having been applied to normal starches, because the increase in the CL% resulted in a decrease of iodine-complexed amylose and blue intensity. In this study, the starch-iodine method was extended to waxy starches, which stained brown with iodine, and the brown intensity decreased with the increase of the CL%. Moreover, the CL% and RL showed a linear-log relationship.

High Amylose-Based Bio Composites: Structures, Functions and Applications.

As biodegradable and eco-friendly bio-resources, polysaccharides from a wide range of sources show steadily increasing interest. The increasing fossil-based production of materials are heavily associated with environmental and climate concerns, these biopolymers are addressing such concerns in important areas such as food and biomedical applications. Among polysaccharides, high amylose starch (HAS) has made major progress to marketable products due to its unique properties and enhanced nutritional values in food applications. While high amylose-maize, wheat, barley and potato are commercially available, HAS variants of other crops have been developed recently and is expected to be commercially available in the near future. This review edifies various forms and processing techniques used to produce HAS-based polymers and composites addressing their favorable properties as compared to normal starch. Low toxic and high compatibility natural plasticizers are of great concern in the processing of HAS. Further emphasis, is also given to some essential film properties such as mechanical and barrier properties for HAS-based materials. The functionality of HAS-based functionality can be improved by using different fillers as well as by modulating the inherent structures of HAS. We also identify specific opportunities for HAS-based food and biomedical fabrications aiming to produce cheaper, better, and more eco-friendly materials. We acknowledge that a multidisciplinary approach is required to achieve further improvement of HAS-based products providing entirely new types of sustainable materials.

Effect of flavonoids from Lycium barbarum leaves on the oxidation of myofibrillar proteins in minced mutton during chilled storage.

Herein, we report the effect of flavonoids from Lycium barbarum leaves (LBLF) on myofibrillar proteins (MP) in minced mutton during chilled storage (4 ± 1 ℃). High performance liquid chromatography (HPLC) analysis showed that the total flavonoid content in LBLF was 322.0 mg/g, of which the rutin content was 297.6 mg/g. The effect of 0.5%, 1.0%, and 1.5% LBLF on the structure and thermodynamic properties of MP in minced mutton was studied systematically. Tyrosine and tryptophan of MP samples treated with LBLF were converted from an exposed state to an embedded state. The interaction between LBLF and MP quenched the internal fluorescence, and improved the thermal stability of MP. The addition of LBLF significantly reduced the carbonyl and sulfhydryl contents of MP (p < 0.05), and decreased the surface hydrophobicity of MP in a dose-dependent manner. Our results indicate that LBLF can combine with free radicals produced by protein oxidation, block the free radical oxidation chain reaction, and inhibit the oxidation of MP. Therefore, LBLF may have great potential as a natural antioxidant in meats and meat products during chilled storage. PRACTICAL APPLICATION: Lycium barbarum is widely distributed in China, especially in Qinghai and Ningxia. The results of this study suggest that flavonoids extracted from L. barbarum leaves may be an effective natural antioxidant for the preservation of meats and meat products.

New insight in crosslinking degree determination for crosslinked starch.

The crosslinked starch has been studied for many years, but it is difficult to characterize degree of substitution on crosslinking of the very high and low crosslinked starches. The available approaches (including viscosity, settling volume, and P content) all have their limitations, i.e., not applicable in a large scope, pollution problem, and can not reflect the internal structure change. Here in this paper starch-iodine (St-I) method was proposed as a new approach to characterize the crosslinking degree. In this investigation, three starches of A, B, and C crystalline pattern with different amount (from very low to very high, 0.01, 0.05, 0.1, 0.5, 1, 5, 10%) of crosslinking reagent added were studied. This method is based on the mechanism that crosslinking reaction take place between amylose/amylopectin, amylopectin/amylopectin, whereas the amylose dose not crosslink one another. After crosslinked to amylopectin, the result amylose-amylopectin complex can be considered as a new amylopectin. Results showed that the St-I method can characterize all the crosslinked starches of the three starches, at low reagent level (0.01-0.1%), the amylose was found to decrease rapidly, this can also replace the viscosity method, whereas at high reagent level (1-10%), although the significant differences can still be observed, the effect was not so obvious as it for the lower crosslinked starches, here we firstly applied dose efficiency to characterize this phenomenon, which was informative and helpful in determining this modification process.

Recrystallization kinetics of starch microspheres prepared by temperature cycling in aqueous two-phase system.

The recrystallization behavior of starch microspheres (SMs) prepared by temperature cycling in aqueous two-phase system (ATPS) was investigated. The SMs were carried out under the temperature-cycled treatment at 4°C, 30°C or 4/30°C for 2 to 20 days. X-ray diffraction (XRD) results showed that the crystalline structure of SMs were different from that of degraded cassava starch. Compared to degraded cassava starch, the relative crystallinity of SMs under different temperature decreased, and the increase in relative crystallinity with the storage time was observed. All gelatinization temperature parameters (To, Tp and Tc) and enthalpy of gelatinization (ΔH) of SMs decreased compared with degraded cassava starch. However, these values of SMs stored at 30°C were higher than that of SMs stored at 4°C and 4/30°C. The Avrami equation was applied to analysis the recrystallization behaviors of SMs. The stability test showed that the samples stored at 30°C were more stable than that stored at 4 °C and 4/30°C.