Development of Emulsion Gels Stabilized by Chitosan and Octenyl Succinic Anhydride-Modified ß-Cyclodextrin Complexes for ß-Carotene Digestion and 3D Printing.

ß-cyclodextrin (ß-CD)-based emulsion gels encapsulated with nutrition for three-dimensional (3D) printing are promising, while obstacles such as low bioaccessibility of bioactive compounds and the molding process in food manufacturing hinder their application. This study intended to develop stable composite emulsion gels using the complexes of chitosan (CS) and octenyl succinic anhydride (OSA)-modified ß-CD (OCD) to conquer these challenges. The esterification of OSA generated more negatively charged OCD and ester groups, which aided in the combination of OCD and CS through enhanced electrostatic and hydrogen bonding interactions. The addition of CS improved the emulsification properties of the complexes and acted as a bridge link in the aqueous phase, thereby increasing the gel strength of the composite emulsion gels. Moreover, the encapsulation of ß-carotene destabilized the strength of the emulsion gels by lowering the interfacial tension. The emulsion gel stabilized by OCD3/CS-0.75% at an initial pH not only successfully encapsulated ß-carotene and presented the highest bioaccessibility of 41.88 ± 0.87% in the in vitro digestion but also showed excellent 3D printability. These results provided a promising strategy to enhance the viscoelasticity of ß-CD-based emulsion gels and accelerate their application in bioactive compound delivery systems and 3D food printing.

Preparation of hydroxybutyl starch with a high degree of substitution and its application in temperature-sensitive hydrogels.

In this work, hydroxybutyl starch prepared by acid, alkali, and acid-base synergistic pretreatments from waxy corn starch exhibited great potential for preparing temperature-sensitive hydrogels. The degree of substitution, morphology, and group structure of hydroxybutyl starch were determined. The hydroxybutyl starch prepared by acid-base synergistic pretreatment had the highest degree of substitution. Relative to the native starch, the surface of hydroxybutyl starch particles was smoother and rounder. The formation, microstructure, and properties of temperature-sensitive hydrogels were also determined in this work. The results indicated that the temperature-sensitive hydrogels containing hydroxybutyl starch had irregular pore structures and higher water absorption rates. As the starch content increased, the pore size of these hydrogels increased and then decreased, the water absorption rate increased and the deswelling rate decreased. The equilibrium swelling ratio of the hydrogel prepared by hydroxybutyl starch was greater than that of native starch.

Chemoenzymatic access to enantiopure N-containing furfuryl alcohol from chitin-derived N-acetyl-D-glucosamine.

BACKGROUND: Chiral furfuryl alcohols are important precursors for the synthesis of valuable functionalized pyranones such as the rare sugar L-rednose. However, the synthesis of enantiopure chiral biobased furfuryl alcohols remains scarce. In this work, we present a chemoenzymatic route toward enantiopure nitrogen-containing (R)- and (S)-3-acetamido-5-(1-hydroxylethyl)furan (3A5HEF) from chitin-derived N-acetyl-D-glucosamine (NAG). FINDINGS: 3-Acetamido-5-acetylfuran (3A5AF) was obtained from NAG via ionic liquid/boric acid-catalyzed dehydration, in an isolated yield of approximately 31%. Carbonyl reductases from Streptomyces coelicolor (ScCR) and Bacillus sp. ECU0013 (YueD) were found to be good catalysts for asymmetric reduction of 3A5AF. Enantiocomplementary synthesis of (R)- and (S)-3A5HEF was implemented with the yields of up to > 99% and the enantiomeric excess (ee) values of > 99%. Besides, biocatalytic synthesis of (R)-3A5HEF was demonstrated on a preparative scale, with an isolated yield of 65%. CONCLUSIONS: A two-step process toward the chiral furfuryl alcohol was successfully developed by integrating chemical catalysis with enzyme catalysis, with excellent enantioselectivities. This work demonstrates the power of the combination of chemo- and biocatalysis for selective valorization of biobased furans.

Hydroxybutyl starch-based thermosensitive hydrogel for protein separation.

The starch-based thermosensitive hydrogel (STH) is a new type of polymer material with great water-absorbing ability. In this study, a series of STHs was synthesized based on hydroxybutyl starch (HS) and polyethylene glycol (PEG). Furthermore, bovine serum albumin (BSA) was used as a model protein for separation from produced hydrogels. This STH exhibited a reversible swelling and deswelling as the temperature changed. It was found that the addition of HS and PEG resulted in more microporous structures and increasing equilibrium swelling ratio (ESR). The improved performance, simple method and low-cost material conferred STH to serve as a considerable biomaterial for protein separation.

Effects of dry heat treatment on the structure and physicochemical properties of waxy potato starch.

The effects of dry heat treatment (DHT) on the structure and physicochemical properties of waxy potato starch were investigated. The scanning electron microscopy, polarized light microscopy, X-ray diffraction, pasting properties, differential scanning calorimeter, swelling power, solubility and in-vitro digestion were evaluated. The surface and cross-polarized crosses structure of all starches had variation. The type of crystallite of waxy potato starch was changed from B to B + A after DHT and promoted a reduction in relative crystallinity. The pasting temperature was reduced through DHT, but the peak viscosity was enhanced. The rapidly digestible starch (RDS) content of starch increased and resistant starch (RS) content of starch decreased after DHT.

Preparation and emulsification properties of dialdehyde starch nanoparticles.

Physicochemical and emulsification properties of dialdehyde starch nanocrystals (DASNCs) and dialdehyde starch nanoparticles (DASNPs) were measured in this study. The starch nanocrystals (SNCs), which are prepared by sulfuric acid hydrolysis, were oxidized by sodium periodate to obtain the DASNCs. The DASNPs were prepared by gelatinization and alcohol precipitation of dialdehyde starch. After oxidization by sodium periodate, the SNCs and SNPs became smaller and more suitable for dispersion. X-ray diffraction results showed that the crystal pattern of the SNCs was preserved after oxidation. However, only a single broad peak at the Bragg angle of the DASNPs was observed. The SNCs and DASNCs can form Pickering emulsions, but the emulsions stabilized by the SNPs and DASNPs could be easily broken. The preparation methods for the two kinds of dialdehyde starch nanoparticles are different, so their structures, properties and applications are different.

Surface chemical functionalization of starch nanocrystals modified by 3-aminopropyl triethoxysilane.

A comparative experiment about the 3­aminopropyl triethoxysilane (APTES) modification of waxy potato starch nanocrystals (WPSNCs) and waxy maize starch nanocrystals (WMSNCs) was employed in the present study. The purpose of surface chemical functionalization was to introduce functional groups and improve hydrophobicity of SNCs for the extensive application. The degree of substitution (DS) of both SNCs displayed the upward trend with the increase of applied APTES, while WPSNCs showed higher DS than that of WMSNCs in the same dosage of APTES. XRD revealed the un-changed crystalline structure and decreased relative crystallinity after the modifications. The structure of silylated SNCs surface was characterized by FT-IR and XPS, which confirmed the presence of functional amino groups. The introduction of amino groups resulted in a simultaneous enhancement of zeta potentials for both SNCs relatively. The modified SNCs could be uniformly dispersed both in water and ethanol phase revealing improved hydrophobicity through wettability experiments.

Preparation of starch nanocrystals through enzymatic pretreatment from waxy potato starch.

A comparative experiment about the production of starch nanocrystals (SNCs) with/without glucoamylase enzymatic pretreatment by sulfate acid hydrolysis from waxy potato starch (WPS) was employed in the present study. The research focused on the enhancement of the preparation efficiency while improving the dispersion of SNCs at the same time. The enzymatic pretreatment resulted in the decrease of acid hydrolysis duration. The minimum size and best dispersibility of nanocrystals was obtained after 5 days of hydrolysis. X-ray diffraction confirmed the increase of crystallinity (from 33% to 50.8%) and the polymorphic transitions (B-A) for nanocrystals harvested at day 5. The structure of nanocrystals was characterized by FT-IR, which suggested the presence of sulfate ester on the surface of SNCs. Zeta potential and size distribution revealed the prominent stability and dispersibility of nanocrystals at pH 7.0. SEM and TEM revealed that SNCs had square shapes with particle sizes ranging from 50 to 100 nm.