Physicochemical properties of heat-moisture treated, stearic acid complexed starch:The effect of complexation time and temperature

Starch modification has been extensively studied to alter its physicochemical properties based on human needs. Lowering the digestion rate of starch is one of the interests in food science research, since when it is nutritionally improved, it can reduce the risk of human chronic diseases. In this study, heat-moisture treatment (HMT) followed by inclusion complexation with stearic acid at various temperatures and times was applied to improve the functional properties of starch. Thermal analysis suggested the formation of type I and type II complexes after complexation at 90 °C, indicated by a endothermal peak at 107 and 122 °C, respectively, while native starch after complexation only resulted in type I complexes. The formation of crystalline complexes was also confirmed by XRD showing peaks at 2θ = 13.1° and 20.1°. Furthermore, the modified starch displayed a higher pasting temperature, considerably less swelling and significantly lower viscosity behavior. This implied that the starch granules were thermally and mechanically more stable. The granular appearance of the modified starch was confirmed with light microscopy that presented more intact granules and less ruptured granules, even after heating to 90 °C. This study offers a way to upgrade the nutritional properties of starch

In vitro Digestibility Study of Starch Complexed with Different Guest Molecules

Digestibility of starch is an essential issue in food science studies due to its close relationship with human health. Most common starchy foods contain rapidly digestible starch, which can lead to chronic diseases, including type II diabetes. Heat–moisture treated potato starch (HPS) followed by inclusion complexation with guest molecules is prepared to improve starch's physicochemical properties, resulting in reduced digestibility. The guest molecules used in this study are linoleic acid (LA), stearic acid (SA), and sodium stearate (SS). The in vitro digestibility of the modified starches over time compared to native starch after gelatinization at 95 °C is examined. The starch complexed with SS results in the least amount of rapidly digestible starch (RDS), followed by LA and SA, consecutively. Furthermore, the starch-SS complexes are the most slowly digestible starch (SDS) and included the highest amount of resistant starch (RS), followed by LA and SA. Sodium stearate results in the highest transformation of RDS to be SDS and RS. Thermal analysis data and microscopy images support the digestion results

Enzymatic synthesis of muconic acid-based polymers:Trans, trans-dimethyl muconate and trans, β-dimethyl hydromuconate

The vast majority of commodity polymers are acquired from petrochemical feedstock, and these resources will plausibly be depleted within the next 100 years. Therefore, the utilization of carbon-neutral renewable resources for the production of polymers is crucial in modern green chemistry. Herein, we report an eco-friendly strategy that uses enzyme catalysis to design biobased unsaturated (co)polyesters from muconic acid derivatives. This method is an attractive pathway for the production of well-defined unsaturated polyesters with minimum side reactions. A suite of characterization techniques was performed to probe the reaction mechanism and properties of the obtained polyesters. It is rationalized that the alkene functionality of the muconate monomers plays an important role in the enzyme catalysis mechanism. The rendered polyesters possessed excellent thermal stabilities and unreacted alkene functionality that can consecutively undergo chain extension, copolymerization, or act as an anchor for other functional groups. These properties open new avenues in the fields of unsaturated polyester resins and photosensitive coatings

Starch ester film properties:The role of the casting temperature and starch its molecular weight and amylose content

Oleic acid and 10-undecenoic acid were used to esterify corn, tapioca, potato and a waxy potato starch, with a maximum degree of substitution of 2.4 and 1.9 respectively. The thermal and mechanical properties were investigated as a function of the amylopectin content and Mw of starch, and by the fatty acid type. All starch esters had an improved degradation temperature regardless of their botanical origin. While the Tg did increase with increasing amylopectin content and Mw, it decreased with increasing fatty acid chain length. Moreover, films with different optical appearances were obtained by varying the casting temperature. SEM and polarized light microscopy showed that films cast at 20 °C had porous open structures with internal stress, which was absent when cast at higher temperatures. Tensile test measurements revealed that films had a higher Young's modulus when containing starch with a higher Mw and amylopectin content. Besides that, starch oleate films were more ductile than starch 10-undecenoate films. In addition, all films were resistant to water at least up to one month, while some light-induced crosslinking took place. Finally, starch oleate films showed antibacterial properties against Escherichia coli, whereas native starch and starch 10-undecenoate did not.</p

Environmentally friendly pathways towards the synthesis of vinyl-based oligocelluloses

Abstract The synthesis of vinyl-based oligocelluloses using cellodextrin phosphorylase as biocatalyst in buffer solution is presented. Various types of vinyl glucosides bearing (meth)acrylates/(meth)acrylamides functionalities served as the glucosyl acceptor in the enzyme catalyzed reverse phosphorolysis reaction and α-glucose 1-phosphate as the glucosyl donor. The enzymatic reaction was followed by thin layer chromatography and the isolated product yields were about 65%. The synthesized vinyl-based oligocelluloses had an average number of repeating glucosyl units and a number average molecular weight up to 8.9 and 1553 g mol−1, respectively. The majority of the bonds at the alpha position of acrylate units in oligocellulosyl-ethyl acrylate was fragmented as characterized by 1H NMR spectroscopy and MALDI-ToF spectrometry. Nevertheless, a minor amount of fragmentation was observed in oligocellulosyl-ethyl methacrylate and oligocellulosyl-butyl acrylate but no fragmentation was detected in the (meth)acrylamide-based oligocelluloses. Crystal lattice of the prepared vinyl-based oligocelluloses was investigated via wide-angle X-ray diffraction experiments

A História da Alimentação: balizas historiográficas

Os M. pretenderam traçar um quadro da História da Alimentação, não como um novo ramo epistemológico da disciplina, mas como um campo em desenvolvimento de práticas e atividades especializadas, incluindo pesquisa, formação, publicações, associações, encontros acadêmicos, etc. Um breve relato das condições em que tal campo se assentou faz-se preceder de um panorama dos estudos de alimentação e temas correia tos, em geral, segundo cinco abardagens Ia biológica, a econômica, a social, a cultural e a filosófica!, assim como da identificação das contribuições mais relevantes da Antropologia, Arqueologia, Sociologia e Geografia. A fim de comentar a multiforme e volumosa bibliografia histórica, foi ela organizada segundo critérios morfológicos. A seguir, alguns tópicos importantes mereceram tratamento à parte: a fome, o alimento e o domínio religioso, as descobertas européias e a difusão mundial de alimentos, gosto e gastronomia. O artigo se encerra com um rápido balanço crítico da historiografia brasileira sobre o tema

Solvent-Responsive Behavior of Inclusion Complexes Between Amylose and Polytetrahydrofuran

Highly crystalline amylose–polytetrahydrofuran (PTHF) complexes can be obtained by employing organic solvents as washing agents after complex formation. The X-ray diffraction (XRD) of the washed complexes appear sharp at 12.9°–13.2° and 19.6°–20.1°, clear signs of the presence of V6I-amylose. Other diffraction peaks correlate with V6II-amylose, which indicates that the complexed amylose helices are in the form of an intermediate or a mixture of V6I- and V6II-amylose. SEM imaging reveals that the amylose–PTHF complexes crystallize in the form of lamellae, which aggregate in a round shape on top of one another with a diameter around 4–8 µm. Some lamellas aggregate as flower-like or flat-surface spherulitic crystals. There is a visible matrix in between the aggregated lamellas which shows that a part of the amylose–PTHF complexes is amorphous

In vitro Digestibility Study of Starch Complexed with Different Guest Molecules

Digestibility of starch is an essential issue in food science studies due to its close relationship with human health. Most common starchy foods contain rapidly digestible starch, which can lead to chronic diseases, including type II diabetes. Heat–moisture treated potato starch (HPS) followed by inclusion complexation with guest molecules is prepared to improve starch's physicochemical properties, resulting in reduced digestibility. The guest molecules used in this study are linoleic acid (LA), stearic acid (SA), and sodium stearate (SS). The in vitro digestibility of the modified starches over time compared to native starch after gelatinization at 95 °C is examined. The starch complexed with SS results in the least amount of rapidly digestible starch (RDS), followed by LA and SA, consecutively. Furthermore, the starch-SS complexes are the most slowly digestible starch (SDS) and included the highest amount of resistant starch (RS), followed by LA and SA. Sodium stearate results in the highest transformation of RDS to be SDS and RS. Thermal analysis data and microscopy images support the digestion results

Synthesis of telechelic and three-arm polytetrahydrofuran-block-amylose

Telechelic amine terminated polytetrahydrofuran (PTHF) is prepared via cationic ring opening polymerization (CROP) of THF, initiated by trifluoromethanesulphonic anhydride (triflic anhydride). Hexamethylene tetramine (HMTA) is used as a terminating agent. The resulting HMTA terminated PTHF is hydrolyzed to result in an amine terminated PTHF. Reductive amination is carried out by reacting the PTHF with maltoheptaose resulting in maltoheptaose-b-PTHF-b-maltoheptaose. The product is prepared as a primer for the enzymatic polymerization to synthesize amylose-b-PTHF-b-amylose. In addition, a three-arm PTHF is prepared via CROP of THF. The initiator is synthesized in situ by the reaction of triflic anhydride and triethanol amine. The resulting amine terminated three-arm PTHF is reacted with maltoheptaose to synthesize a three-arm PTHF-b-maltoheptaose which can be used for the enzymatic synthesis of three-arm PTHF-b-amylose. Characterization of the products is difficult due to the amphiphilic behavior of both telechelic amylose-b-PTHF-b-amylose and three-arm PTHF-b-amylose. Therefore, the analysis of the products is mainly based on attenuated total reflectance Fourier transform infrared spectroscopy. Telechelic and three-arm polytetrahydrofuran-block-amylose can be synthesized by coupling telechelic and three-arm polytetrahydrofuran with maltoheptaose, followed by enzymatic polymerization to elongate the saccharide blocks. The covalently attached amylose in these block copolymers can form inclusion complexes with suitable guest molecules which leads to a facile approach in modifying block copolymers to result in highly ordered supramolecules

Characterization of Oligocellulose Synthesized by Reverse Phosphorolysis Using Different Cellodextrin Phosphorylases

Much progress was made in the straightforward and eco-friendly enzymatic synthesis of shorter cellulose chains (oligocellulose). Here, we report the determination of a molar mass distribution of the oligocellulose synthesized from cellobiose (CB) and α-glucose 1-phosphate by reverse phosphorolysis, using enzymes cellodextrin phosphorylase from Clostridium stercorarium or Clostridium thermocellum as catalyst. The oligocellulose molar mass distribution was analyzed using three different methods: 1H NMR spectroscopy, matrix assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-ToF MS) and size exclusion chromatography (SEC). The molar mass distribution of the synthesized oligocellulose was only dependent on the concentration of cellobiose used in the reaction. Data obtained from MALDI-ToF MS and SEC were almost identical and showed that oligocellulose synthesized using 10 mM CB has an average degree of polymerization (DPn) of ∼7, while a DPn of ∼14 was achieved when 0.2 mM CB was used in the reaction. Because of solvent limitation in SEC analysis, MALDI-ToF MS was shown to be the technique of choice for accurate, easy and fast oligocellulose molar mass distribution determination