Starch transitions of different gluten free flour doughs determined by dynamic thermal mechanical analysis and differential scanning calorimetry

Investigation of the effect and mechanism of nanocellulose on soy protein isolate- konjac glucomannan composite hydrogel system

To enrich the application of nanocomposite hydrogels, we introduced two types of nanocellulose (CNC, cellulose nanocrystals; CNF, cellulose nanofibers) into the soy protein isolate(SPI)- konjac glucomannan (KGM) composite hydrogel system, respectively. The similarities and differences between the two types of nanocellulose as textural improvers of composite gels were successfully explored, and a model was developed to elaborate their interaction mechanisms. Appropriate levels of CNC (1.0 %) and CNF (0.75 %) prolonged SPI denaturation within the system, exposed more buried functional groups, improved molecular interactions, and strengthened the honeycomb structural skeleton formed by KGM. The addition of CNC resulted in greater gel strength (SKC1 2708.53 g vs. Control 810.35 g), while the addition of CNF improved the elasticity (SKF0.75 1940.24 g vs. Control 405.34 g). This was mainly attributed to the reinforcement of the honeycomb-structured, water binding and trapping, and the synergistic effect of covalent (disulfide bonds) and non-covalent interactions (hydrogen bonds, ionic bonds) within the gel network. However, the balance and interactions between proteins and polysaccharides were disrupted in the composite system with excessive CNF addition (≥0.75 %), which broken the stability of the honeycomb-like structure. We expect this study will draw attention on potential applications of CNC and CNF in protein-polysaccharide binary systems and facilitate the creation of novel, superior, mechanically strength-regulated nanofiber composite gels.

Insight into the biphasic transition of heat-moisture treated waxy maize starch through controlled gelatinization

Biphasic transition is an important behavior of starch caused by heat-moisture treatment (HMT). Starch may change from typical single endotherm to biphasic endotherm (G1, G2) by HMT which corresponded to two viscosity peaks (PV₁ and PV₂) in pasting analysis. During PV₁, remarkable disruption of birefringence occurred in the inner region of starch granules, accompanied by a decreased relative crystallinity from 20.59 to 14.73%. Native starch completely lost their birefringence at 73 °C, while the HMT starch still showed strong birefringence in granule periphery. The HMT starch only lost crystallites at 80 °C (PV₂). A crystallite stability hypothesis was developed that G1 was mainly due to the gelatinization of the inner crystalline lamellae of starch granule, and the newly formed G2 was caused by the peripheral ones enhanced by HMT. This work also provided details on the mechanism of HMT and a potential method for the thermal transition study on starch.

Determination of thermal transitions of gluten-free chestnut flour doughs enriched with brown seaweed powders and antioxidant properties of baked cookies

A protocol for determining the characteristic temperatures of thermomechanical transitions on gluten-free flour doughs is proposed. This protocol is based on the mathematical analysis of experimental curve of storage modulus (G′) vs temperature obtained by means of Dynamic Mechanical Thermal Analysis (DMTA) technique. Doughs at constant consistency of chestnut flour with different levels (3, 6 and 9% flour basis, f.b.) of brown seaweed (Bifurcaria bifurcata, Fucus vesiculosus and Ascophyllum nodosum) powders addition, 2% f.b. of guar gum and 1.8% f.b. of salt with different water absorption were used to test the proposed protocol. The ranges of temperatures corresponding to starch gelatinization (59–97 °C), amylopectin crystallites melting (82–101 °C), reversible dissociation of lipid-amylose complexes (107–128 °C) and amylose melting (133–171 °C) showed a strong dependence with water absorption of samples. Doughs with the same water absorption submitted to starch gelatinization during mixing were also analysed to corroborate the protocol suitability. Total polyphenols content and radical scavenging activity of extracts from chestnut flour-seaweed powder blends and seaweed-enriched chestnut cookies baked at 180 °C were determined. Extraction assisted with ultrasounds was carried out employing acetone-water (70:30 v/v) solution as solvent during 4 min with a liquid/solid ratio of 30 w/w. Seaweed powder addition had a positive effect on antioxidant properties of doughs before baking. However, the seaweed powder addition effect on baked products (cookies) is not clear due to antioxidant activity is overlapped by Maillard's products generated during baking.

Interactions between soluble dietary fibers and wheat gluten in dough studied by confocal laser scanning microscopy

Four soluble dietary fiber (SDF) fractions characterized by major components of AXs, relatively narrow molecular weight distribution, different substituted ratio, and structure-sensitive parameter (ρ) were prepared from wheat bran. The fractions were added to wheat dough to determine the interactions between the dough's network and the SDF fractions relative to their physicochemical characteristics. Furthermore, a comprehensive study focusing on the dough texture characteristic, tensile properties, thermodynamic stability, and the microstructure was conducted by performing texture profile analysis (TPA), differential scanning calorimetry (DSC), and confocal laser scanning microscopy (CLSM) experiments. Additionally, an estimation function of the interactions parameters between the dough's network and the SDF fractions related to the factor molecular weight and ρ of the SDFs was established. The results indicated that the SDF fractions exhibiting a medium molecular weight, and a higher substitution degree and di-substituted ratio, were the most suitable fortifier providing benefits to the dough's qualities. Furthermore, the research methodology might support the high potential of SDF fractions as fortifier for flour-based products.