Effect of Ethanol Extract of Tea on the Microstructural Features and Retrogradation Characteristics of Glutinous Rice Starch

The glutinous rice starch (GRS) regeneration process could lead to decreased product quality and shorter shelf life. The purpose of this study was to analyze the effect of an ethanol extract of tea (EET) on the regeneration properties of GRS. The microstructure of starch was determined via scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR) spectroscopy was used to determine the microstructure of starch-polyphenol molecular groups, an X-ray diffraction (XRD) instrument was used to determine the starch crystal structure, a differential scanning calorimeter (DSC) was used to determine the thermodynamic properties of starch, and the inhibitory effect of EET on GRS regeneration was comprehensively evaluated. The effect of EET on the in vitro digestion properties of GRS was also determined. The results showed that the addition of EET in GRS resulted in an increase in solubility and swelling power and a decrease in crystallinity and ΔHr. Compared to the control group, when retrograded for 10 days, the ΔHr of GRS with 1%, 2.5%, 5%, and 10% addition of EET decreased by 34.61%, 44.53%, 52.93%, and 66.79%, respectively. Furthermore, the addition of EET resulted in a decrease in the content of RDS and an increase in the content of SDS and RS in GRS. It was shown that the addition of EET could significantly inhibit the retrogradation of GRS, improve the processability, and prolong the shelf life of GRS products.

The impact of different concentrations of hyaluronic acid on the pasting and microstructural properties of corn starch

Starch aging in starchy foods is a major problem affecting their quality. In order to improve the viscosity and textural properties of native starch gelatinization and retrogradation, this study investigated the effect of hyaluronic acid (HA) at different concentrations (2 %, 4 %, 6 % w/w) on the pasting and microstructure of corn starch (CS). The findings revealed that the addition of HA significantly enhanced the peak viscosity, solubility, and water-holding capacity of the CS-HA mixtures. Moreover, it reduced the pasting temperature, swelling force, and leaching of amylose. All the mixtures exhibited shear thinning and thixotropic properties. The CS-HA mixtures created a thicker pseudoplastic system with significantly enhanced shear stability. The structures of the mixtures were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. It was observed that HA effectively inhibited short-term retrogradation of starch, enhanced the interaction between CS and HA, and formed a dense honeycomb three-dimensional mesh structure. In conclusion, as a novel anionic hydrocolloid, HA holds great potential to improve the retrogradation properties of starch-based products.

Structural and physicochemical characteristics of wheat starch as influenced by freeze-thawed cycles and antifreeze protein from Sabina chinensis (Linn.) Ant. cv. Kaizuca leaves

The effects of freeze-thawed cycles (FTs) and a new antifreeze protein from Sabina chinensis (Linn.) Ant. cv. Kaizuca leaves (ScAFP) on the structure and physicochemical characteristics of wheat starch were studied. The mechanical breaking exerted by ice crystals on starch granules during FTs gradually deepened, sequentially squeezing the surface (2-6 FTs), amorphous region (8 FTs) and crystalline region (10 FTs) of starch granules. These changes led to reduced thermal stability, increased retrogradation tendency, and weakened gel network structure. The addition of ScAFP retarded the damage of ice crystals on starch granule structure and crystal structure during FTs, and significantly reduced the retrogradation tendency. Compared with native starch, the hardness of freeze-thawed starch without and with added ScAFP after 10 FTs decreased by 17.85% and 9.22%, respectively, indicating ScAFP improved the gel texture properties of freeze-thawed starch. This study provides new strategies for improving the quality of frozen starch-based foods.

Effects of Combining High Pressure Processing Treatments and Konjac Glucomannan and Sodium Caseinate on Gel Properties of Myosin Protein

Effects of two high pressure processing treatments and various levels of konjac glucomannan (KGM) and sodium caseinate (SC) on texture properties, water-holding capacity, and ultra-structure of gels of rabbit myosin protein were investigated. The two high pressure processing treatments were as follows: (1) mean pressure (200 MPa), low temperature (37 °C), and holding for a short time (5 min) followed heating (80 °C for 40 min) (gel LP + H), and (2) high pressure (500 MPa), high temperature (60 °C), and holding for a long time (30 min) (gel HP). Gel LP + H have better gel properties (increased hardness, springiness, gumminess, adhesiveness, cohesiveness, and water binding capacity) than gels HP. Above all, gels myosin + SC:KGM (2:1) have best gel properties. KGM and SC both significantly improved the gel texture properties and water binding capacity.

Physicochemical and Structural Properties of Gluten-Konjac glucomannan Conjugates Prepared by Maillard Reaction

Gluten (Glu) is important to wheat products by forming a three-dimensional matrix. This study aimed to investigate the physicochemical and structural properties of gluten after conjugation with konjac glucomannan (KGM) through the Maillard reaction. The study revealed that the degree of graft increased with the prolonged reaction time. The Glu-KGM conjugates were possessed of increased β-sheet but decreased α-helix and β-turn, as well as unfolding and loose tertiary structures as the reaction proceeded. Among three different proportions, the Glu-KGM 1:1 conjugate was proved to have the most excellent foaming and emulsifying properties, and could form more rigid and firm gelation structures, which could be related to the decreased particle size and increased zeta potential of the conjugate. Overall, the physicochemical and structural properties of gluten were significantly related to the KGM ratios as well as the reaction period.

Study on the quality characteristics of hot-dry noodles by microbial polysaccharides

The effect of curdlan gum (CG), gellan gum (GG), and xanthan gum (XG) on the quality characteristics of hot-dry noodles (HDN) was investigated. The rheology properties were used to evaluate the quality of the dough, the textural, viscosity, cooking characteristics and water states were investigated to study the quality changes of HDN. Three microbial polysaccharides were found that it could improve the quality of wheat flour and significantly increase the starch viscosity of HDN and delay the water migration rate of HDN. When 0.2% CG, 0.5% GG, and 0.5% XG were added, the HDN showed the best flour swelling power, texture, and tensile properties, and the structure of gluten network was significantly improved. The flourier transform infrared spectroscopy results showed that microbial polysaccharides with appropriate concentrations changed the formation of hydrogen bond in HDN, decreased α-helix and increased β-turn content. Meanwhile, the relative continuous and complete gluten network was formed, which could be proven by microstructure observation. This study provides a reference for functionality applications of HDN with microbial polysaccharides.

Impact of Konjac Glucomannan with Different Molecular Weight on Retrogradation Properties of Pea Starch

The impact of konjac glucomannan (KGM) with different molecular weight (Mw) on the retrogradation properties of pea starch, such as color, viscoelasticity, gel strength, water holding capacity (WHC), moisture distribution and crystallinity, was investigated. At the same time as the Mw of KGM decreased, the lightness, elastic modulus, gel strength, water freedom and crystallinity of pea starch showed an increasing trend, whereas the viscosity modulus and WHC showed a decreasing trend. At one day of storage, compared with single pea starch, KGM with low Mw made gel strength increase from 40 g to 45 g, WHC decrease from 82% to 65% and crystallinity increase from 21.3% to 24.0%. Therefore, KGM with low Mw could promote retrogradation of pea starch in the short-term. At 7 days or even 14 days of storage, KGM with medium-high Mw had smaller indices than those of pure pea starch, including the lightness, storage modulus, gel strength, water freedom and crystallinity. This indicated that KGM with medium-high Mw could inhibit the long-term retrogradation of starch. The larger the Mw of KGM, the more noticeable the inhibition effect.

Effects of Konjac Glucomannan on Retrogradation of Amylose

The effect of konjac glucomannan (KGM) on the retrogradation of amylose was explored during storage. The color, rheological properties, texture, water-holding capacity (WHC), low-field nuclear magnetic resonance (LF-NMR), and X-ray diffraction (XRD) were investigated. Results of color and rheological measurements showed that with the increasing amount of KGM, the L value of the system decreased, but the elastic modulus, viscous modulus, and tangent value of loss angle increased. The textural result presented that KGM obviously inhibited the growth rate of gel strength of amylose. Results from WHC and XRD suggested after 14 days of storage, when the concentration of KGM increased from zero to 0.3% in the mixture, the WHC grew from 80% to 95% and the crystallinity degree declined from 35.3% to 25.6%. The LF-NMR result revealed that KGM limited the conversion of free water to bound water in the system. In general, a small amount of KGM in a mixed system could inhibit the short-term and long-term retrogradation of amylose. This research could provide a theoretical reference for the influence of hydrophilic colloids on the retrogradation of starch, and it could also provide support for the processing and production of starch-based food.

Effects of Konjac glucomannan with different viscosities on the rheological and microstructural properties of dough and the performance of steamed bread

Konjac glucomannan (KGM) is used as an additive to improve the properties of wheat products. The effects of three types of KGM on the rheological properties and microstructure of dough, as well as the performance of steamed bread were investigated in this study. Particularly, dough with KGM displayed new features such as reduced peak viscosity, breakdown and setback. As the viscosity of KGM increased, the stability of the dough structure increased, while the viscosity and fluidity of the dough decreased. More interestingly, the gluten film of dough also increased with increasing substitution level and viscosity of KGM. Consistently, KGM with higher viscosity improved the quality of steamed bread. Generally, three types of KGM have different effects on the rheological characteristics and microstructure of dough, as well as the performance of steamed bread, which provide useful information for the proper application of KGM in wheat-based foods.