Effects of damaged starch on glutinous rice flour properties and sweet dumpling qualities

Impacts of transglutaminase on the processing and digestion characteristics of glutinous rice flour: Insight of the interactions between enzymic crossing-linked protein and starch

Glutinous rice is extensively consumed due to its nutritious content and wonderful flavor. However, glutinous rice flour has a high glycemic index, and the storage deterioration of sweet dumplingsissevere. Transglutaminase (TG) was used to cross-link glutinous rice protein and improve the characteristics of glutinous rice products. The findings demonstrated that TG significantly catalysed protein cross-linking to form a dense protein network, reduced the viscosity of glutinous rice paste and improved the thermal stability. The protein network may physically block the access of starch granules to digestive enzymes to lower the digestion rate of starch, and attenuate the damage of ice crystal molecules to the starch structure to improve the freezing stability of starch gels. The cracking rate and water loss of sweet dumplings prepared using glutinous rice flour with TG treated for 60 min reduced significantly. In conclusion, this study broadened the application of TG in starch products.

Appearance, components, pasting, and thermal characteristics of chalky grains of rice varieties with varying protein content

This study investigated two rice varieties, GuichaoII and Jiazao311, with distinct protein content to determine the variation in appearance, components, pasting, and thermal properties of rice with different chalkiness degrees. Grain length, width, head rice weight, and whiteness of both varieties markedly increased as chalkiness increased from 0% to 50%. However, the variation in components, pasting, and thermal characteristics of chalky grain substantially differed between the rice varieties. The protein content of GuichaoII (low protein content) significantly increased with the chalkiness degree, along with a significant increase in onset, peak, and conclusion temperatures and gelatinization enthalpy. In Jiazao311 (high protein content), the chalkiness degree increased with the protein content but decreased with the starch content, along with increased trough, final, setback, and consistency viscosities. Compared to amylose content, protein content had a greater influence on the thermal properties and pasting characteristics of chalky grains of GuichaoII and Jiazao311, respectively.

Evaluation Method of Texture of Glutinous Rice Cakes (Niangao) and Its Key Impact Indicators

This study aimed to find a unique method to assess the textural properties of Niangao (glutinous rice cakes), to determine the relationship between the textural properties of rice cakes and the indicators of glutinous rice, and to identify the key indicators that significantly affect the textural properties of Niangao. The study encompassed the analysis of the chemical composition and pasting characteristics of 22 glutinous rice varieties, revealing the substantial impact of variety on lipid content, straight-chain starch content, and pasting performance. Subsequently, the textural features of the resulting Niangao were subjected to principal component analysis (PCA) to derive a mathematical method for evaluating their textural attributes, with the obtained scores employed in hierarchical cluster analysis (HCA) to identify 12 key textural characteristics. Further analysis using stepwise linear regression (SLR) demonstrated that the regression model incorporating final and peak viscosities of the glutinous rice significantly predicted the composite score of the Niangao's textural properties. This highlights the importance of final and peak viscosities as key indicators for assessing the textural quality of Niangao.

Impact of molecular structure of starch on the glutinous taste quality of cooked chestnut kernels

Chestnuts are a starchy food with a characteristic glutinous taste that is often used to assess their quality. In this study, our findings indicated that chestnuts with higher glutinous taste quality had lower amylose content and microcrystalline structures, as well as higher subcrystalline structures and relative crystallinity in both the raw and steamed starches. In the leached starch, chestnuts with higher glutinous taste quality had lower amylopectin B1 chains and microcrystalline structure, but higher amylopectin B2 chains, subcrystalline structure and relative crystallinity. These results suggest that amylose content, relative crystallinity, and amylopectin chain length distribution are important factors determining the glutinous taste quality of chestnuts. To further enhance our understanding of these factors, an sensory evaluation model was developed based on textural profile analysis parameters. This study provides valuable insights into the relationship between molecular structure of starch and the glutinous taste quality of starchy foods.

The Effect of Different Milling Methods on the Physicochemical and In Vitro Digestibility of Rice Flour

Preparation methods have been found to affect the physical and chemical properties of rice. This study prepared Guichao rice flour with wet, dry, semi-dry, and jet milling techniques. Differences in the particle size distribution of rice flour were investigated in order to assess their impact on pasting, thermal, gel, starch digestibility, and crystalline structure using an X-ray diffractometer (XRD) and a Rapid Visco Analyzer (RVA) across in vitro digestibility experiments. The results showed that semi-dry-milled rice flour (SRF) and wet-milled rice flour (WRF) were similar in damaged starch content, crystalline structure, and gelatinization temperature. However, compared with dry-milled rice flour (DRF) and jet-milled rice flour (JRF), SRF had less damaged starch, a higher absorption enthalpy value, and a higher gelatinization temperature. For starch digestibility, the extended glycemic index (eGI) values of WRF (85.30) and SRF (89.97) were significantly lower than those of DRF (94.47) and JRF (99.27). In general, the physicochemical properties and starch digestibility of WRF and SRF were better than those of DRF and JRF. SRF retained the advantages of WRF while avoiding the high energy consumption, high water consumption, and microbial contamination disadvantages of WRF and was able to produce better rice flour-associated products.

Effects of semidry milling on the properties of highland barley flour and the quality of highland barley bread

BACKGROUND

This study aimed to investigate the effects of semidry milling on the quality attributes of highland barley flour and highland barley bread. Highland barley flours were prepared by dry (DBF), semidry (SBF), and wet (WBF) milling methods. The properties of different highland barley flours were analyzed, and highland barley breads made from different highland barley flours were evaluated.

RESULTS

The results showed that WBF had the lowest damaged starch content (15.2 g kg^-1 ), and the contents of damaged starch in SBF-35 and SBF-40 (43.5 g kg^-1 and 24.1 g kg^-1 respectively) were lower than that of DBF (87.6 g kg^-1 ). And SBF-35 and SBF-40 with large particles exhibited low hydration performance. In addition, SBF-35 and SBF-40 had higher pasting viscosity, pasting temperature, ΔH, and relative crystallinity, consequently resulting in better gel properties than other highland barley flours. These properties could help SBF-35 and SBF-40 develop high-quality bread with large specific volume and superior crumb structure and texture that is similar to the bread with WBF.

CONCLUSION

Overall, semidry milling not only could improve the characteristics of HBF, but also avoid high starch damage by dry milling and water wasting by wet milling. What is more, highland barley breads with SBF-35 and SBF-40 had preferable appearance and crumb texture. Therefore, semidry milling could be regarded as a feasible way to produce highland barley flour. © 2023 Society of Chemical Industry.

Effects of egg powder on the structure of highland barley dough and the quality of highland barley bread

The influences of egg white (EW), egg yolk (EY) and whole egg (WE) on the structure of highland barley dough and the quality of highland barley bread were explored. The results showed that egg powder reduced G' and G" of highland barley dough, which led to the softer texture of dough and endowed bread with a larger specific volume. EW increased the percentage of β-sheet of highland barley dough, EY and WE promoted the transformation from random coil to β-sheet and α-helix. Meanwhile, more disulfide bonds were formed from free sulfhydryl groups in the doughs with EY and WE. These properties of highland barley dough could help highland barley bread develop a preferable appearance and textural feature. It is worth noting that highland barley bread containing EY has more flavorful substances and a better crumb structure, which were similar to that of whole wheat bread. The highland barley bread with EY received a high score according to the sensory evaluation in consumer acceptance.

Understanding effects of glutelin on physicochemical and structural properties of extruded starch and the underlying mechanism

This work studied effects of different amounts of rice glutelin (RG) on physicochemical and structural properties of extruded rice starch (ERS) and explored the underlying mechanism of interaction between rice starch and RG upon extrusion processing. The results showed that the addition of RG altered the pasting properties, improved the viscoelastic, and increased the water mobility of ERS. The weight loss of ERS decreased from 71.40 % to 62.61 %, while the degradation temperature increased from 290.48 °C to 296.25 °C as the RG content increased from 0 % to 12 %. The complex index of extruded starch-glutelin complexes significantly elevated from 10.40 % to 35.81 % when RG content increased from 6 % to 12 %. Fourier-transform infrared spectra confirmed that RG interacted with starch via Maillard reactions, and the binding strength between RG and starch was enhanced at a higher RG content. Furthermore, results of rheological property and chemical interactions demonstrated that hydrogen bonding, hydrophobic, and electrostatic interaction were formed between RG and starch during extrusion. In summary, the obtained results of this study can further enrich the theory of starch-protein interactions and show the possibility of RG applied in the extruded starchy foods.

Structural, physicochemical and digestive properties of rice starch modified by preheating and pullulanase treatments

The structural, physicochemical and digestive properties of rice starch modified by the combination of different temperature (60, 70, 80, 90 and 100 °C) preheating and pullulanase (PUL60, PUL70, PUL80, PUL90 and PUL100) treatments were investigated. The PUL60 treatment mainly modified the surface layer of starch granules, which increased the amylose content and damaged some ordered structures, resulting in slight decreases of gel strength and estimated glycemic index (eGI). With the increase of preheating temperature, PUL could act on more enzymatic sites to release a large amount of linear chains, reduce the ordered degree, and transform the A-type crystalline structure into B-type. The low molecule interaction strength between linear chains weakened the gel network structure, and some stable crystal structures formed by longer chains resisted the enzyme digestion. The gel strength and eGI value of PUL70 starch decreased significantly, and the properties of PUL80-100 starches tended to be stable, showing a further significant decrease of gel strength and a slight reduction of eGI value. Therefore, the preheating treatments at 60, 70 and 80 °C were suitable for the PUL modification of rice starch to obtain strong, medium and weak gel strength respectively, and the digestibility decreased with increasing preheating temperature.

The Possibility of Replacing Wet-Milling with Dry-Milling in the Production of Waxy Rice Flour for the Application in Waxy Rice Ball

Due to the large consumption and discharge of water in wet milling, dry-milling is an alternative to produce waxy rice flour. The physical properties and sensory characteristics for preparing waxy rice balls in dry-milled waxy rice flour were compared in this study. The results showed that the damaged starch content increased significantly with the particle size of dry-milled flour, which decreased from 160 to 30 μm. The reduction in particle size increased the pasting viscosity of waxy rice flour, which further improved the stretch ability of dough and increased the viscoelasticity of the rice ball. The increase in damaged starch content directly led to a significant increase in the solubility of dry-milled flour, thereby increasing the freeze cracking rate of the rice ball and reducing its transparency, resulting in a decline in quality. In comparison with wet-milled waxy rice balls, dry-milled waxy rice balls made from rice flour in the range of 40 μm to 60 μm particle size had a similar texture and taste to that of wet-milled ones, moderate freeze cracking rate and better storage stability, as well as a stronger aroma of waxy rice that the consumer favored. GC-MS analysis showed that the content of key aroma compounds, such as grassy and fruity, noted nonanal in dry-milled flour, was 15-30% higher than that in the wet-milled depending on the difference of waxy rice variety. In conclusion, dry-milled waxy rice flour with a particle size in the range of 40 μm to 60 μm could be a candidate to replace wet-milled flour in the preparation of a waxy rice ball.

Effect of high-pressure homogenisation-modified bacterial cellulose on rice starch retrogradation

Delaying rice starch (RS) retrogradation can improve the quality parameters of rice-based starchy foods during storage. Modification of insoluble dietary fibre has always been used in the starchy food industry. Compared with vegetal insoluble dietary fibre, bacterial cellulose (BC) has many advantages such as high purity, smaller particle size, and elevated water absorption capacity. In the present work, BC was modified by high-pressure homogenisation (MBC) with different pressure levels (0, 50, 80, 120, and 160 MPa) to investigate the effect of MBC on RS retrogradation. Results showed that high-pressure homogenisation could decrease the particle size of BC. MBC addition to RS decreased paste breakdown and setback, thus suggesting that MBC might be a good candidate for increasing the stability of RS paste, and inhibiting its short-term retrogradation. The thermal properties and X-ray diffraction patterns of RS indicated that supplementing MBC could decrease the gelatinised enthalpy and relative crystallinity of RS paste during storage. Results also indicated that MBC could provide an opportunity to restrain RS retrogradation, and might be suitable for designing fibre-enriched products.

Structure and Processing Properties of Nine Yam (Dioscorea opposita Thunb) Starches from South China: A Comparison Study

In order to explore the processing and application potential of Chinese yam starch, nine kinds of Chinese yam starch (GY11, GY5, GY2, GXPY, LCY, SFY, MPY, SYPY, ASY) from South China were collected and characterized. The chemical composition, rheological properties, thermal properties, and in vitro starch digestion were compared, and the correlation between the structure and processing properties of these yam starches was analyzed using Pearson correlation. The results show that GY2 had the highest amylose content of 28.70%. All the yam starches were similarly elliptical, and all the yam starch gels showed pseudoplastic behavior. Yam starches showed similar pasting temperatures and resistant starch content, but SYPY showed the largest particle size (28.4 μm), SFY showed the highest setback (2712.33 cp), and LCY showed the highest peak viscosity (6145.67 cp) and breakdown (2672.33 cp). In addition, these yam starches also showed different crystal types (A-type, B-type, C-type), relative crystallinity (26.54-31.48%), the ratios of 1045/1022 cm-1 (0.836-1.213), pasting properties, and rheological properties, so the yam starches have different application potentials. The rheological and pasting properties were related to the structural properties of starch, such as DI, Mw, and particle size, and were also closely related to the thermodynamic properties. The appropriate processing methods and purposes of the processed products of these yam starches can be selected according to their characteristics.

Enhanced treatment of organic matters in starch wastewater through Bacillus subtilis strain with polyethylene glycol-modified polyvinyl alcohol/sodium alginate hydrogel microspheres

Starch wastewater is a wide range of environmental issues with organic pollutants. A high efficiency and stability hydrogel-organic degradation system was designed via Bacillus Subtilis with Polyethylene glycol (PEG)-modified Polyvinyl alcohol (PVA)/Sodium alginate (SA) hydrogel microspheres. Bacillus subtilis was immobilized on the surface or inside of PEG-modified PVA/SA hydrogels microspheres via physical adsorption. Results showed PEG-modified PVA/SA microspheres had an effect of adsorption on Bacillus subtilis with enhancing bearing rate to 54.22% compared to the blank control group. The effect of microspheres on degradation was remarkable in simulation starch wastewater with a maximum COD removal rate of 93.35% and compared in reality starch wastewater with 90.02% under the optimal condition of pH = 6, 35℃, 20% dosage, 180 rpm. This novel biological method on starch wastewater enhanced tolerance of microorganisms and degradation effect, reflecting safety, effectiveness, and economy with great significance to environmental protection.

Modulating Structure and Properties of Glutinous Rice Flour and Its Dumpling Products by Annealing

In this study, annealed glutinous rice flour treated under different conditions (ANN1, ANN2 and ANN3) were prepared. The structure as well as physicochemical characteristics of the flour and its dumpling products were investigated. The crystallinity of the annealed flour samples increased, while the hydration ability decreased. The content of bound water raised, and immobilized water as well as the freezing enthalpy value decreased for the fast-frozen dumplings made from annealed flour samples. It showed that annealed treatment could reduce the formation of large ice crystals, thus decrease the cracking of fast-frozen dumplings. The freezing enthalpy value of annealed dumplings decreased which was conducive to protect the structure and quality of products. The boiled dumplings made of annealed flour had better eating quality as demonstrated by the increase in the transmittance of the soup. It indicated that moderate annealed glutinous rice flour ANN2 had optimal physicochemical properties to make high quality dumplings. This study would pave the way for further study of the annealing glutinous rice flour and provide theoretical guidance for the application of annealing treatment in starchy food product.

Effects of Different Processing Methods and Internal Components on Physicochemical Properties and Glycemic Index of Adzuki Bean Powder

The estimated glycemic index (eGI) value of adzuki bean powder prepared by steamed cooking (SC), extruded cooking (EC) and roller cooking (RC) was studied comparatively. Results showed that RC had the highest eGI, with 80.1, and both EC and SC resulted in a lower eGI value of 70.0 and 49.7, respectively. Compared with the EC and RC methods, the SC method provided a more intact physical barrier for starch digestion, resulting in a less destroyed cell structure. As the essential components that form the cell wall, the study further investigated the effects of protein and fiber on physicochemical properties, in vitro starch digestibility and the eGI of adzuki bean powder processed with the SC method. Viscozyme and Protamax were used to obtain the deprotein and defiber samples. Results showed that the SC treatment with Viscozyme and Protamax, respectively, had significant effects on in vitro starch digestibility. The eGI of different samples were given as follows: steamed cooking adzuki bean powder (49.7) < deproteined adzuki bean powder (60.5) < defibered adzuki bean powder (83.1), which indicates that fiber may have a greater influence on the eGI than protein.