Effects of different gelatinization degrees of starch in potato flour on the quality of steamed bread

Insight into the mechanism of digestibility inhibition by interaction between corn starch with different gelatinization degree and water extractable arabinoxylan

On the basis of revealing the interaction mechanism between corn starch (CS) and water-extractable arabinoxylan (WEAX) with high/low molecular weight (H-WEAX, L-WEAX), the degree of gelatinization (DG) on structural behaviors and in vitro digestibility of CS-WEAX complexes (CS/H, CS/L) was evaluated. With the increased DG from 50 % to 95 %, the water adsorption capacity of CS/L was increased 64 %, 58 %, 47 %, which were higher than that of CS/H (39 %, 54 %, 33 %). The gelatinization of starch was inhibited by WEAX, resulting in the enhancement of crystallinity, short-range ordered structure and molecular size of CS-WEAX complexes. Stronger interaction was detected in CS/L than with CS/H as proved by the increased hydrogen bonds and electrostatic force. Complexes exhibited higher resistant starch content (RS) at diverse DG, especially for CS/L. Notability, RS content of samples with 50 % DG were increased from 27.72 % to 32.89 % (CS/H), 36.96 % (CS/L). Except for the reduction of gelatinization degree by adding WEAX, the other possible mechanisms of retarding digestibility were explained as the small steric hindrance of L-WEAX promoted encapsulation of starch granules, limiting enzyme accessibility. Additionally, the fragmentation of CS granules with high DG promoted the movement of H-WEAX, reducing the difference in digestibility compared to CS/L.

Structural modification of starch and protein: From the perspective of gelatinization degree of oat flour

To clarify the relationship between gelatinization degree and structure characteristics, oat kernels were roasted to different gelatinization degree of 15 %-90 % based on tempering water content of 22.5 %-35 %, and the structure characteristics of starch and protein were evaluated. The results showed that the increased gelatinization degree dependent on tempering water content promoted protein aggregation on the surface of starch particles, forming larger aggregates with molecular weight >100 kDa. Oat kernels presented a dense starch gel network structure induced by gelatinized starch. Partial gelatinization of starch led to a decrease in pasting viscosities (setback viscosity, 3.91 Pa·s-1.59 Pa·s) and enthalpy (5.12 J/g-0.11 J/g). With the increase of gelatinization degree, the starch crystal structure conversed from A + V type to V type, accompanied by the formation of starch-lipid complexes and a decrease of relative crystallinity (22.28 %-8.72 %). Moreover, 50 % gelatinized oat flour possessed the highest β-sheet structure (38.04 %), but a decrease in surface hydrophobicity and an increase in endogenous fluorescence intensity were found in oat flour of gelatinization degree >50 %. This study provided a theoretical reference for the application of oat flour with different gelatinization degrees to match suitable products.

Effect of partial substitution of wheat flour with kiwi starch on dough rheology, microstructure, the quality attributes and shelf life of Chinese steamed bread

Chinese steamed bread (CSB), a conventional high-GI staple food, with a short shelf life and a single flavor. In this work, 10-20 % kiwi starch (KS) was used to substitute wheat flour for the production of CSB and the effects of different substitution ratios on the quality and shelf life of mixed flour, dough, and CSB were explored. The results showed that the substitution of KS could improve the water binding capacity of mixed flour and lead to easier pasting in the system, lower the cooking power consumption, increase and improve the viscoelasticity and gas holding capacity of the dough, and make the microstructure more compact and uniform. As the substitution ratio increased, the reduction in protein content within the system further affected the formation of the gluten network, leading to a significant decrease in the CSB's specific volume and cohesiveness, whereas the chewiness and hardness were significantly improved. Meanwhile, KS substitution significantly reduced the starch hydrolysis rate and estimated glycemic index of CSB. 10 % KS substitution enriched the aroma and color of CSB, improved its internal organizational structure, and became more popular among consumers. A substitution ratio of 15-20 % was beneficial for extending the shelf life of CSB.

Effects of barley seedling powder on rheological properties of dough and quality of steamed bread

In order to find the optimal share of barley seedling powder (BSP) to improve the rheological properties of wheat dough and physico-chemical properties of steamed bread (SB), BSP was added with wheat flour at various proportions (2-10%). Results showed that with the increasing amount of BSP additive, the farinograph index (86.33-123), dough stability (9.37-12.63 min), and dough development time (6.23-7.63 min) in blend flour increased. Similarly, with the increasing BSP, SB became darker and more greenish, and the total flavonoid content increased. The content of chlorophyll-b, and total chlorophyll demonstrated a faster increase than that of chlorophyll-a. The hardness and chewability of SB improved as well whereas the springiness increased first and then decreased. The best springiness and gumminess of SB were found with 2% and 8% BSP additives respectively. 2%, 4%, and 6% addition of BSP resulted in a slight fluctuation in the bound water quantity than 8% and 10% BSP additive. No new compound formation was confirmed by Infrared analysis and there was only a heat and mass transfer process. Results from this study indicated that SB with improved quality attributes can be prepared from wheat flour fortified with BSP at 2-4%.

Interaction of starch and non-starch polysaccharides in raw potato flour and their effects on thickening stability

The present study sought to explore the potential of raw potato flour prepared from two common potato varieties (Atlantic and Favorita) as a thickener and the underlying mechanisms of its thickening stability based on the chemical component content, chemical group, starch, pectin, cell wall integrity, and the cell wall strength of raw potato flour. The raw potato flour prepared from Favorita potato (FRPF) showed great potential as a thickener with a valley viscosity/peak viscosity of 97.24 %. Additionally, the viscosity of FRPF after heat treatment, acid treatment and shear treatment was maintained at 70.73 %, 65.99 % and 78.89 % of the original viscosity, respectively, which is better than that of ARPF (44.98 %, 47.03 % and 61.57 %, respectively). The results also revealed that high pectin content, cell wall integrity and strength contributed significantly to the thickening stability of potato meal, which was achieved by limiting the swelling and disintegration of starch. Finally, the correctness of the principle was verified using the raw potato flour prepared from four types of potatoes (Heijingang, Innovator, Qingshu No. 9, and Guinongshu No. 1). Overall, the development of thickener from raw potato flour has broadened the variety of clean label additives in the food industry.

Enhancing the quality of steamed oat cake by partially gelatinized starch in oat flour and its molecular mechanism

The aim of this study was to investigate the effect and mechanism of partially gelatinized starch in oat flour on the rheological characteristics of the oat batter and the quality of steamed oat cakes. The results showed that an increase in the gelatinization degree of oat flour destroyed the starch granular structure and the long-range molecular order of starch, accompanied by a decrease of crystallinity from 22.28 % to 8.72 % and the formation of a starch-lipid complex. The increased gelatinization degree of oat flour destroyed the protein network and promoted the formation of the starch gel network in oat batter. Meanwhile, the addition of gelatinized oat flour enhanced the elastic behavior of the oat batter and the gas retention ability of the fermented oat batter, while decreased the total gas volume from 1075.5 mL to 827.0 mL. The steamed oat cake containing 50 % gelatinization degree of oat flour (G50) showed moderate hardness, springiness and chewiness, as well as the largest cell area fraction (37.35 %), due to the formation of a dense starch gel-protein double network and the enhancement of long/short-range molecular order of starch. Thus, this study provided the feasibility of improving the quality of oat-based fermented products by changing the gelatinization degree of oat starch.

Study of ultrasonic treatment on the structural characteristics of gluten protein and the quality of steamed bread with potato pulp

Physicochemical properties and microstructure of gluten protein, and the structural characteristics of steamed bread with 30 % potato pulp (SBPP) were investigated by ultrasonic treatments. Results showed that 400 W ultrasonic treatment significantly (P < 0.05) increased the combination of water and substrate in the dough with 30 % potato pulp (DPP). The contents of wet gluten, free sulfhydryl (SH), and disulfide bond (SS) were influenced by ultrasonic treatment. Moreover, UV-visible and fluorescence spectroscopy demonstrated that the conformation of gluten protein was changed by ultrasonic treatment (400 W). Fourier transform infrared (FT-IR) illustrated that the β-sheet content was significantly (P < 0.05) increased (42 %) after 400 W ultrasonic treatment, and the surface hydrophobicity of gluten protein in SBPP increased from 1225.37 (0 W ultrasonic treatment) to 4588.74 (400 W ultrasonic treatment). Ultrasonic treatment facilitated the generation of a continuous gluten network and stabilized crumb structure, further increased the specific volume and springiness of SBPP to 18.9 % and 6.9 %, respectively. Those findings suggested that ultrasonic treatment would be an efficient method to modify gluten protein and improve the quality of SBPP.