图 6. 回生大米淀粉凝胶的 SAXS 分析结果。A 至 C 分别代表回转半径(R g )、横截面的回转半径(R c )和簇结构中圆柱模型长度(L)。
一般来说,所有样品的 R c 值在 15 天储存期间趋于增加(图 6B)。这表明更多的解开的 DNA 双螺旋链发生交联和聚集,导致淀粉凝胶的回生。PRSP 的添加也降低了未储存样品的 R c 值,这归因于解开的双螺旋链伸展不足,与 R g 结果一致。
圆柱模型(L)的长度如图 6C 所示。L 的变化趋势与 R g 相似。R g 可能主要受 L 控制,换句话说,是淀粉分子链的长度。在 5 天后,凝胶样品的 L 值随时间增加,可能是由于直链淀粉分子在长期回生过程中重新结合形成更长的链结构。此外,添加 20% PRSP 的样品 L 值较低,表明 PRSP 的添加可以抑制较大簇状结构的形成。
散射物体具有表面分形结构,其分形维度 D s = 6 − p,当 3 < p < 4 时;而质量分形结构用分形维度 D m = p 描述,当 1 < p < 3 时。较高的 D m 值表示散射物体的结构更紧凑(Suzuki 等,1997)。无储存样品的分形维度列于表 1。所有 p 值均在 1 < p < 3 的范围内,表明所有样品在凝胶化后均表现出质量分形结构。添加了 PRSP 的样品的 D m 值高于未添加 PRSP 的样品,对应于 RS 的更致密内部结构。这一结果可能归因于未解缠淀粉链扩展空间不足,表明 PRSP 在凝胶化过程中对 RS 膨胀的抑制作用。
表 1. 无储存的淀粉凝胶的质量分形维数(D m )。
样本
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SAXS 数据表明,未储存的凝胶样品的 R g 值通过添加 PRSP 而降低,而 D m 值则增加。这或许为 PRSP 对原生 RS 膨胀的抑制作用提供了证据,导致 RS 的内部结构更加致密。R g 、R c 和 L 值表明,添加 20%PRSP 可以减小淀粉回生过程中的聚集体大小。SAXS 结果提示,添加 PRSP 可能抑制纳米尺度有序聚集体的形成,这与淀粉的回生有关。
To effectively inhibit the retrogradation of staple foods, the effects of maltotetraose-forming amylase(G4-amylase) on the short and long-term retrogradation of different staple starches such as rice starch (RS), wheat starch (WS), potato starch (PS) were studied. The results indicated that G4-amylase decreased the content of amylose. Amylose contents (21.09%) of WSG4 were higher than that (14.82%) of RSG4 and (13.13%) of PSG4. WS had the most obvious change in the chain length distribution of amylopectin. A chains decreased by 18.99% and the B1 chains decreased by 12.08% after G4-amylase treatment. Compared to RS (662 cP) and WS (693 cP), the setback viscosity of RSG4 (338 cP) and WSG4 (385 cP) decreased. Compared to RS (0.41), WS (0.45), and PS (0.51), the long-term retrogradation rate of RSG4 (0.33), WSG4 (0.31), and PSG4 (0.38) significantly reduced. It indicated that G4-amylase significantly inhibited the long-term retrogradation of WS, followed by RS and PS.
Rice cake is a common traditional food in China. In this study, the effect of Polygonatum cyrtonema (PC) on the qualities and characteristics of rice cake was investigated. The incorporation of PC powder in rice cakes endowed a light-yellow color and increased the water content and water absorption of products. Rheological analysis showed that the rice cake containing PC exhibited weak-gel properties. Additionally, PC (40%) inhibited the rice cake aging and lowered the hardness of rice cakes to 13.86 N after 4 h storage. In vitro starch digestion analysis showed that PC (40%) reduced the digestibility of rice cakes by decreasing the starch hydrolysis rate from 88.70 to 58.95%, displaying a low estimated glycemic index (eGI) of 52.14. The findings mentioned above indicated that the inclusion of PC powder in rice cakes enhanced their characteristics and attributes, which also provided an approach for the development of PC products.
To ameliorate the limitations associated with the processing and utilization of corn starch (CS), Ficus pumila Linn. polysaccharide (FPP) was used to modulate the physicochemical properties of CS. In this study, the influence of FPP on gelatinization, structural properties, antioxidant capacity and digestibility of CS were evaluated. The results showed that the addition of FPP inhibited the short-term retrogradation of CS and delayed the gelation process of CS. Furthermore, FPP decreased the storage modulus and loss modulus, while diminishing the strength and hardness of the gel, and impeding moisture translocation. FPP reduced the formation of ordered structure and thermal stability of the gels by binding to amylose. Notably, in addition to the processing properties, FPP was found to enhance the antioxidant capacity and reduce the digestibility of CS, as demonstrated by the pronounced antioxidant activities in the CS-FPP composites and an increment in resistant starch (RS) content. Collectively, these insights furnish a significant contribution to the potential application of FPP in enhancing the quality of starch-based alimentary products.
2024, International Journal of Biological Macromolecules
IF 7.7SCIEJCR Q1化学1区TopEI
Octenyl succinic anhydride (OSA)-modified starches have gained widespread interest, but the modification can produce two starches with different states ignored. Herein, the two types of starches, esterified starch (ES) and pregelatinized esterified starch (PES), prepared by OSA modification were separated, and their structural and functional characteristics were comprehensively explored. Results showed that compared with native starch (NS), ES and PES exhibited high water-holding capacity, solubility, and swelling power and significantly decreased pasting temperature and thermal stability. Dynamic rheological tests illustrated that OSA modification changed the rheological behavior of starches. Fourier transform infrared spectroscopy confirmed that PES with higher degree of substitution showed more obvious ester carbonyl and carboxylate groups than ES. Laser confocal micro-Raman spectroscopy revealed that the short-range molecular order of ES, especially PES, decreased after modification. X-ray diffraction indicated that OSA modification disrupted the crystalline structure of starch, and that more amylose–lipid complex was formed in PES. Scanning electron microscopy showed that OSA modification eroded starchs surface and reduced its smoothness, and significantly disrupted PES integrity. ES and PES could be developed as food additives for retrogradation inhibition of dough. These results provide new insights into OSA modification and expand its functional application in foods.
Temperature-induced textural, cooking properties and structural variations of retrograded instant rice noodles (IRN) during the long-term storage were systematically investigated. IRN samples stored at 4 °C exhibited a relative high cooking loss (2.45 %), and their hardness values gradually increased with prolonged storage. Moreover, the higher storage temperature (35 °C) accelerated the deterioration of IRN texture. Fresh IRN displayed a typical B-type XRD pattern with 9.65 % relative crystallinity (RC). During the initial 2 weeks of storage, the formation of a long-range ordered structure led to an increase in RC, which was closely related to the duration and temperature of storage (ranging from 4 °C to 25 °C to 35 °C). Over the 12-week storage period, there was likely a disorganization of the supra-molecular structure, as evidenced by the considerably decreased RC and reduced water mobility. Furthermore, Pearson's correlation analysis highlighted that the tight integration between starch molecules and water molecules endowed IRN samples with enhanced smoothness and tenderness in flavor profiles. Hence, the study is expected to provide a comprehensive understanding of the mechanisms underlying molecular order changes in retrograded starch gel products during the long-term storage.
In starch gel foods processing, lactic acid fermentation is an effective strategy to improve the quality of the gel. This study revealed the effects of Lactobacillus plantarum fermentation for rice on the textural and rheological properties of the corresponding gels. The hardness, adhesiveness and chewiness of the gel showed ascending trends with the forwarding of fermentation. The role of Lactobacillus plantarum on rheological properties of gel depended on fermentation time. As the time was within 3 days, the process reduced the viscoelastic of the gel, while as the time was for 5 days, the process enhanced the viscoelastic of the gel. During fermentation, amylose content increased from 21.56 ± 1.17% to 27.39 ± 0.63%, and crude protein content descended from 12.60 ± 0.44 g/100 g DW to 4.8 ± 0.49 g/100 g DW. Total organic acids were ascending in the whole process, and lactic acid (LA), acetic acid (AA) and citric acid (CA) made the dominant contribution. The enthalpy change (ΔH) of the rice flour fermented for 5 days was significantly (p < 0.05) increased to 9.90 ± 0.24 J/g, indicating the formation of more double helix structures. These organic acids may contribute to the formation of the pores on the surface of granules by hydrolyzing the components, which provides a channel for enzymes to enter the interior of granules. These results provide the basis for the development of fermented rice-based foods.