Causal relations among starch hierarchical structure and physicochemical characteristics after repeated freezing-thawing

Effects of cold plasma pretreatment before different drying process on the structural and functional properties of starch in Chinese yam

This article compared the effects of hot air drying (HAD), infrared drying (IRD), and cold plasma (CP) as a pretreatment on the structure, quality, and digestive characteristics of starch extracted from yam. As the most commonly used drying method, HAD was used as a control. SEM and CLSM images showed that all treatments preserve the integrity of the yam starch. CP caused some cracks and breaks in the starch granules. IRD did not destroy the crystal structure of starch molecules, but made the spiral structure tighter and increased short-range orderliness. However, CP led to the depolymerization and dispersion of starch molecular chains, resulting in a decrease in average molecular weight and relative crystallinity. These molecular conformation changes caused by different processes led to differences in solubility, swelling power, pasting parameters, digestion characteristics, and functional characteristics. This study provided an important basis for the reasonable drying preparation and utilization of yam starch.

Effect of oxidized starch on the storage stability of frozen raw noodles: Water distribution, protein structure, and quality attributes

Freezing is a popular method of food preservation with multiple advantages. However, it may change the internal composition and quality of food. This study aimed to investigate the effect of modified starch on the storage stability of frozen raw noodles (FRNs) under refrigerated storage conditions. Oxidized starch (OS), a modified starch, is widely used in the food industry. In the present study, texture and cooking loss rate analyses showed that the hardness and chewiness of FRNs with added OS increased and the cooking loss rate decreased during the frozen storage process. Low-field nuclear magnetic resonance characterization confirmed that the water-holding capacity of FRNs with OS was enhanced. When 6% OS was added, the maximum freezable water content of FRNs was lower than the minimum freezable water content (51%) of FRNs without OS during freezing. Fourier-transform infrared spectroscopy showed that after the addition of OS, the secondary structures beneficial for structural maintenance were increased, forming a denser protein network and improving the microstructure of FRNs. In summary, the water state, protein structure, and quality characteristics of FRNs were improved by the addition of OS within an appropriate range.

Effect of carboxymethyl chitosan on the storage stability of rice dough during frozen storage

In this study, we aimed to determine the effect of carboxymethyl chitosan (CMCh) and carboxymethyl cellulose sodium (CMCNa) on the quality of frozen rice dough. We used a variety of methods to conduct a thorough investigation of frozen rice dough, including nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, size exclusion high-performance liquid chromatography (SE-HPLC), X-ray diffraction (X-RD), differential scanning calorimetry (DSC), and rapid visco analyzer (RVA). Our findings showed that frozen storage caused significant damage to the texture of rice dough, and this damage was reduced by the inclusion of CMCh, which led to a gradual change in the orderly structure of proteins. The degree of cross-linking between CMCh-B (DS:1; 0.5 %, 1 %, and 1.5 %) and the large protein polymer was significantly higher than that between CMCh-A (DS:0.8; 0.5 %, 1 %, and 1.5 %) and CMCNa (DS:1; 1 %), which decreased the ability of bound water to become free water. This resulted in the increase of tan δ, which effectively delayed the structural transformation of frozen rice dough. Furthermore, the introduction of CMCh delayed the immediate order of starch and crystal structure modifications, altering the thermal properties and pasting qualities of the frozen rice dough. Therefore, 1.5 % CMCh-B showed the best protective effect on frozen rice dough.

Impact of starch chain length distributions on physicochemical properties and digestibility of starches

Changing starch structure at different levels is a promising approach to promote desirable metabolic responses. Chain length distribution (CLD) is among the starch structural characteristics having a potential to determine properties of starch-based products. Therefore, the objective of the current review is to summarize recent findings on CLD and its impact on physicochemical properties and digestion. Investigations undertaken to enhance understanding of starch structure have shown clearly that CLD is a significant determining factor in modulating starch digestibility. Enzymatic modifications and processing treatments alter the CLD of starch, which in turn affects the rate of digestion, but the underlying molecular mechanisms have yet to be fully elucidated. Even though advances have been made in manipulating CLD using different methods and to correlate the changes with various functional properties, in general the area needs further investigations to open new awareness for enhancing healthiness of starchy foods.

Starch ordered structures control starch reassembly behaviors during heat-moisture treatment for modulating its digestibility

This study investigated the effect of starch crystallinity on starch reassembly behaviors during the heat-moisture treatment (HMT) using starches with A-type crystal content of 0.00%-19.03%. The results showed that HMT reduced the native starch crystal content from 19.03% to 15.02% and increased starch thermostability, leading to a decrease in rapidly digestible starch (RDS) content from 86.91% to 76.71%. Moreover, starches containing a crystal content of 2.51%-8.11% exhibited significant reassembly during the HMT, and the resulting modified starches had more crystals and less RDS of 63.43%-69.31%. Interestingly, starches lacked A-type crystals but had some helical structures exhibiting A-type crystalline structures and lower digestibility after HMT. These findings verified that starch could significantly reassemble to form crystalline structures during the HMT. Controlling the crystal content of starch granules, particularly between 2.51% and 8.11%, was a promising approach for promoting starch reassembly during HMT and reducing starch digestibility.

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 frozen storage on the quality characteristics of frozen whole buckwheat extruded noodles

The effects of frozen storage (-18 °C, 180 days) on the quality of frozen whole buckwheat extruded noodles (FWBEN) were investigated. The water content of FWBEN decreased, while the reheating time, water absorption, and dry consumption rate increased with prolonged storage time. Cooking loss increased from 3.20% to 4.31%. Texture analysis indicated that the hardness initially increased, then decreased. Microstructure results showed that the starch gel structure was damaged to a certain extent after storage for a longer period of time, whereas the porous structure became non-uniform with the appearance of cracks. The relative crystallinity gradually increased, and the freezable water content decreased with prolonged storage. These results demonstrated that FWBEN quality was affected by starch retrogradation and ice recrystallization. In general, FWBEN quality was relatively stable during 180 days of frozen storage at -18 °C.

A comprehensive review on starch: Structure, modification, and applications in slow/controlled-release fertilizers in agriculture

This comprehensive review thoroughly examines starch's structure, modifications, and applications in slow/controlled-release fertilizers (SRFs) for agricultural purposes. The review begins by exploring starch's unique structure and properties, providing insights into its molecular arrangement and physicochemical characteristics. Various methods of modifying starch, including physical, chemical, and enzymatic techniques, are discussed, highlighting their ability to impart desirable properties such as controlled release and improved stability. The review then focuses on the applications of starch in the development of SRFs. It emphasizes the role of starch-based hydrogels as effective nutrient carriers, enabling their sustained release to plants over extended periods. Additionally, incorporating starch-based hydrogel nano-composites are explored, highlighting their potential in optimizing nutrient release profiles and promoting plant growth. Furthermore, the review highlights the benefits of starch-based fertilizers in enhancing plant growth and crop yield while minimizing nutrient losses. It presents case studies and field trials demonstrating starch-based formulations' efficacy in promoting sustainable agricultural practices. Overall, this review consolidates current knowledge on starch, its modifications, and its applications in SRFs, providing valuable insights into the potential of starch-based formulations to improve nutrient management, boost crop productivity, and support sustainable agriculture.

A review of starch swelling behavior: Its mechanism, determination methods, influencing factors, and influence on food quality

Swelling behavior involves the process of starch granules absorbing enough water to swell and increase the viscosity of starch suspension under hydrothermal conditions, making it one of the important aspects in starch research. The changes that starch granules undergo during the swelling process are important factors in predicting their functional properties in food processing. However, the factors that affect starch swelling and how swelling, in turn, affects the texture and digestion characteristics of starch-based foods have not been systematically summarized. Compared to its long chains, the short chains of amylose easily interact with amylopectin chains to inhibit starch swelling. Generally, reducing the swelling of starch could increase the strength of the gel while limiting the accessibility of digestive enzymes to starch chains, resulting in a reduction in starch digestibility. This article aims to conduct a comprehensive review of the mechanism of starch swelling, its influencing factors, and the relationship between swelling and the pasting, gelling, and digestion characteristics of starch. The role of starch swelling in the edible quality and nutritional characteristics of starch-based foods is also discussed, and future research directions for starch swelling are proposed.

Starch chain-length distributions determine cooked foxtail millet texture and starch physicochemical properties

Starch chain-length distributions play an important role in controlling cereal product texture and starch physicochemical properties. Cooked foxtail millet texture and starch physicochemical properties were investigated and correlated with starch chain-length distributions in eight foxtail millet varieties. The average chain lengths of amylopectin and amylose were in the range of DP 24-25 and DP 878-1128, respectively. The percentage of short amylopectin chains (Ap1) was negatively correlated with hardness but positively correlated with adhesiveness and cohesion. Conversely, the amount of amylose intermediate chains was positively correlated with hardness but negatively correlated with adhesiveness and cohesion. Additionally, the amount of amylose long chains was negatively correlated with adhesiveness and chewiness. The relative crystallinity (RC) of starch decreased with reductions in the length of amylopectin short chains in foxtail millet. Pasting properties were mainly influenced by the relative length of amylopectin side chains and the percentage of long amylopectin branches (Ap2). Longer amylopectin long chains resulted in lower gelatinization temperature and enthalpy (ΔH). The amount of starch branched chains had important effects on the gelatinization temperature range (ΔT). These results can provide guidance for breeders and food scientists in the selection of foxtail millet with improved quality properties.

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Thermal processing remains the key processing technology for food products. However, there are some limitations for thermal processing such as loss of sensory and nutritional quality. Furthermore, nowadays consumers are looking forward for fresh like products which are free from chemical preservatives, yet having longer shelf life. Thus, alternative processing techniques are gaining popularity among food processors to replace conventional thermal processing keeping nutritional quality, sensory attributes and food safety in mind. The alternative processing techniques such as ultrasound, gamma irradiation, high pressure processing and microwave treatment causes several modifications (structural changes, effects on swelling and solubility index, gelatinization behaviour, pasting or rheological properties, retrogradation and cooking time) in physicochemical and functional properties of pulse starches which offers several advantages from commercial point of view. This review aims to summarize the effect of different alternative processing techniques on the structure, solubility, gelatinization, retrogradation and pasting properties of various pulse starches.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05557-3.

Starch intrinsic crystals affected the changes of starch structures and digestibility during microwave heat-moisture treatment

The structural and functional changes of starch during hydrothermal treatment are influenced by its intrinsic properties. However, how the intrinsic crystalline structures of starch affect changes in structure and digestibility during microwave heat-moisture treatment (MHMT) has not been well understood. In this study, we prepared starch samples with varying moisture content (10 %, 20 %, and 30 %) and A-type crystal content (4.13 %, 6.81 %, and 16.35 %) and investigated the changes in their structures and digestibility during MHMT. Results showed that starch with a high A-type crystal content (16.35 %) and moisture levels of 10 % to 30 % exhibited less ordered structures after MHMT, while starches with lower A-type crystal content (4.13 % to 6.18 %) and moisture content of 10 % to 20 % showed more ordered structures after treatment; but less ordered structures when the moisture content was 30 %. All starch samples had lower digestibility after MHMT and cooking; however, starches with lower A-type crystal content (4.13 % to 6.18 %) and moisture content of 10 % to 20 % displayed significantly lower digestibility after treatment compared to modified starches. Accordingly, starches contained content of A-type crystals of 4.13 %-6.18 % and moisture of 10 %-20 % potentially had better reassembly behaviors during the MHMT to slow starch digestibility in a larger magnitude.

Effect of starch-catechin interaction on regulation of starch digestibility during hot-extrusion 3D printing: Structural analysis and simulation study

Recent developments of hot-extrusion 3D printing (HE-3DP) have made it possible to manipulate starch digestibility. This work investigated the regulating mechanism of starch-catechin (EC) interactions on rice starch digestibility during HE-3DP by using modern analytical techniques and computational models. The results showed that the HE-3DP processing with starch-EC interactions could significantly decrease the starch digestibility (p < 0.05) due to the formation of ordered structures including short-range ordered structure, nano-aggregates and V-type crystalline structure. Meanwhile, molecular dynamics simulations were performed to reveal the mechanism of EC as an enzyme inhibitor to enhance the resistant starch contents of rice starch to 46.1%. Results showed that EC could loosely attach to starch chains, thereby facilitating binding to Trp59 of pancreatic α-amylase and preventing starch from binding to its active pocket. These findings provide useful structural information for EC to reduce starch digestibility in the HE-3DP environment.

Microstructure, Digestibility and Physicochemical Properties of Rice Grains after Radio Frequency Treatment

Radio frequency (RF) energy has been successfully applied to rice drying, sterilization, and controlling pests. However, the effects of RF treatment on the microstructure, physicochemical properties, and digestibility of rice have rarely been studied. This study investigated the alteration of a multiscale structure, pasting, rheology, and digestibility of rice grains after the RF treatment. A microstructure analysis demonstrated that the RF treatment caused starch gelatinization and protein denaturation in rice grains with an increasing treatment time. After the RF treatment, indica and japonica rice (IR and JR) remained as A-type crystals, with the formation of an amylose–lipid complex. In contrast, the crystalline structure of waxy rice (WR) was disrupted. The RF treatment led to a decrease in crystallinity and short-range ordered structures. However, the DSC results indicated that the RF treatment enhanced the T_o, T_p, and T_c of IR and JR. The RF treatment resulted in an increase in the resistant starch (RS) of IR and JR, thereby reducing the digestibility. In addition, the pasting profiles of IR and JR after RF treatment were reduced with the increase in treatment time, while the RF-treated WR showed an opposite trend. The storage modulus (G′) and loss modulus (G″) of all samples after the RF treatment obviously increased compared to the control.