The influence of Konjac glucomannan on the functional and structural properties of wheat starch

Evaluation of glucomannan as a fat replacer in the dough and cookies made from fermented cassava flour and soy protein concentrate

This work evaluated the structure and quality parameters of dough and cookies prepared using fermented cassava flour, soy protein concentrate, and glucomannan. Glucomannan was incorporated as a fat replacement. The levels of fat replacement were 0%, 10%, 20%, and 30% (CS100, GL90, GM80, and GH70, respectively) relative to the original fat content. Rheological analysis showed that the loss tangent of GH70 dough was the lowest (0.39) with an angular frequency of 0.62 rad/s. Thus, glucomannan affected the dough and caused it to exhibit more solid-like behaviors. Glucomannan covered the starch granules, which mimicked that of fat. A complex interaction was confirmed among starch, glucomannan, and protein in the dough. Glucomannan decreased dough hardness and adhesiveness but significantly increased (p < 0.05) cookie hardness, crispiness, and spread ratio. Dough with low rheological properties, adhesiveness, and hardness will produce good-quality cookies. Glucomannan can be applied as a fat replacer in cookies.

A starch-binding domain of α-amylase (AmyPG) disrupts the structure of raw starch

Most raw starch-digesting enzymes possess at least one non-catalytic starch-binding domain (SBD), which enhances enzymatic hydrolysis of insoluble starch granules. Previous studies of SBD-starch interaction mainly focus on binding affinity for substrates, while the mechanism involved disruption of starch granules remains partially understood. Raw starch-digesting α-amylases AmyPG and AmyP were from Photobacterium gaetbulicola and an uncultured marine bacterium, respectively. Here, comparative studies on the two α-amylases and their SBDs (SBDPG and SBDAmyP) with high sequence identity were carried out. The degradation capacity of AmyPG towards raw starch was approximately 2-fold higher than that of AmyP, which was due to the stronger disruptive ability of SBDPG rather than the binding ability. Two non-binding amino acids (K626, T618) of SBDPG that specifically support the disruptive ability were first identified using affinity gel electrophoresis, amylose‑iodine absorbance spectra, and differential scanning calorimetry. The mutants SBDPG-K626A and SBDPG-T618A exhibited stronger disruptive ability, while the corresponding mutants of AmyPG enhanced the final hydrolysis degree of raw starch. The results confirmed that the disruptive ability of SBD can independently affect raw starch hydrolysis. This advancement in the functional characterization of SBDs contributes to a better understanding of enzyme-starch granule interactions, pushing forward designs of raw starch-digesting enzymes.

Effect of Konjac Glucomannan on Structure, Physicochemical Properties, and In Vitro Digestibility of Yam Starch during Extrusion

In this study, the effect of konjac glucomannan (KGM, 0-5%) on the structure, physicochemical properties, and in vitro digestibility of extruded yam starch (EYS) was investigated. The EYS became rougher on the surface and the particle size increased as observed using scanning electron microscopy and particle size analysis. X-ray diffraction and Raman results revealed that the relative crystallinity (18.30% to 22.30%) of EYS increased, and the full width at half maxima at 480 cm-1 decreased with increasing KGM content, indicating the increment of long-range and short-range ordered structure. Differential scanning calorimetry and rheological results demonstrated that KGM enhanced thermal stability and the gel strength of EYS due to enhanced interaction between KGM and YS molecules. Additionally, a decrease in the swelling power and viscosity of EYS was observed with increased KGM content. The inclusion of KGM in the EYS increased the resistant starch content from 11.89% to 43.51%. This study provides a dual-modified method using extrusion and KGM for modified YS with high thermal stability, gel strength, and resistance to digestion.

Investigating the Impact of Dragon Fruit Peel Waste on Starch Digestibility, Pasting, and Thermal Properties of Flours Used in Asia

As a by-product of dragon fruit consumption, dragon fruit peel (DFP) was developed into powder as a natural ingredient. Nevertheless, the effect of DFP on the physicochemical properties of flours used in Asian food processing and cooking remains unknown. In this study, starch digestibility, thermal, pasting, and physicochemical properties of DFP and flours (potato, rice, glutinous rice, and wheat) were characterized. It was found that DFP contained 65.2% dietary fiber together with phenolic compounds, betacyanins, and antioxidant activity. The results demonstrated that DFP (from 125 to 500 mg) reduced starch digestibility of flours, rapidly digestible starch, and slowly digestible starch, along with an increased proportion of undigested starch. A marked increase in phenolic compounds, betacyanins, and antioxidant activity occurred when DFP and flour were incubated for 180 min under simulated gastrointestinal digestion. The results indicate that bioactive compounds in DFP were highly bioaccessible and remained intact after digestion. Moreover, DFP exerted a significantly lower gelatinization enthalpy of flours with increasing peak viscosity and setback with decreasing pasting temperature. FTIR confirmed the decreased ratio at 1047/1022 cm−1, indicating the disruption of short-range orders of starch and DFP. These findings would expand the scope of DFP food applications and provide a knowledge basis for developing DFP flour-based products.

Effects of Konjac Glucomannan on Oil Absorption and Safety Hazard Factor Formation of Fried Battered Fish Nuggets

The purpose of this study was to investigate the effects of konjac glucomannan (KGM) on oil absorption and the formation of safety hazard factors in fried battered fish nuggets by measuring advanced glycation end products (AGEs) and acrylamide contents. Other physicochemical properties were determined to explore the reason for oil absorption and formation of safety hazard factors. The acrylamide was found mainly in the crust. The addition of 0.8% KGM could significantly reduce the acrylamide content (p < 0.05). For the battered sample, the AGEs content was far lower than the unbattered. The addition of 0.8% KGM could significantly reduce the AGEs content in the inner layer (p < 0.05). The microstructure showed that the sample with 0.8% KGM had the most compact crust. The compact crust reduced oil and malondialdehyde contents. Combined with the other indicators, the inhibitory effect of 0.8% KGM on acrylamide was closely related with the decreased extent of oil oxidation and Maillard reaction in the samples with 0.8% KGM. The inhibitory effect of 0.8% KGM on AGEs might originate from its lower oil content.

Mimic Pork Rinds from Plant-Based Gel: The Influence of Sweet Potato Starch and Konjac Glucomannan

This study investigated the effect of sweet potato starch (SPS) and konjac glucomannan (KGM) on the textural, color, sensory, rheological properties, and microstructures of plant-based pork rinds. Plant-based gels were prepared using mixtures of soy protein isolate (SPI), soy oil, and NaHCO₃ supplemented with different SPS and KGM concentrations. The texture profile analysis (TPA) results indicated that the hardness, cohesiveness, and chewiness of the samples improved significantly after appropriate SPS and KGM addition. The results obtained via a colorimeter showed no significant differences were found in lightness (L*) between the samples and natural pork rinds after adjusting the SPS and KGM concentrations. Furthermore, the rheological results showed that adding SPS and KGM increased both the storage modulus (G’) and loss modulus (G’’), indicating a firmer gel structure. The images obtained via scanning electron microscopy (SEM) showed that the SPS and KGM contributed to the formation of a more compact gel structure. A mathematical model allowed for a more objective sensory evaluation, with the 40% SPS samples and the 0.4% KGM samples being considered the most similar to natural pork rinds, which provided a comparable texture, appearance, and mouthfeel. This study proposed a possible schematic model for the gelling mechanism of plant-based pork rinds: the three-dimensional network structures of the samples may result from the interaction between SPS, SPI, and soybean oil, while the addition of KGM and NaHCO₃ enabled a more stable gel structure.

Thermoplastic starch nanocomposites: sources, production and applications - a review

The development of materials based on thermoplastic starch (TPS) is an excellent alternative to replace or reduce the use of petroleum-derived polymers. The abundance, renewable origin, biodegradability, biocompatibility, and low cost of starch are among the advantages related to the application of TPS compared to other thermoplastic biopolymers. However, through the literature review, it was possible to observe the need to improve some properties, to allow TPS to replace commonly used polyolefins. The studies reviewed achieved these modifications were achieved by using plasticizers, adjusting processing conditions, and incorporating fillers. In this sense, the addition of nanofillers proved to be the main modification strategy due to the large number of available nanofillers and the low charge concentration required for such improvement. The improvement can be seen in thermal, mechanical, electrical, optical, magnetic, antimicrobial, barrier, biocompatibility, cytotoxicity, solubility, and swelling properties. These modification strategies, the reviewed studies described the development of a wide range of materials. These are products with great potential for targeting different applications. Thus, this review addresses a wide range of essential aspects in developing of this type of nanocomposite. Covering from starch sources, processing routes, characterization methods, the properties of the obtained nanocomposites, to the various applications. Therefore, this review will provide an overview for everyone interested in working with TPS nanocomposites. Through a comprehensive review of the subject, which in most studies is done in a way directed to a specific area of study.

Recent patents on water-soluble polysaccharides for advanced drug delivery, tissue engineering and regenerative medicine

Water-soluble polysaccharides have unique properties and have found wide application in the design of advanced drug-delivery systems and the biofabrication of tissue engineered scaffolds in regenerative medicine. This patent review provides a concise incursion into the mechanisms that define the key properties of water-soluble polysaccharides that have found embodiment within active patents recently granted (2020-2021). In addition, the relationship between their solubility and structural features such as molecular weight, ionic profile, degree of branching/crosslinking, side-chain flexibility and the presence/modification of functional groups that have been discusses. An assimilation of patents in which water-soluble polysaccharides are central to the design of therapeutic interventions applied to specialized treatments in oncology, infectious diseases and neuronal disorders is provided.

A review of wheat starch analyses: Methods, techniques, structure and function

Wheat starch has received much attention as an important source of dietary energy for humans, an interesting carbohydrate and a polymeric material. The understanding of the structure and function of wheat starch has always been accompanied by newer technological tools. On the one hand, the general knowledge of wheat starch is constantly being enriched. On the other hand, an increasing number of studies are trying to add new insights to what is already known from two frontier perspectives, namely, wheat starch supramolecular structures and wheat starch fine structures (CLDs). This review describes the structure and function of wheat starch from the perspective of wheat starch analysis techniques (instruments).

Effects of two contrasting dietary polysaccharides and tannic acid on the digestive and physicochemical properties of wheat starch

In this study, konjac glucomannan, κ-carrageenan, and tannic acid were selected to study the effects of different combinations on the in vitro digestibility and physicochemical properties of wheat starch. Results showed that the addition of konjac glucomannan, κ-carrageenan, and tannic acid could decrease the digestion of starch and increase the content of resistant starch. Besides, the two polysaccharides weakened the extent of tannic acid on starch digestion. Moreover, although the two polysaccharides had different effects on the in vitro digestion of starch, they had no significant increase in the content of resistant starch. DSC and XRD results demonstrated that the polysaccharides and tannic acid showed synergistic effects on the rebuilding of starch microstructure. FTIR results further manifested that κ-carrageenan and konjac glucomannan could significantly increase the strength of hydrogen bonds in starch. At the same time, the addition of tannic acid would weaken the molecular interaction between polysaccharides and starch. SEM and CLSM results showed that tannic acid added to the polysaccharide-starch mixture not only interacted with starch but also influenced the structure of polysaccharide gel.

Effect of four viscous soluble dietary fibers on the physicochemical, structural properties, and in vitro digestibility of rice starch: A comparison study

The effect of carboxymethyl cellulose (CMC), high-methoxyl pectin (HMP), konjac glucomannan (KGM), and xanthan gum (XG) on the physicochemical, structural properties, and digestibility of rice starch were investigated and compared. The four viscous soluble dietary fibers (VSDFs) increased the viscosity, storage modulus and loss modulus while decreased the pasting temperature and gelatinization enthalpy. Moreover, XG produced the lowest peak viscosity and dynamic modulus compared with the other VSDFs. Furthermore, the degree of short-range ordered structure of starch with KGM increased from 0.8448 to 0.8716; and the relative crystallinity of starch with XG increased by 12%. An ordered and reunited network structure was observed in SEM. In addition, VSDF inhibited the digestibility of rice starch and significantly increased the resistant starch content. This study compared the effect of four VSDFs on the physicochemical, structural and digestion properties of rice starch to fully understand and develop their application to starchy foods.