Rheological and textural studies of fresh and freeze-thawed native sago starch–sugar gels. II. Comparisons with other starch sources and reheating effects

Preparation and Characterization of a Novel Longzhua mushroom Polysaccharide Hydrogel and Slow-Release Behavior of Encapsulated Rambutan Peel Polyphenols

Natural polyphenols have drawbacks such as instability and low bioavailability, which can be overcome by encapsulated slow-release systems. Natural polymer hydrogels are ideal materials for slow-release systems because of their high biocompatibility. In this study, Longzhua mushroom polysaccharide hydrogel (LMPH) was used to encapsulate rambutan peel polyphenols (RPP) and delay their release time to improve their stability and bioavailability. The mechanical properties, rheology, stability, swelling properties, water-holding capacity, RPP loading, and slow-release behavior of LMPH were investigated. The results showed that LMPH has adequate mechanical and rheological properties, high thermal stability, excellent swelling and water-holding capacity, and good self-healing behavior. Increasing the polysaccharide content not only improved the hardness (0.17-1.13 N) and water-holding capacity of LMPH (90.84-99.32%) but also enhanced the encapsulation efficiency of RPP (93.13-99.94%). The dense network structure slowed down the release of RPP. In particular, LMPH5 released only 61.58% at 48 h. Thus, a stable encapsulated slow-release system was fabricated using a simple method based on the properties of LMPH. The developed material has great potential for the sustained release and delivery of biologically active substances.

Development of Novel Cornstarch Hydrogel-Based Food Coolant and its Characterization

The food, pharmaceutical, and supply transport storage chain is seeking coolants that come with plastic-free packaging, are nontoxic, environmentally friendly, robust, reusable, and reduce water waste. To meet this demand, a new food coolant based on cornstarch hydrogel was developed and tested using the regeneration method. This study investigated the reusability, water retention, rehydration, and surface cleanliness of the hydrogel, along with its application in freshness retention for fruits. The results of the gel strength and differential scanning calorimetry (DSC) analysis showed that the ideal concentration of cornstarch hydrogel was 8%. Freezing and thawing experiments demonstrated that the hydrogel had the potential to be used as a cooling medium for refrigerated fresh foods. Moreover, the gel strength, scanning electron microscopy images (SEM), DSC, and thermogravimetric analysis (TG) revealed that the freeze-thaw reuse only slightly affected its freezable water content and that its gel strength gradually increased during reuse. Water retention and rehydration tests showed that the hydrogels could be better preserved at -20 °C compared to 4 °C, and the water lost during reuse could be replenished through rehydration. The flexibility in terms of shape and size also allows the hydrogel ice to be used as a customized coolant for various food shapes, as demonstrated by preservation experiments. Additionally, washing the hydrogel after each use can result in a significant reduction in Escherichia coli, Salmonella, and Staphylococcus aureus concentrations by 3.03, 3.47, and 2.77 log CFU/hydrogel, respectively. Overall, the new cornstarch hydrogel coolant is a promising alternative to conventional ice, with the potential to serve as a food coolant.

Hydrogel properties of non-conventional starches from guabiju, pinhão, and uvaia seeds

The physicochemical properties of starch vary depending on the botanical sources, thereby influencing the gelatinisation/retrogradation properties and subsequently affecting the hydrogels characteristics. This study aimed to assess the influence of botanical sources influence on starch and hydrogel properties using non-conventional starch derived from guabiju, pinhão, and uvaia seeds. Hydrogels were prepared by starch gelatinisation followed by 6 h ageing period at room temperature (20 ± 2 °C) and subjected to five freeze-thaw cycles. Pinhão starch exhibited a higher viscosity peak and breakdown, along with a lower final viscosity and setback, compared to guabiju and uvaia starches. The significantly different pasting properties influenced the porous microstructure, water absorption (p-value: 0.01), and resistance of the hydrogels (p-value: 0.01). The guabiju starch hydrogels showed a uniform pore structure without cavities, whereas pinhão and uvaia starch hydrogels exhibited agglomerated and spongy pore structures. Furthermore, the guabiju starch hydrogel demonstrated the lowest water absorption (4.56 g/g) and the highest compression resistance (1448.50 g) among all the studied starch hydrogels. In contrast, the pinhão starch hydrogel showed the highest water absorption (7.43 g/; p-value: 0.01) among all studied starch hydrogels. The hardness of uvaia starch hydrogel did not differ significantly from the guabiju and pinhão starch hydrogel. The different non-conventional starches reveal important variations in the hydrogels characteristics. This provides insights into how amylose and amylopectin interact and present alternatives for using these unique starch-based hydrogels in diverse applications.

Rheological parameters of mixed Brazilian Cerrado fruits sugar-free preserves: the effect of body agents

The aim of this study was to evaluate the effect of the bodying agents (erythritol, sorbitol, xylitol, and polydextrose) and their mixtures on the preparation of mixed Brazilian Cerrado fruit preserves (marolo, soursop, and sweet passion fruit). Mixture design was used for product optimization and the preserves were evaluated by texture profile, stress relaxation test, and uniaxial compression test. The research data were analyzed using regression equations on SAS software. The results indicated that the rheological parameters were affected by the body agents. Erythritol should not be used as an isolated component because it provoked changes in the properties of the final product (harder and brittle preserves); xylitol and sorbitol made preserves more elastic, cohesive, and more fragile; and polydextrose showed a synergistic effect with erythritol for rupture deformation and lesser effects for hardness, adhesiveness, and gumminess.

Locust bean gum provides excellent mechanical and release attributes to soy protein-based natural hydrogels

The current study concentrated on designing soy protein (SP)-based natural hydrogels in the presence of locust bean gum (LBG). For this, the gums were recovered from the kernel of the relevant plant and incorporated into SP gel models. Three more hydrogels were fabricated using commercial carbohydrates (gum Arabic (GA), maltodextrin (MD), and pectin (PC)) to decipher exactly the ability of LBG in these models. The chemical and morphological structures of the samples were elaborated by FTIR and SEM analyses. The coexistence of protein and carbohydrates led to an enhancement in functional (water holding capacity (WHC), swelling ratio, protein leachability, volumetric gel index (VGI)) and mechanical (textural and rheological behavior) features of natural gels compared to SP alone (control) but the quality of hydrogels was impressed by the carbohydrate type. Hydrogels designed with LBG came to the fore in terms of these attributes. Additionally, these gel models created awareness for phenolic delivery.

Impact of Guar Gum and Locust Bean Gum Addition on the Pasting, Rheological Properties, and Freeze-Thaw Stability of Rice Starch Gel

Improving the gel texture and stability of rice starch (RS) by natural hydrocolloids is important for the development of gluten-free starch-based products. In this paper, the effects of guar gum and locust bean gum on the pasting, rheological properties, and freeze−thaw stability of rice starch were investigated by using a rapid visco analyzer, rheometer, and texture analyzer. Both gums can modify the pasting properties, revealed by an increment in the peak, trough, and final viscosities, and prevent the short-term retrogradation tendency of RS. Dynamic viscoelasticity measurements also indicated that the starch−gum system exhibits superior viscoelastic properties compared with starch alone, as revealed by its higher storage modulus (G′). Compared with the control, the hysteresis loop area of the guar gum-containing system and locust bean gum-containing system was reduced by 37.7% and 24.2%, respectively, indicating that the addition of gums could enhance shear resistance and structure recovery properties. The thermodynamic properties indicated that both gums retard short-term retrogradation as well as long-term retrogradation of the RS gels. Interestingly, the textural properties and freeze−thaw stability of the RS gel were significantly improved by the addition of galactomannans (p < 0.05), and guar gum was more effective than locust bean gum, which may be due to the different mannose to galactose ratio. The results provide alternatives for gluten-free recipes with improved texture properties and freeze−thaw stability.

CRISPR/Cas9-Mediated Mutagenesis of the Granule-Bound Starch Synthase Gene in the Potato Variety Yukon Gold to Obtain Amylose-Free Starch in Tubers

Potato (Solanum tuberosum L.) is the third most important food crop after rice and wheat. Its tubers are a rich source of dietary carbohydrates in the form of starch, which has many industrial applications. Starch is composed of two polysaccharides, amylose and amylopectin, and their ratios determine different properties and functionalities. Potato varieties with higher amylopectin have many food processing and industrial applications. Using Agrobacterium-mediated transformation, we delivered Clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9 (CRISPR/Cas9) reagents to potato (variety Yukon Gold) cells to disrupt the granule-bound starch synthase (gbssI) gene with the aim of eliminating the amylose component of starch. Lugol-Iodine staining of the tubers showed a reduction or complete elimination of amylose in some of the edited events. These results were further confirmed by the perchloric acid and enzymatic methods. One event (T2-7) showed mutations in all four gbss alleles and total elimination of amylose from the tubers. Viscosity profiles of the tuber starch from six different knockout events were determined using a Rapid Visco Analyzer (RVA), and the values reflected the amylopectin/amylose ratio. Follow-up studies will focus on eliminating the CRISPR components from the events and on evaluating the potential of clones with various amylose/amylopectin ratios for food processing and other industrial applications.

Effect of pre-swelling and freezing/thawing cycles on the structure of molecular, morphological, and functional properties of potato starch

This study aimed to investigate the effect of pre-swelling at 55°C for 1 hr followed by freezing-thawing cycles (PFTCs), and freezing-thawing cycles (FTCs) in the starch granules to improve the freeze-thaw stability and evaluate its impact on the molecular, morphological, and functional properties of potato starch (PS). FTCs at 1 cycle and 7 cycles were applied for both treated PS. Microscopical structure, thermal, molecular, and functional properties (i.e., swelling power, solubility, shear viscosity, and gel strength) were comprehensively analyzed. In terms of granule structures, treated PS by FTC showed a slightly affected on the surface of starch granules, while treating PS by PFTC showed an affected in the form of small cracks and holes in the outer surface of starch granules. The gelatinization enthalpy (∆H_gel ) values decreased in the treated PS compared with the native. Thus, decreasing was systemically increased with the number of applied cycles from 1- to 7-cycle. The viscosity of treated PS decreased systematically with molecular degradation or the physical modification, with remarkable reduction, particularly at a higher shear rate (150°C). Treated PS by FTC showed a clear difference (p ≤ .05) in gel values compared with the native at disintegration temperature 115°C. Finally, the degradation of the molecular properties showed significant differences between the native and treated PS either by the FTC or PFTC in molecular weight of starch and amylose without debranching and after debranching by pullulanase enzyme. PRACTICAL APPLICATIONS: Freezing is one of the standard preservation methods used for ready-to-eat products. When this type of food's exposed to more freeze-thaw cycles, the phase separation will be increased due to the increase in retrogradation of amylopectin. To avoid such changes during frozen storage, native potato starch (PS) was modified using both pre-swelling followed by freezing-thawing cycles (PFTCs) and freezing-thawing cycles (FTCs) at 1- and 7-cycle to enhance starch properties, such as swelling power, solubility, shear viscosity, and gel strength. The findings of this study might add to the theoretical understanding of modified PS and act as a guideline for modified starch manufacturing.

Complexation between burdock holocellulose nanocrystals and corn starch: gelatinization properties, microstructure, and digestibility in vitro

Holocellulose nanocrystals (hCNCs), with hydrodynamic diameters (D_Z) ranging from about 600 to 200 nm, were prepared by treating burdock insoluble dietary fiber (IDF) with enzymes and ultrasonic power. It was revealed that hCNCs improved the viscosity of corn starch (CS) during pasting and inhibited its short-term retrogradation. Besides, the crystallinity, short-range order of the double helix, viscoelastic properties, and microstructure compactness of CS gels improved remarkably in the presence of burdock hCNCs. These effects were both size- and dose-dependent, which primarily originated from the hydrogen bonding between hCNCs and amylopectin or leached amylose. In this regard, the digestion of CS gels containing hCNCs was remarkably retarded because of the reduced accessibility of digestive enzymes to the glycosidic bonds. Therefore, burdock hCNCs, prepared from natural resources using green techniques, hold potential applications in functional foods of a low glycemic index.

Modification of Kutki millet (Panicum sumatrense) starch properties by the addition of amino acids for the preparation of hydrogels and its characterization

Starch is a biopolymer containing hydrophilic groups and is used in hydrogels preparation. Amino acids are multifunctional monomers of proteins that can be used as a cross linker to modify the starch by incorporating new functional groups into its chains. In this study, the Kutki millet starch was isolated and modified with lysine (positively charged), aspartic acid (negatively charged), and threonine (neutral) at varying pH levels. These modified starches were characterized for their various functional, structural, pasting, and textural properties. Hydrogels prepared from Lys9-KMS, Thr9-KMS, and AA11-KMS, possessing less adhesiveness, strong integrity, and hardness were then characterized for their XRD and morphological characterization. The principal component analysis (PCA) biplot showed that the samples modified at higher pH levels are positively correlated with the textural properties, swelling power and amylose content (I and IV quadrants), than those modified at lower pH. It may be inferred that starch modified with amino acid at higher pH have good textural properties than those at lower pH. Results of the overall investigation indicated that among these three amino acids, lysine could be a better cross linker for modification of Kutki millet starch and preparation of their gels for the delivery of nutraceuticals.

Effect of starch concentration and resistant starch filler addition on the physical properties of starch hydrogels

Corn starch-based hydrogels are safe and biodegradable polymers with a wide array of applications in food science. The aim of this study was to investigate the effects of starch and natural filler resistant starch type 2 (RS2) particles concentration on the textural properties of corn starch hydrogels. Native starch (NS) hydrogels of 8%, 10%, 12%, and 15% w/v were prepared; in each of these dispersions, part of the NS was substituted with RS2 to a concentration of 2% or 10%. NS hydrogels with the highest concentrations had the maximum hardness, cohesiveness, and gumminess values, whereas the addition of RS2 particles did not affect gel textural properties. Native and substituted RS2 hydrogels showed close similarities in their rheological and textural characteristics. Water-holding capacity greatly decreased with increasing starch concentration, suggesting that the hydrogels with the highest NS concentration had the densest network as depicted by SEM micrographs. Subsequently, hardness, gumminess, and consistency coefficient were linearly correlated to starch concentration and storage time. Fluid release was exponentially dependent on starch concentration. The degree of crystallinity by X-ray diffraction (XRD) indicated that by increasing starch concentration and substitution level, crystallinity increased. Consequently, NS concentration determined the textural properties of corn starch hydrogels. On the other hand, RS2 substitutions did not affect any of these parameters, indicating their potential role as inactive fillers with a beneficial effect on the maintenance of normal blood glucose levels. Therefore, the consistency of a food gel can be optimized by changing the ratio of inactive filler to starch gel matrix.

Optimization of extraction and bioactivity detection of celery leaf flavonoids using BP neural network combined with genetic algorithm and response

In the present study, ultrasound-assisted extraction was employed to extract the general flavone from celery leaves using response surface methodology and BP neural network model with a genetic algorithm (GA). The effects of temperature, time, solid-liquid ratio, and ethanol concentration on the extraction results were assessed by Box-Behnken design. Further optimization of the process was performed by GA-BP. Our results showed that the optimal conditions were an ethanol concentration of 70.31%, a temperature of 67.2 °C and an extraction time of 26.6 min. In addition, significant antioxidant activity and in vitro bacteriostasis were observed. We found that the total flavonoids of the celery leaves exerted a strong inhibitory effect on Escherichia coli, Staphylococcus aureus, and Bacillus subtilis. Additionally, considerable DPPH· and ·OH scavenging effects were exerted by flavonoids. Therefore, flavonoids from celery leaves can be considered natural antioxidants and bacterial inhibitors.

Rheological behaviors, structural properties and freeze-thaw stability of normal and waxy genotypes of barley starch: a comparative study with mung bean, potato, and corn starches

The rheological behaviors, structural properties and freeze-thaw stability of starch isolated from Tetonia barley (Normal genotype, Reg. No. CV-334, PI 646199) and Transit barley (Waxy genotype, Reg. No. CV-348, PI 660128) were investigated, along with other common starch sources for comparison. Transit barley starch showed the highest loss tangents (tan δ) during a frequency sweep test, which suggested a predominance of elastic properties over viscous properties. However, the tan δ of Tetonia barley starch was similar to that of potato starch, which indicated more solidity in comparison to Transit barley starch. Transit barley starch had the highest gelatinization temperature and the lowest gelatinization enthalpy (P < 0.05). Moreover, Tetonia and Transit barley starches displayed weak diffraction peak intensities by X-ray diffraction analysis. Additionally, Transit barley starch showed the lowest % syneresis even when freeze-thawed up to five cycles (P < 0.05). However, Tetonia barley starch had the worst freeze-thaw stability (P < 0.05), which was verified via scanning electron microscopy analysis of freeze-thawed starch gels. The results of present study indicate that barley starch can be practically applied as a functional ingredient in some specialty starchy foods.

Use of Gum Cordia (Cordia myxa) as a Natural Starch Modifier; Effect on Pasting, Thermal, Textural, and Rheological Properties of Corn Starch

Incorporation of hydrocolloid gums in native starches help to improve their pasting, thermal, rheological and textural properties along with improvement in the stability of starch gels. The use of Cordia gum is not widely studied as a starch modifier and this fact could make this study more interesting and unique. This study investigated the effects of the non-conventional hydrocolloid gum (Cordia gum) on corn starch properties. Corn starch and gum Cordia (GC) blends were prepared at different replacement levels (0%, 3%, 6%, 9%, and 12%). The effect of GC levels on pasting, thermal, rheological, and textural properties were evaluated using rapid viscoanalyzer, differential scanning colorimeter, rheometer, and texture analyzer. The presence of GC significantly increased starch gelatinization temperatures, enthalpies, peak viscosities, final viscosities, and setback viscosities. GC improved freeze thaw stability in starch. The shear rate (1/s) versus shear stress (σ) data of all samples fitted well to the simple power law model (R² = 0.97–0.99). The control had the lowest flow behavior index (n; 0.17), which increased to (0.36–0.56) with increasing GC levels. The consistency index (K) of the starch-gum blends increased with increasing GC levels. The dominance of elastic properties over viscous properties was demonstrated by G′ > G″. The magnitudes of G′ and G″ increased with increasing GC concentration. The outcomes could help to use this modification method as an alternative to chemical and enzymatic modification with respect to cost, safety, less time consumption and less requirement of process modifications.

Effect of thermal and freezing treatments on rheological, textural and color properties of basil seed gum

Hydrocolloids are macromolecular carbohydrates that are added to many foodstuffs to achieve the appropriate rheological and textural properties and to prevent synersis or to increase the viscosity and stability of foodstuffs. In this study the effect of different thermal treatments (25, 50, 75, 100 and 121°C for 20 min) and freezing treatments (-18 and -25 °C for 24 h) on rheological, textural and color change of basil seed gum as a new source of hydrocolloids was investigated. The results demonstrated that basil seed gum solutions had desirable rheological and textural properties. Power law model well described non-newtonian pseudoplastic behavior of basil seed gum in all conditions. When the hydrocolloid samples were heated or frozen, increase in viscosity of basil seed gum solutions was observed. Hardness, adhesiveness and consistency of basil seed gel for control sample were 13.5 g, 16.79, 52.59 g.s, respectively and all increased after thermal treatments. The results revealed that basil seed gum has the excellent ability to stand against heat treatment and the highest hardness, adhesiveness and consistency value of gum gels were observed in sample treated at 121 °C for 20 min. In addition this gum gel has the good ability to stand against freeze-thaw treatment and its textural properties improved after freezing. Therefore, basil seed gum can be employed as a textural and rheological modifier in formulation of foods exposed to thermal and freezing temperatures.