The application of gelatinisation techniques in modification of cassava and yam starches using precipitation method.

Starches modified using the precipitation method which are added to edible film formulation were shown to lower water vapor transmission rates and increase the mechanical strength of the film. The effect may not only be due to the changes in starch morphology, but other aspects of the starch granules, such as their size and chemical properties in particular, are also suggested as reasons for improvements to the quality of edible film by modified starches. The aim of this research was to determine physicochemical changes in modified cassava and yam starches using several gelatinisation techniques in the precipitation method. The gelatinisation techniques used in this study were two methods of heating (using a hotplate and autoclave reactor + oven heating) and two types of starch solvent (distilled water and a mixture of distilled water and ethanol 1:1, v/v). The results showed that both cassava and yam starch granules modified using a hotplate at a heating temperature of 100 °C for 30 min were more badly damaged and smaller than those modified using autoclave reactor + oven heating at 140 °C for 1 h. However, the latter suffered more damage and were smaller in size when the heating time was increased to 3-5 h. All techniques applied in the modification increased the intensities of stretching vibration of O-H and C-H, and bound water bending vibration. The use of ethanol in the starch solvent enabled the starches to retain the shape and size of the granules despite the rearrangement of intra and intermolecular bonding as confirmed by FTIR spectra.

Development and characterization of elephant foot yam starch-hydrocolloids based edible packaging film: physical, optical, thermal and barrier properties.

The study aimed at the development of elephant foot yam starch (EFYS) based edible film through blending of Xanthan (XG) and agar-agar (AA). Film thickness and density increased with increase in concentration of hydrocolloids and the respective highest value 0.199 mm and 2.02 g/cm3 were found for the film possessing 2% AA. The film barrier properties varied with hydrocolloids and the lowest value of water vapour transmission rate (1494.54 g/m2) and oxygen transmission rate (0.020 cm3/m2) was observed for the film with 1% XG and 1.5% AA, respectively. Mechanical and thermal properties also improved upon addition of hydrocolloid. Highest tensile strength (20.14 MPa) and glass transition temperature (150.6 °C) was observed for film containing 2% AA. Fourier transform infrared spectroscopy demonstrated the presence of -OH, C-H, and C=O groups. The change in crystallinity was observed through peak in X-ray diffraction analysis, which increased with increase in the hydrocolloids' concentration.

Composition and Physicochemical Properties of Three Chinese Yam (Dioscorea opposita Thunb.) Starches: A Comparison Study.

The aim of this work was to compare the composition and physicochemical properties (SEM, XRD, solubility, swelling power, paste clarity, retrogradation, freeze-thaw stability, thermal property, and pasting property) of three Chinese yam (Dioscorea opposita Thunb.) starches (CYYS-1, CYYS-2, and CYYS-3) in Yunlong town, Haikou, Hainan Province, China. Our results show that all the CYYS gave a typical C-type X-ray diffraction pattern. The swelling power of CYYS varied from 10.79% to 30.34%, whereas solubility index was in the range of 7.84-4.55%. The freeze-thaw stability of each CYYS showed a contrary tendency with its amylose content. In addition, CYYS-3 showed the highest To (81.1 °C), Tp (84.8 °C), Tc (91.2 °C), and ΔH (14.1 J/g). The pasting temperature of CYYS-1 increased significantly with sucrose addition. NaCl could inhibit the swelling power of CYYS. There were significant decreases in pasting temperature and pasting time of CYYS when pH decreased.

Recrystallization of starches by hydrothermal treatment: digestibility, structural, and physicochemical properties.

Gelatinized starches were recrystallized under hydrothermal treatment and their properties were characterized by X-ray diffractometry, solid-state (13)C cross-polarization and magic-angle spinning nuclear magnetic resonance, differential scanning calorimetry, gel-permeation chromatography, high-performance anion-exchange chromatography using pulsed amperomeric detection, high-performance size-exclusion chromatography with attached multiangle laser light scattering and refractive index detectors, and digestibility analysis. Amylopectin molecules of hylon (V, VII) and water yam starch contained long side-chains with high proportion of fb1 and fb2. Under hydrothermal treatment, the double helix proportion and relative crystallinity significantly increased and reached maxima of water yam (48.7 and 28.2 %, respectively). Except water yam starch, X-ray diffraction pattern of all starches exhibited the evidence of type 2 amylose-lipid complex. Besides, under DSC measurement, potato and hylon starches showed the endotherm of amylose-amylose interaction. The hydrothermal treatment caused the recrystallization resulting in the decrease of RDS, especially in case of hylon and water yam starch. HTT water yam contained highest SDS (48.3 %) and HTT hylon VII contained highest RS (44.5 %). The relationship between structure and digestibility was observed, in which, high amylose content and specific structures of amylopectin molecule were necessary for the production of RS and/or SDS of hydrothermally treated starches.

Effect of extrusion on the formation, structure and properties of yam starch-gallic acid complexes.

This paper investigated the effects of twin-screw extrusion treatment on the formation, structure and properties of yam starch-gallic acid complexes. Yam starch and gallic acid were extruded. The microstructure, gelatinization characteristics, and rheological properties of the samples were determined. The microstructure of extruded yam starch-gallic acid complexes presented a rough granular morphology, low swelling, and high solubility. The X-ray diffraction analysis showed that the extruded yam starch-gallic acid complexes exhibited A + V-type crystalline structure. Fourier transform infrared spectroscopy results showed that the extrusion treatment could destroy the internal orderly structure of yam starch, and the addition of gallic acid could further reduce its molecular orderliness. Differential scanning calorimetry analysis showed a decrease in the enthalpy of gelatinization of the sample. Dynamic rheological analysis showed that the storage modulus and loss modulus of the extruded yam starch-gallic acid complexes were significantly reduced, exhibiting a weak gel system. The results of viscosity showed that extrusion synergistic gallic acid reduced the peak viscosity and setback value of starch. In addition, extrusion treatment had an inhibitory effect on the digestibility of yam starch, and enhanced the interaction of gallic acid with yam starch or hydrolytic enzymes. Therefore, extrusion synergistic gallic acid has improved the structure and properties of yam starch-related products, which can provide new directions and new ideas for the development of yam starch.

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.

Understanding the multi-scale structure, physicochemical and digestive properties of extruded yam starch with plasma-activated water.

In this study, the synergistic effect of plasma-activated water (PAW) combined with twin-screw extrusion (TSE) on multi-scale structure, physicochemical and digestive properties of yam starch (YS) was studied. PAW-TSE resulted in higher amylose content in YS than TSE alone. Compared with single TSE, the relative crystallinity, short-range ordered degree, and gelatinization enthalpy of YS were increased by PAW-TSE according to the results of X-ray diffraction, Fourier transform infrared, Raman spectroscopy, and differential scanning calorimetry. Furthermore, rapid viscosity and dynamic rheological analysis showed that the peak and breakdown viscosity of PAW-TSE treated YS paste were considerably reduced, and the storage modulus and loss modulus were significantly increased, indicating that the gel strength and thermal stability were improved. In addition, the resistant starch (RS) content of YS treated by PAW-TSE increased from 6.04 % to 21.21 %. Notably, the effect of PAW-TSE on YS enhanced with the preparation time of PAW increased. Finally, correlation analysis indicated that the characteristic indexes of PAW had a significant impact on the long or short-range ordered structure, thermal properties, and in vitro digestibility of YS during extrusion. Therefore, PAW-TSE, as an emerging dual modification technology, will greatly expand the application of extrusion technology.

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.

Characterization of Polylactic Acid Biocomposites Filled with Native Starch Granules from Dioscorea remotiflora Tubers.

Biocomposites were fabricated utilizing polylactic acid (PLA) combined with native starch sourced from mountain's yam (Dioscorea remotiflora Knuth), an underexplored tuber variety. Different starch compositions (7.5, 15.0, 22.5, and 30.0 wt.%) were blended with PLA in a batch mixer at 160 °C to produce PLA/starch biocomposites. The biocomposites were characterized by analyzing their morphology, particle size distribution, thermal, X-ray diffraction (XDR), mechanical, and dynamic mechanical (DMA) properties, water absorption behavior, and color. The results showed that the amylose content of Dioscorea remotiflora starch was 48.43 ± 1.4%, which corresponds to a high-amylose starch (>30% of amylose). Particle size analysis showed large z-average particle diameters (Dz0) of the starch granules (30.59 ± 3.44 µm). Scanning electron microscopy (SEM) images showed oval-shaped granules evenly distributed throughout the structure of the biocomposite, without observable agglomeration or damage to its structure. XDR and DMA analyses revealed an increase in the crystallinity of the biocomposites as the proportion of the starch increased. The tensile modulus (E) underwent a reduction, whereas the flexural modulus (Eflex) increased with the amount of starch incorporated. The biocomposites with the highest Eflex were those with a starch content of 22.5 wt.%, which increased by 8.7% compared to the neat PLA. The water absorption of the biocomposites demonstrated a higher uptake capacity as the starch content increased. The rate of water absorption in the biocomposites followed the principles of Fick's Law. The novelty of this work lies in its offering an alternative for the use of high-amylose mountain's yam starch to produce low-cost bioplastics for different applications.

Zearalenone removal using inactivated yeast embedded in porous modified yam starch aerogels and its application in corn silk tea.

Zearalenone contaminates food and poses a threat to human health. It is vital to develop cost-effective and environmentally-friendly adsorbents for its removal. By screening Sporobolomyces pararoseus (SZ4) and modified yam starch (adsorption capacity (qe) of 1.33 and 0.94 mg/g, respectively), this study prepared a novel composite aerogel adsorbent (P-YSA@SZ410). The compressive strength of P-YSA@SZ410 was 1.35-fold higher than unloaded yeast. It contained several functional groups and three-dimensional interconnected channels, achieving a 0° contact angle within 0.18 s, thereby demonstrating excellent water-absorbent properties. With a qe of 2.96 mg/g at 308 K, the adsorption process of P-YSA@SZ410 was spontaneous, endothermic, and matched pseudo-second-order and Langmuir models. The composite adsorbed zearalenone via electrostatic attraction and hydrogen bonding, maintaining a qe of 2.24 mg/g after five cycles. P-YSA@SZ410 was found to remove zearalenone effectively under various conditions and could be applied to corn silk tea, indicating its great potential as an adsorbent material.

Characterization of gallic acid-Chinese yam starch biodegradable film incorporated with chitosan for potential use in pork preservation.

The widely use of petroleum-based plastics causes serious environmental pollution and oil resource shortage. In this work, biodegradable films were prepared based on gallic acid (GA)-induced Chinese yam starch (YS) and chitosan (CS). The fresh-keeping effect of biodegradable films on the pork meat preservation were investigated. The prepared GA/YS/CS biodegradable films exhibited thinner thickness and better light transmittance, because CS effectively decreased the viscosity of film-forming solution and weaken its internal link structure. The SEM results and mechanical results revealed that the YS, GA, and CS had a good compatibility, GA modification and adding CS markedly improved the tensile strength of YS-based film, because the interaction between CS and starch molecular was facilitate owing to the NH3+ of CS tended to form hydrogen bonds with the hydroxyl group of starch. Sensory analysis results suggested that GA/YS/CS films can effectively improve the quality of pork during storage compared to the package of polyethylene film. In summary, the prepared GA/YS/CS film in this work had practical application potential in pork preservation due to its excellent mechanical, antibacterial, oxidation resistance properties, and the development and application of biodegradable starch film can greatly reduce the increasingly serious environmental pollution pressure.

Preparation and Characterization of Extruded Yam Starch-Soy Protein Isolate Complexes and Their Effects on the Quality of Dough.

Extrusion is a method of processing that changes the physicochemical and rheological properties of starch and protein under specific temperature and pressure conditions. In this study, twin-screw extrusion technology was employed to prepare yam starch-soy protein isolate complexes. The structure and properties of the complexes and their effects on the quality of dough were studied. The results showed changes in the X-ray diffraction, rheology, and in vitro digestibility of the complexes. The extruded starch-protein complex formed an A+V-type crystal structure with the addition of soy protein isolate. A small amount of soy protein isolate could improve the complex's viscoelasticity. As the content of soy protein isolate increased, the content of slow-digesting starch and resistant starch in the complexes increased, and the digestibility decreased. The microstructure of the dough indicated that the network structure of the puffed yam starch-protein complex dough was more uniform than that of the same amount of puffed yam starch. The moisture distribution of the dough showed that with the addition of extruded flour, the closely bound water content of the dough increased, and the weakly bound water content decreased. The hardness, gumminess, chewiness, and resilience of the dough decreased. In conclusion, extruded starch-protein complexes can improve dough quality and provide technical support for the broad application of yam.

The structure-glycemic index relationship of Chinese yam (Dioscorea opposita Thunb.) starch.

Yam (Dioscorea opposita Thunb.) is an important functional food in Asia. Yam starch usually has a low glycemic index. What is the structure requirement of starch to obtain a low glycemic index remains unknown. In order to understand the structure-glycemic index relationship, six yam starches from various regions with apparent structure difference were analyzed. Chinese yam starch (CYS) showed the lowest glycemic index. It presented as oval or round granules. Meanwhile, CYS showed a distinct A-type crystal structure while the others presented C-type crystal structure. The largest crystallinity, Rw, Mw/Mn, RS level, RS + SDS level, and the lowest peak viscosity, trough viscosity and C∞ values were found for CYS. These data explained the lowest glycemic index of CYS. The above results suggested that CYS was a good neutraceutical candidate and could be used in the diet of diabetes population.

A mechanically robust biodegradable bioplastic of citric acid modified plasticized yam starch with anthocyanin as a fish spoilage auto-detecting smart film.

The current scenario of environmental pollution caused by non-biodegradable plastic and depleting non-renewable resources has called upon the need for biodegradable bioplastic production from renewable resources. Starch bioplastics production from underutilized sources is a viable option for packaging materials that are non-toxic, environmentally benign, and easily biodegradable under disposed conditions. Pristine bioplastic production results in some undesirable qualities and hence requires further modification in order to elevate its potential applicability in real-world scenarios. In this work, yam starch was extracted from a local variety of yams through an eco-friendly and energy-efficient process which was further utilized for bioplastic production. The produced virgin bioplastic was subjected to physical modification through the introduction of plasticizers such as glycerol, while citric acid (CA) was employed as modifier in order to produce the desired starch bioplastic film. The different compositions of starch bioplastics were analyzed for their mechanical properties and maximum tensile strength of 24.60 MPa was observed as the best possible experimental result. The biodegradability feature was further highlighted through soil burial test. Apart from their general function of preservation and protection, the produced bioplastic can be employed for pH-sensitive food spoilage detection through the minute introduction of plant-derived anthocyanin extract into it. The produced pH-sensitive bioplastic film showed distinct changes in color upon an extreme change in the pH value and hence has potential to be used as a smart food packaging material.

Effect of the mode of incorporation on the disintegrant properties of acid modified water and white yam starches.

Acid modified starches obtained from two species of yam tubers namely white yam - Dioscorea rotundata L. and water yam - D. alata L. DIAL2 have been investigated as intra- and extra-granular disintegrants in paracetamol tablet formulations. The native starches were modified by acid hydrolysis and employed as disintegrant at concentrations of 5 and 10% w/w and their disintegrant properties compared with those of corn starch BP. The tensile strength and drug release properties of the tablets, assessed using the disintegration and dissolution (t 50 and t 80 - time required for 50% and 80% of paracetamol to be released) times, were evaluated. The results showed that the tensile strength and the disintegration and dissolution times of the tablets decreased with increase in the concentration of the starch disintegrants. The acid modified yam starches showed better disintegrant efficiency than corn starch in the tablet formulations. Acid modification appeared to improve the disintegrant efficiency of the yam starches. Furthermore, tablets containing starches incorporated extragranularly showed faster disintegration but lower tensile strength than those containing starches incorporated intragranularly. This emphasizes the importance of the mode of incorporation of starch disintegrant.

Effects of carboxymethyl chitosan on physicochemical, rheological properties and in vitro digestibility of yam starch.

The effects of carboxymethyl chitosan (CMCS) on the pasting, rheological, and physical properties of yam starch (YS) were investigated. Different concentrations of CMCS were added to the YS, followed by heating paste treatment at 95 °C. Then the blends were subjected to the determination of physicochemical, rheological properties and in vitro digestibility. Our results showed that CMCS reduced the paste viscosity of YS and the addition of CMCS did not effectively inhibit the movement of water molecules. Rheological measurements results showed that YS-CMCS blends exhibited shear thinning behavior. Furthermore, because of the presence of amylose inhibited the swelling of the starch and leaching of amylose, the addition of CMCS had no significant difference between solubility and swelling power of YS.

Development and characterization of dual-modified yam (Dioscorea rotundata) starch-based films.

The current consumer demand for fresh food and the interest in caring for the environment have driven the development of biodegradable film packaging to replace synthetic films to preserve the integrity of food. The objective of this work was to evaluate the effects of starch modifications (oxidized, cross-linked, and dual: oxidized/cross-linked), starch concentration (1 and 2%), and glycerol concentration (5 and 15%) on water vapor permeability (WVP), mechanical properties (tensile strength and elongation), optical, and structural properties of films based on "hawthorn" yam starch. The WVP of the films was 4.4 × 10-10 to 1.5 × 10-9 g/m∗s∗Pa, where the films with oxidized yam starch showed a 58.04% reduction concerning the native starch. The tensile strength of oxidized yam starch films showed a decrease of 17.51% with an increase in glycerol concentration. For the 1% starch concentration, elongation increased by 17.03% when the glycerol concentration was increased from 5 to 15%. Modification of starch, starch concentration, and glycerol have a significant effect on the barrier, mechanical, physical, and structural properties of films made with yam starch, where films made with oxidized yam starches at a concentration of 1% starch and 5% glycerol showed the best responses of the properties evaluated.

Physicochemical and structural properties of low-amylose Chinese yam (Dioscorea opposita Thunb.) starches.

Nuoshanyao (NSY), Tiegunshanyao (TSY) and Huaishanyao (HSY) are the main cultivars of Chinese yam (Dioscorea opposita Thunb.) widely grown in China. The composition, physicochemical properties, morphology, and thermal properties of the starches from these cultivars were investigated in this study. NSY starch (17.0%) was much lower in amylose content than other cultivars (33.4-34.5%). The average particle diameter of the starches ranged from 25.83 to 28.93 µm. Weight-average molecular weights (Mw) and number-average molecular weights (Mn) ranged from 1.29 to 1.84 × 105 g/mol and 5.93 to 8.36 × 104 g/mol, respectively. NSY starch had higher gelatinization temperature (71.5 °C), enthalpy (14.14 J/g), peak viscosity (8590 cP) and swelling power (12.0%) than TSY and HSY. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) tests indicated that Chinese yam starches had CB-type crystalline structure with crystallinity ranging from 21.91% to 27.08% and a short-range ordered structure. To, Tp, ΔH, peak viscosity and swelling power at 95 °C were significantly correlated to amylose content. The low-amylose NSY starch was found to have high gelatinization temperature, enthalpy, peak viscosity and swelling power. These specific physicochemical and structural properties indicated the industrial potential of low-amylose yam starch.

Physico-functional and structural characterization of ultrasonic-assisted chemically modified elephant foot yam starch.

Limited studies are present on dual modification of elephant foot yam (EFY) starch and no study investigated the combined effect of citric acid (CA) and ultra-sonication (US). In the present study, EFY starch was subjected to different concentrations of CA with and without US. Changes in different properties such as functional, morphology, thermo-pasting etc. were examined. Both treatments increased the water and oil absorption capacity of starch. Pasting properties significantly (p < 0.05) reduced with US modification, except pasting viscosity and pasting temperature. CA modification decremented the glass transition temperature which further reduced with US. Starch morphology revealed aggregation of individual granules upon CA modification whereas CA + US broke the aggregates and caused surface fissures and cracks. Overall crystallinity enhanced with an increase in the citric acid concentration. Changes in functional groups identified by FTIR analysis showed new peak formation (1710-1690 cm-1) associated with CA modification. The results showed that CA and CA + US changed the functionality, morphology and other structural characteristics of EFY starch which enable us to use the modified starch in the range of application i.e. bakery products, extruded products, thickening agent and other.

Effect of various drying pretreatments on the structural and functional properties of starch isolated from Chinese yam (Dioscorea opposita Thumb.).

The objective of the present investigation was to compared the structural and functional properties of starch isolated from fresh raw Chinese yam (FYS) and the Chinese yam after freeze-drying pretreatment (FDS), after hot-air drying pretreatment (HADS), after subcritical dimethyl ether dewaterization pretreatment (SDDS). Freeze-drying (FD) process reduced the short-and long-range molecular order of Chinese yam starch. Hot-air drying (HAD) process promoted the formation of ordered structure of starch granules. SEM images displayed the presence of protein-starch complexes in the HADS and SDDS samples. The FDS had the smallest Mw of amylopectin with 4.09 × 106 g/mol, but the Mw values of amylose molecules for FYS was highest. The branch chain length of amylopectin in HADS had a smaller proportion of short chains and less long chains and higher proportion of long chains compared with other starches. These molecular structure changes caused by the various drying pretreatment processes, resulting in the difference in functional properties including solubility and swelling power, gelatinization parameters, pasting characteristics and rheological properties. This study provided important information for the suitable application of starches isolated from various dried Chinese yam.