Structural, morphological, chemical, vibrational, pasting, rheological, and thermal characterization of isolated jicama (Pachyrhizus spp.) starch and jicama starch added with Ca(OH)2

Effects of nitrogen fertilizer application on the physicochemical properties of foxtail millet (Setaria italica L.) starch

The use of nitrogen fertilizer is a crucial agronomic practice to increase crop output and quality. This study investigated the impact of five nitrogen application levels (0, 60, 135, 210, and 285 kg N/hm2) on the physicochemical properties of foxtail millet (FM) starch. Optimal nitrogen application (210 kg N/hm2) significantly increased L*, a*, and b* values, water and oil absorption capacity, water solubility, and swelling power of starch. The number of small starch granules increased as the nitrogen application rate increased, but the granule morphology and typical A-type pattern did not change among the treatments. Nitrogen application increased the relative crystallinity and ordered structure, resulting in a higher gelatinization enthalpy. Compared to the control group (7.02 J/g), the enthalpy increased by 21.94 %, 66.38 %, 73.50 %, and 103.28 % under the nitrogen application rates, respectively. Moreover, nitrogen application greatly increased the percentage of A and B3 chains while it lowered the apparent amylose content, peak viscosity, and final viscosity. The effects of 210 and 285 kg N/hm2 treatments on the water solubility and swelling power, water and oil absorption, and light transmission of starch were greater compared to the 60 and 135 kg N/hm2 treatments. These results indicate that nitrogen fertilization significantly affects the physicochemical properties of FM starch.

Effect of non-thermal acidic and alkaline modifications on the structural, pasting, rheological, and functional properties of cassava (Manihot esculenta) starch

This study aimed to investigate the effects of acid or alkali modification of isolated cassava starch (ICS) on its physicochemical properties. Acetic acid concentrations of 5%, 10%, and 20% v/v (0.87, 1.73, and 3.46 M, respectively) and calcium hydroxide concentrations of 0.15%, 0.20%, and 0.30% w/w (0.02, 0.025, and 0.04 M, respectively) were tested independently and compared with untreated isolated starch. The scanning electron microscope (SEM) shows starches with polyhedral and semispherical shapes; these modifications do not change the surface of the starch granules. Nanocrystals with orthorhombic crystal structure were extracted from ICS. Transmission electron microscopy (TEM) shows crystallites with a size (two-dimensional) of 20 ± 5 nm in length and 10 ± 2 nm in width and reveals that this starch contains nanocrystals with orthorhombic crystal structure. The X-ray patterns show that these nanocrystals are unaffected by acidic or alkaline treatments. The Ca+2 and CH3COO- ions do not interact with these nanocrystals. The alkaline treatment only affects the gelatinization temperature at a Ca(OH)2 concentration of 0.30%. Low concentrations of acidic and alkaline treatments affect the ability of cassava starch to absorb water and reduce the peak and final viscosity. The infrared spectra show that the modifications lead to C-H and C═C bond formations. ICS-B 0.30 can modify the amorphous regions of the starch, and the acid treatment leads to acetylation, which was confirmed by the presence of an IR band at 1740 cm-1.

Effect of fortified calcium compounds from oyster shell on the quality of tapioca pearls

This study aimed to determine the effect of calcium fortification from dried oyster shells (DOS) and calcined oyster shells (COS) at concentrations of 2, 4 and 6 %(w/w) on physical and chemical properties of tapioca pearls. The results showed that the optimal cooking time of TP-COS decreased compared to TP-DOS and TP (control). The TP-DOS and TP-COS exhibited a remaining calcium content ranging from 8.39 to 41.03 mg/g. During seven days of refrigerated storage, TP-COS showed delayed hardness along with decreases in both the enthalpy of gelatinization and retrogradation. The functional groups observed in TP-DOS and TP-COS showed varying intensities compared to TP. Morphology images depicted the distribution of DOS and COS within tapioca pearls, revealing that TP-DOS and TP-COS possessed a denser and more compact structure. The results suggest that COS fortification could improve the nutritional value and delay the change in the texture of tapioca pearls after storage.

Jicama (Pachyrhizus spp.) a nonconventional starch: A review on isolation, composition, structure, properties, modifications and its application

Starch attracts food industries due to their availability in nature, cheapness, biodegradability and possibilities of endless applications. The starch properties and their modification affect food quality. Compared to other cereals, tuber and root starches, more systematic information is needed on the jicama starches (JS). This review article summarizes the isolation, composition, morphology, rheological, thermal and digestibility properties of JS. The modifications and its current and potential applications are also discussed. The chemical composition and structure of JS are different from other starches, influencing its properties. JS has been modified by physical and chemical methods to improve the properties of starch. However, there are very few studies on the modification of JS as compared with other commercial starch although it has been used in food formulation as a stabilizer and to improve the texture of food products. It is also applied as an edible coating to preserve the quality of food products and use as a raw material for making edible and bioplastic packaging. However, large-scale utilization of JS is unexplored compared to commercial starches. Therefore, this review would provide useful information and suggestions for more research on Jicama starch and its industrial applications.

Effects of biochar coupled with chemical and organic fertilizer application on physicochemical properties and in vitro digestibility of common buckwheat (Fagopyrum esculentum Moench) starch

Common buckwheat starch, a functional ingredient, has wide food and non-food applications. Excessive chemical fertilizer application during grain cultivation decreases quality. This study examined the effects of different combinations of chemical fertilizer, organic fertilizer, and biochar treatment on the physicochemical properties and in vitro digestibility of starch. The amendment of both organic fertilizer and biochar was observed to have a greater impact on the physicochemical properties and in vitro digestibility of common buckwheat starch in comparison to organic fertilizer amendment solely. The combined application of biochar, chemical, and organic nitrogen in an 80:10:10 ratio significantly increased the amylose content, light transmittance, solubility, resistant starch content, and swelling power of the starch. Simultaneously, the application reduced the proportion of amylopectin short chains. Additionally, this combination decreased the size of starch granules, weight-average molecular weight, polydispersity index, relative crystallinity, pasting temperature, and gelatinization enthalpy of the starch compared to the utilization of chemical fertilizer alone. The correlation between physicochemical properties and in vitro digestibility was analyzed. Four principal components were obtained, which accounted for 81.18 % of the total variance. These findings indicated that the combined application of chemical fertilizer, organic fertilizer, and biochar would improve common buckwheat grain quality.

Rheology, Texture and Swallowing Characteristics of a Texture-Modified Dysphagia Food Prepared Using Common Supplementary Materials

A dysphagia diet is a special eating plan. The development and design of dysphagia foods should consider both swallowing safety and food nutritional qualities. In this study, the effects of four food supplements, namely vitamins, minerals, salt and sugar, on swallowing characteristics, rheological and textural properties were investigated, and a sensory evaluation of dysphagia foods made with rice starch, perilla seed oil and whey isolate protein was carried out. The results showed that all the samples belonged to foods at level 4 (pureed) in The International Dysphagia Diet Standardization Initiative (IDDSI) framework, and exhibited shear thinning behavior, which is favorable for dysphagia patients. Rheological tests showed that the viscosity of a food bolus was increased with salt and sugar (SS), while it decreased with vitamins and minerals (VM) at shear rates of 50 s^-1. Both SS and VM strengthened the elastic gel system, and SS enhanced the storage modulus and loss modulus. VM increased the hardness, gumminess, chewiness and color richness, but left small residues on the spoon. SS provided better water-holding, chewiness and resilience by influencing the way molecules were connected, promoting swallowing safety. SS brought a better taste to the food bolus. Dysphagia foods with both VM and 0.5% SS had the best sensory evaluation score. This study may provide a theoretical foundation for the creation and design of new dysphagia nutritional food products.

Yam Bean (Pachyrhizus erosus L. Urban) Powder Improves Grass Carp Myofibrillar Protein Gel by Forming Disulfide Bonds, Hydrogen Bonds, and Proper Microstructure

This study aimed to analyze the impact of different additions (0-1.25%) of yam bean powder (YBP) on myofibrillar protein (MP) gel characteristics such as the structure, water-holding capacity (WHC), chemical interaction strength of grass carp MP, and texture. The results showed that the YBP exhibited a strong water absorption capacity and filled in the protein heat-induced polymerization gel network well, which enabled the gel network to capture and retain water effectively, resulting in MP gels containing YBP with excellent WHC and gel strength (0.75%). In addition, YBP induced the formation of hydrogen and disulfide bonds in proteins and inhibited the conversion of α-helices to β-sheets and β-turn structures, facilitating the formation of high-strength gel networks (p < 0.05). In conclusion, YBP can significantly improve the thermally induced gelling properties of grass carp MP. In particular, the addition of 0.75% YBP had the best effect in terms of filling the gel network of grass carp MP, resulting in the formation of a continuous and dense protein network, leading to the composite gel with the best WHC and texture.

Effect of Calcium Hydroxide on Physicochemical and In Vitro Digestibility Properties of Tartary Buckwheat Starch-Rutin Complex Prepared by Pre-Gelatinization and Co-Gelatinization Methods

This study examined the effect of calcium hydroxide (Ca(OH)₂, 0.6%, w/w) on structural, physicochemical and in vitro digestibility properties of the complexed system of Tartary buckwheat starch (TBS) and rutin (10%, w/w). The pre-gelatinization and co-gelatinization methods were also compared. SEM results showed that the presence of Ca(OH)₂ promoted the connection and further strengthened the pore wall of the three-dimensional network structure of the gelatinized and retrograded TBS-rutin complex, indicating the complex possessed a more stable structure with the presence of Ca(OH)₂, which were also confirmed by the results of textural analysis and TGA. Additionally, Ca(OH)₂ reduced relative crystallinity (RC), degree of order (DO) and enthalpy, inhibiting their increase during storage, thereby retarding the regeneration of the TBS-rutin complex. A higher storage modulus (G') value was observed in the complexes when Ca(OH)₂ was added. Results of in vitro digestion revealed that Ca(OH)₂ retarded the hydrolysis of the complex, resulting in an increase in values in slow-digestible starch and resistant starch (RS). Compared with pre-gelatinization, the complex process prepared with the co-gelatinization method presented lower RC, DO, enthalpy, and higher RS. The present work indicates the potential beneficial effect of Ca(OH)₂ during the preparation of starch-polyphenol complex and would be helpful to reveal the mechanism of Ca(OH)₂ on improving the quality of rutin riched Tartary buckwheat products.

The role of alkali in sweet potato starch-Mesona chinensis Benth polysaccharide gels: Gelation, rheological and structural properties

According to the Chinese traditional black jelly production process, a critical step to ensure the quality of jelly is to add alkali to it. In this study, the effects of sodium carbonate (Na₂CO₃) and sodium bicarbonate (NaHCO₃) on the pasting, rheological, textural, and structural properties of sweet potato starch (SPS)-Mesona chinensis Benth polysaccharide (MCP) gels were evaluated. Adding Na₂CO₃ at low concentration reduced the final viscosity (FV) of SPS-MCP gels, whereas adding it at a high concentration increased the FV. Adding NaHCO₃ can increase the FV of SPS-MCP gels in a concentration-dependent manner. Rheological results indicated that adding NaHCO₃ at a low concentration decreased the storage modulus of SPS-MCP gels, whereas adding it at a high concentration increased the storage modulus. The storage modulus of SPS-MCP gels increased with increasing concentration of NaHCO₃. The addition of Na₂CO₃ and NaHCO₃ improved the textural properties of SPS-MCP gels and decreased the water mobility. Infrared results indicated that adding alkali can enhance the hydrogen bonding between SPS and MCP. Scanning electron microscopy results suggested that alkali can reduce the size of gels, and make the structure more compact.

Influences of Extraction Methods on Physicochemical and Functional Characteristics of Three New Bulbil Starches from Dioscorea opposita Thunb. cv. Tiegun

Starches from the bulbils of Dioscoreae opposita Thunb. cv. Tiegun were isolated by aqueous steeping (SBS), enzyme extraction (EBS), and alkaline extraction (ABS) methods, respectively. The physicochemical, mineral composition, thermal and morphological characteristics of these starches were investigated. The starch granules were oval, spherical and kidney-shaped and its crystal type is a mixture of A-type and B-type patterns. The starches having larger average granule size showed more amylose and phosphorus contents than those with smaller average granule size. Differential scanning calorimetry (DSC) showed that the SBS had an endothermic transition ranging from 65.8 °C to 76.3 °C with an enthalpy of 2.0 J/g. The endothermic transitions of ABS and EBS showed the regions of 67.9 °C to 73.0 °C, and 66.8 °C to 82.0 °C, respectively. The gelationization enthalpies of ABS and EBS were 13.8 and 11.5 J/g, respectively. Additionally, ABS presented greater clarity in comparison with EBS and SBS. Pasting properties indicated that ABS had the highest peak viscosity, breakdown, but SBS had the lowest trough, final viscosity, setback, and pasting temperature. Generally, ABS and EBS could be used as food thickener or frozen food additives. SBS and EBS were potential technological alternatives in quality preservation of frozen starch-based products and other industrial applications.