A-, B- and C-type starch granules coexist in root tuber of sweet potato

Determination of starch digestibility in white sweet potato after acid hydrolysis and heat-moisture treatment using terahertz spectroscopy

Acid hydrolysis and heat-moisture treatment (HMT) have been used to alter digestibility of starch in white sweet potato, providing health benefits. The potential of terahertz spectroscopy for rapid and non-destructive determination of starch digestibility in white sweet potato treated with acetic acid and citric acid, followed by HMT, was investigated. An in vitro starch digestibility assay was employed to measure the contents of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS). The intensities of the peaks attributed to covalent vibrational modes at 9.0, 10.5, and 13.1 THz showed a strong correlation with RDS content (R2 > 0.95). Moreover, the intensities of the peaks sensitive to non-covalent forces within and between double helices of starch, around 5.0 and 7.9 THz, were correlated with RS content (R2 > 0.65). These results indicate, after acid hydrolysis and HMT, the starch digestibility of white sweet potato can be determined using THz peaks.

Fabrication of oat β-glucan-starch composite systems by sequential extraction as batters for deep-fried mushrooms to prevent oil penetration

Deep-fat frying (DF) of mushrooms is favored by consumers due to its appealing sensory characteristics. However, their high oil absorption can lead to obesity and elevated cholesterol levels. Therefore, developing healthy food coatings as oil barriers and water-holding layers is essential. In this study, oat starch (OS), oat β-glucan (OBG), and OS-OBG composite systems were prepared and evaluated for their effects on the processing characteristics and oil-repellent capacity of DF mushrooms. Results from 13C solid-state NMR and microstructures demonstrated that incorporating OBG into OS restricted the expansion of OS and reduced moisture migration, thereby forming continuous layers with enhanced cohesive strength. Confocal laser scanning microscopy (CLSM) and gas chromatography-mass spectrometry (GC-MS) further confirmed that OS-OBG decreased oil uptake, improved the nutritional quality and desirable aroma typically associated with fried mushrooms. This study offers scientific and economic guidance for the large-scale production of low-fat fried foods using oat starch-β-glucan system as coatings.

Chemical characterization of single helical mung bean amylopectin

The distinctive chemical properties of amylopectin are attributable to the single and double helical structures that are characteristic of the polysaccharide. In the extant literature, amylopectin is generally described as a combination of these two structural forms, with limited studies focusing exclusively on the chemical properties of the single helical ones. In this paper, the single/double helical mung bean amylopectin (SMBA/DMBA) was prepared by the innovative methodology developed in-house and its chemical properties were characterized by molecular weight, chain length distribution, light micrographs, FT-IR、13C Solid-state NMR, XRD, and DSC. The results indicated that the primary branch diameter of SMBA aggregates was approximately half that observed in the double helical structure. Furthermore, the number-average molecular weight (Mn) of SMBA was found to be 123,538 g/mol, with a higher proportion of chains with 1, 10-13 glucose residues. The wavenumbers of 1022.6 and 1020.6 cm-1 represented the amorphous structure composed of SMBA and DMBA, respectively. In comparison with DMBA, the resonances of carbon atoms, excluding C4, in SMBA exhibited a lower field shift. The diffraction angles of single-helix mung bean amylopectin were found to be 2θ at 17.54 o and 22.28 o. The findings of this study provide a reliable marker for the identification of single helix in starch and its influence on the properties of starch.

Structural and physicochemical properties of debranched lotus seed starch treated with high hydrostatic pressure

Lotus seeds represent a significant economic crop and are abundant in starch. To further enhance their application value, this study investigates the structural characteristics of lotus seed starch (LS) under the combined influence of pullulanase and high hydrostatic pressure (HHP). Pullulanase increased amylose content from 39.80 % to 72.26 %, and HHP increased amylose content further. LS crystals changed from C-type to B-type, and the ordered structure of LS was destroyed by enzymatic hydrolysis, and amylose single helix and partial double helix structure were formed. At low concentration, lotus seed amylose single helix tends to form amylose double helix structure with itself. At high concentrations, they tend to aggregate, forming a network structure with large surface area and loose order. HHP destroys the double helix structure of amylose, resulting in the decrease of starch crystallinity. These findings provide new insights into improving the processing properties and application range of lotus seed starch.

Structural evolution of maize starches with different amylose content during pasting and gelation as evidenced by Rapid Visco Analyser

This study examined multi-scale structural alterations of maize starches varying in amylose content during pasting and gelation, using Rapid Visco Analyser (RVA). At 50 °C, starch granules maintained their morphology with low viscosity. As the temperature increased to 95 °C, helical and crystal structures were destroyed, leading to granule swelling, distortion and porosity, as identified by Wide Angle X-ray Scattering and Fourier Transforms Infrared measurements at 90% moisture. This resulted in increased viscosity and the formation of a loose gel network structure. Subsequently, maintaining the temperature at 95 °C caused a decrease in viscosity as most granules disappeared, forming a reorganized flaky gel structure with larger pores. As the temperature decreased, gel porosity reduced. In high amylose content starch, the viscosity remained low and granules were partially gelatinized since the heating temperature was below the gelatinization temperature. This study is the first to detail starch multilevel structural dynamics during RVA gelatinization.

Changes of crystalline structure and physicochemical properties of Pueraria lobata var. thomsonii starch under water deficit

Crystal type is an important physicochemical property of starch. However, it is currently unclear whether changes in crystal type affect other properties of starch. This study discovered that water deficit resulted in an increase in small starch granules and transparency in Pueraria lobata var. thomsonii, while causing a decrease in amylose content and swelling power. Additionally, the crystal type of P. Thomsonii starch changed from CB-type to CA-type under water deficit, without significantly altering the short-range ordered structure and chain length distribution of starch. This transformation in crystal type led to peak splitting in the DSC heat flow curve of starch, alterations in gelatinization behavior, and an increase in resistant starch content. These changes in crystalline structure and physicochemical properties of starch granules are considered as adaptive strategies employed by P. Thomsonii to cope with water deficit.

Physicochemical properties of starches from sweet potato root tubers grown in natural high and low temperature soils

Three sweet potato varieties grew in natural high temperature (HT) and low temperature (LT) field soils. Their starch physicochemical properties were affected similarly by HT and LT soils. Compared with LT soil, HT soil induced the increases of granule size D[4,3] from 18.0-18.7 to 19.9-21.8 μm and amylopectin average branch-chain length from 21.9-23.1 to 24.1-24.7 DP. Starches from root tubers grown in HT and LT soils exhibited CA- and CC-type XRD pattern, respectively. Starches from root tubers grown in HT soil exhibited stronger lamellar peak intensities (366.8-432.0) and higher gelatinization peak temperature (72.0-76.8 °C) than those (176.2-260.5, 56.4-63.4 °C) in LT soil. Native starches from root tubers grown in LT soil were hydrolyzed more easily (hydrolysis rate coefficient 0.227-0.282 h-1) by amylase than those (0.120-0.163 h-1) in HT soil. The principal component analysis exhibited that starches from root tubers grown in HT and LT soils had significantly different physicochemical properties.

Structural, Thermal, Pasting and Digestion Properties of Starches from Developing Root Tubers of Sweet Potato

Three sweet potato varieties with white-, yellow- and purple-fleshed root tubers were harvested at 100, 120, 140 and 160 days after planting (DAP). Their starch structural, thermal, pasting and digestion properties were measured to reveal the influences of harvesting dates on the physicochemical properties of sweet potato root tuber starch. Though starches from different varieties displayed some differences in physicochemical properties due to their different genetic backgrounds, they were influenced by harvesting date in similar ways. Starches isolated from root tubers at 100 and 160 DAP exhibited lower granule sizes than those at 120 and 140 DAP. The amylose content was higher in root tubers at 100 and 120 DAP than at 140 and 160 DAP. Starches from root tubers at 100 DAP exhibited CA-type X-ray diffraction patterns, and then the B-type crystallinity gradually increased at later harvesting dates. The different harvesting dates had no significant effects on the short-ranged ordered structure and lamellar thickness of starch, but the lamellar peak intensity decreased significantly at later harvesting dates. Starch had a lower gelatinization temperature and a wider gelatinization temperature range in root tubers at 140 and 160 DAP than at 100 and 120 DAP. The higher peak viscosity and lower pasting temperature were associated with the late harvesting date. The digestion of starch had slight differences among root tubers at different harvesting dates. The harvesting dates of root tubers played more important roles in starch properties than the variety. This study would be helpful for breeders, farmers and sweet potato starch users.

Baked sweetpotato textures and sweetness: An investigation into relationships between physicochemical and cooked attributes

Sweetpotato varieties vary greatly in perceived textures and sweetness. This study identified physicochemical factors that influence these attributes in cooked sweetpotatoes. Fifteen genotypes grown on three plots were baked and evaluated by a trained descriptive sensory analysis panel for sweetness and 13 texture attributes. Mechanical parameters were measured by texture profile analysis (TPA); and composition (starch, cell wall material, sugar contents), starch properties (thermal, granule type ratios, granule sizes), and amylase activities were characterized. TPA predicted fracturability and firmness well, whereas starch and sugar contents, B-type starch granule ratio, and amylase activities influenced prediction of mouthfeel textures. Sweetness perception was influenced by perceived particle size and sugar contents; and maltose generation during baking was highly correlated with raw sweetpotato starch content. These relationships between physicochemical sweetpotato properties and baked textures and sweetness could benefit breeders and processors in selecting biochemical traits that result in consumer preferred products.

Effect of high voltage dielectric barrier discharge (DBD) atmospheric cold plasma treatment on physicochemical and functional properties of taro (Colocasia esculenta) starch

The goal of the proposed study is to investigate the effects of three different power levels (30, 32 and 34 kV) and exposure time (2, 4 and 8 min) of dielectric barrier discharge (DBD) atmospheric cold plasma treatment on the functional and physicochemical characteristics of taro starch. Investigations were done into how different treatments impact the multi-structural, functional and physicochemical attributes of taro starch. The findings showed that cold plasma treatments substantially impacted starch granule shapes (3.60-2.54 μm), such as reduced aggregations and developed fissures on granule surface due to the generation of an etching by plasma species and enhancement in the surface topography and roughness of treated starch as compared with native by SEM and AFM analysis. Besides this, no variations were detected in the functional groups of taro starch using FT-IR analysis after cold plasma treatments. However, the A-type pattern in the XRD did not affect it, while a reduction in relative crystallinity (14.20-11.50 %) was seen as a function of the active plasma species depolymerization. Furthermore, depending on the cold plasma voltage and treatment time, amylose content (20.12-15.98 %), paste clarity (24.48-31.27 %), solubility (0.41-65.53 %), freezing thaw stability (% syneresis) (32.10-42.58 %), color properties (L*, 94.79-97.52), whiteness index (79.37-84.66), molecular weight distribution (Peak 1, 12.79-5.35 × 108 g/mol; Peak 2, 4.20-1.56 × 107 g/mol) and in vitro digestibility (RDS, 64.10-64.08 %) significantly changed. So, based on these excellent properties, this study suggested that cold plasm-treated taro starch can be used in the field of food packaging material, functional food and pharmaceutical products. Therefore, a potential approach for physically altering starch is plasma treatment.

Shortening growth year improves functional features of kudzu starch by tailoring its multi-scale structure

Kudzu is usually consumed at different growth years, yet the influences of growth years on its multi-scale structures and physicochemical features have not been fully disclosed. In this study, those influences occurred on kudzu starches (KS2, KS10, KS30 and KS50, isolated using precipitation method) were investigated. The granules size, crystallinity, short-range ordered structure, amylose content, intermediate and longer amylose chains reduced but the average thickness of crystalline lamella increased as the rise of growth years. KS2 had lower content of defective crystal structure and higher content of near-perfect crystal structure. Those signified that bulk density of molecules packing into starch substrate was higher for KS2, which was not beneficial for water molecules and enzymes entering into starch granules and thus elevated pasting temperature and reduced digestion rate. Besides, reduced proportions of defective ordered structures and enhanced lipid-amylose complex also reduced digestion rate. Both the peak and breakdown viscosity were in order of KS2 > KS10 > KS30 ≈ KS50. And KS2, KS10, and KS30 exhibited enhanced retrogradation tendency during cooling than KS50 as evidenced by the relative higher setback viscosity. Those results are favor for rational screen and usage of kudzu starch resources with different growth years for food applications.

Recent preparation, modification and application progress of starch nanocrystals: A review

Due to the advantages of wide sources, high biocompatibility and favorable biodegradability, starch nanocrystals (SNCs) have gradually attracted attention and have bright development prospects in food, agriculture, materials, medicine and other fields. However, the traditional preparation method of SNCs is time-consuming and inefficient, and the physicochemical properties cannot fully meet the needs of multiple applications. Fortunately, the unique onion-like structure of starch granules and the large number of hydroxyl groups present on the surface entitle SNCs to efficient preparation and modification. This paper comprehensively reviewed the improvement methods of SNCs preparation process in recent years, and the advantages and disadvantages of the two improvement strategies were compared. Besides, the importance of introducing different pretreatment methods into the SNCs preparation process was emphasized. It also focused on the different modification treatment and application progress of SNCs, especially in the starch-based surface coating of fruits and vegetables. The information will contribute to further improve the preparation efficiency and physicochemical properties of SNCs, and ultimately expand the application field.

Relationships between X-ray Diffraction Peaks, Molecular Components, and Heat Properties of C-Type Starches from Different Sweet Potato Varieties

C-type starches with different proportions of A- and B-type crystallinities have different intensities and crystallinities of X-ray diffraction peaks. In this study, the intensities and crystallinities of X-ray diffraction peaks, molecular components and heat properties of C-type starches were investigated in seven sweet potato varieties, and their relationships were analyzed. The intensity and crystallinity of a diffraction peak at 5.6° were significantly positively correlated to the DP6-12 branch-chains of amylopectin and significantly negatively correlated to the true amylose content (TAC) determined by concanavalin A precipitation, gelatinization temperature, gelatinization enthalpy, water solubility at 95 °C, and pasting temperature. The intensity of diffraction peaks at 15° and 23° were significantly positively correlated to the gelatinization temperature and pasting temperature and significantly negatively correlated to the pasting peak viscosity. The significantly positive relationships were detected between the crystallinity of a diffraction peak at 15° and the DP13-24 branch-chains of amylopectin, gelatinization conclusion temperature and water solubility, between the crystallinity of diffraction peak at 17–18° and the TAC, gelatinization onset temperature, water solubility and pasting temperature, between the crystallinity of a diffraction peak at 23° and the gelatinization conclusion temperature and pasting peak time, and between the total crystallinity and the TAC, gelatinization conclusion temperature, water solubility and pasting temperature. The score plot of principle component analysis showed that the molecular components and heat property parameters could differentiate the C-type starches and agreed with their characteristics of X-ray diffraction peaks. This study provides some references for the utilizations of C-type starches.

Sizes, Components, Crystalline Structure, and Thermal Properties of Starches from Sweet Potato Varieties Originating from Different Countries

Sweet potato is a root tuber crop and an important starch source. There are hundreds of sweet potato varieties planted widely in the world. Starches from varieties with different genotype types and originating from different countries have not been compared for their physicochemical properties. In the research, starches from 44 sweet potato varieties originating from 15 countries but planted in the same growing conditions were investigated for their physicochemical properties to reveal the similarities and differences in varieties. The results showed that the 44 starches had granule size (D[4,3]) from 8.01 to 15.30 μm. Starches had different iodine absorption properties with OD680 from 0.259 to 0.382 and OD620/550 from 1.142 to 1.237. The 44 starches had apparent amylose content from 19.2% to 29.2% and true amylose content from 14.2% to 20.2%. The starches exhibited A-, C_A-, C_C-, or C_B-type X-ray diffraction patterns. The thermograms of 44 starches exhibited one-, two-, or three-peak curves, leading to a significantly different gelatinization temperature range from 13.1 to 29.2 °C. The significantly different starch properties divide the 44 sweet potato varieties into different groups due to their different genotype backgrounds. The research offers references for the utilization of sweet potato germplasm.

Relations between starch fine molecular structures with gelatinization property under different moisture content

Although gelatinization property has been intensively investigated with its relation to starch structures, how a combination of starch molecular structures and moisture content affect the gelatinization remains unclear. The gelatinization of six rice starches with a wide range of amylose content was investigated under different moisture content in this study. Results showed that starch gelatinization temperatures increased and biphasic endothermic peaks appeared over the decreased moisture content. For the first time, amylose content was shown to have a parabolic relationship with gelatinization temperatures. Distinct linear relations among starch fine molecular structures with gelatinization parameters were observed under different moisture contents, which suggested that amylose short chains were involved in the first endothermic peak, while interactions among amylose intermediate chains and relatively shorter amylopectin trans-lamellar chains dominantly contributed to the second endothermic peak when gelatinized under limited moisture content. These results help in better understanding of starch structure-gelatinization relation.

Nonconventional Hydrocolloids’ Technological and Functional Potential for Food Applications

This review aims to study the alternatives to conventional industrial starches, describing uncommon sources along with their technological characteristics, processing, and performance on food products. Minor components remaining after extraction play an important role in starch performance despite their low percentage, as happens with tuber starches, where minerals may affect gelatinization. This feature can be leveraged in favor of the different needs of the food industry, with diversified applications in the market being considered in the manufacture of both plant and animal-based products with different sensory attributes. Hydrocolloids, different from starch, may also modify the technological outcome of the amylaceous fraction; therefore, combinations should be considered, as advantages and disadvantages linked to biological origin, consumer perception, or technological performance may arise. Among water-based system modifiers, starches and nonstarch hydrocolloids are particularly interesting, as their use reaches millions of sales in a multiplicity of specialties, including nonfood businesses, and could promote a diversified scheme that may address current monocrop production drawbacks for the future sustainability of the food system.

Effects of Variety and Growing Location on Physicochemical Properties of Starch from Sweet Potato Root Tuber

Three sweet potato varieties with purple-, yellow-, and white-fleshed root tubers were planted in four growing locations. Starches were isolated from their root tubers, their physicochemical properties (size, iodine absorption, amylose content, crystalline structure, ordered degree, lamellar thickness, swelling power, water solubility, and pasting, thermal and digestion properties) were determined to investigate the effects of variety and growing location on starch properties in sweet potato. The results showed that granule size (D[4,3]) ranged from 12.1 to 18.2 μm, the iodine absorption parameters varied from 0.260 to 0.361 for OD620, from 0.243 to 0.326 for OD680 and from 1.128 to 1.252 for OD620/550, and amylose content varied from 16.4% to 21.2% among starches from three varieties and four growing locations. Starches exhibited C-type X-ray diffraction patterns, and had ordered degrees from 0.634 to 0.726 and lamellar thicknesses from 9.72 to 10.21 nm. Starches had significantly different swelling powers, water solubilities, pasting viscosities, and thermal properties. Native starches had rapidly digestible starch (RDS) from 2.2% to 10.9% and resistant starch (RS) from 58.2% to 89.1%, and gelatinized starches had RDS from 70.5% to 81.4% and RS from 10.8% to 23.3%. Two-way ANOVA analysis showed that starch physicochemical properties were affected significantly by variety, growing location, and their interaction in sweet potato.

Study of morphological, structural, thermal, and pasting properties of flour and isolated starch from unripe plantain (Musa paradisiaca)

This work focused on studying the mineral composition, morphology, thermal, structural, and pasting properties of isolated plantain starch. Plantain starch is rich in K, and other ions as Mg, Ca, P, and Si were found. This starch exhibits lenticular, elliptical, and semispherical morphologies. Two endothermal events present in the thermogram were identified as the hexagonal and orthorhombic solvation. C-type starch formed by hexagonal and orthorhombic nanocrystal was completely indexed. The ash content showed the presence of calcium phosphate (KCaP₂O₇), Calcium Magnesium Phosphate (Ca_2.71Mg_0.29(PO₄)₂), and silicon oxide (SiO₂). The pasting profile of this starch behaves between a custard and a hydrogel. Scanning electron microscopy of the lyophilized samples along pasting profile confirms that the shear and van der Walls forces and slurry morphology govern the pasting profile changes.

Characterization of underutilized root starches from eight varieties of ramie (Boehmeria nivea) grown in China

Ramie root is an underutilized starch source. In this study, eight ramie varieties were investigated for starch properties. Starch content ranged from 18.6% to 50.1% in dry root. Starches from different varieties showed similar morphology including ellipsoidal, spherical and truncated granules with size D[4,3] from 10.1 to 14.1 μm. Starch had amylose content from 20.8% to 28.5%. All ramie varieties had B-type starches with relative crystallinity from 24.8% to 27.1%, ordered degree from 0.724 to 0.897 and lamellar thickness from 9.1 to 9.6 nm. Starches had gelatinization peak temperature from 70.5 to 73.8 °C and enthalpy from 14.9 to 15.8 J/g. Starches had swelling power and water solubility from 27.9 to 31.9 g/g and from 11.7% to 15.5%, respectively, at 95 °C, and exhibited different pasting properties with breakdown viscosity from 36 to 377 mPa s and setback viscosities from 1295 to 1863 mPa s. Starch pastes exhibited pseudoplastic behavior and different rheological properties. Native, gelatinized and retrograded starches had resistant starch from 81.7% to 83.9%, from 1.7% to 5.1% and from 5.6% to 13.3%, respectively. The eight varieties were divided into 3 groups according to starch properties. This study is helpful for selecting suitable ramie variety as starch source.

Physicochemical and structural characterization of starches from Andean roots and tubers grown in Colombia

The preservation of Andean roots and tubers (ART) depends on the recognition of their health-promoting and nutritional metabolites and their transformation into other products such as starches. The objective of this study was to determine the physicochemical and structural properties of native starches obtained from Canna edulis K., Oxalis tuberosa M., and Ipomoea batatas L. from the Colombian Andean agroecosystem. The physicochemical properties of starches were determined by traditional methods of analysis. The thermal properties were determined by gravimetric thermal analysis (TGA) and differential scanning calorimetry (DSC), while the structural characteristics were studied with X-ray diffractometry and infrared spectrometry. The ART showed a starch yield of between 53.3% and 75.4% (dry basis) and amylose content between 28.4% and 35.6%. Starches from I. batatas showed the highest percentage of amylose, lowest gel clarity, lowest water absorption index, and highest gel temperature. X-ray diffractograms showed a type A crystallographic pattern for I. batatas starch, and a type B pattern for C. edulis and O. tuberosa starches, while infrared spectra (FTIR-ATR) corroborated the structural characteristics of each type of starch. The results suggest that starches from Andean resources can be used as a substitute for traditional starches from corn and potato. In addition, their amylose content makes them potential sources of resistant starch and dietary fiber.