Effects of cassava variety and growth location on starch fine structure and physicochemical properties

Effect of gamma ray dose on granular and molecular structures of gamma ray-irradiated cassava starch and its application in bioplastics

In this study, the effect of gamma ray irradiation on the granular and molecular structures of cassava starch was examined. Cassava starch was irradiated with various gamma ray doses of 25, 50, 75, and 100 kGy. After irradiation, the starch turned yellow, but its granular morphological characteristics remained intact. However, the inner part and the 'Maltese cross' of the starch granules irradiated with 100 kGy were broken, and its crystallinity decreased considerably. The pH reduction (from 5.6 to 3.7) and carboxyl content increase (up to 0.38 %) confirmed the formation of carboxyl groups on the irradiated starch chains. Gamma ray irradiation caused glycosidic bond cleavages, resulting in shortened amylose chains and debranched amylopectin chains containing terminal carboxyl groups. The irradiated starches with different molecular weights have high potential for use in food and non-food applications, for example, in bioplastics. Thermoplastic-irradiated starch (TPIS) materials, and their blends with poly(lactic acid) (PLA) were prepared via extrusion. Both TPIS and PLA/TPIS blends exhibited considerably increased melt flow index values compared with those from the unirradiated starch at approximate increases of 420-2260% and 2-55%, respectively. The improved melt flow ability and reduced viscosity are advantages for some plastic conversion processes such as injection molding.

Insight to starch retrogradation through fine structure models: A review

The retrogradation of starch is crucial for the texture and nutritional value of starchy foods products. There is mounting evidence highlighting the significant impact of starch's fine structures on starch retrogradation. Because of the complexity of starch fine structure, it is a formidable challenge to study the structure-property relationship of starch retrogradation. Several models have been proposed over the years to facilitate understanding of starch structure. In this review, from the perspective of starch models, the intricate structure-property relationship is sorted into the correlation between different types of structural parameters and starch retrogradation performance. Amylopectin B chains with DP 24-36 and DP ≥36 exhibit a higher tendency to form ordered crystalline structures, which promotes starch retrogradation. The chains with DP 6-12 mainly inhibit starch retrogradation. Based on the building block backbone model, a longer inter-block chain length (IB-CL) enhances the realignment and reordering of starch. The mathematical parameterization model reveals a positive correlation between amylopectin medium chains, amylose short chains, and amylose long chains with starch retrogradation. The review is structured according to starch models; this contributes to a clear and comprehensive elucidation of the structure-property relationship, thereby providing valuable references for the selection and utilization of starch.

Effects of cooking methods on the physical properties and in vitro digestibility of starch isolated from Chinese yam

The objective of this study was to compare the structural and functional attributes of Chinese yam starches obtained via different domestic cooking methods. Cooking changed the crystalline type from the C type to the CB type, and disrupted the short- and long-range molecular order of Chinese yam starch. The average chain length of amylopectin in BOS (boiling starch) was the smallest at 22.78, while RWS had the longest average chain length, reaching 24.24. These alterations in molecular structure resulted in variations in functional properties such as solubility, swelling power (SP), pasting characteristics, and rheological properties. Among these alterations, boiling was the most effective method for increasing the water-binding capacity and SP of starch. Specifically, its water holding capacity was 2.12 times that of RWS. In vitro digestion experiments indicated that BOS has a higher digestion rate (k = 0.0272 min-1) and lower RDS (rapidly digestible starch), which may be related to its amylopectin chain length distribution. This study can guide us to utilize yam starch through suitable cooking methods, which is relevant for the processing and application of Chinese yam starch.

Impact of Corn Starch Molecular Structures on Texture, Water Dynamics, Microstructure, and Protein Structure in Silver Carp (Hypophthalmichthys molitrix) Surimi Gel

This study systematically investigates the impact of corn starch molecular structures on the quality attributes of surimi gel products. Employing molecular analyses to characterize corn starch, three amylopectin fractions (A, B1, and B2), categorized by the degree of polymerization ranges (6 < X ≤ 12, 12 < X ≤ 24, and 24 < X ≤ 36, respectively) were specifically focused on. The surimi gel quality was comprehensively assessed through texture profile analysis, nuclear magnetic resonance, scanning electron microscopy, stained section analysis, and Fourier transform infrared spectroscopy. Results indicated the substantial volume expansion of corn amylopectin upon water absorption, effectively occupying the surimi gel matrix and fostering the development of a more densely packed protein network. Starch gels with higher proportions of A, B1, and B2 exhibited improved hardness, chewiness, and bound water content in the resultant surimi gels. The weight-average molecular weight and peak molecular weight of corn starch showed a strong positive correlation with surimi gel hardness and chewiness. Notably, the secondary structure of proteins within the surimi gel was found to be independent of corn starch's molecular structure. This study provides valuable insights for optimizing formulations in surimi gel products, emphasizing the significance of elevated A, B1, and B2 content in corn starch as an optimal choice for crafting dense, chewy, water-retaining surimi gels.

Physicochemical Properties of Granular and Gelatinized Lotus Rhizome Starch with Varied Proximate Compositions and Structural Characteristics

As a traditional and popular dietary supplement, lotus rhizome starch (LRS) has health benefits for its many nutritional components and is especially suitable for teenagers and seniors. In this paper, the approximate composition, apparent amylose content (AAC), and structural characteristics of five LRS samples from different regions were investigated, and their correlations with the physicochemical properties of granular and gelatinized LRS were revealed. LRS exhibited rod-shaped and ellipsoidal starch granules, with AAC ranging from 26.6% to 31.7%. LRS-3, from Fuzhou, Jiangxi Province, exhibited a deeper hydrogel color and contained more ash, with 302.6 mg/kg iron, and it could reach the pasting temperature of 62.6 °C. In comparison, LRS-5, from Baoshan, Yunnan Province, exhibited smoother granule surface, less fragmentation, and higher AAC, resulting in better swelling power and freeze-thaw stability. The resistant starch contents of LRS-3 and LRS-5 were the lowest (15.3%) and highest (69.7%), respectively. The enzymatic digestion performance of LRS was positively correlated with ash content and short- and long-term ordered structures but negatively correlated with AAC. Furthermore, the color and network firmness of gelatinized LRS was negatively correlated with its ash content, and the retrograde trend and freeze-thaw stability were more closely correlated with AAC and structural characteristics. These results revealed the physicochemical properties of LRS from different regions and suggested their advantages in appropriate applications as a hydrogel matrix.

Effects of different altitudes on the structure and properties of potato starch

The main element influencing the quality of potato starch is the environment. To investigate the effects of different altitude cultivation locations on the molecular structure and physicochemical properties of starch, two potato varieties, Jiusen No.1 B1 and Qingshu No.9 B2, were planted in three different altitude zones: A1 at low altitude (Chongzhou 450 m), A2 at middle altitude (Xichang 2800 m), and A3 at high altitude (Litang 3650 m). The results showed that the average volume, number, surface area diameter, average branched polymerization degree, crystallinity, and gelatinization temperature of two potato granules in high altitude areas were significantly lower than those in middle and low altitude areas were, and the gelatinization performance of potato starch was affected according to the correlation of starch structure characteristics. Potato starch with more short-branched chains and less long branched chains resulted in a lower gelatinization temperature in high altitude areas. The results showed that Jiusen No. 1 and Qingshu No. 9 were mainly affected by accumulated radiation and accumulated rainfall in Litang, a high altitude area, and by effective accumulated temperature in Xichang, a middle altitude area. This study quantified the influence of meteorological factors on the main starch quality of potato tubers. The results can be used as a theoretical basis for the scientific planting of high-quality potatoes.

Effects of selenium solution on the crystalline structure, pasting and rheological properties of common buckwheat starch

Selenium is an important element that affects human growth and development, and also affects the yield and quality of common buckwheat. In our study, two common buckwheat varieties were sprayed with different concentrations (0 g/hm², 5 g/hm², 20 g/hm²) of sodium selenite solution at the initial flowering period and the full flowering period, respectively, to determine the effects of selenium solution on the physicochemical properties of common buckwheat starch. With increasing selenium levels, the amylose content, peak viscosity, breakdown, relative crystallinity, pasting temperature and gelatinization enthalpy first decreased and then increased, while the transparency showed a trend of increasing and then decreasing. All samples exhibited a typical A-type pattern, while at high selenium level, the degree of short-range order of common buckwheat starches changed. From the rheological properties, it can be seen that the starch paste is dominated by elastic properties, while the low selenium treatment decreases the viscosity of the starch paste. These results showed that spraying different concentrations of selenium solutions at different periods significantly affected the physicochemical properties of common buckwheat starch.

Impact of Cassava Starch Varieties on the Physiochemical Change during Enzymatic Hydrolysis

The enzymatic modification of starch extends its industrial use to flavor delivery and probiotic encapsulants, among other uses. However, it is not known how starch from different cassava varieties responds to enzymatic hydrolysis. Starches from two Ecuadorian cassava varieties (INIAP 650, an edible starch, and INIAP 651, an industrial starch) were partially modified at three enzymatic hydrolysis degrees (0%, 30%, and 50%), and their physicochemical properties were assessed. The structural analysis revealed that both varieties showed progressive structural damage as hydrolysis increases, probably due to exo-hydrolysis. However, deeper pores were observed in INIAP 651 with the SEM analysis. The crystallinity percentage obtained by XRD analyses remained constant in INIAP 651 and decreased (by 26%) in INIAP 650 (p < 0.05). In addition, the amylose−lipid complex index in INIAP 650 remained constant, while INIAP 651 increased (p < 0.05) at 30% hydrolysis (by 93%). In both varieties, hydrolysis increased (p < 0.05) the water holding capacity (WHC) (by 10−14%) and the water binding capacity (WBC) (by 16%), but 50% hydrolysis of INIAP 650 was needed to significantly affect these properties. No differences were observed in the varieties’ thermal properties. Regarding the rheological properties, the variety did not influence the changes in the storage module (G′) and the loss modulus (G″) with the hydrolysis (p > 0.05). However, the phase angle decreased significantly (p < 0.05) with the hydrolysis, being higher in the INIAP 650 variety than in the INIAP 651 variety. In general, the results indicate that the variety affects the response of the starch granule to enzymatic hydrolysis (noticeable in the principal component analysis, PCA) and opens up the possibility to modulate starch properties.

Effects of single and dual modifications through electron beam irradiation and hydroxypropylation on physicochemical properties of potato and corn starches

In this study, electron beam irradiation (EBI; 2, 4, 6, 8 and 10 kGy), hydroxypropylation (HP) and dual modification of EBI-HP were applied to modify corn and potato starches. The results showed that the molar substitution (MS) of EBI-HP modified corn and potato starches were in the range of 0.060-0.087 and 0.080-0.124, respectively. After modifications, amylose content of corn (30.0 %) and potato (31.2 %) starches were declined to 24.2-28.1 % and 26.1-29.5 %, respectively, and relative crystallinity was reduced from 35.5 to 30.0 % for corn and 34.1 to 20.2 % for potato. Pasting properties decreased significantly in both starch sources with increasing irradiation dose. EBI decreased springiness, enthalpy of retrograded starch (ΔHr) and percentage of retrogradation (R%) on corn starches, which were different from those effects observed on potato starches. Meanwhile, HP increased peak viscosity up to 312.6 RVU and 1359.3 RVU for corn and potato starches, respectively. Moreover, EBI-HP was highly responsible for the decreases in the textural, gelatinization and retrogradation properties and relative crystallinity in both corn and potato starches. These results enhance the understanding of starch functionality modified by using both physical and chemical methods, and provide further insights on food and non-food applications.

Structure and Processing Properties of Nine Yam (Dioscorea opposita Thunb) Starches from South China: A Comparison Study

In order to explore the processing and application potential of Chinese yam starch, nine kinds of Chinese yam starch (GY11, GY5, GY2, GXPY, LCY, SFY, MPY, SYPY, ASY) from South China were collected and characterized. The chemical composition, rheological properties, thermal properties, and in vitro starch digestion were compared, and the correlation between the structure and processing properties of these yam starches was analyzed using Pearson correlation. The results show that GY2 had the highest amylose content of 28.70%. All the yam starches were similarly elliptical, and all the yam starch gels showed pseudoplastic behavior. Yam starches showed similar pasting temperatures and resistant starch content, but SYPY showed the largest particle size (28.4 μm), SFY showed the highest setback (2712.33 cp), and LCY showed the highest peak viscosity (6145.67 cp) and breakdown (2672.33 cp). In addition, these yam starches also showed different crystal types (A-type, B-type, C-type), relative crystallinity (26.54-31.48%), the ratios of 1045/1022 cm-1 (0.836-1.213), pasting properties, and rheological properties, so the yam starches have different application potentials. The rheological and pasting properties were related to the structural properties of starch, such as DI, Mw, and particle size, and were also closely related to the thermodynamic properties. The appropriate processing methods and purposes of the processed products of these yam starches can be selected according to their characteristics.

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.

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.

Rheological and textural properties of lafun, a stiff dough, from improved cassava varieties

We studied the textural and rheological (viscoelastic) properties of fresh lafun dough, a fermented cassava product, and their changes during storage at 45 °C for 5 and 24 h, in order to determine after-cooking storability. Lafun flours were produced from three types of cassava varieties: seven improved white-fleshed varieties, seven improved provitamin A carotenoids (pVAC) varieties and two local white-fleshed varieties; and processed into lafun doughs. Pasting properties of the flours were assessed. Flours from local varieties had pasting profiles with highest viscosities, while pVAC flours had the lowest. The three types of cassava varieties varied significantly in most of their pasting properties. Four promising improved varieties were identified, based on high peak viscosity (55.8-61.5 P) and stiffer texture than local varieties during storage. Undesirable varieties were also found, which softened during storage instead of hardening. Optimum texture of lafun dough was obtained after 5 h of storage.