Properties Of Sweet Potato Starch Research Articles

Physicochemical properties of starch isolated from eight different varieties of Korean sweet potatoes

The physicochemical properties of sweet potato starch (SPS) isolated from different Korean varieties, purple-fleshed Shinjami and Borami, orange-fleshed Juwhangmi and Shinwhangmi, and white/cream-fleshed Shinyulmi, Shinchunmi, Yeowhangmi, and Jeungmi, were investigated. The crude protein contents of Shinwhangmi and Jeungmi SPS were higher, and the crude lipid contents of Shinwhangmi and Shinyulmi SPS were lower than those of others. The amylose (AM) contents ranged from 14.66% (Juwhangmi) to 30.51% (Shinchunmi). The water binding capacity (WBC), swelling powers, and solubilities at 80°C were 95.78–79.32%, 15.69–23.39 g/g, and 3.77–11.01%, respectively. The XRD patterns were A and Cb-types. The granular shapes exhibited polygonal and semi-oval, but the sizes differed among different varieties. The initial pasting temperature ranged from 69.4 (Juwhangmi) to 76.4°C (Shinchunmi). Differences between onset and conclusion temperatures of orange-fleshed SPS were greater than those of others. The molecular weight of AM and amylopectin (AP) were (1.26–1.92) × 106 and (5.37–5.99) × 107, respectively. The gelatinization temperatures, amylose contents, and WBCs of SPS were correlated with unit chains of DP6-12 (negative) and DP13-24 (positive) in their APs.

Dual‐frequency ultrasound effect on structure and properties of sweet potato starch

AbstractEffects on the structure and properties of sweet potato starch under single frequency ultrasound of 25, 80 kHz and dual‐frequency ultrasound of 25 and 80 kHz were investigated at the same treating conditions else. Dents and pores were found by SEM at the surface of starch with both ultrasounds. Starch–iodine complex analysis showed above ultrasounds destroyed amylopectin and starch chains. FT‐IR indicated that with ultrasonic treatments, the functional groups of starch were not destroyed, but its crystal structure was damaged. As a result, its crystalline index decreased. Brabender curves showed that the peak viscosity of starch with dual‐frequency ultrasound was 14.09% lower than that of the native starch. In addition, the solubility and transmittance of starch increased by ultrasound, and the solubility went up as ultrasonication time was increased. It reached the maximum when the starch was treated for 60 min by dual‐frequency ultrasound, which increased by 2.69% compared to that of native starch. The starch being treated by dual‐frequency ultrasound for 30 min showed maximum transmittance, increasing it by 5.1% compared to the native starch; however, continuously increasing ultrasonic treatment resulted in a decrease of transmittance. Therefore, compared to single frequency ultrasound, dual‐frequency ultrasonic treatment caused more obvious changes to the structure and properties.

Composition, structure, and physicochemical properties of sweet potato starches isolated by sour liquid processing and centrifugation

AbstractThe proximate composition, structure, and physicochemical properties of sweet potato starches prepared by sour liquid processing (SLPS) and centrifugation (CFS) in the laboratory, and those of commercial grade starches, were examined and compared. The total amylase activities (α‐, β‐amylase) of the sour liquid and starch supernatant were also determined. The apparent amylose, Al, Mg, Fe, and Zn contents, granule size, XRD crystalline peak intensities, gelatinization enthalpy, peak viscosity, and setback ratio of SLPS were lower than those of CFS, whereas the protein, lipid, ash, phosphorous, K, and Ca contents, L* value, swelling power (55–95°C), solubility (55–95°C) and stability ratio of SLPS were higher than those of CFS. The surfaces of SLPS granules appeared corroded, showing pits and fissures, whereas the surfaces of CFS granules appeared smooth. In addition, the total amylase activity of the starch supernatant was 150.83 units/100 mL, and reached a maximum value of 214.28 units/100 mL in the sour liquid after 4 h of fermentation.

Effect of Water State on Thermal Properties of Sweet Potato Starch

Effect of Water State on Thermal Properties of Sweet Potato Starch

Effect of heat treatment on quality, thermal and pasting properties of sweet potato starch during yearlong storage

Proper postharvest handling and storage of sweet potato is an important link in the chain from producer to consumer or manufacturing industry. Heat treatments have been used as a non-chemical means to modify the postharvest quality and reduce pathogen levels and disease development of a wide variety of horticultural products. The objective of this study was to investigate the effects of hot water treatment (HWT) on the quality, gelatinisation enthalpy and pasting properties of sweet potato starch during long-term storage. The weight loss, sprouting, spoilage and sugar content of sweet potato were also determined. HWT significantly inhibited the sprouting and decay of sweet potato during the storage period. There were no significant differences (P < 0.05) in the pasting properties and onset (T(O)), peak (T(P)) and endset (T(E)) temperatures of gelatinisation of sweet potato starch among all treatments, especially between heat-treated and non-heat-treated samples. HWT also had no significant impact on the quality of the internal components of the roots. Less than 4% of the yearlong-stored roots were discarded owing to spoilage. HWT supplied a lethal dose of heat to surface pathogens and black spot without damaging the nutritional and processing qualities of sweet potato. HWT was an effective method to reduce root sprouting and deterioration without significant impact on the quality of the internal components of sweet potato. This novel technique will open a new avenue to extend the storage life of sweet potato with good quality and minimal waste.

Effects of cross‐linking on the rheological and thermal properties of sweet potato starch

AbstractSweet potato starches were modified with three different concentrations of phosphorus oxychloride (POCl3) (0.01, 0.02, and 0.03%, based on dry weight of starch) as a cross‐linking agent. The effects of crosslinking on rheological and thermal properties of sweet potato starch (SPS) pastes were evaluated. Cross‐linking considerably reduced the swelling power, consistency index (K), apparent viscosity (ηa), and yield stress (σoc) values of SPS, which significantly decreased with increase in POCl3 concentration. The gelatinization temperature (Tp) and enthalpy (ΔH) values of the cross‐linked SPS, which were determined using differential scanning calorimetry, were higher than those of native SPS. Storage modulus (G′), loss modulus (G″), and complex viscosity (η*) of the cross‐linked SPS pastes determined using small deformation oscillatory rheometry, were higher than native starch, and they also decreased with increase in POCl3 concentration from 0.01 to 0.03%. The tan δ (ratio of G″/G′) values (0.15–0.19) of the cross‐linked SPS samples were much lower than that (0.37) of the native SPS, indicating that the elastic properties of the SPS pastes were strongly influenced by modifications from cross‐linking. Finally, Cox–Merz plots showed that η* was much higher than ηa for the cross‐linked SPS pastes.

Effect of hydroxypropylation on physical and rheological properties of sweet potato starch

Sweet potato starches (SPS) were hydroxypropylated to evaluate the effect of molar substitution (MS, 0.042–0.153) on the rheological properties, thermal properties, freeze-thaw stability, paste clarity, and gel strength of hydroxypropylated sweet potato starches (HPSPS). The swelling power and solubility values of HPSPS were higher than those of native sweet potato starch (SPS) and increased with an increase in MS. The transition temperatures ( T o, T p, and T c), and enthalpy (Δ H) of gelatinization of HPSPS were lower than those of native SPS, and significantly decreased with an increase in MS.Rheological properties of HPSPS pastes were measured under the conditions of steady and dynamic shear. Their consistency index (K), apparent viscosity ( η a,100), Casson yield stress ( σ oc), complex viscosity ( η*), and dynamic moduli ( G′ and G″) values decreased with an increase in MS, while their flow behavior index ( n) and tan δ (ratio of G″/ G′) values increased. The dependence of apparent viscosity on temperature followed the Arrhenius model for all samples. The paste clarity of HPSPS paste was more pronounced with increasing MS of hydroxypropyl groups. The HPSPS gels showed lower gel strength and also better freeze-thaw stability with a significant decrease in syneresis (g/100 g) compared to native SPS.

Comparison of the effect of sugars on the viscoelastic properties of sweet potato starch pastes

SummaryViscoelastic properties of sweet potato starch (SPS) pastes (5% w/w) were studied in the presence of various sugars (sucrose, glucose, fructose, and xylose) at different concentrations (0, 10 and 20%) by small‐deformation oscillatory measurements. Dynamic frequency sweeps at 20 °C indicated that all SPS–sugar mixtures were more elastic than viscous with storage moduli (G′) higher than loss moduli (G′′) at all values of frequency with a frequency dependency. Dynamic moduli (G′ and G′′) values increased with the increase in sugar concentration from 10 to 20%. Changes in the dynamic moduli were more pronounced with xylose in comparison to the control (no sugar) and other sugars. G′ values as a function of ageing time (10 h) at 4 °C continuously increased with time during ageing without a plateau region. In general, G′ values of SPS–sugar mixtures during ageing decreased in the following order: pentose (xylose) &gt; hexose (glucose and fructose) &gt; control &gt; disaccharide (sucrose), indicating that the xylose had the greatest ability in retarding retrogradation of SPS.

여러 종류의 검 첨가가 국내산 고구마전분의 유동특성 및 Vane 항복응력에 미치는 영향

7종류의 상업용 검(xanthan gum, guar gum, pectin, gum arabic, gellan, locust bean gum, sodium alginate)을 국내산 고구마전분에 대해 0%, 0.3%, 0.6% 농도로 첨가한 전분-검혼합 페이스트(5%, w/w)의 유동특성과 항복응력을 측정하였다. 고구마전분-검 혼합물은 대부분 검 농도가 0.3%에서 0.6%로 증가할 때 팽윤력이 증가하였다. 또한 유동특성은 power law 모델식으로부터 결정되었고, 항복응력 측정을 위해 vane 방법이 사용되었다. 고구마전분-검 혼합물은 25℃에서 shear-thinning 거동특성을 보여주었고, 겉보기 점도 (?a,<SUB>100</SUB>)와 점조도 지수(K)는 pectin과 sodium alginate를 제외한 모든 시료에서 검의 농도가 증가함에 따라 증가하는 경향을 나타내었다. Pectin은 다른 검에 비해 매우 낮은 항복응력 값을 나타내었고, gellan은 매우 높은 항복응력 값을 나타내었다. 고구마전분-검 혼합물은 pectin, gum arabic 그리고 sodium alginate를 제외한 다른 검 첨가에서 탄성적 상승효과를 나타냈다. 일반적으로 고구마전분의 유동특성과 vane 항복응력은 검 첨가에 의해 크게 영향을 받으며, 검 종류와 농도에 의존함을 알 수 있었다.

Solar and tray-drying methods and physicochemical properties of sweetpotato starch

Two drying methods were investigated to determine if drying is possible without affecting the quality of starch. The drying methods were solar dryer (53-55 °C) and electrically powered tray dryer (60 °C). The physicochemical properties of starch from five sweetpotato were evaluated after dehydration using the two methods. The results showed that drying methods had effect on some physicochemical properties of sweetpotato starch. The tray-dried starches had higher moisture, ash, viscosity, and L* values. The swelling power and solubility values for tray-dried starches were significantly different from solar-dried ones, except for the tray-dried “Sauti” starch. Although the water binding capacity and amylase content were higher in solar-dried starches relative to tray-dried starches, statistically there was no significant difference(P starch factory, the need is to consider the type of drying method to be used.

Steady and dynamic shear rheology of sweet potato starch–xanthan gum mixtures

The effect of xanthan gum at different concentrations (0.2–0.6% w/w) on the rheological properties of sweet potato starch (SPS) pastes was evaluated under steady and dynamic shear conditions. The presence of xanthan resulted in an increase in the consistency index and vane yield stress of SPS. The effect of temperature on the apparent viscosity of SPS–xanthan mixtures is well described by the Arrhenius equation. Dynamic moduli ( G ′, G ″, and η * ) values of the mixtures increased with an increase in xanthan concentration while the tan δ values decreased. The addition of xanthan appeared to contribute to the elastic properties of the weak network of the SPS pastes. The structure development rate constant ( k ) of gelation during ageing was strongly influenced by the presence of xanthan. This suggests that the phase separation process caused by the incompatibility phenomena between the amylose component in starch and xanthan can increase the elastic characteristics of the SPS–xanthan mixtures.

Rheological properties of sweet potato starch before and after denaturalization

Based on the sweet potato starch, cationic starch, acetic starch and cationic-acetic compoundedly modified starch were made through chemical denaturalization. The above three kinds of static rheological parameter and dynamic rheological parameter were measured, respectively. The experimental result reveals that the thermal stability of starchy viscosity increases after chemical denaturalization. Under the condition of identical shearing rate, the shear stress of cationic-acetic ester compoundedly modified sweet potato starch paste is the largest among these kinds of sweet potato starch. This attributes to a phenomenon of shearing thinning. Furthermore, raw sweet potato starch has a larger gel intensity than that of modified starch.

Altering Pasting Characteristics of Sweet Potato Starches through Amino Acid Additives

This study assessed the effects of amino acid additives, aspartic acid, leucine, lysine, and methionine, on the pasting and thermal characteristics of white- and orange-fleshed Beauregard sweet potato starches. A rapid visco analyzer 3D was used to determine pasting properties. In comparing pasting characteristics, starch from orange-fleshed sweet potato was found to be easier to cook, had a lower potential for retrogradation, and was less stable during heating than the white-fleshed sweet potato starch. The RVA analysis showed that the charged amino acids, aspartic acid and lysine, altered pasting characteristics of the 2 starches more than the neutral amino acids, leucine and methionine. Aspartic acid had similar effects on both starches, making them less stable during cooking and lowering the potential for retrogradation. Lysine, when added to the orange-fleshed sweet potato starch, decreased the breakdown, allowing for more stability during cooking. This study showed that pasting properties of sweet potato starches can be altered by the addition of amino acids.

Rheology of Mixed Systems of Sweet Potato Starch and Galactomannans

AbstractThe effect of galactomannans (guar gum and locust bean gum) at different concentrations (0, 0.2, 0.4 and 0.6%, w/w) on rheological properties of sweet potato starch (SPS) was studied. The flow behaviors of SPS‐galactomannan mixtures were determined from the rheological parameters of power law and Casson models. The SPS‐galactomannan mixtures had high shear‐thinning fluid characteristics (n = 0.30‐0.36) exhibiting yield stress at 25°C. The presence of galactomannans resulted in the increase in consistency index (K), apparent viscosity (ηa,100) and Casson yield stress (σoc). In the temperature range of 25‐70°C, the mixtures followed the Arrhenius temperature relationship. Dynamic rheological tests at 25°C indicated that the SPS‐galactomannan mixtures had weak gel‐like behavior with storage moduli (G′) higher than loss moduli (G") over most of the frequency range (0.63‐62.8 rad/s) with frequency dependency. The magnitudes of dynamic moduli (G′, G" and η*) of the SPS‐galactomannan mixtures were higher than those of the control (0% gum), and increased with an increase in gum concentration. The tan δ (ratio of G"/G′) values (0.41‐0.46) of SPS‐guar gum mixtures were much lower than those (0.50‐0.63) of SPS‐locust bean gum mixtures, indicating that there was a more pronounced effect of guar gum on the elastic properties of SPS.

Influence of Delayed Harvest Time on Physico‐chemical Properties of Sweetpotato Starch

AbstractEight varieties of sweetpotato [Ipomoea batatas (L.) Lam] were transplanted in June, and harvested in October, November, December 1999 and January 2000. Starch content and starch properties of the tuberous roots were compared on delaying the harvest date. The shoot tops got blighted in early December and chilling injury rate of roots (average of eight varieties) increased up to 76.7% in January with decrease in temperature. Starch contents in October (24.0 g/100 g fresh weight, fw) and November (25.0 g/100 g fw) were almost the same, but the content decreased remarkably in December (21.2 g/100 g fw) and January (15.5 g/100 g fw). In December and January, the sucrose content of the roots had higher values. Hardness and leaked water percentage (LWP) of the starch gels remarkably increased from November to December (hardness: 76.4 to 112.3 g, LWP: 6.6 to 10.9%). On the contrary, the changes in amylose content and pasting properties of the starches were not consistent with decrease in temperature. This suggests that the effect of low temperature on these properties is insignificant after the growth period of sweetpotato. There were significant differences among the varieties in terms of starch retrogradation. The selection of varieties such as Kyushu 123 with the lowest percentage of retrogradation and Kyukei90142‐8 with the lowest chilling injury rate will help to lengthen the storage time in the field at least until December.

Genetic variation in the physical properties of sweet potato starch.

Sweet potato starch, prepared from 44 genotypes adapted to Philippine conditions, showed wide variation and distinctly different pasting profiles in Rapid Visco-Analyzer (RVA) analysis at 11% and 7% starch concentration. At 11% starch concentration, the pasting profiles were type A, characterized by high to moderate peak with a major breakdown and low cold paste viscosity. At 7%, the pasting profile was generally type C, characterized by the absence of a distinct peak with none to very slight breakdown and high cold paste viscosity. However, differentiation among genotypes was better achieved from RVA pasting profiles at 11% starch concentration. Peak viscosity (PV) and hot paste viscosity (HPV) at 11% starch paste concentration had significant negative correlation with amylose content. PV, HPV, and setback ratio were significantly correlated to adhesiveness of the starch gel. Sweet potato starch generally had high swelling volume but low solubilities at 92.5 degrees C.

Relationship between α-amylase degradation and physico-chemical properties of sweet potato starches

Six varieties of sweet potatoes, grown under identical conditions, produced starches that displayed different characteristics. Susceptibility to pancreatic α-amylase varied between starches produced by the different clones. Structural characteristics at various levels, such as ratio of major fractions, size of amylose, gelatinization temperature and granule morphology, were also different between clones. Correlating structural attributes with susceptibility led to the suggestion that granule structure, including amylopectin: amylose ratio and molecular associations, were important critical factors in the hydrolysis of sweet potato starch granules. High amylopectin content of sweet potato starch was associated with a high gelatinization temperature and correspondingly less susceptibility to α-amylase attack. The hydrolysis pattern was correlated with degree of hydrolysis. Extensive surface erosion was shown to indicate a high degree of hydrolysis, whereas less surface erosion indicated less degradation.

Varietal and Annual Variations in Pasting Properties of Sweet Potato Starch.

To analyze the varietal and annual variations in starch pasting properties in sweet potato storage roots, twenty cultivars and strains were grown in both 1996 and 1997. The starch pasting properties were investigated using a Rapid Visco-Analyzer (RVA), and the amylose content and starch content were also examined. The pasting properties showed wide ranges of variation among cultivars and strains, and the amylose content ranged between 13.3 and 17.2%. The correlation coefficients of the pasting temperature, peak viscosity, setback, amylose content and starch content between the two years were 0.867***, 0.654**, 0.784***, 0.902*** and 0.864*** respectively. Analysis of variance showed that the varietal differences were significant at 0.1% Ievel for the pasting temperature, setback, amylose content and starch content. The differences among strains and years were significant at 1% Ievel for the pasting temperature, peak viscosity and breakdown. The estimated heritability values of the pasting temperature, peak viscosity, setback, amylose content and starch content were 0.80, 0.49, 0.77, 0.88 and 0.85, respectively. The amylose content showed significant positive correlations in both years with the pasting temperature, the peak viscosity temperature and the setback. The starch content did not show any significant correlatioui with the pasting properties and the amylose content. These results indicate that it is possible to breed for the improvement of the starch pasting properties in sweet potato.

Properties of Sweet Potato Starches from Different Tissue Zones

AbstractSweet potato starches prepared from the peel (P), cambium (C), and inner‐tissue (IT) were tested for physicochemical properties. The average granule sizes of the IT starches were tended to be larger than those of the P and C starches. Amylose contents of starches from the different tissue zones did not differ significantly. The onset and peak temperatures (To, Tp) of the P starches determined by differential scanning calorimetry (DSC) were somewhat high. The C starches were readily digested by the four glucoamylases.

Developmental Changes in Properties of Sweet Potato Starches

AbstractSweet potato starches extracted from two varieties at different stages of development were investigated for various physicochemical properties. Average granule size increased in the early stage of development. The amylose content calculated from the blue value (BV) remained almost constant. The onset temperature (To) determined by differential scanning calorimetry (DSC) was lowest in the latest stage of development. The heat of gelatinization (ΔH) was lowest in the earliest stage of development. Digestibility by two glucoamylases tendet to be lower in the later stage of development.