Influence of acetylation on physicochemical, functional and thermal properties of potato and cassava starches

Starches were isolated from cassava (Manihot esculenta) and potato (Solanum tuberosum) tubers. They were further modified by acetylation. The physicochemical, functional and thermal properties of native and modified starches, prepared using acetic anhydride at different times (10 and 20 min) were compared. Potato starch (Sipiera/20) showed higher acetyl percentage and degree of substitution values than cassava (2425/20) starch when acetylated for 20 min. Proximate analysis revealed that the acetylated starches retained more moisture than the native ones. Above 75 °C, acetylation improved the water binding capacity of the native cassava starch; the same trend was observed for potato starch from 60 to 90 °C after acetylation. The X-ray powder diffraction patterns derived from acetylated potato starches were similar to its native form, which was expected as B-type pattern; the same trend was observed for modified cassava starch. However the modified starches showed increased crystalline index.     

Physico-chemical properties of potato starches

Starches were isolated and characterised from 10 potato cultivars grown under the same conditions (with a commercial starch for reference). The chemical composition revealed some differences amongst the starches with protein ranging from 0.30% to 0.34%, amylose 25.2% to 29.1% and phosphorus 52.6–66.2 mg 100 g⁻¹. High performance size-exclusion chromatography (HPSEC) fractionation of isoamylase debranched amylopectin showed that the amylopectin molecules were less branched and consisted of more B1, but less A-chains, than cereal starches. Gelatinisation onset (T_o), peak (T_p) and conclusion (T_c) temperatures of the native potato starches ranged from 58.7 to 62.5 °C, 62.5 to 66.1 °C and 68.7 to 72.3 °C, respectively, whilst the gelatinisation enthalpies ranged from 15.1 to 18.4 J g⁻¹. The gelatinisation temperatures of the starches increased in common with the amounts of short and intermediate sized amylopectin chains. The ¹³C magic angle spinning nuclear magnetic resonance (¹³C CP-MAS NMR) and wide angle X-ray diffraction (XRD) data (30.6% ± 0.22% crystallinity on average) showed little variance amongst the samples. Particle sizing results, however, revealed more variance (20.6–30.9 μm mean diameter). Overall, these data reveal the subtleties of cultivar specific variation against a background of constant environmental conditions.     

Pasting properties of hydroxypropylated starches before or after proteinase treatment

To examine the effect of starch protein on hydroxypropylation, corn (normal and waxy) and potato starches were hydroxypropylated with propylene oxide at two levels (8.3 and 12.3% based on dry basis of starch weight) before or after proteinase (thermolysin) treatment, and then pasting properties of the starches were measured. For normal corn starch, protein appeared to be involved in hydroxypropylation, especially at the higher concentration of reagent (12.3%); the starch hydroxypropylated after proteinase treatment (Enz‐HP) showed less reaction efficiency than that only hydroxypropylated (HP) or proteinase treated starch after hydroxypropylation (HP‐Enz). This suggests a possible reaction between some of the reagent and the starch proteins that exist in the channel and surface of the starch granules. However, not much difference was found with the waxy corn starch, as it contains much lower amounts of amylose and protein than normal corn starch. The potato starch, which has no channels, showed complicated protein effects. For potato starch, a different access of the enzyme and chemical reagents to the granule matrix could be possible.     

Gelatinisation properties of native and annealed potato starches

The relationship between the gelatinisation parameters of native and annealed starches extracted from ten different potato varieties grown at the same site at the same time was studied. The objective was to identify how native gelatinisation temperatures and enthalpies impacted on annealed starch gelatinisation parameters. Prior to ANN, the initial onset (T_o), peak (T_p) and conclusion (T_c) gelatinisation temperatures ranged from 58.71 to 62.45, 62.52 to 66.05 and 68.67 to 72.27°C, respectively, which increased to 66.15 to 69.12, 70.22 to 72.30 and 76.21 to 77.44°C, respectively, post ANN. Overall, the greater the initial gelatinisation temperatures the smaller the increment (ΔGT) post ANN. Comparable enthalpy values pre‐ and post‐ANN were 15.13 to 18.37 and 15.76 to 18.37 J/g, respectively. These data indicate that the more ‘perfect’ the crystallites were before ANN the less they could be enhanced by the ANN process and that against a constant background of α‐glucan structure, the pattern (rate) of starch deposition might be the primary differentiator of starch architecture across the varieties.     

Influence of moisture content on the degradation of waxy and normal corn starches acid-treated in methanol

Waxy and normal corn starches with different moisture contents, 5.1-16.9% and 4.8-15.9%, respectively, were prepared and treated in methanol containing 0.36% HCl at 45 °C for 1 h. Recovery of all the treated starches was found to be above 90%. Peak viscosity, gelatinization temperature and enthalpy change of gelatinization of waxy and normal corn starches decreased after treatment and this decrement was found to be more in treated starches having lower initial moisture content. The weight-average degree of polymerization and chain length (CL) of waxy and normal corn starches decreased upon acid-methanol treatment. The decrement ratio of molecular weight of modified starches was found to be negatively correlated with the initial moisture content of the starches. The decrement ratio of normal corn starch was higher than waxy corn starch with similar moisture content of starch. The content and CL of long chain fraction of amylopectin for waxy corn starch slightly decreased after treatment, while no obvious trend was found among starches with different moisture contents. CL of amylose for acid-methanol-treated normal corn starch decreased and this change was found to be higher in starches with lower initial moisture contents. Results demonstrated that the initial moisture content of starch granules strongly influenced the functional properties and degradation of starch treated by acid in methanol.     

Physicochemical properties of starches obtained from Polish potato cultivars

Selected physicochemical, thermal, and rheological properties of starches isolated from new Polish potato varieties were determined. The starches contained 25.7–30.0 g/100 g d.m. of amylose and 59.5–90.2 mg/100 g d.m. of phosphorus. Gelatinization temperatures were 62.6–64.0, 68.9–69.9, and 73.6–77.0°C for T_O, T_P, and T_E, respectively, whilst enthalpy of gelatinization amounted to 11.1–15.3 J/g. The retrogradation degree of starch was from 52.90 to 78.53%. Pasting curves showed significant differences between the starches. Peak viscosity and final viscosity ranges were 2035–4458 and 1931–2985 mPa · s, respectively. Starch pastes exhibited non‐Newtonian, shear thinning, and thixotropic behavior. After cooling they demonstrated diversified viscoelastic properties, however, all of them were classified as weak gels. Significant linear correlations among selected rheological parameters and amylose and phosphorus content were found. Results of principal component analysis demonstrated an ability to differentiate the starches isolated from different potato varieties.     

Glycerol-enhancing heat-moisture treatment of A-type rice and cassava starches and B-type potato and canna starches

Effects of glycerol on the heat-moisture treatment (HMT) of A-type rice and cassava starches and B-type potato and canna starches were investigated. Starch samples were soaked in water or glycerol solution, adjusted to 25% moisture, and then subjected to HMT at 100 °C for 1, 6, and 16 h. Pasting profiles of all four starches plasticised with water clearly showed the B-type potato and canna starches were more susceptible to HMT than the A-type rice and cassava starches. The effect of HMT on the pasting properties of glycerol-plasticised samples was inconclusive; the B-type canna and A-type cassava starches were altered, but not the B-type potato and A-type rice starches, which remained comparable to the water-plasticised samples. Thus, the type of plasticiser as well as the environment surrounding the crystalline region, which is specific to each starch type, also affect the alteration of starch during HMT.     

Amylopectin structure of heat–moisture treated starches

The effects of heat–moisture treatment (HMT; moisture content of 25%, at 100°C for 24 h) on starch chain distribution and unit chain distribution of amylopectin in normal rice, waxy rice, normal corn, waxy corn, normal potato, and waxy potato starches were investigated. After HMT, starch chain distribution (amylose and amylopectin responses) of waxy corn and potato starches were identical to those of untreated starches, whereas the chromatographic response of waxy rice starch showed a slight decrease, but with a slight increase in peak tailing. This result indicated that HMT had no (or very limited) effect on the degradation of amylopectins. Analysis of unit chain distribution of amylopectins revealed that waxy characteristics affected the molecular structure of amylopectin in untreated starches, i.e., the CL of normal‐type starches was greater than that of waxy‐type starches. After HMT, the CL and unit chain distribution of all starches were no different than those of untreated starches. The results implied that changes in the physico‐chemical properties of HMT starches would be due to other phenomena rather than the degradation of amylopectin molecular structure. However, the thermal degradation of amylopectin molecules of waxy starches could occur by HMT at higher treatment temperatures (120 and 140°C).     

有机酸-湿热复合处理土豆抗性淀粉的益生特性

采取有机酸-湿热复合处理制备了土豆抗性淀粉(AH-HMT RS3),重点研究了有机酸种类及浓度、淀粉乳浓度对土豆AH-HMT RS3中慢速消化淀粉(SDS)、抗性淀粉(RS)的形成及其益生作用的影响。结果表明:无酸湿热处理土豆淀粉时,淀粉乳浓度对SDS、RS的形成几乎无影响;与无酸湿热复合处理相比,无论淀粉乳浓度高低,4种有机酸-湿热复合处理所得土豆AH-HMT RS3中RS含量增高了21.89%~45.09%,且高浓度酸比低浓度酸更能促进RS的生成,促进RS水平增高程度从大到小依次为柠檬酸、乙酸、琥珀酸和乳酸。随着土豆AH-HMT RS3中RS含量增加,其对双歧杆菌、乳酸杆菌的增殖作用更大,更能促进短链脂肪酸(SCFAs)特别是丁酸的大量产生。因此,土豆AHHMT RS3具有开发成为新益生素的潜力。     

Correlation between the compositional and pasting properties of various potato starches

Multiple linear regression equations were used to develop the correlation between the compositional and rapid visco-analysis (RVA) pasting properties of various potato starches. The amylose of potato starches had a negative correlation with the peak viscosity (PV) and breakdown (BD) and a positive correlation with the setback viscosity (SV) and peak viscosity temperature (PVT). By contrast, phosphorus had a positive correlation with PV, BD, and SV and a negative correlation with PVT. In addition, the median granule size had a positive correlation with PV and BD. By contrast, a negative correlation of the median granule size was observed with SV and PVT. The correlation coefficients of amylose–phosphorus, amylose–granule size, and phosphorus–granule size interactions indicated that amylose had more influence than had phosphorus or had the median granule size on PV and BD. Furthermore, amylose had a greater influence than had the granule size on SV and PVT. Similarly, amylose had more influence than had phosphorus or had the median granule size on PVT. However, the correlation developed in this study was useful for predicting the influence of a specific component and the compositional interaction on the RVA pasting properties.     

Properties of enzyme modified corn, rice and tapioca starches

Corn, rice and tapioca starches were partially hydrolyzed by treating the starch dispersions with heat stable α-amylase. Dextrose equivalent (DE) of 8–12 was achieved by hydrolyzing the starch samples (10–20% w/v) for 30 min at 90 ± 2 °C. Scanning electron micrographs showed that starch granules had broken down to smaller particles. High performance liquid chromatography with refractive index detection indicated that oligosaccharides with broad molecular weight distributions are present in the reaction products. Hydrolyzed starch dispersions were analyzed for their rheological properties. The storage modulus values (G′) for 20% solid containing slurries were 7373 and 1470 Pa for untreated and enzyme treated samples, respectively, indicating a marked decrease in solid properties due to enzyme action. The complex viscosities (η^*) for native corn starch and hydrolyzed corn starch were 8243 and 1637 Pas, respectively, which indicate that the enzyme treatment decreases the overall resistance of the sample to flow such that the product can spread easily. Further 13C CP/MAS NMR and FTIR studies revealed the loss of ordered structures in the enzyme modified starches. Free flowing fat substitute in the form of fine powder was prepared by spray drying the hydrolyzed starch slurry.     

玉米淀粉和马铃薯淀粉共混糊化及凝胶特性的研究

本文研究了不同比例（100:0、75:25、50:50、25:70及0:100）玉米淀粉和马铃薯淀粉混合物的糊化及凝胶特性。结果表明,玉米淀粉的峰值黏度(3.07 Pa?s)、最终黏度(2.99 Pa?s)、稠度系数（11.31）及流体行为指数（0.39）均显著低于马铃薯淀粉（分别7.04 Pa?s、3.98 Pa?s、33.18和0.62）,而糊化温度（76.18℃）显著高于马铃薯淀粉（71.05 ℃）,混合物的相应值均介于2种纯淀粉之间,但并不呈线性关系,凝胶的破断力和水分子状态等参数也呈类似特征,表明2种淀粉在搅拌下加热糊化时发生了相互作用。静置状态下加热测得的凝胶化焓值呈累加效应。     

Some properties of corn starches II: Physicochemical,gelatinization, retrogradation,pasting and gel textural properties

The physicochemical, thermal, pasting and gel textural properties of corn starches from different corn varieties (African Tall, Ageti, Early Composite, Girja, Navjot, Parbhat, Partap, Pb Sathi and Vijay) were studied. Amylose content and swelling power of corn starches ranged from 16.9% to 21.3% and 13.7 to 20.7 g/g, respectively. The enthalpy of gelatinization (ΔH_gel) and percentage of retrogradation (%R) for various corn starches ranged from 11.2 to 12.7 J/g and 37.6% to 56.5%, respectively. The range for peak viscosity among different varieties was between 804 and 1252 cP. The hardness of starch gels ranged from 21.5 to 32.3 g. African Tall and Early Composite showed higher swelling power, peak, trough, breakdown, final and setback viscosity, and lower ΔH_gel and range of gelatinization. Pearson correlations among various properties of starches were observed. Gelatinization onset temperature (T_o) was negatively correlated to peak-, breakdown-, final- and setback viscosity (r = −0.809, −0.774, −0.721 and −0.686, respectively, p < 0.01) and positively correlated to pasting temperature (r = 0.657, p < 0.01). ΔH_gel was observed to be positively correlated with T_o, peak gelatinization temperature and (T_p) and gelatinization conclusion temperature T_c (r = 0.900, 0.902 and 0.828, respectively, p < 0.01) whereas, it was negatively correlated to peak- and breakdown- (r = −0.743 and −0.733, respectively, p < 0.01), final- and setback viscosity (r = −0.623 and −0.611, respectively, p < 0.05). Amylose was positively correlated to hardness (r = 0.511, p < 0.05) and gumminess (r = 0.792, p < 0.01) of starch gels.     

Studies on noodle quality of potato and rice starches and their blends in relation to their physicochemical, pasting and gel textural properties

The physicochemical, pasting, and gel textural properties of potato and rice starches and their blends were studied in relation to their noodle making performance. Amylose content, swelling power and solubility values of potato starch were significantly (P ≤ 0.05) higher than for rice starch. Pasting properties showed higher peak, final and setback viscosity for potato starch as compared to rice starch. Texture profile analysis revealed that potato starch gel had higher hardness, cohesiveness and chewiness as compared to rice starch gel. Potato starch noodles showed higher cooked weight and cooking loss and were scored higher by sensory panellists especially with respect to transparency and slipperiness. On the other hand, rice starch noodles were more firm with lower cooking loss. Addition of potato starch to rice starch significantly (P ≤ 0.05) affected the noodle characteristics. Among the starch blends studied, blending of potato and rice starch in the ratio of 1:1 resulted in good quality noodles in terms of their lower cooking time, higher cooked weight, transparency and slipperiness. The results revealed the possibility of blending of potato starch with rice starch in equal proportions to produce noodles of acceptable quality.     

Fine structure of amylopectin and relation with physicochemical properties of three coloured potato starches

In this study, yellow, red and purple potato starches were selected as the research objects to analyse the fine structure and the relation to the physicochemical properties. Enzymatic hydrolysis and high-performance anion-exchange chromatograph were employed to characterise the structure of clusters and φ, β-limit dextrins. The average degree of polymerisation of clusters from the yellow potato starch was larger (188.57) than in red (91.31) and purple (107.32) potato starch. The molar percentage of fingerprint B chains in yellow, red and purple potato amylopectin were 58.01%, 63.60% and 60.78%, respectively, while major part of short B chains were 15.92%, 17.16% and 16.49%, respectively. The yellow potato amylopectin showed the highest density of branches values indicated that it was more tightly branched. The Pearson correlation coefficients results indicated that the fine structure of amylopectin had significant effects on the physicochemical properties of potato starches, and we can better understanding the differences of the properties among the three potato starches by studying the amylopectin fine structure.     

Synthesis and characterization of highly acetylated sago starch

This study was carried out to understand and establish the changes in physicochemical parameters of sago starch after acetylation. Highly substituted starch acetate was prepared by reaction with native sago starch and acetic anhydride in organic solvent. Their formation was confirmed by the titrimetric analysis and FT‐IR. The presence of absorption band in FT‐IR at 1748 cm⁻¹ confirmed the carbonyl group attachment. The thermal behavior of native and acetyl substituted sago starch was investigated using thermo gravimetric analysis (TGA) and DSC. The results reveal that highly substituted starch acetate was more thermally stable as compared to native form. The XRD patterns showed loss of crystalline nature and its transformation into amorphous form. The SEM study suggested that the smooth surfaces of starch granules were changed into fibrous form after acetylation.     

Experimental design to optimization of beta cyclodextrin production from ungelatinized sago starch

The aim of this study is to produce beta cyclodextrin (β-CD) from ungelatinized, but annealed (65 °C) sago starch using cyclodextrin glucosyltransferase (CGTase). The optimization processes were conducted at three stages using Response Surface Methodology. Preliminary data have shown that the three (3) highest points for each of the studied parameters were pH, concentration of sago starch and enzyme, and also agitation. In the second stage, two level full factorial design (2ⁿ FFD) was applied to determine the significant parameters affecting the production of β-cyclodextrin. Statistical analyses showed that pH, enzyme and sago starch concentration were the significant parameters. The final stage of optimization involved the use of Central Composite Design to determine and predict the optimum yield of β-cyclodextrin. The optimum condition for production cyclodextrin was at pH 8.62 (Glycine–NaOH buffer 0.05 M), 0.65% v/v sago starch and 15% w/v enzyme concentration, where 8.43 g β-cyclodextrin/L was produced after 4 h of reaction.     

A comparison of native and oxidized normal and waxy corn starches: Physicochemical, thermal, morphological and pasting properties

The effect of sodium hypochlorite on the physicochemical and functional properties of normal and waxy corn starches was investigated in this study. It was found that both carboxyl and carbonyl contents of oxidized starches from normal corn were higher than those of waxy corn. The introduction of carboxyl and carbonyl groups resulted in lower amylose content and swelling power. Both amylose and amylopectin were oxidized and degraded during oxidation but amylose was more susceptible to oxidation. Studies conducted on paste clarity revealed that the percentage transmittance increased after oxidation. The morphology of the starches was not altered after oxidation. Thermal properties measured by differential scanning calorimeter, showed that oxidation reduced transition temperatures (onset temperature, T_o; peak temperature, T_p; and conclusion temperature, T_c), gelatinization and retrogradation enthalpies of both normal and waxy corn starches. The retrogradation tendency was reduced after oxidation both in normal and waxy corn starches. Oxidation produced waxy starch with significantly higher peak (P_V), trough (T_V), breakdown (B_V), final (F_V), and setback viscosity (S_V) as demonstrated by using a rapid visco analyzer. Oxidation reduced the pasting temperature of both normal and waxy corn starches. Also, the principal component analysis (PCA) study was conducted to find the overall variations among the oxidized starches studied. Together, the first two components represent 88.7 g/100 g of the total variability.