Characterisation of 2-octen-1-ylsuccinylated waxy rice amylodextrins prepared by dry-heating

Waxy rice amylodextrins substituted with 2-octen-1-ylsuccinic acid (OSA) were prepared by heating a dried mixture of waxy rice starch and OSA (3% OSA based on starch solids) at 130–150 °C and pH 3–5 for 1–3 h. The effects of the heating conditions, such as pH, temperature and heating time on the degrees of substitution (DS) and dextrinisation, and the physical properties of the dextrins were evaluated. Substitution and dextrinisation were more affected by the reaction pH than by the physical conditions (temperature and time). Heating under a more acidic condition resulted in a higher DS and a lower molecular weight (M_w). Pasting viscosity profiles showed reduced pasting temperatures but increased peak viscosities, due to the presence of OSA, compared to unsubstituted dextrin counterparts. The X-ray diffraction patterns of the OSA dextrins were similar to that of the native starch, indicating that the dextrinisation occurred mainly in the amorphous regions of the starch granules. Fat-free whipped creams were prepared with the OSA dextrins and skim milk powder to examine the fat-replacing effects of the dextrins. The OSA dextrins effectively substituted the fat in dairy cream, providing good foaming ability and storage stability.     

Changes of Carbohydrates and Molecular Structure of Dextrins During Enzymatic Liquefaction of Starch

Investigations of potato starch hydrolysis during bacterial α-amylase “Amylogal CS” liquefaction to a different dextrose equivalent were carried out at 85deg;C and pH 6,5. DE-values, carbohydrate compositions and molecular structure of dextrins were investigated in starch hydrolyzate samples taken at DE-values from 3.4 to 20.6. In the progress of liquefaction, that is at increasing DE-values, changes in carbohydrate compositions, and there the decrease only of maltoheptaose and dextrins content in hydrolyzate were observed. Simultaneously, it was found that molecular weight and number of dextrin branchings decreased particularly rapidly to a significant degree of nearly 3.4 DE. At further increase of DE-value during starch liquefaction the decrease of dextrins molecular weight and the number of branchings was lower and not that significant.     

New starch preparations resistant to enzymatic digestion

BACKGROUND: New starch preparations were produced by thermolysis of potato starch in the presence of inorganic (hydrochloric) and organic (citric and tartaric) acids under controlled conditions. The starch preparations were physicochemically and structurally characterised and analysed for their resistance to enzymatic digestion in vitro. RESULTS: The content of resistant fraction in dextrin D1, obtained by heating starch acidified with hydrochloric and citric acids, determined by the AOAC 2001.03 and pancreatin‐gravimetric methods was similar (～200 g kg^?1). In the case of dextrin D3, obtained by heating starch acidified with hydrochloric and tartaric acids, the result of determination by the pancreatin‐gravimetric method was almost four times higher than that obtained with the AOAC 2001.03 method. The enzymatic tests revealed that dextrin D3 obtained with excess tartaric acid can be classified as RS4, which can only be partially determined by enzymatic‐gravimetric methods. Tartaric acid at high concentration had a significantly stronger influence on starch hydrolysis than citric acid. This was confirmed by chromatographic analysis of dextrins and chemical investigation of the reducing power. CONCLUSION: The results confirmed the possibility of applying dextrins, prepared under specific conditions, as soluble dietary fibre. Copyright © 2011 Society of Chemical Industry     

Melting Properties and Lintnerisation of Potato Starch with Different Degrees of Phosphorylation

Lintner dextrins were prepared from size fractionated potato starch granules from two potato varieties (90BKG22 and Lady Rosetta) that contain high or low natural content of esterified phosphate, respectively. The time course of hydrolysis showed the typical two‐phase kinetics, with a maximal degree of hydrolysis of between 74% and 81% after 30 days of hydrolysis, except for the fraction of smallest granules of the low phosphorylated variety (low P), which was hydrolysed to 98%. The relative amount of retained glucose‐6‐P in the Lintner dextrins was 18.6% for the low P variety and 46.6% for the high P variety. However, when calculating the relative distribution of phosphate in the granules, it was shown that approximately 80% (low P) and 35.5% (high P) was located in the amorphous region. Melting characteristics were followed by differential scanning calorimetry (DSC). The DSC endothermic peak became low and broad during the time course of hydrolysis, with rise in enthalpy change, indicating a strong dependency on the amorphous region of the granules. After annealing the same fractions showed the typical raise in gelatinisation temperature and narrowing of gelatinisation peak. The values of the melting temperatures (T_o, T_m and T_c) are positively correlated to the degree of phosphorylation of the starch dextrin fractions both before and after annealing.     

Studies on the Structure of Pea Starches Part 4: Intermediate Material of Wrinkled Pea Starch

β-Limit dextrins were isolated from wrinkled pea starch, fractionated into different sizes, and their molecular weight distribution analysed by gel chromatography. A minor part of the dextrins had high molecular weight and long chains typical for amylose. The major part of the dextrins had low molecular weight and possessed unit chains of the same types as was found in the amylopectin of smooth pea starch. However, the proportion of long chains was significantly higher. The hydrolysis of wrinkled pea starch with α-amylase was fast and reflected the large content of amylose, whereas the hydrolysis of the β-limit dextrin was slow. The intermediate dextrin products obtained from the latter had similar molecular weights as those produced from other amylopectins, which indicated that it was build up of clusters of branchings. Structure models that show the mode of interconnection of the clusters in the intermediate material are suggested.     

Changes of Carbohydrate Compositions During Enzymatic Hydrolysis of Starches of Various Origin

Hydrolysis of starch of various origin, liquefied with bacterial α-amylase to DE 13.5 and then saccharified only with glucoamylase and simultaneously with pullulanase to DE 97–98, was investigated. It was found that the hydrolysis of wheat starch was delayed in relation to the hydrolysis of potato and maize starch, particularly in the first period of saccharification. The delay decreased with time but at the end of the saccharification it was still 24 h. The carbohydrate composition of wheat starch hydrolyzates differed from the hydrolyzates of potato- and maize starch in a smaller content of glucose and lower oligosaccharides (G₁-G₄) and a greater content of higher oligosaccharides and dextrins (G₅-G_n). This, among other things, could have an influence on higher viscosity of solutions of wheat starch hydrolyzates in relation to respective hydrolyzates of potato and maize starch.     

Firming of starch gels and amylopectin retrogradation as related to dextrin production by α-amylase

 The effect of dextrins produced by α-amylase on the firming and amylopectin retrogradation of wheat starch gels was studied. Different gel samples were prepared and included several ingredients, for example, α-amylase, vital gluten and glucoamylase. Amylopectin retrogradation, gel firming and the dextrin profile were analysed throughout a 5-day storage period. Both processes, i.e. firming and starch retrogradation, increased with time, and were not affected by the incorporation of gluten into the mixture. The well-known effect of α-amylase to retard bread crumb firming was also found to be relevant to starch gels. From the results obtained in this work, it seems that this anti-firming effect is not due to modifications of the starch but to dextrins produced by starch hydrolysis, since the effect did not occur when dextrins were removed by glucoamylase. Received: 30 December 1996     

Durchstrahlungselektronenmikroskopische Untersuchung des Lösungszustandes technischer Dextrine nach Gefrierätzung

Transmission Electron Microscopic Studies on the Solubilization State of Industrial Dextrins after Freeze-Etching . The solubilization state of dextrins is discernible after freeze-etching as a preparation method for transmission electron microscopic investigations. A just disintegrated dextrin on the basis of potato starch is composed of obviously native granula with diameters from 100 to 200 nm. After uncomplete disintegration these granula keep unchanged despite of a ripening process of several months. Only a higher grade of agglomeration of the granula can be observed. However, the granula of a completely disintegrated dextrin subject to a swelling and solvatation process during which the phase boundary between the granula and the water as solvent is disappearing more and more.     

Carbohydrate Compositions and Molecular Structure of Dextrins in Enzymatic High Conversion Starch Syrups

35% DS potato starch slurry liquefied with bacterial α-amylase to 13,6 DE was saccharified with a combination of fungal α-amylase and glucoamylase at different enzyme dosages ratios. Saccharification was carried out 44 h at 55°C and pH 5.0. DE-value, carbohydrate compositions, molecular structure of dextrins and viscosity at 35°C were investigated in starch hydrolyzate samples taken after 4, 8, 20, 32 and 44 h. In dependence on the ratio of enzyme dosages of fungal α-amylase to glucoamylase and on hydrolysis (DE) progress, changes in carbohydrate composition, decrease of molecular weight and number of dextrin branchings were observed and in dependence on them viscosity of hydrolyzate solutions decreased.     

The tartaric acid-modified enzyme-resistant dextrin from potato starch as potential prebiotic

Enzyme-resistant dextrin, obtained as a result of heating potato starch with tartaric acid, was tested as the carbon source for selected strains of probiotic bacteria and also bacteria isolated from feces of healthy 30-year old men volunteers. The dynamics of growth of bacterial monocultures in broth containing tartaric acid (TA)-modified dextrin was estimated. It was also investigated whether probiotic lactobacilli and bifidobacteria cultured with intestinal bacteria in the presence of resistant dextrin would be able to dominate the intestinal isolates. Prebiotic fermentation of resistant dextrin was analyzed using prebiotic index (PI). Fermentation products were determined by HPLC. It was shown that all of the tested bacteria were able to grow and utilize TA-modified dextrin as a source of carbon, albeit to varying degrees. In co-cultures of intestinal and probiotic bacteria, the environment was found to be dominated by the probiotic strains of Bifidobacterium and Lactobacillus, which is a beneficial effect.     

Structural and rheological properties of potato starch affected by degree of substitution by octenyl succinic anhydride

The objective of the present study was to investigate the structural and rheological properties of octenyl succinic anhydrate (OSA) modified potato starch. Potato starch was modified with different concentrations of OSA (0, 1, 3, and 5%, v/v). X-ray results suggested that OSA modification did not disrupt the crystallinity of the native starch, and esterification occurs primarily in the amorphous regions. The use of ¹H-NMR spectra confirmed the presence of methyl protons in substituted OSA groups, which interacted with the starch molecules. In steady shear rheological analysis, OSA modified starch pastes showed a pronounced shear thinning behavior (n = 0.47–0.54). The consistency index (K) and yield stress (σ_oc) values of OSA modified starch pastes were significantly lower than those of the native starch. Dynamic shear rheological tests indicated that OSA modified starch pastes had weak gel-like behavior with storage moduli (G’) higher than loss moduli (G’’). OSA potato starch pastes were more viscous as compared to the native potato starch paste, as evidenced by their higher tan δ values.     

Mathematical approach for two component modeling of salep–starch mixtures using central composite rotatable design: Part I. Physicochemical and steady shear properties

A 2-factor-5-level central composite rotatable design (CCRD) of response surface methodology (RSM) was used to model linear, interaction and quadratic effects of some processing variables (salep and each starch type, the composition variables) on the response variables; physicochemical characteristics (pH, brix and turbidity) and steady shear rheological properties (apparent viscosity η, consistency coefficient K, shear stress σ and flow-behavior index n) of salep–starch mixtures (SSM); namely, salep–corn starch mixture (SCSM), salep–wheat starch mixture (SWSM) and salep–potato starch mixture (SPSM). The linear, interaction and quadratic effects of the processing variables were also modeled to develop predictive models for the tested properties to optimize the effect of these variables (salep and each starch type) using ridge analysis involved with RSM. It was concluded that salep and all starch types increased the apparent viscosity (η), shear stress (σ) and consistency coefficient (K) values; decreased the flow-behavior index (n) values of SSM samples. Salep was observed to vastly increase the viscosity of mixture samples when mixed with corn, wheat or potato starches. However, potato starch exhibited very different performance as compared to the other starches in terms of the physicochemical and steady shear rheological properties. The ridge analysis used to optimize these effects revealed that maximum η (0.84, 0.46 and 1.38 Pa s), and K (16.64, 6.48 and 28.86 Pa sⁿ) values for the SCSM, SWSM and SPSM samples, respectively would occur at salep = 0.54% and starch = 2.83% w/w.     

Mechanical and Structural Properties of Expanded Extrudates Produced from Blends of Native Starches and Natural Fibers of Henequen and Coconut

The aim of this research was to evaluate the effects of barrel temperature (130‐180ºC), feed moisture (14.6‐24.5%) and fiber content (0.0‐15.0%) on the physicochemical and structural properties of starch‐derived loose‐fill packaging materials (LFPM). Two blends were analyzed: one of corn starch and henequen fiber (Agave americana) (CS‐HF), and the other of potato starch and coconut fiber (PS‐CF). An experimental laboratory extruder with a 2.9 mm internal diameter die‐nozzle was used, and a hybrid central composite design was employed to study the LFPM, and the influence of some extrusion variables on mechanical properties, i.e. tensile strength (ϵ),stress (σ), flexion modulus (E_f), and structural properties; expansion index (EI), water absorption capacity (WAC), crystallinity by X‐ray diffraction, viscosity profiles and scanning electronic microscopy (SEM). In both extruded blends feed moisture was the most significant variable, increasing the values of EI and ϵ, and decreasing the values of σ and E_f when the feed moisture was decreased. The blend of PS‐CF had the highest values of EI, ϵ, σ and E_f,, and is the more appropriate for the preparation of LFPM. X‐ray diffraction analysis of the LFPM samples suggested the formation of almost completely amorphous structures, similar to those of commercial LFPM prepared from polystyrene. This research indicated that blends from natural sources like corn starch with henequen, and potato starch with coconut fibers have the potential to be used in the preparation of LFPM with similar characteristics to commercial LFPM, with the additional advantage of being biodegradable.     

Studies on the morphological,thermal and rheological properties of starch separated from some Indian potato cultivars

The starches separated from five different Indian potato cultivars (Kufri Chandermukhi, Kufri Badshah, Kufri Jyoti, Kufri Sindhuri and S1) were investigated for morphological, thermal, rheological, turbidity and water-binding properties. The starch separated from all the five potato cultivars had a granule size ranging between 15–20 μm and 20–45 μm. The shape of starch granules varied from oval to irregular or cuboidal. Starch isolated from cv. Kufri Badshah had largest irregular or cubiodal granules while starch from cv. Kufri Chandermukhi had small and oval granules. The transition temperatures and enthalpy of gelatinization (ΔH_gel) were determined using differential scanning calorimetry (DSC). The enthalpy of retrogradation (ΔH_ret) of gelatinized starch was also determined after 14 days of storage at 4°C using DSC. Kufri Chandermukhi starch showed the lowest ΔH_gel and ΔH_ret while Kufri Badshah starch showed the highest values. ΔH_gel and ΔH_ret values of 12.55 J/g and 6.42J/g, respectively, for Kufri Chandermukhi starch against 13.85 J/g and 8.61 J/g, respectively, for Kufri Bhadshah starch were observed. Rheological properties of starches from different potato cultivars, measured using the Dynamic Rheometer during heating and cooling, also differed significantly. The starch from cv. Kufri Badshah showed the highest peak G′ and G″ and lowest tan δ. The starches having higher peak G′(G′ at gelatinization temperature) showed higher breakdown in G′ and vice versa. The turbidity of gelatinized aqueous starch suspensions from all potato cultivars increased with increase in storage period. Starches with low water binding capacity had higher G′ and G″ and lower tan δ values.     

STRUCTURAL ANALYSIS ON THE AMYLOPECTIN OF WAXY-BARLEY LARGE STARCH GRANULES

The hydrolysis of waxy-barley starch by the α-amylase of B. subtilis was followed by gel chromatography on Sepharose CL 6B. A range of intermediate dextrins were initially produced, and at later stages dextrins with a degree of polymerization in the range 100–200 accumulated. Maltohexaose was produced simultaneously from the external chains. The hydrolysis of the amylopectin β-limit dextrin followed a similar pattern, though smaller amounts of the low-molecular weight material were formed. The sizes of the more resistant products in the hydrolysis mixtures suggested that the amylopectin contained two types of unit clusters with d.p. for the β-limit dextrins of 65 and 85. A regular model for the structure of the amylopectin that shows the possible mode of interconnection of the unit clusters is presented .     

Laminar flow cleaning of gelatinised,partially hydrolysed starch

The cleanability of food contact materials is, among others, determined by the physico-chemical properties of the soiling material. In the current study, starch of different origin was gelatinised and partially hydrolysed with diastase. The degree of hydrolysis was determined as the reducing capacity in terms of dextrose equivalents, and by the changes in apparent viscosity and surface tension. After spreading the starch paste on electropolished stainless steel coupons and subsequent drying, the removal was studied with a laboratory flow cell. These cleaning tests revealed a higher cleaning effectivity for smaller dextrins, which can be attributed to corresponding changes in solubility. Furthermore, the addition of commercially available diastase to demineralised water increased the cleaning effectivity of starch and dextrin soils at 25 °C. The results indicate that smaller starch breakdown products require reduced energy for removal so that cleaning processes can be adequately adjusted.     

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 (ΔH) 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.     

Time Domain Nuclear Magnetic Resonance (TD-NMR) to evaluate the effect of potato cell membrane electroporation

Time Domain-Nuclear Magnetic Resonance (TD-NMR) was used here for the first time to analyze potato specimens cut from tubers before and after electroporation. The proton transverse relaxation time, T₂, was used to identify the modifications that occur at the cell level involving water molecules mobility in potato tubers after the electroporation treatment. Since electroporation modifies the tissue conductivity, the samples were also analyzed in terms of conductivity, water content, and microscopic morphology of the tissue. Comparison analyses were performed on dried potato (zero water content) and water-potato starch mixtures with different water contents. All the data confirm that the effect of the electroporation process can be identified with a variation of the position of the peaks in T₂ distribution, associated to sub-cellular modifications.     

Structural properties and gelatinisation characteristics of potato and cassava starches and mutants thereof

The molecular size of amylopectin (AP) and amylose (AM), AP chain length distribution, crystallinity and granular structure (morphology and granule size distribution) of five wild type potato starches (wtps), five AM free potato starches (amfps), four high-AM potato starches (haps), one wild type cassava starch (wtcs) and one AM free cassava starch (amfcs) were investigated and related to their gelatinisation characteristics. Starches with higher levels of short chains [degree of polymerisation (DP) 6–9 and DP 10–14)] had lower gelatinisation onset (T_o), peak (T_p) and conclusion (T_c) temperatures, whereas higher contents of longer chains (DP 18–25 and DP 25–80) led to higher gelatinisation temperatures. Gelatinisation enthalpies (ΔH) increased with degree of crystallinity. The granules of wtps were larger than those of amfps and haps, respectively. No differences in morphology were observed between wtps and amfps granules, but the haps granules had more irregular surfaces and showed multi-lobed granules.     

Effects of enzymically modified amylopectin on the rheological properties of amylose-amylopectin mixed gels

Branched α-dextrins with different molecular weights were prepared from waxy maize. A series of β-limit dextrins was prepared from α-dextrins and native amylopectin. The fine structure of the dextrin samples was investigated by debranching, and was found to be similar to the unit chain distribution of native amylopectin. The absolute molecular weights of α- and β-limit dextrins and commercial potato amy lose were determined by gel-permeation chromatography (GPC) and with a dual light-scattering detector. Solubilized potato amy lose and α- and β-limit dextrins were mixed at different ratios to give a total concentration of 8%. Dynamic viscoelastic measurements showed that gel formation of amylose was highly dependent both on the ratio of amylose to α-dextrin and on the molecular weight of α-dextrin. α-Dextrin caused an increase of storage modulus, G, when the amylose: α-dextrin ratio was low and the molecular weight of α-dextrin was high. The high-molecular-weight α-dextrin influenced amylose gelation in the same way as native waxy maize starch, but the medium- and low-molecular-weight α-dextrins weakened the gel formation, especially at a ratio of 25:75 (amylose: α-dextrin). When low-molecular-weight β-limit dextrins were mixed with amylose, the resulting gels were more rigid than those in which amylose was mixed with corresponding α-dextrins. When high-molecular-weight β-limit dextrins were mixed with amylose, the resulting gels were weaker.