Corn Starch-Xanthan Gum Interaction and Its Effect on the Stability During Storage of Frozen Gelatinized Suspension

The knowledge of starch pastes behavior during frozen storage becomes necessary to understand more complex systems (e.g. sauces, dressings and desserts) The effect of sub-zero storage on the quality attributes of corn starch pastes (10% w/w) with and without xanthan gum (0.3% w/w) was analyzed. Pastes were frozen at different rates (0.3 to 270cm/h) and stored at −5, −10 and −20°C. Exudate production (syneresis) and rheological behavior were studied by means of capillary suction and rotational viscometry respectively. Ice recrystallization was analyzed by indirect microscopic observations using isothermal freeze fixation and amylopectin retrogradation by differential scanning calorimetry (DSC). Samples stored at −5°C (glass transition temperature) or higher temperatures were under the rubbery state evidenced by starch recrystallization. This state favored molecular mobility leading to deteriorative changes (like spongy structure formation related to amylose retrogradation). At lower storage temperatures (−10 and −20°C) under the glassy state, starch retrogradation was not detected and deteriorative changes can be related to ice recrystallization. The addition of xanthan gum minimized amylose retrogradation, syneresis and rheological changes, however, its presence did not prevent ice recrystallization nor amylopectin retrogradation.     

Retrogradation of Potato Starch as Studied by Fourier Transform Infrared Spectroscopy

Retrogradation kinetics for a potato starch-water system (10% w/w gel) was monitored by Fourier Transform Infrared spectroscopy and compared with waxy maize starch. The spectra showed the C-C and C-O stretching region (1300-800 cm⁻¹) to be sensitive to the retrogradation process. A multi-stage process was observed during the retrogradation of potato starch and characterized as the formation of short- and long-range order. The first stage was characterized as the formation of helices and the fast formation of crystalline amylose regions. The second stage was described as the induction time for amylopectin helix aggregation. Stage three was described as the helix-helix aggregation and the crystallization of amylopectin. The overall-first order calculated rate constant of potato starch was (9.6±1.4) 10⁻ 3h⁻¹. The calculated rate constant were in agreement with the known difference in retrogradation kinetics of waxy maize and potato starch. The effects were explained by the differences in retrogradation rate of amylopectin and amylose. Potato starch consists of amylose as well as amylopectin. Whereas amylose crystallization occurs within a few hours, amylopectin crystallization is slow and takes a few weeks.     

Effects of temperature on the physicochemical properties of starches extracted from microtubers grown from different potato cultivars

Twelve potato cultivars were grown as microtubers in constant environment chambers at two temperatures in total darkness for 28 days. For starch extracted from microtubers grown at 12 or 22 °C, the amylose content ranged from 25.0 to 29.0% (average 27.3 ± 1.4%) or 29.5 to 32.7% (average 30.9 ± 1.4%), the amylose/amylopectin ratio from 1:2.5 to 1:3.0 (average 1:2.7) or 1:2.1 to 1:2.4 (average 1:2.2) and the phosphorus content from 0.41 to 0.93 g kg⁻¹ (average 0.72 g kg⁻¹) or 0.38 to 1.67 g kg⁻¹ (average 0.97 g kg⁻¹) respectively. Two major fractions (F1 and F2) were obtained for isoamylase‐debranched starch (amylopectin), with the chain length (CL) averaging 56 ± 3 or 55 ± 1 for F1 and 20 ± 1 or 21 ± 1 for F2 from 12 or 22 °C growth temperature respectively. Peak gelatinisation temperature (T_p) and enthalpy (ΔH) were influenced strongly by growth temperature, with T_p ranging from 60.8 to 64.5 °C (average 62.1 ± 1.0 °C) or 66.9 to 69.6 °C (average 68.2 ± 0.9 °C) and ΔH from 13.3 to 16.9 J g⁻¹ (average 14.8 ± 1.0 J g⁻¹) or 11.3 to 19.5 J g⁻¹ (average 16.3 ± 2.4 J g⁻¹) from 12 or 22 °C growth temperature respectively. The collective data generated at 12 °C were generally more comparable to data published elsewhere (but discussed in the text) for the same potato cultivars grown in field plots (Perthshire). However, there were cultivar specific responses to field or constant environment chambers which make direct comparisons between starches produced from the two systems subject to some variation. Copyright © 2004 Society of Chemical Industry     

Effects of oligosaccharides on phase transition temperatures and rheological characteristics of waxy rice starch dispersion

BACKGROUND: The creation of starch‐based foods incorporated with functional ingredients such as probiotics is of great current interest in the food industry. This study aimed to investigate the effects of prebiotic oligosaccharides on the phase transition temperatures and rheological characteristics of waxy rice starch dispersions. Four oligosaccharides were applied to the rice starch dispersions: chitooligosaccharides, fructooligosaccharides, isomaltooligosaccharides and xylooligosaccharides. RESULTS: The addition of 125 g kg^?1 oligosaccharides elevated the onset and peak temperatures for gelatinisation of 200–400 g kg^?1 waxy rice starch dispersions. The temperature of the storage modulus (G′) for gelatinisation increased markedly on adding fructooligosaccharides to 200–300 g kg^?1 waxy rice starch. For gelatinisation of 300 g kg^?1 rice starch dispersion the effectiveness of the oligosaccharides in changing the above parameters was as follows: chitooligosaccharides > fructooligosaccharides > isomaltooligosaccharides > xylooligosaccharides. Moreover, their effectiveness was dependent on the amylose content, as illustrated by comparing waxy and non‐waxy rice starches (amylose contents 9–256 g kg^?1). Importantly, the logarithmic G′₉₅ change was linearly and negatively correlated with amylose content. CONCLUSION: The results suggest that oligosaccharide‐containing rice starch dispersions may potentially be used for the formulation of oligosaccharide‐containing starchy functional foods owing to the rheological changes of these starch dispersions. Copyright © 2011 Society of Chemical Industry     

Functional properties and retrogradation behaviour of native and chemically modified starch of mucuna bean (Mucuna pruriens)

Mucuna bean (Mucuna pruriens) starch was isolated and subjected to chemical modification by oxidation and acetylation. The proximate analysis of the non‐starch components of the native starch on a dry weight basis was 92 g kg^?1 moisture, 5 g kg^?1 ash, 2 g kg^?1 fat, 7 g kg^?1 crude fibre and 19 g kg^?1 protein. Chemical modification reduced the values for all the non‐starch components except the moisture level. For all the samples, swelling power and solubility increased as the temperature increased in the range 50–90 °C. The swelling power of mucuna native starch (MNS) and mucuna acetylated starch (MAS) increased with increasing acidity and alkalinity, while that of mucuna oxidised starch (MOS) only increased with increasing pH in the acidic range. The maximal solubility of all the starches was observed at pH 12. All the starch samples absorbed more oil than water. The lowest gelation concentration followed the trend MAS < MNS < MOS. Chemical modification reduced the gelatinisation temperature (Tp), while peak viscosity (Pv), hot paste viscosity (Hv) and cold paste viscosity (Cv) decreased after oxidation but increased following acetylation. The setback tendency of the native starch was reduced significantly after chemical modification. However, the breakdown value of MNS, 65 BU (Brabender units), was lower than that of MOS (78 BU) but higher than that of MAS (40 BU). Differential scanning calorimetry studies of gelatinisation and retrogradation revealed that chemical modification reduced the onset temperature (T_o), peak temperature (T_p) and conclusion temperature (T_c). Oxidation and acetylation reduced the gelatinisation and retrogradation enthalpies of the native starch. The enthalpy of retrogradation of the starches increased as the length of storage increased. Copyright © 2003 Society of Chemical Industry     

Substitution of wheat starch with non-wheat starches and cross-linked waxy barley starch affects sensory properties and staling of Arabic bread

Substitution of starch from barley, corn, oat, potato, rice or sorghum for prime wheat starch in the formulation of Arabic bread resulted in breads with significantly (P < 0.05) different textural attributes from regular wheat bread except for barley starch. Substitution of waxy barley starch (957 g kg⁻¹ amylopectin) for wheat starch (279 g kg⁻¹ amylopectin) resulted in bread that was not significantly different from regular wheat bread when assessed in the fresh state. However, upon aging, the waxy barley starch-containing bread staled at a significantly (P < 0.05) faster rate than regular wheat bread. Breads made with waxy barley starch cross-linked with 50, 200 or 500 ppm phosphorus oxychloride showed higher enthalpy of melting (ΔH) upon aging and staled faster than the bread formulated with waxy barley starch. These findings suggest that amylopectin retrogradation is one of the determinants of Arabic bread staling and that cross-linking promotes recrystallisation of amylopectin, possibly by keeping the polymer chains in close proximity. The rate of staling in breads formulated with cross-linked waxy barley starch decreased with increasing levels of cross-linking, possibly owing to restrictions in the degree of starch swelling. © 1999 Society of Chemical Industry     

Characterisation of starches separated from sorghum cultivars grown in India

Starches from 15 Indian sorghum cultivars were separated and evaluated for physicochemical, morphological, thermal, retrogradation, pasting and textural properties. The morphological characterisation revealed the presence of irregular-polyhedral as well as spherical shaped granules. A wide variation in amylose content ranging from 11.2% to 28.5% was observed. Thermal, retrogradation, pasting and textural characteristics also showed significant differences amongst all the starch cultivars. Principal component analysis was carried out to extract five principal components that could explain 75% of the total variance. The first two principal components PC1 (T_o, T_p, T_c and ΔH_gel) and PC2 (amylose content, range of gelatinisation, PHI and pasting and textural properties) could explain a cumulative variance of 44%, indicating the importance of amylose, thermal and textural properties on the sorghum starch functionality.     

Development and Testing of Methods to Screen Chickpea Flour for Starch Characteristics

Rapid screening methodology has been developed for assessing the chemical composition and the gelatinisation and pasting properties of starch using flour from chickpea seeds. The methodology allows samples to be assessed using a minimal amount of sample and for starch information to be interpreted in the presence of other components present in the flour. The starch content of the flour and the amylose content of the starch was determined by modifying existing kit-based methods (Megazyme International Ltd). Using the Differential Scanning Calorimeter (DSC), starch gelatinisation characteristics can be assessed based on temperature of gelatinisation (T_p), specific heat capacity (Cp^sp ) and half width of transition (½ΔT). Pasting properties could be assessed using the Rapid Visco Analyser (RVA), based on the determination of onset temperature for the RVA profile (T \displaystyle _o^{RVA} ), T_p − T \displaystyle _o^{RVA} and final viscosity (FV) values. The developed methodology was tested using a range of chickpea samples. No significant variation was found between the samples for starch content or for the proportion of amylose/amylopectin in the various starches. Significant variation was found in the starch properties of two of the samples, while the variation between the remaining samples was very small.     

Effect of cross‐linking on some properties of potato (Solanum tuberosum L.) starches

Starches separated from different potato cultivars were modified using two different cross‐linking agents: epichlorohydrin (EPI) and phosphoryl chloride (POCl₃) at different concentrations (1.0 and 2.0 g kg^?1 POCl₃; 2.5, 5.0 and 10 g kg^?1 EPI). Differential scanning calorimetry, rheological and retrogradation measurements were performed to characterise the influence of cross‐linking on the properties of potato starches. Cross‐linking considerably reduced swelling power, solubility, water‐binding capacity and paste clarity. The decrease became greater as the reagent concentration increased. The starches treated with 1.0 g kg^?1 POCl₃ exhibited exceptionally higher swelling power than their counterpart native starches. Neither cross‐linking agent caused any change in morphology of the starch granules. Studies on the phase transitions associated with the gelatinisation showed significantly higher values for the onset temperature (T_o), peak temperature (T_p), conclusion temperature (T_c) and enthalpy of gelatinisation (ΔH_gel) for the cross‐linked starches than the native starches. Starches treated with both the reagents showed lower peak storage modulus (G′) and loss modulus (G″) than their native counterparts. The tendency of the starch pastes towards retrogradation increased considerably with increases in storage duration. However, the starches treated with 1 g kg^?1 POCl₃ exhibited much lower syneresis than the other cross‐linked starches. Copyright © 2006 Society of Chemical Industry     

Physicochemical and structural characteristics of starches from Chinese hull‐less barley cultivars

Fourteen hull‐less barley cultivars, collected from four major cultivated areas in China, were employed to investigate the structural and physicochemical properties of their starches in this study. Relatively wide variations in physicochemical properties of the starches were observed. Amylose content ranged from 23.1% to 30.0%, swelling power and water solubility index ranged from 12.8 to 19.9 g g^?1 and 12.7% to 23.7% respectively. Peak viscosity was from 170 to 346 Rapid Visco Unit (RVU), peak temperature (T_p) of starch gelatinisation was from 55.6 to 61.8 °C and enthalpy of starch retrogradation ranged from 0.3 to 3.1 J g^?1. Weight‐based chain‐length proportions of fa, fb₁, fb₂ and fb₃ in amylopectins ranged from 21.65% to 24.95%, 44.48% to 49.44%, 15.56% to 17.19% and 9.83% to 16.66% respectively. Correlation analyses showed that amylose content was inversely related to pasting parameters and enthalpy of gelatinisation. Pasting properties and amylopectin structures were the most important parameters to differentiate starch properties among different hull‐less barley cultivars in this study. This work will be useful for exploring applications of Chinese hull‐less barley starches in food and non‐food industries.     

Resistant starch and thermal,morphological and textural properties of heat‐moisture treated rice starches with high‐, medium‐ and low‐amylose content

This study investigated the effects of heat‐moisture treatment (HMT) on the resistant starch content and thermal, morphological, and textural properties of rice starches with high‐, medium‐ and low‐amylose content. The starches were adjusted to 15, 20 and 25% moisture levels and heated at 110°C for 1 h. The HMT increased the resistant starch content in all of the rice starches. HMT increased the onset temperature and the gelatinisation temperature range (T_finish–T_onset) and decreased the enthalpy of gelatinisation of rice starches with different amylose contents. This reduction increased with the increase in the moisture content of HMT. The morphology of rice starch granules was altered with the HMT; the granules presented more agglomerated surface. The HMT affected the textural parameters of rice starches; the high‐ and low‐amylose rice starches subjected to 15 and 20% HMT possessed higher gel hardness.     

In vitro availability of starch in heat‐treated potatoes as related to genotype,weight and storage time

The objective of the study was to determine the influence of potato variety, weight and storage time after lifting on the glycaemic index (GI) and resistant starch (RS) content predicted from measurement of the rate and extent of in vitro starch hydrolysis, respectively. The potatoes were either boiled, or boiled and subjected to different heat‐cycling conditions selected to promote retrogradation of amylose or amylopectin, respectively. The hydrolysis indices (HI) and predicted GIs of all 19 potato products were high and fell within narrow ranges of 122–144 and 118–138, respectively. No correlation between average weight of the potato tuber and HI was found. Furthermore, there was no difference in HI between potatoes stored for 1–3 or 8–10 months, nor between varieties of new potato and winter potato. However, the HI was significantly lowered by temperature cycling at conditions known to promote retrogradation of amylopectin (6 °C, 48 h) compared with 6 °C for 24 h followed by 70 °C for 24 h. RS content was already substantial in boiled potatoes, 4.5 g 100 g^?1 (starch basis), and could be increased further by temperature cycling, the highest yield obtained, 9.8 g 100 g^?1 (starch basis), following heat treatment at 6 °C for 24 h followed by 70 °C for 24 h; that is at conditions known to favour amylose retrogradation. Copyright © 2004 Society of Chemical Industry     

Starch Retrogradation: A Comprehensive Review

Starch retrogradation is a process in which disaggregated amylose and amylopectin chains in a gelatinized starch paste reassociate to form more ordered structures. Starch retrogradation has been the subject of intensive research over the last 50 years, mainly due to its detrimental effect on the sensory and storage qualities of many starchy foods. However, starch retrogadation is desirable for some starchy food products in terms of textural and nutritional properties. To better understand the effect of starch retrogradation on the quality of starchy foods, measurement methods of starch retrogradation and factors that influence starch retrogradation have been studied extensively. This article provides a comprehensive review of starch retrogradation including the definition of the process, molecular mechanisms of how it occurs, and measurement methods and factors that influence starch retrogradation. The review also discusses the effect of retrogradation on the in vitro enzyme digestibility of starch. Spectroscopic methods such as FTIR and Raman are considered to be very promising in characterizing starch retrogradation at a molecular level, although more studies are needed in the future.     

Influence of hydroxypropylation on retrogradation properties of native,defatted and heat-moisture treated potato starches

Recent studies have shown that defatting and heat-moisture treatment cause structural changes within the amorphous and crystalline regions of potato starch. Furthermore, the alkaline reagents (NaOH and Na₂SO₄) used during hydroxypropylation has been shown to cause structural changes within the amorphous and crystalline regions of native, defatted and heat-moisture treated starches. In this study, we have compared (using different techniques) the retrogradation properties of potato starch before and after physical (defatting and heat-moisture treatment), and chemical (alkaline treatment and hydroxypropylation) modification. Turbidity measurements showed that changes in turbidity during storage (4°C for 24 h and then at 40°C for 29 days) of native, defatted and heat-moisture treated gelatinized starch pastes were influenced by the interplay of two factors: (1) interaction between leached starch components (amylose–amylose, amylose–amylopectin, amylose–amylopectin), and (2) interaction between granule remnants and leached amylose and amylopectin. In alkali treated gelatinized native, defatted and heat-moisture treated starch pastes, turbidity changes on storage was influenced by aggregation of granule remnants. Hydroxypropylation decreased the rate and extent of increase in turbidity during storage of native, defatted and heat-moisture treated starches. The change in turbidity during storage of hydroxypropylated starch pastes was influenced by the interplay between: (1) steric effects imposed by hydroxypropyl groups on chain aggregation, (2) aggregation between small granule remnants, and (3) settling of large granule remnants beneath the path of the spectrophotometer beam. Stored gelatinized pastes of native, defatted and heat-moisture treated starches gave a `B' type X-ray pattern. A similar pattern was also observed after alkaline treatment, and hydroxypropylation. However, the X-ray intensity of the strong reflection at 5.2 Å decreased after alkaline treatment and hydroxypropylation. The retrogradation endotherm (monitored by differential scanning calorimetry) occurred after 2 days storage in native, defatted and heat-moisture treated starches. A similar trend was also observed after alkaline treatment. However, the retrogradation endotherm appeared only after 7 days in hydroxypropylated starches. The enthalpy of retrogradation in all starches decreased on alkaline treatment and hydroxypropylation.     

Retrogradation of sweet potato amylose and amylopectin with narrow molecular weight distribution

Retrogradation of sweet potato amylose and amylopectin with narrow molecular weight distribution at different temperatures was investigated by X-ray diffraction (XRD). Atomic force microscope (AFM), scanning electron microscope (SEM) and light microscopy were combined to study the morphology of the molecular assemblies during retrogradation. Avrami equation was used to the retrogradation kinetics the of above starches by determining the crystallinity and the ratio of peak area of two distinctive peaks. It was found that only the ratio of peak area/total area at 2θ = ~16.3° could represent the crystallinity of retrograded starch-containing amorphous regions. Considering the crystallinity as retrogradation rate, only the retrogradation kinetics of sweet potato amylose could be analysed by Avrami equation, but not the amylopectin’s. All Avrami exponents n of amyloses at any temperatures were less than 1.0, indicating instantaneous nucleation and rod-like growth. AFM results showed that the maximum heights of layered structure for sweet potato amylose, amylopectin and blending of both were approximately 4800, 180 and 200 nm, respectively. The height of the former two decreased during storage, but the height of blending remained unchanged. Amylose served as nuclei of amylopectin during starch retrogradation.     

Effect of temperature on the synthesis,composition and physical properties of potato microtuber starch

Potato microtubers (cv Maris Piper) were grown at 10, 16 and 24°C in total darkness for 28 days. Soluble and insoluble starch synthase, ADPglucose pyrophosphorylase, sucrose synthase and fructokinase were assayed in extracts of the microtubers and, in the case of soluble and insoluble starch synthase, activity was found to be particularly sensitive to increasing growth temperature. The starch content of the microtubers increased slightly with increasing growth temperature, but with little effect on the number of granules per microtuber and a small increase in the average granule size. The microtuber starch granules were much smaller than those found in commercial potato starch (c 8–9 μm modal diameter compared to c 21 μm). Although the amylose content of the microtuber starches tended to increase with increasing growth temperature, the phosphorus content was variable. Gel permeation chromatographic elution profiles of native and debranched microtuber and a commercial potato starch showed that no differences could be detected in either amylose or amylopectin molecular size, polydispersity or unit chain distribution of amylopectin (which contained two major unit chain fractions at DP 21 and 56). The onset, peak and conclusion temperatures of the DSC gelatinisation endotherm increased linearly as a function of growth temperature whilst the enthalpy of gelatinisation decreased. It is suggested that elevated temperature during starch biosynthesis facilitates ordering of amylopectin double helices into crystalline domains. © 1998 SCI.     

Starch retrogradation

Abstract

Starch granules heated in excess water undergo an order‐disorder phase transition called gelatinization (1) over a temperature range characteristic of the starch source. This phase transition is a non‐equilibrium process associated with the diffusion of water into the granule, hydration and swelling of the starch granules, uptake of heat, loss of crystallinity, and amylose leaching (1–3). On cooling, the starch chains (amylose and amylopectin) in the gelatinized paste associate, leading to the formation of a more ordered structure. These molecular interactions are termed collectively “retrogradation” and have important textural and dietary implications (not covered in this review). This review summarizes the present knowledge on amylose gelation and amylopectin crystallization, and on the factors that influence starch retrogradation.     

Purification and some properties of a novel raw starch‐digesting amylase from Aspergillus carbonarius

A medium was developed to obtain the maximum yield of raw starch‐digesting amylase from Aspergillus carbonarius (Bainier) Thom IMI 366159 in submerged culture with raw starch as the sole carbon source. The amylase was purified to apparent homogeneity by sucrose concentration and ion exchange chromatography on S‐ and Q‐Sepharose (fast flow) columns. SDS‐PAGE revealed two migrating protein bands corresponding to relative molecular masses of 31.6 and 32 KDa. The enzyme was optimally active at pH 6.0–7.0 and 40 °C, was uninfluenced across a relatively broad pH range of 3.0–9.0 and retained over 85% activity between 30 and 80 °C after 20 min incubation. The enzyme was strongly activated by Co²⁺ and only slightly by Fe²⁺, while Ca²⁺, Hg²⁺, EDTA and N‐bromosuccinamide elicited significant repression of the enzyme activity. The enzyme hydrolysed amylopectin (K_m 0.194 mg ml ⁻¹), glycogen (K_m 0.215 mg ml ⁻¹), pullulan (K_m 0.238 mg ml ⁻¹), amylose (K_m 0.256 mg ml ⁻¹) and raw potato starch (K_m 0.260 mg ml ⁻¹), forming predominantly maltose and relatively smaller amounts of glucose. © 2000 Society of Chemical Industry     

Resistant starch production from mango starch using a single‐screw extruder

Resistant starches were prepared from mango starch by extrusion. An experimental design with independent variables temperature, screw speed and moisture content produced 20 samples that were studied to determine the effect of these variables on resistant starch (RS) content, water absorption index (WAI) and water solubility index (WSI). RS content was affected by moisture content and temperature. Screw speed and temperature also influenced RS content, the highest level (97 g kg⁻¹) being obtained at low screw speed and high temperature, this pattern can be associated with a longer residence time, which gives rise to more opportunity for amylose chain association. The regression model fitted to the RS experimental results showed a good correlation coefficient (0.80). When moisture content and temperature decreased, WAI increased (105–142 g kg⁻¹), but low WAI values (70–77 g kg⁻¹) were obtained at moisture contents between 200 and 300 g kg⁻¹ and high temperatures (140–150 °C). When moisture content and temperature increased, WSI increased (222–332 g kg⁻¹), but at high temperature value (120 °C) assayed and the lowest moisture content (150 g kg⁻¹), WSI also increased. In the range of moisture contents tested and at low temperatures, only partial gelatinisation occurred and low solubility was obtained. Copyright © 2005 Society of Chemical Industry     

Effect of Starch of Textural Properties of Surimi Gel

The proportion of amylose and amylopectin, and the rheological behavior of eight starches were correlated with the textural properties of starch-containing surimi gels. Findings included the following: increased firmness and cohesiveness with increases in water-holding ability and viscosity of the starch; increased expressible moisture and penetration force with an increase in the amylose fraction due to increased retrogradation: increased tensile force with an increase in the amylopectin fraction: and increased cohesiveness and chewiness after refrigerated storage for all starches with a greater increase for high amylose starches. Surimi gels containing potato starch were the firmest and most cohesive. The textural properties of starch-containing surimi gel correlated well (r = 0.90 to 0.97, P>0.05) with the viscosity of starch paste if 100% amylopectin-containing and pregelatinized starches were excluded from the correlation.