Waxy Potato Starch Research Articles

Fabrication and characterization of food‐grade fibers from mixtures of maltodextrin and whey protein isolate using needleless electrospinning

ABSTRACTFood‐grade fibers were fabricated from dispersions of maltodextrin and whey protein isolate (WPI) using needleless electrospinning. Two maltodextrins (DE 2) from different starch sources were used and the maltodextrin/WPI ratio was varied. Molecular weight, intrinsic viscosity, entanglement concentration, shear stability, and electrical conductivity were studied as function of maltodextrin type and mixing ratio and correlated to fiber production rate and morphology. The results show that a high molecular weight of the maltodextrin was beneficial to its spinnability. Waxy potato starch maltodextrin (P‐MD) (Mw = 129.6 kDa) and WPI produced fibers with diameters between 1.40 and 1.67 µm at production rates up to 1.65 g/h; while the dispersions with waxy maize starch maltodextrin (M‐MD) (Mw = 85.9 kDa) showed poor spinnability and ruptured fibers. P‐MD/WPI dispersions had a higher viscosity and stronger shear thinning behavior attributed to a stronger entangled polymer network which is beneficial to electrospinning. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46328.

Preparation of starch nanocrystals through enzymatic pretreatment from waxy potato starch

A comparative experiment about the production of starch nanocrystals (SNCs) with/without glucoamylase enzymatic pretreatment by sulfate acid hydrolysis from waxy potato starch (WPS) was employed in the present study. The research focused on the enhancement of the preparation efficiency while improving the dispersion of SNCs at the same time. The enzymatic pretreatment resulted in the decrease of acid hydrolysis duration. The minimum size and best dispersibility of nanocrystals was obtained after 5 days of hydrolysis. X-ray diffraction confirmed the increase of crystallinity (from 33% to 50.8%) and the polymorphic transitions (B–A) for nanocrystals harvested at day 5. The structure of nanocrystals was characterized by FT-IR, which suggested the presence of sulfate ester on the surface of SNCs. Zeta potential and size distribution revealed the prominent stability and dispersibility of nanocrystals at pH 7.0. SEM and TEM revealed that SNCs had square shapes with particle sizes ranging from 50 to 100 nm.

Influence of amylose content and oxidation level of potato starch on acetylation, granule structure and radicals’ formation

This study was aimed at determining the effect of the amylose content of starch and oxidation level of potato starch on the structure of starch granules, and susceptibility to chemical modification (acetylation) and subsequent generation of radicals. Potato starch and waxy potato starch were oxidised with sodium hypochlorite applied in doses corresponding to 10, 20, and 30gCl/kg starch, and then acetylated with acetic acid anhydride. The carboxyl, carbonyl, acetyl groups were determined in modified starches. Structural properties of starch granules were evaluated based on gelatinisation, crystallinity, specific surface, intrinsic viscosity, and microphotographs by SEM microscope. The electron paramagnetic resonance (EPR) measurements were carried out to establish starch susceptibility to radical creation upon chemical modification and UV radiation. The amount of formed radicals was treated as a measure of the starch structure stability. The higher amount of amylose and the highest level of oxidation led to strong starch structure destruction and consequently facilitated radical generation. Study results showed also that amylose content as well as the degree of starch oxidation modified consecutive acetylation process. The different effectiveness of the acetylation processes influenced the morphology and structure of starch granules.

Octenylsuccinate starch spherulites as a stabilizer for Pickering emulsions.

This study investigated structure and morphology of starch spherulites prepared from debranched waxy maize and waxy potato starches. Debranched waxy potato starch favored the formation of B-type crystals with longer branch chains (average chain length, 26.14), whereas A-type polymorphic aggregates were generated from debranched waxy maize under same recrystallization condition. Spherulites had smaller particle size distribution (D[3,2], ∼3.7μm), higher dissociation temperature (80-120°C) and crystallinity (80∼90%), compared to native waxy starches. Intact spherulites could be used as an edible particle emulsifier after modifying by octenylsuccinic anhydride (OSA). The emulsion produced using 2wt.% of octenylsuccinate (OS) starch spherulites as emulsifier was quite stable over 2months, and its Pickering emulsions displayed protective effect on stability of oil droplets.

Octenyl succinylation of granular and debranched waxy starches and their application in low-fat salad dressing

The reactions of octenyl succinic anhydride (OSA) at 3% and 15% concentrations (based on weight of starch) with granular and debranched starch forms of waxy rice and waxy potato starches were investigated and compared. Reaction efficiencies of debranched starches with 3% OSA (83.6–87.4%) were significantly higher than those of the granular starches (51.2–56.1%), but their recovery yields were lower (80–85% and 94–98% for debranched and granular starches, respectively). Similar trends were found for the starches modified with 15% OSA but with less reaction efficiencies. Molecular weights of the modified debranched starches were substantially higher than the unmodified ones, presumably due not only to the substituted groups, but also the association of starch chains. Native, debranched, 3% OS granular and 3% OS debranched starches were then evaluated as a fat replacer in a low-fat salad dressing. Viscosities of the dressings incorporated with native and OS granular starches were reduced markedly after storage for 3 d, while the consistency and appearance of the dressings containing debranched starches, either modified or not, were similar to commercial low-fat dressing at up to 90 d storage. Relative calorie values of the dressings containing debranched starches were approximately 50% and 10% less than the reference formula and commercial dressing, respectively.

Thixotropic properties of waxy potato starch depending on the degree of the granules pasting

This paper presents the rheological instability (thixotropy/antithixotropy) of waxy potato starch (WPS) pastes depending on their concentration (1–5% w/w) and pasting temperature (80, 95 and autoclaved: 121°C, at 0.1MPa). The hysteresis loop, apparent viscosity at constant shear rate as well as the in-shear structural recovery tests with and without pre-shearing were applied. The pastes were also characterized by the granularity profile, molecular weight, polydispersity and optical transmittance.Differences in rheological properties of the pastes prepared at 80 and 95°C as well as autoclaved resulted from degree of granules pasting. At 121 °C dissolution of the granules occurred, while at the lower temperatures only the partial pasting of the granules took place. Pasting temperature of WPS significantly influenced rheological parameters of the resulted pastes which had thixotropic, antithixotropic or mixed thixotropic/antithixotropic behavior. Autoclaved pastes, regardless their concentration were antithixotropic as demonstrated by the areas of hysteresis loops derived from the flow curves signalized by the degree of structure recovery (DSR) which exceeded unity. The apparent viscosity of WPS pasted at 121°C strongly decreased as compared to the samples pasted at lower temperatures. Samples pasted at 80 and 95°C showed both thixotropic and antithixotropic behavior, with a predominance of the latter. The starch concentration played an important role in the formation of the rheological properties of the resulted pastes. Its influence was strongly connected with the degree of the granules pasting, therefore with the temperature of pastes preparation. For the pastes prepared at 80 and 95°C the values of thixotropy and apparent viscosity increased, while the values of DSR decreased with an increase of concentration. In the autoclaved pastes the antithixotropy, DSR and apparent viscosity increased with increasing starch concentration. It was also found that apart from the concentration and temperature also the shear rate influence the thixotropic behavior.

In situ study starch gelatinization under ultra-high hydrostatic pressure using synchrotron SAXS

The gelatinization of waxy (very low amylose) corn and potato starches by high hydrostatic pressure (HHP) (up to ∼1 GPa) was investigated in situ using synchrotron small-angle X-ray scattering (SAXS) on samples held in a diamond anvil cell (DAC). The starch pastes, made by mixing starch and water in a 1:1 ratio (by weight), were pressurized and measured at room temperature. During HHP, both SAXS peak areas (corresponding to the lamellar phase) of waxy corn and potato starches decreased suggesting the starch gelatinization increases with increasing pressure. As pressure increased, lamellar peak broadened and the power law exponent increased in low q region. 1D linear correlation function was further employed to analyse SAXS data. For both waxy potato and waxy corn starches, the long period length and the average thickness of amorphous layers decreased when the pressure increased. While for both of waxy starches, the thickness of the crystalline layer first increased, then decreased when the pressure increased. The former is probably due to the out-phasing of starch molecules, and the latter is due to the water penetrating into the crystalline region during gelatinization and to pressure induced compression.

Structural characteristics of slowly digestible starch and resistant starch isolated from heat–moisture treated waxy potato starch

The objective of this study was to investigate the structural characteristics of slowly digestible starch (SDS) and resistant starch (RS) fractions isolated from heat–moisture treated waxy potato starch. The waxy potato starch with 25.7% moisture content was heated at 120°C for 5.3h. Scanning electron micrographs of the cross sections of RS and SDS+RS fractions revealed a growth ring structure. The branch chain-length distribution of debranched amylopectin from the RS fraction had a higher proportion of long chains (DP≥37) than the SDS+RS fraction. The X-ray diffraction intensities of RS and SDS+RS fractions were increased compared to the control. The SDS+RS fraction showed a lower gelatinization enthalpy than the control while the RS fraction had a higher value than the SDS+RS fraction. In this study we showed the RS fraction is composed mainly of crystalline structure and the SDS fraction consists of weak crystallites and amorphous regions.

Physicochemical and structural properties of debranched waxy rice, waxy corn and waxy potato starches

Starch gels of waxy rice (WR), waxy corn (WC) and waxy potato (WP) were hydrolyzed with pullulanase, and the products obtained were analyzed for unit chain length distribution and certain physicochemical properties. Average chain lengths of debranched WR, WC and WP starches were 18.2, 19.2 and 25.6, respectively. The debranched starches had a greater ability to form complexes with iodine and possessed higher solubility but lower viscosity compared with their corresponding dispersed native starches. Their complexing abilities with fatty acids (palmitic and butyric acids) were found to be dependent on the unit chain length. Among the three debranched starches, debranched waxy potato starch exhibited the greatest ability to form complexes with iodine and fatty acids, while debranched waxy rice starch had the highest solubility and lowest viscosity. The debranched starches formed stable gels at high concentrations (10–20%) and formed precipitates at concentrations up to 5%.

Effect of repeated retrogradation on structural characteristics and in vitro digestibility of waxy potato starch

The effects of repeated retrogradation (RR) treatment on the structural characteristics and in vitro digestibility of waxy potato starch were investigated. The cycling times of RR ranging from 1 to 5 were designated as RR-1, RR-2, RR-3, RR-4, and RR-5, respectively. A maximum SDS content (40.41%) was obtained by RR-2 treatment with the time interval of 48h. RR-2-treated starch product exhibited a narrower melting temperature range, a higher onset temperature and a lower melting enthalpy compared with RR-1 treatment. Compared with native starch, X-ray diffraction patterns of treated starches were altered from B-type to C-type. The variation in relative crystallinity of RR-treated starch products was consistent with that in melting enthalpy. Moreover, compared with RR-1-treated starch, a large number of cavities were observed on the surface of RR-2-treated starch product with a time interval of 48h, whereas more smooth regions were found on the surface of RR-5-treated starch product. This study suggested that structural changes of waxy potato starch treated with different cycling times of RR significantly affected the digestibility.

Effect of temperature-cycled retrogradation on in vitro digestibility and structural characteristics of waxy potato starch

The effects of temperature-cycled retrogradation treatment on the structural characteristics and in vitro digestibility of waxy potato starch were investigated in this study. The results showed that the maximum yield of slowly digestible starch (SDS) in waxy potato starch reached 38.63% by retrogradation treatment under temperature cycles of 4/25°C for 3 days with an interval of 24h. The starch products prepared under the temperature cycles of 4/25°C exhibited a narrower melting temperature range (Tc−To), a higher melting enthalpy (ΔH) and a higher IR absorbance ratio (1047cm−1/1022cm−1) than that prepared at a constant temperature of 25°C. Compared to native starch, X-ray diffraction pattern of treated starch was altered from B-type to C-type. Furthermore, the relative crystallinity of the starch products prepared under temperature-cycled retrogradation was the highest. This study suggests that more imperfect crystallites are formed in the crystalline matrix under temperature-cycled retrogradation, resulting in a high yield of SDS.

Preparation, structure, and digestibility of crystalline A- and B-type aggregates from debranched waxy starches

Highly crystalline A- and B-type aggregates were prepared from short linear α-1,4 glucans generated from completely debranched waxy maize and waxy potato starches by manipulating the chain length and crystallization conditions including starch solids concentration and crystallization temperature. The A-type crystalline products were more resistant to enzyme digestion than the B-type crystalline products, and the digestibility of the A- and B-type allomorphs was not correlated with the size of the aggregates formed. Annealing increased the peak melting temperature of the B-type crystallites, making it similar to that of the A-type crystallites, but did not improve the enzyme resistance of the B-type crystalline products. The possible reason for these results was due to the compact morphology as well as the denser packing pattern of double helices in A-type crystallites. Our observations counter the fact that most B-type native starches are more enzyme-resistant than A-type native starches. Crystalline type per se does not seem to be the key factor that controls the digestibility of native starch granules; the resistance of native starches with a B-type X-ray diffraction pattern is probably attributed to the other structural features in starch granules.

Time‐dependent phenomena as evidence for structure‐forming properties of starches

AbstractThe study discusses the rheological properties of four different starches (amylose (AM), potato starch (P), waxy potato starch (WXP), and maize amylopectin (AP)) in the form of aqueous pastes and solutions in DMSO. Additionally, osmotic characteristics of diluted solutions of these starches are presented. The results of the qualitative hysteresis loop tests revealed that AM paste and AM solution in DMSO are rheologically stable fluids. Using the scaling of the concentration, it has been shown that the behavior of AM paste is complex. AP and WXP in form of pastes and their solutions in DMSO are rheologically unstable fluids. The course of the flow curves, carried out at the decreasing shear rate, indicates that AP paste accumulates energy. Equilibrium tests performed using AP paste, AP, WXP 1 and 5% solutions in DMSO showed a few interesting effects (chaotic behavior, oscillations, no change, small increase or decrease in apparent viscosity as a function of time). The nature of time‐dependent type phenomena, however, hinders the application of the Cheng and Evans viscosity theories to describe and model the rheological behavior. As the study results demonstrate, the rheological instability of the starch solutions is also based on the phenomena of energy accumulation, i.e. in viscoelastic effects.

Influence of starch acetylation on selected rheological properties of pastes

AbstractSelected rheological properties of acetylated starch pastes of different amylose content were discussed in the study. The rheological studies were carried out immediately after the preparation of the pastes as well as after 1 and 7 days of storage. For the paste of acetylated potato starch (P‐A), a phenomenon of oscillatory changes of viscosity with time was observed. The pastes of the acetylated amylostarch (AMY‐A) and acetylated waxy potato starch (AP‐A) exhibited the phenomenon of thixotropy. Based on the flow curves, the distribution of the time constants of the exponential rheological equation of state has been determined. They served to describe the contributions forming rheological properties. It has been noticed that during shear the phenomenon of the energy dissipation is predominant in AMY‐A (rheological characteristic time of 0.3 s) and AP‐A, whereas the elastic contributions are specific for the paste of acetylated potato starch (rheological characteristic time of 10−6 s). In order to describe the structural changes of AMY‐A and AP‐A pastes during flow, i.e. for the systems exhibiting frictional properties, the Cheng and Evans viscous structural theory has been applied. The rheological properties were then interpreted in light of the results of chromatographic and osmometric analyses.

Comparison of waxy and normal potato starch remaining granules after chemical surface gelatinization: Pasting behavior and surface morphology

To understand the contribution of granule inner portion to the pasting property of starch, waxy potato starch and two normal potato starches and their acetylated starch samples were subjected to chemical surface gelatinization by 3.8mol/L CaCl2 to obtain remaining granules. Native and acetylated, original and remaining granules of waxy potato starch had similar rapid visco analyzer (RVA) pasting profiles, while those of two normal potato starches behaved obviously different from each other. All remaining granules had lower peak viscosity than the corresponding original granules. Contribution of waxy potato starch granule's inner portion to the peak viscosity was significant more than those of normal potato starches. The shell structure appearing on the remaining granule surface for waxy potato starch was smoother and thinner than that for normal potato starches as observed by scanning electron microscopy, indicating a more regular structure of shell and a more ordered packing of shell for waxy potato starch granules. The blocklet size of waxy potato starch was smaller and more uniform than those of normal potato starches as shown by atomic force microscopy images of original and remaining granules. In general, our results provided the evidence for the spatial structure diversity between waxy and normal potato starch granules: outer layer and inner portion of waxy potato starch granule had similar structure, while outer layer had notably different structure from inner portion for normal potato starch granule.

Impact on molecular organization of amylopectin in starch granules upon annealing

This study investigated the influence of the internal structure of amylopectin on annealing (3h, 24h) of starches from four different types of amylopectin (Bertoft, Koch, & Aman, 2012; Bertoft, Piyachomkwan, Chatakanonda, & Sriroth, 2008). Regardless of the starch source and incubation time, annealing significantly increased the onset gelatinization temperature (To) and narrowed and deepened the amylopectin endotherm. However, the extent of the change in the melting temperature (Tm) and the enthalpy of gelatinization (ΔH) differed among the types. In terms of the To and Tm, starches from type 1 (oat, rye, barley, and waxy barley) showed the most significant response to annealing. The Tm of starches belonging to type 2 (waxy maize, rice, waxy rice, and sago) remained unchanged after 3h of annealing. Type 1 and type 2 starches with the lowest gelatinization temperatures showed the greatest increase in melting temperature after annealing. However, type 3 (tapioca, mung bean, and arrowroot) and type 4 (potato, waxy potato, canna, and yam) starches were not in line with these observations. Instead, starches from type 3 and type 4 showed a pronounced increase in the ΔH. The inter-block chain length (IB-CL) (distance between tightly branched units within a cluster) correlated positively (r=0.93, p<0.01) with the change in enthalpy after 24h of annealing. These data indicate that a short IB-CL affects the optimum registration of double helices within the crystalline lamellae. The relationship between the gelatinization parameters before and after annealing suggests that type 1 and 2 starches might possess a high number of unpacked double helices (type 1>type 2) compared to other types. Longer IB-CLs, which facilitate the parallel packing of splayed double helices, and the lengthening of double helices likely increased the ΔH in type 3 and type 4 starches. It is concluded that annealing can be used as a probe for visualizing the organization of glucan chains (alignment of double helices/degree of perfection) within crystalline lamellae.

Nano-structure of heat–moisture treated waxy and normal starches

Surface regions of untreated and heat–moisture treated (HMT) normal rice, waxy rice, normal corn, waxy corn, normal potato, and waxy potato starch granules were examined by atomic force microscopy (AFM). AFM images revealed surface roughness of untreated starch granules and protrusions with a diameter of approximately 15–90nm. After treatment, the smooth surface region on starch granules was observed, especially in normal rice, waxy rice, and normal corn starches. A significant reduction in the size of protrusions on the surface of HMT potato starch granules was also detected. The newly formed structures may act as barriers and retard water penetration into starch granules. The blocklet model of starch granule architecture was also confirmed by the AFM images.

Processing of waxy starch/xanthan gum mixtures within the gelatinization temperature range

Pasting experiments of waxy potato and waxy maize starch systems were set up in which temperatures close to the gelatinization temperature were selected (67.5, 70 and 72.5°C). DSC measurements showed that under these conditions small fractions of the starches remained ungelatinized. During the pasting process two different shear rates were imposed (50s−1 and 150s−1) to investigate the shear stability of the different starch containing systems. Swelling of the granules occurred in a more controlled manner and granule breakdown during pasting could be limited. As a result of these heating conditions more swollen granules are present, as confirmed by laser light diffraction. This positive effect was clearly noticeable in the flow curves of the cooled pastes. Xanthan gum addition could further reduce breakdown either by restricting the swelling or by stabilizing the granules. At higher starch contents the former is most likely dominating.

Amylopectin structure of heat–moisture treated starches

AbstractThe 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).

Study on melting and crystallization of short-linear chains from debranched waxy starches by in situ synchrotron wide-angle X-ray diffraction

In situ melting and crystallization of short-linear α-1,4-glucan (short-chain amylose, or SCA) from debranched waxy starches were investigated by synchrotron wide-angle X-ray diffraction. Amorphous SCA was prepared by dissolving completely debranched waxy starches in alkaline solution and neutralized by hydrochloric acid. When hydrated with 50% water at 25°C, all amorphous SCA crystallized immediately and gave a B-type structure. The SCA from debranched waxy potato starch had a longer average chain length and a higher melting temperature but relatively lower crystallinity upon hydration; it was not completely melted at 100°C and retained its original B-type structure during rapid cooling. In contrast, the SCA from debranched waxy wheat and waxy maize starches had a large portion of low molecular weight fractions, a higher crystallinity upon hydration, and a lower melting temperature. These differences suggest that amylopectin short chains crystallized more readily but their crystals were weaker than those of long chains. After the B-type crystals of hydrated SCA from waxy wheat and waxy maize starches melted, they reformed into the A-type polymorph upon rapid cooling. The thermal properties showed that the A-type polymorph of debranched waxy wheat and waxy maize starches had a higher melting temperature than their B-type structure.