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The influence of glucose syrup on the retrogradation of cereal starches was investigated. Laboratory isolated starches from wheat (WS) and oats (OS – oat starch and ROS – residual oat starch) were used in this research. ROS was isolated from the flour left after the industrial separation of β-glucans. Gelatinization temperature of oat starches (63.82 °C and 64.01 °C for OS and ROS, respectively) was higher than for WS (62.26 °C), whereas gelatinization enthalpy for oat starches (8.87 J/g and 9.09 J/g for OS and ROS, respectively) was lower than for WS (9.99 J/g). Moreover, retrogradation percentage (%R) was similar for both oat starches (29.76% and 27.72% for OS and ROS, respectively), and was substantially lower than for WS (42.04%). The introduction of glucose syrup into system reduced the extent of the retrogradation. Rate of the process was suppressed for WS and ROS, whereas for OS it was increased. β-Glucan production process had no significant effect on the gelatinization and retrogradation of oat starch. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of process called micronization, applied during preparation of beta-glucan concentrate, on properties of residual oats flour, and respective starch. The properties of residual oats flour (ROF) and starch isolated from this material (ROS) were compared with commercial flours: oats (COF) and wheat (CWF), and the respective starches (COS and CWS). It was shown, that micronization caused changes in starch fraction. Starch granules present in ROF not occur in clusters, and were only slightly damaged, which had no influence on molar mass of starch glucans, as well as on swelling and pasting properties of starch and mechanical modulus at linear viscoelasticity range. It was observed that flour pasting properties are determined not only by starch properties but also the presence other flour constituents (lipids, soluble and insoluble protein fractions, and to slightly lesser degree the content of beta – glucans). [ABSTRACT FROM AUTHOR]

Starch is a natural polysaccharide for which the technological quality depends on the genetic basis of the plant and the environmental conditions of the cultivation. Growing plants under cover without soil has many advantages for controlling the above-mentioned conditions. The present research focuses on determining the effect of under cover hydroponic potato cultivation on the physicochemical properties of accumulated potato starch (PS). The plants were grown in the hydroponic system, with (greenhouse, GH) and without recirculation nutrient solution (foil tunnel, FT). The reference sample was PS isolated from plants grown in a tunnel in containers filled with mineral soil (SO). The influence of the cultivation method on the elemental composition of the starch molecules was noted. The cultivation method also influenced the protein and amylose content of the PS. Considering the chromatic parameters, PS-GH and PS-FT were brighter and whiter, with a tinge of blue, than PS-SO. PS-SO was also characterized by the largest average diameters of granules, while PS-GH had the lowest crystallinity. PS-SO showed a better resistance to the combined action of elevated temperature and shear force. There was a slight variation in the gelatinization temperature values. Additionally, significant differences for enthalpy and the retrogradation ratio were observed. The cultivation method did not influence the glass transition and melting. [ABSTRACT FROM AUTHOR]

Potatoes, especially colored, are perceived as a valuable source of bioactive compounds, and they are also an important raw material for starch production. There is virtually no information about starch from colored potatoes grown in Central Europe. Therefore, starches from light and colored potato varieties are isolated, and their particle size distributions, molecular masses, phosphorus content, gelatinization properties, water binding capacity, and solubility are analyzed. It is found that the mean and minimum granule size is similar for all investigated varieties, but colored varieties have larger granules. Moreover, starches isolated from colored potatoes are characterized by a higher phosphorus content than those isolated from light ones. It is shown that the solubility and water‐binding capacity of starch from colored potatoes is greater than that of light flesh, especially at higher temperatures. Starches from light flesh potatoes are characterized by significantly higher gelatinization enthalpy values than those from colored potatoes. [ABSTRACT FROM AUTHOR]

Background: Gels of potato starches with varying amylose content were prepared and the degree of pasting and the course of retrogradation were studied. The average molar masses of granular and pasted starches were estimated. Determination of the degree of pasting involved use of optical microscopy and the study of pasting characteristics. The studies of susceptibility to retrogradation considered mechanical spectra, hardness, syneresis, resistant starch content, and X‐ray measurements. Results: Heating of the starch suspensions at 95 °C resulted in almost complete deterioration of granules. Changes in storage modulus (G') exceeded these of loss modulus (G"). Values of G' and G", hardness and syneresis increased with the period of the sample storage and, simultaneously, the relevant tangent of the phase shift angle (tg (G"/G')) decreased. A tendency was observed for the resistant starch (RS) content to increase on prolonged storage of gels. The patterns of diffractograms for the pasted and lyophilized samples only differed slightly. Conclusion: The pastes of all the studied potato starches were characterized by a similar degree of pasting. The most essential changes in the physicochemical properties of the gels were observed between the 30th and 90th days of storage. The susceptibility of potato starch gels to retrogradation, especially within the first 2 h, was controlled, mainly by the amylose content. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The aim was to study the rheological, especially thixo- and antithixotropic properties of normal potato starch (NPS) with the addition of locust bean gum (LBG) depending on the pasting temperature, the starch concentration and the amount of LBG. All the pastes under study were rheologically unstable, non-Newtonian, shear thinning fluids. The increase in the LBG content obstructed pasting of the starch granules and increased viscosity of the pastes. In a vast majority of cases obstruction in swelling granules and, hence, higher amount of non-pasted granules evoked thixotropy. In turn, a higher numbers of well swollen granules and, hence pasted granules led to antithixotropy. Apart from the concentration of both polysaccharides and pasting temperature the results depended also on the measuring method applied. [ABSTRACT FROM AUTHOR]

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 0.1 MPa). 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. [ABSTRACT FROM AUTHOR]

The aim of this paper was the study of the rheological instability (thixotropy and/or antithixotropy) of normal potato starch (NPS) pastes depending on their concentration (2–5%) and degree of pasting. Flow curves with hysteresis loops, apparent viscosity at constant shear rate and in-shear structural recovery tests were carried out. Granule size profiles, the pasting characteristic of corresponding starch suspensions and the transmittance of the pastes, the molecular weights and polydispersity of granular starch and its pastes prepared at 80, 95 and 121 °C were also studied. The degree of pasting was dependent on the temperature and the concentration and influenced strongly the rheological behavior of the pastes. All pastes belonged to the non-Newtonian liquids thinned by shear and were rheologically unstable to the various extent. Thixotropic properties were connected to the size and the number of the starch granules in the pastes as well as depended on the measuring method used. In the 2 and 3% samples pasted at 80 °C the swelling of the granules prevailed their destruction (thixotropy was observed). In the other samples the destruction predominated the swelling (antithixotropy observed). [ABSTRACT FROM AUTHOR]