Study On Structure And Properties Of Different Varieties Potato Starches

The development of deeply processed potato starch products is a very important part toincrease the value of the potato industry chain while potato variety suitable for processingplays a crucial role for the stability of potato starches and the development of potatostarch-based high value-added products. Especially, the relationship between the structure andproperty of different varieties potato starches is the fundament of the variety breeding for thedifferent processing. Therefore, systematical investigation about the relationship between thestructure and property of different varieties potato starches will be of great significance for thestability of potato starch products quality and the variety breeding of special potato forprocessing.Focus on the main variety of potato starch from Qinghai province and their structure andproperties, the aggregate state structure and chain structure (including particle,semi-crystalline lamellae, molecular mass, distribution and conformation) of different varietypotato starch were systematically evaluated by using optical microscope, scanning electronmicroscope(SEM), small angel X-ray scattering(SAXS), polarized light microscope, wideX-ray diffraction(XRD), infrared spectrum, gel permeation chromatograph(GPC), multi-anglelight scattering(MALS) and energy spectrum. Consequently, the relationship between potatostarch variety and its microstructure was obtained. The results indicated that in the aggregatestate structure aspect, particle size of different variety potato starch was different with theaverage size37-51μm and all the potato starches were surface fractal. The thickness andorderliness of semi-crystalline lamellae and uniformity of the double helix structurearrangement was different owing to different variety potato starches. The Long3potato starchhad the thinnest semi-crystalline lamellae and highest degree of ordering in double helixstructure in semi-crystalline lamellae. The Qing2potato starch had the thickestsemi-crystalline lamellae and the highest degree of ordering in semi-crystalline lamellae. TheFavourate potato starch had the thinnest crystalline lamellae in semi-crystalline lamellaestructure. The crystal morphology of all the different variety potato starches were B-typecrystal. Xiazhai65, Qing6and Favourate had higher crystallinity while Qing168and Qing2had lower crystallinity. In the chain structure aspect, the weight-average molecular mass(Mw) of all the ten different variety potato starches reached to~107g/mol. The Mw of starchmolecule of Favourate, Qing5and Qing8was higher while that of Qing168, Qing10andLong3was lower. The mean square radius of gyration of Qing8starch was biggest while thatof Qing6was smallest. All the potato starches were compact globular structure except Qing5in solvent DMSO. The potato starch of Qing168, Long3, Qing9, Qing5, Xiazhai65hadhigher amylose content while the potato starch of Qing2, Qing8and Favourate had loweramylose content. Qing6had the highest phosphorus content while Qing5had the lowestphosphorus content.Moreover, the gelatinization properties, rheological behavior, gelling characteristics,freeze-thawing stability and resistance to digestion of different variety potato starches wereanalyzed by rotary rheometer, gel texture and in-vitro digestion method and the relationshipbetween structure differences and property differences were obtained. Compared with othersamples, the potato starch of Xiazhai65possessed the lowest pasting temperature, the biggestbreakdown value, setback value, consistency coefficient and apparent viscosity, the beststability of hot and cold paste, the best thixotropy of paste, the most obvious shear-thinningeffect, easiest to gelatinization, good freeze-thawing stability, hardest gel and bestcohesiveness. Correspondingly, the potato starch of Qing8possessed most difficult togelatinization, the worst stability of hot and cold paste and freeze-thawing stability, thesmallest setback value and consistency coefficient and most non-obvious shear-thinning effect.The potato starch of Qing5had the smallest breakdown value and apparent viscosity, theworst thixotropy of paste, cohesiveness and freeze-thawing stability but the hardest gel. Thepotato starch of Qing6had the best stability of hot paste while Long3acquired quite obviousshear-thinning effect. The potato starch of Qing8had most non-obvious shear-thinning effectwhile Favourate had quite good freeze-thawing stability. The resistant starch content of thedifferent variety potato starches was not high below1%.On the basis of the analysis of the properties of different varieties potato starches, thevariation of semi-crystalline structure, length of molecular side-chains and its distribution wasfurther investigated according to the significance of their property distinction through SAXS,GPC and MALS combined with heat-moist treatment and enzyme treatment and therelationship between the multi-scale structure and the properties were concluded by correlation analysis. The results show that due to species differences, pasting properties,rheological properties, gel texture properties and freeze-thaw stabilities were significantlyaffected by the multi-scale structure such as the particle fractal structure, the semi-crystallinelayer thickness, the degree of ordering and the crystal thickness, the crystal morphology andcrystallinity and the length of molecular side-chains and its distribution. The thixotropy wasbatter for the potato starch with smoother surface. The potato starch with higher degree ofordering in semi-crystalline lamellar regions had lower peak viscosity, setback value andfreeze-thaw stability while better stability of cold paste and the gel cohesiveness. The potatostarch which crystallline structure was easy destroyed by heat had a lower initialgelatinization temperature, the bigger peak viscosity, breakdown value, setback value and gelspringiness, the smaller gel hardness and the worse freeze-thaw stability. The potato starcheswith a higher side chains which polymerization degree is between600and1200had lowerinitial gelatinization temperature, lower gel hardness and bigger peak viscosity, consistencycoefficient, apparent viscosity, breakdown value and cohesiveness.From multi scale of structure, this research systematically investigated the aggregatestructure and chain structure of potato starch molecule from different varieties. The resultsshowed the effects of different varieties on the changes of multi-scale structure of potatostarch and revealed the effect of structural differences of different varieties on their properties.These results will provide the theoretical basis and basic data for the quality stability of potatostarch, and for breeding and application of processing potatoes. Meanwhile, the research willplay an important role in promoting the development of the potato industry.