| Agriophyllum squarrosum(A.squarrosum),belonging to the Amaranthaceous family within the order of Caryophyllales,is the seed of Agriophyllum squarrosum(L.)Moq.Agriophyllum squarrosum(L.)Moq.has been investigated in studies on seed banks and climate change in the desert and semi-desert regions of Asia because it can tolerate extremely high temperatures,drought,wind erosion and sand burial.As a pioneer plant for windbreak and sand fixation,it is widely cultivated in desert and decertified area in northwest China.The yield of A.squarrosum seeds in the intensive area of wild A.squarrosum can reach 500-950 kg/hm~2.It is a kind of high-quality characteristic desert resource.The content of starch in dehulled A.squarrosum seed is more than 70%,but there were a few reports on the structure,function and application of A.squarrosum starch from different habitats.Ultrasound treatment and heat-moisture treatment,as the eco-friendly technology,are regard as effectively physical method of starch modification.In this study,the physicochemical properties and multi-hierarchy structure of A.squarrosum starch which were from Minqin area of Tengger Desert,Gansu province,Ulanbuhe Desert,Inner Mongolia,and Taole area,Pingluo county,Ningxia province were systematically investigated,and ultrasonic treatment and heat-moisture treatment were used to modify the starch.The result of this study were of economic value to the excavation of Agriophyllum squarrosum(L.)Moq.,which would contact desert ecological management with agricultural development.And it would promote rural revitalization in sand areas,and ensure national food security.The main conclusions are as follows:(1)Three A.squarrosum starches granules had a smooth spherical shape with a mean particle diameter range of 1.12–1.15?m.Both starch samples showed a typical A-type diffraction pattern,and the crystalline degree of three A.squarrosum starch(AS)samples(34.6%-37.95%)were significantly lower(P<0.05)than quinoa starch(QS)(42.79%).AS amylopectin isolated from three A.squarrosum sources had significantly higher Mw(ranging from 5.21×10~6 to 6.13×10~6 g/mol)than QS(Mw,3.27×10~6g/mol)(P<0.05).The fractions content of low DP unit chains(DP 6-24)of amylopectin in AS(83.95%-88.66%)was significantly higher than QS(79.18%).These results confirmed that there were more branching and substituted molecular structures on the glucosyl backbone of AS amylopectin.QS gel had higher RDS content(73.3%)and lower SDS content(20.3%)than the AS samples(ranging from 67.0%to 70.0%,and from 23.2%to 23.8%,respectively).The starch molecules in freshly gelatinized starches are amorphous and susceptible to digestive enzymes.(2)There were two peaks representing CI values of AS-DA(A.squarrosum starch-dodecanoic acid)systems at 10 min(54.98%)and at 12 min(47.50%)during forming,while there was only one peak(51.58%)observed for MS-DA(maize starch-dodecanoic acid)systems.There were different formation behaviors between AS-DA and MS-DA complexes,and AS-DA complexes underwent a process of combination-disruption-recombination with ongoing cooling.The changes on?H,RC,the ratio of1047/1022 values,and RS content of AS-DA samples with different forming time were consistent with the CI values in the time-course experiment.The different formation behaviors between AS-DA and MS-DA complexes may be due to the characteristics of the small granule starch,but the specific reasons need to be further studied.(3)There were no significantly(P<0.05)changes between A.squarrosum starch applied ultrasonic treatment(UT)or heat-moisture treatment(HMT)and native one on the morphological and crystal line(A-type)characteristics.Compared to A.squarrosum starch,the amylose content(from 24.47%to 21.00%,and 17.82%,respectively),molecular weight of amylopectin,swelling power(from 10.00%to 8.53%,and 2.80%,respectively)and solubility(from 13.43%to 10.96%,and 8.35%,respectively)decreased,while the content of resistant starch(from 8.39%to 10.55%,and 14.40%)increased significantly(P<0.05)after UT or HMT.Moreover,the pasting viscosity reduced but the gelatinization temperature increased by dual treatments of HMT and UT.The Mw of UT-HMT starch(1.01×10~6 g/mol)was significantly(P<0.05)lower than HMT starch(2.99×10~6 g/mol).These results indicated that both UT and HMT could significantly change the physicochemical properties of starch,such as gelatinization and in vitro digestion.UT can enhance the sensitivity to HMT.To sum up,AS from three habitats was of A-type starch,which is different from QS.There were more branching molecular structures in AS,and its thermal stability was good.AS-DA complexes underwent a process of combination-disruption-recombination.Compared with maize starch,the complexes forming of A.squarrosum starch and lipid is more controllable.The resistant starch content of A.squarrosum starch could be significantly(P<0.05)increased by UT and HMT.The result showed that A.squarrosum starch was a good material for preparing functional starch. |
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