Comparison Of Endosperm Starch Granule Development,Degradation And Physicochemical Properties Of Starches From Waxy And Non-waxy Barley

Waxy barley shows special starch quality due to the high amylopectin content,directly affects the edible and processing quality of barley and has potential application value in the food processing and brewing industry.Therefore,the research of waxy barley starch has become a focus of attention.In order to study the structural and physicochemical properties of waxy barley starch,waxy barley cultivars,C2-2 and GK5,and non-waxy barley cultivars,YNP10 and SLM1,were used as materials in this paper.Morphologic changes and differences of endosperm amyloplast in the process of caryopsis development and germination were investigated by using resin semi-thin section technology,histochemical staining technology,frozen section technique and scanning electron microscope observation.Differences of starch structural features and physicochemical properties of four barley cultivars were studied by using Rapid Visco Analyser(RVA),X-ray power diffractometer(XRD)and Fourier transform infrared spectroscopy(FTIR).Main results were as follows.(1)Changes of morphology,fresh and dry weight and water content in the process of caryopsis development of waxy and non-waxy barley cultivars were basically the same,the growth curve showed“S”type.Compared with non-waxy barley,waxy barley has low apparent amylose and total starch content and high soluble sugar content during the whole development period.(2)Compared with non-waxy barley,waxy barley endosperm amyloplast appeared earlier,and the proportion of small amyloid and starch enrichment degree were high.Endosperm amyloplast extended and multiplied along with the development of caryopsis;the accumulation speed of endosperm amyloplast became faster at 9?20 DAF,and the endosperm cells were highly enriched at 27 DAF.(3)The endosperm and pericarp of waxy and non-waxy barley showed difference in response to I2-KI.The developing endosperm of non-waxy barley was stained black blue by I2-KI,while those of waxy barley were stained reddish-brown,but both the pericarp dyeing characteristics consistent in black blue.(4)The degradation of endosperm starch in waxy and non-waxy barley followed certain sequences:consumption of endosperm started from the region adjacent to the embryo,and expanded to the dorsal side away from the embryo along the ventral groove in four germinating barley varieties.Compared with non-waxy barley,the extinction of endosperm amyloplast was earlier in waxy barley,and the rate of degradation of endosperm amyloplast was faster.(5)Waxy and non-waxy barley starch granularity distribution was bimodal,starch grains were divided into A-type large amyloplast(granule size?10?m)and B-type small amyloplast(granule size<10?m),the large amyloplast was spherical-or ellipsoidal-shaped,and most small amyloplasts were more spherical-or irregular-or polyhedral-shaped.Compared with non-waxy barley,waxy barley starch grains have not smooth surface,with more depressions and obvious micropores.There were no significant differences in the polarized crosses of the two types of barley starch grains,and the cross points were located at the center of the starch granules.(6)XRD spectrum analysis showed that waxy and non-waxy barley starch was typical A-type crystal starch,similar diffraction peak,but showed different intensity.The relative crystallinity of waxy barley starch was significantly higher than that of waxy barley.(7)FTIR spectra analysis showed that waxy and non-waxy barley starch have different resonance peak strength in the place of 995 cm-1 and 1045 cm-1,1022 cm-1,with the ratio of 1045/1022 cm-1 and 1022/995 cm-1 formant exist significant difference.Compared with non-waxy barley,the surface structure of waxy barley starch has higher degree of order(8)Waxy and non-waxy barley starch gelatinization characteristics were different,waxy barley had lower gelatinization temperature,low viscosity and back value than non-waxy barley,but had high solubility,swelling potential,initial temperature,peak temperature,temperature,Peak viscosity and attenuation values.(9)NMR spectrum analysis showed that,the area of waxy barley starch C1 crystallization peak strength significantly higher than that of non-waxy barley,and the intensity of amorphous peaks was low.Waxy barley starch in the three conditions of PPA,AAG and HCl of the hydrolysis degree of hydrolysis were significantly higher than that of non-waxy barley.In conclusion,the development and demise of amyloplasts in waxy and non-waxy barley were basically the same,but there were significant differences in coloring characteristics,amyloplasmic forms,starch accumulation,extinction rate and physicochemical properties.The above results not only deepened the research of waxy barley starch,but also provided important information for the application of waxy barley starch in food and non-food industry.