Identification Of Aging Seeds Of Grains And Legumes By Infrared Spectroscopy

Seed aging affects seed emergence rate in the field and quality of food.Therefore,the identification of seed aging is of great significance for agricultural production and the quality of seeds as food.In this dissertation,Grain and legume seeds were identified by Fourier transform infrared spectroscopy?FTIR?,second derivative infrared spectroscopy?SD-IR?and two-dimensional correlation infrared spectroscopy?2D-IR?combined with curve-fitting analysis and multivariate statistical analysis?correlation analysis,soft independent modeling classification?SIMCA?and hierarchical cluster analysis?HCA??.The results are as follows:The results showed that the FTIR absorption peaks of five kinds of grain seeds were similar to the starch.The spectra of legume seeds were mainly composed of protein and carbohydrate's absorption peaks.The overall characteristics of the original spectra of seeds in different aging time were similar,but there are some differences in absorption intensity ratio.The absorption intensity ratios showed an increasing trend with the increase of aging time.The ratios were A₂₉₂₇/A₁₀₂₀,A₁₀₇₉/A₁₀₂₀020 for barley seed,A₂₉₂₇/A₁₀₂₀,A₁₁₅₃/A₁₀₂₀020 and A₁₀₇₉/A₁₀₂₀020 for wheat,A2927/A1017,A1156/A1017,A1079/A1017 and A1652/A1017 for sorghum,A2927/A1083,A1155/A1020,A₁₀₈₃/A₁₀₂₀,and A₁₆₄₉/A₁₀₂₀020 for rice,A₂₉₂₇/A₁₀₇₉,A₂₉₂₇/A₁₀₂₀,and A₁₆₅₂/A₁₀₂₀020 for corn,A₁₆₄₉/A₂₉₂₆,A₁₆₄₉/A₁₀₅₂,and A₁₆₄₉/A₁₂₄₀240 for broad bean,A₁₆₄₉/A₂₉₂₉,A₁₆₄₉/A₁₀₅₂,and A₁₆₄₉/A₁₂₄₀240 for red kidney bean,and A₁₆₅₉/A₂₉₂₃923 and A₁₀₆₁/A₂₉₂₃923 for soybean.There were significant differences in SD-IR spectra for grain seeds in the range of1800-800 cm^-11 and for legume seeds in the range of 1800-700 cm^-1.In 2D-IR spectra,the numbers,locations and intensities of auto-peaks and cross-peaks were obvious different in the range of 1000-1350 and 1400-1800 cm^-11 for legume seeds,and in the range of 860-1100,1125-1250 and 1380-1700 cm^-11 for grain seeds.The auto-peaks numbers decreases with the increase of aging time and the intensities decreases with the increase of aging time.Curve fitting analysis showed that there were obvious differences in the positions and superimposed band for grain seeds in polysaccharide region(1200-950 cm^-1)and for legume seeds in protein amide I band(1700-1600 cm^-1)and polysaccharide region(1180-980 cm^-1)at different aging times.Relative content of corresponding peaks of grain seeds of C-O-H,C-O,C-H and C-C changed obviously.And in the aging process of legume seeds,relative content of protein secondary structure?-sheet,?-helix,disordered structure,beta-corner and polysaccharide area's absorption peak were obvious differences in superimposed band.The correlation analysis,SIMCA classification and hierarchical cluster analysis can distinguish seeds with different aging time effectively by using the second derivative spectrum in the range of1800-800 cm^-1.The clustering accuracy can reach 100%.The results showed that it could identify different aging time seeds simply,quickly and nondestructively by using Fourier transform infrared spectroscopy combined with second derivative infrared spectroscopy,two-dimensional correlation infraredspectroscopy,curve-fittinganalysis,softindependentmodeling classificationand systematic cluster analysis.It is hopeful to develop a simple and effective spectral method for identifying seed aging.