| Almond(Prunus dulcis),which is also called Amygdalus communis L or American almond,is an important member among tree nut brands.It is mainly cultivated in such countries as Australia,USA(California),Spain and China(Xinjiang);besides it is also one of the most important cash crops around the world.In China,more than 90% of almonds are planted in Xinjiang province with the cultivation area covering nearly one million mu along with more than one billion economical benefits.It is of important significance to the development of regional economy,social stability and national unity.At present,research on the nutrition and functional property of Xinjiang almond has just started and few literaturesare reported on the composition of almond kernel protein,structure and function.Therefore,it is essential to carry out research on the composition of Xinjiang almond kernel protein and functional property and it also has practical guiding significance to the exploration of Xinjiang almond and the industrial development.The paper took several typical almond varieties in south Xinjiang region as the research object,it analyzed their nutrition characteristics by comparison and contrast,majorly focusing on the systematic study of the protein composition of different almond types and their functional properties.The major research results are listed as the following:(1)It analyzed the functional properties of defatted and isolated protein in the 5 tested types of Xinjiang almond varieties.The research result showed that the nutrition content of Xinjiang almond kernel was rich and the content of total protein was comparatively higher.The composition of amino acid in isolated almond kernel protein wasrelatively all-around.The experimental result on the functional properties of defatted and isolated proteins showed that the water-holding rated and oil-holding rate in SC-1 defatted powder was the highest.The water-holding rate in SC-MP isolated almond kernel protein was the highest.The oil-holding rate in SC-1 isolated almond kernel protein was the highest.The order of surface hydrophobicity capacity of defatted almond protein powder was consistent with that of its solubility capacity.(2)It studied the influences of these three defatted processing methods of supercritical fluid extraction,mechanical compression and solvent extraction on protein functional properties of Xinjiang SC-1 almond.The experimental results showed: the denaturation temperature of these three selected proteins was 68.4?,48.1? and 63.4?respectively;the solubility capacity was 50.63%,36.51% and 41.77% respectively;the water-holding capacity was 259.55%,242.16% and 230.86% respectively;the oil-holding capacity was 314.35%,315.28% and 338.24% respectively;the emulsion property was 60.42%,56.14% and 59.55% respectively;the emulsion stability property was 37.50%,49.39% and 28.03% respectively.Such result indicated that the influential impact of defatted methods on almond kernel protein was distinct,and the denaturation temperature,water-holding capacity,solubility capacity and emulsibility of almond kernel protein processed by supercritical defatted method were higher and better;the emulsion stability property processed by mechanical compression was much better and the oil-holding capacity processed by solvent extraction was much better.(3)By LC-MS/MS(Liquid Chromatograph-Mass Spectrometer)technology,it carried out comprehensive detection analysis on full protein of Xinjiang SC-1 almond kernel and 434 kinds of identified proteins were determined by this experiment for the first time.GO analysis was used to determine these identified 434 kinds of proteins and the following biological processes were found: metabolic processes(67.5%),cellular processes(54.1%)and unicellular processes(43.3%);the major molecular functions of almond kernel protein were catalytic activity(48.0%),binding force(45.4%)and structural molecular activity(11.9%);the distribution of protein were in cell(59.9%),cell organelle(44.9%)and cell membrane(22.8%).(4)The Osborne classification method was used to extract albumin,globulin and glutenin from defatted almond powder,and the structure features and unique properties were determined.The experimental results showed that the percentages of essential amino acids in total amino acids among albumin,globulin and glutenin in SC-1 almond kernel were 24.56 %,32.22 % and 39.96 % separately.The content ofsulfhydryl in albumin was the highest,up to 161.64 ?mol/g.The content of disulfide in glutenin was the highest,up to 54.29 ?mol/g.The fluorescence spectra and ultraviolet absorption spectra showed that the content of Trp and Tyr residues on the surface of glutenin moleculein SC-1 almond kernel was the highest among the four proteins.SDS-PAGE analysis revealed that the molecular weight of subunits in SC-1 almond kernel albumin almond was distributed in the range from 245 kDa-21.1 kDa,and the molecular weight of subunits in globulin was in the range from 219 kDa to 11.4 kDa,while the molecular weight of subunit in glutenin was 11 kDa.The major secondary structures of these three proteins were ?-sheet and random coil,and also contained a little amount of ?-helical and ?-turn.(5)It carried out the study of isolation and purification of SC-1 almond kernel 2S-albumin.In SDS-PAGE,the crude extractions in almond kernel albumin were composed of 7 sub bands,in which the contents of 9 kDa,18.5 kDa and 20 kDa were higher.Based on Q Sepharose FF isolation and purification,the major sub bands after purification were mainly distributed in 18.0kDa and 19.5kDa bands.The almond kernel 2S-albumin after purification contained 17 kinds of amino acids,in which the contents of aspartic acid(Asp),glutamic acid(Glu)and arginine(Arg)were obviously higher.By HPLC/MS analysis,it showed that the accurate molecular weight of almond kernel 2S-albumin after purification was 31.40 kDa.In its secondary structure,the ?-sheet was 65.9%,the ?-helix was 9.7%,the ?-turn was 4.5% and the irregular curl was 19.9%.The content of purified protein carbonyl in almond kernel 2S-albumin was 4.45nmol/mg,the content of active sulphur was 39.95?mol/g,the content of total sulphur was 57.11?mol/g and the surface hydrophobicity was 23.45?g.The denaturation temperature was 43.3?. |
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