The Fundamental Study On Utilization Of Longan Seed

Longan(Dimocarpus Longan Lour),is a famous sapindaceae fruit and have 2000 years in China.Longan is a very important south-asian tropic fruit.However longan will metabolize vehemence,loose moisture and browning because longan mature in the hot and humid period of the year,which influence the storage and distribution of longan.The storage tecniof longan is still unmature,with the develop of longan wine, longan cane,dried longan and other production of longan,the separation between pulp and seed of longan and the utilization ratio of longan seed are both low at present. This article is not only studing on the main nutrient components,the extraction processing and characteristic of longan seed's brown pigment,but the antioxidant of longan seed's brown pigment and The results are showed as follows:(1)The longan seed is full of amylum,reducing sugar,coarse-fibred,protein,pectic and flavone,meanwhile it contains multiform nutrient elements such as mineral elment,vitamin and amino acid ect,is a potential source.The content of amylum, reducing sugar,coarse-fibred,protein,pectic,tannic acid,fat,ash and flavone is 60.88%,9.67%,6.85%,5.58%,5.19%,4.72%,3.23%,2.05%and 0.14%.(2)The distilled water or 60%is good for extracting the longan seed's brown pigment,the extraction rates was 0.1301%or 0.1303%,is appropriate for extracting the longan seed's brown pigment,but the acetone or methanol is not.Orthogonal test results showed that the best technology for extracting the longan seed's brown pigment is:60%ethanol,extract at 30℃for 12 h.In the extract flow of longan seed's brown pigment by ethanol,the consentration of ethanol play a major role,followed by the extraction temperature,the last is extraction time.Application software matlab7.01 to study on three factors of concentration of alcohol,extraction temperature and extraction time,and it showed that the best technology for extracting the longan seed's brown pigment is:60%ethanol,extract at 37℃for 12 h,basically the same with the orthogonal test results.Verification test results showed that the best technology for extracting the longan seed's brown pigment is:60%ethanol,extract at 37℃for 12 h.(3)The longan brown pigment in UV sect have two absorption peak,one is strong, the other is weak.The best isλ_max=240nm,there is a weak absorption peak atλ=350nm The longan brown pigment is water color,which is easy dissolve in polar solvent and difficult in non-polar solvent;the stability against of light,heat,neutral and alkaline medium is good,in alkaline condition,absorbance will raise,and some reversible structure could be found in molecules.It has good oxidation resistance and anti-reduction and oxidation resistance is stronger than anti-reduction.Add H₂O₂ and Na₂SO₃ will let the original maximum absorption peak shift,that isλmax moved from 240 nm to 270 nm;It will keep stable when meet with 4 metal ions:K⁺,Na⁺,Mg²⁺, Ba²⁺,while adding CuSO₄ and FeCl₃,the color changes.Al³⁺and Ca²⁺can deepen the color of the pigment,when Zn²⁺is equivalent to 2.5%C₄H₆O₄Zn·2H₂O,The abosoption of longan seed's brown pigment decline.Some common food additives have little effect on pigment's absorbance except for citric acid and V_c,The abosoption of longan seed's brown pigment decline as citric acid or V_c being added. Longan seed's brown pigment is a mixture of flavonoid and anthocyanin.(4)The clearance of extraction of longan seed against NaNO₂,O₂^-,and.OH is 78.0%,90.23%and 86.54%respectively.The effect of factors on O₂^- eliminated by longan seed's extract are different from each other,the temperature and NaCl, MgCl₂'effect is a little,while the effect of time is great,with the extension of time, the capability of the extraction declines;V_c can increase effectiveness of the extraction;There are no distinct impact on this capability with adding NaCl,MgCl₂; as for AlCl₃,CaCl₂,the capability of the extract decline obviously.