| Coix seed(Coix lacryma-jobi L.var.mayuen Stapf)is a dry mature seed,which is a commonly used traditional Chinese medicine and a popular and commonly eaten food.It has been proven to have detoxification,dehumidification,reduce cancer risk and other effects.However,coix seed itself is hard to cook and inconvenience to people's daily consumption.Studies show that coix seed esters in Coix seed extract,in particular 1-palmitoyl-2-linoleic acid-3-oleic acid Glyceryl ester(PLO),is the major representative substances in Coix seed.Therefore,a quantitative method of 1-palmitoyl-2-linoleyl-3-oleylglycerol(PLO)was established.The changes of representative substances in cooking,microwave,roasting,and extrusion processes and the best way to further develop instant coix seed powder were systematically studied to determine a process method with high content of representative substances and good quality.PLO was prepared by semi-preparative HPLC,and the purity of PLO verified by LC-MS was 98.74%,which could be used as standards in follow-up research.Ten triacylglycerol fractions of CSO were separated in this article and it's necessary to mention that it upgraded the separation of triacylglycerol in CSO from 7 to 10 by high performance liquid phase with evaporative light scattering detector.A mobile phase consisting of acetonitrile(A)and isopropanol/n-hexane(v:v,1:1)(B)was used for separation with a gradient elution at a flow rate of 1 mL/min.Conditions of analysis: column,a Nacalai Cosmosil C18-MS-II column(250 mm × 4.6 mm,5 ?m)was kept at 30°C and gradient elution was performed as follows: from 0 min 30% B,up to 18 min 35% B,up to 35 min 40% B,up to 40 min 35% B,finally returned to 30% B at 50 min.The inner day and intraday precision of PLO were 1.10%,2.46%,accuracy(recovery): 99.20%.Thus,the method is precise and reliable for quantitative analysis of PLO.And to ensure the product has sufficient representative ingredients,we compared eight kinds of coix seeds in China,the ZJ(Zhejiang Kanglaite unpeeled coix seed)with the highest content of representative substances was selected as processing raw materials.Second,the changes of representative substances in cooking,microwave,roasting,and extrusion processes were studied,as well as the relationship of representative substances with the power,pressure,moisture content,temperature,and time within each processing method,and the reasons for the change of representative compounds.The results showed that the time,temperature,pressure and other factors have less effect on the oil content compared with the processing methods.During the processing,the C18:2,C16:0 fatty acid content in the coix seed oil decreased,while the C18:1 fatty acid increased.The percentage of triglyceride containing linoleic acid in triglycerides,especially in the 1st or 3rd place,decreased particularly significantly.It can be seen that the content of PLO is not only affected by oil content,fatty acid composition,but also its triglyceride.Ester position configuration is associated.Since the linoleic acid contained in the triglyceride PLO is in the second position of triglycerides,it is relatively stable,and thus it can be seen that the content of PLO is not only affected by the oil content,fatty acid composition,but also related to its triglyceride position.The result showed that the content of representative substances(PLO)was: roasting(7.34 mg/g)> cooking(6.72 mg/g)> microwave(6.45 mg/g)> extrusion(4.32mg/g).Thus,roasting is the ideal choose.Then,the best way to further develop instant coix seed powder was studied.The stability,fluidity,solubility and color of the powders were compared for cooking,microwave,roasting and extrusion,and the power,pressure,moisture content,temperature,and time within each processing method on these properties were also compared.It was found that the product quality of coix seed powder was directly related to the processing method,and not closely related to the other factors within the processing method.The results showed that the extrusion is the optimal choose.Because the content of representative substances and the qualities of powder are directly determined by the processing method,it is not possible to obtain the instant coix seed powder with high representative substance content and good product properties by squeezing segmented processing or segmented roasting.Therefore,both extrusion and roasting were chosen to produce the product.Taking the rehydration and the content of representative compounds as indicators,the best process conditions of roasting is: temperature: 150°C,time: 30 min;extrusion parameters is: temperature: 150°C,moisture content: 20%,and the roasting/extrusion powder ratio was 1:2.In this condition the instant coix seed powder are of good quality,and meet people's demands. |
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