| Chinese Yam is the rhizome of Dioscorea opposite Thunb of Dioscorea plants,which has sweet flavor and is neutral in nature.Because of its invigorating the spleen,the lung, kidney, nourishing the stomach and other effects, Chinese yam is widelyused in clinical practice. Fresh yam is a common nutritious ingredient, while the yamslices used on the clinical are made of fresh yam through the drying process. Thetraditional sulfitation drying yam method had existed for hundreds of years in history,but in recent years, it is found that the residual sulfur dioxide after sulfur fumigationhas great harm to the human body. In order to study the feasibility of the traditionalChinese yam processing method, this paper trys to compare the overall differencesbetween traditional and free-sulfur yam through the active ingredients β-sitosterol,adenosine, linoleic acid in yam, and explore the drying technology of traditional andfree-sulfur yam.Objective: Determined the content of β-sitosterol, adenosine and linoleic acid inthe traditional and sulfur-free yam, and by contrast, to explore the feasibility of thetraditional yam processing methods.Methods:1.According to the provisions of the2010edition “ChinesePharmacopoeia†about yam, determined the moisture, water-soluble extract, total ashcontents and sulfur dioxide residues of the traditional and free-sulfur yam.2.Preferred the best extraction methods of β-sitosterol, adenosine and linoleic acid bysingle factor and orthogonal experiment. Builded the HPLC determination methods ofβ-sitosterol, adenosine and linoleic acid in yam. Used ultrasonic(40KHZ,280W) withthe extraction solvent chloroform which was twenty times of the yam powder toextract β-sitosterol. Used twenty milliliters20%methanol to extract adenosine in onegram yam powder by ultrasonic(40KHZ,420W) one hour. The linoleic acid of yamextraction technology was as follows: ultrasound (40KHZ,350W)30min to extract theoil(free type linoleic acid) of yam by using solid-liquid ratio1:10of methanol as the extraction solvent. The resulting oil in10%NaOH solution, water bathed two hoursunder the condition of temperature80℃,and then extracted with chloroform afterneutralization the solvent with dilute sulfuric acid (bound linoleic acid). The HPLCchromatographic conditions of β-sitosterol were that: acetonitrile–water(97:3) as themobile phase at the flow rate of0.8ml/min,and detected at210nm wavelength, columntemperature was35℃.The HPLC chromatographic conditions of adenosine were that:methanol-phosphate buffer (PH=6.52)20:80as the mobile phase at the flow rate:0.7ml/min, and detected at the wavelength of260nm, column temperature was30℃.The best detection conditions of free type and bound linoleic acid in yam were thatacetonitrile-0.2%acetic acid solution (88:12) as the mobile phase at the flow rate of1.0ml/min, and detected at the wavelength of205nm, the column temperature was35℃.3. Used the three components β-sitosterol, adenosine and linoleic acid in yam asindicators to investigated the effects of heater drying methods on free-sulfur yam andthe amount of sulfur on traditional yam respectively.Results:1.The moisture, water-soluble extract, total ash contents and sulfurdioxide residues in traditional and free-sulfur yam were significantly different. Theirmoisture, water-soluble extract content and sulfur dioxide residues were in line withPharmacopoeia requirements, but most samples’ total ash content was higher thanPharmacopoeia predetermined.2. The β-sitosterol showed a good linear curve in therange of0.4624～2.312μg(R2=0.9999), the average recovery was98.88%with RSDof0.46%. The adenosine showed a good linear curve in the range of0.41～40.88μg/ml(R2=0.9999), the average recovery was98.37%with RSD of0.56%. Thelinoleic acid showed a good linear curve in the range of6.6722～133.5440μg(R2=0.9996), the average recovery of free-type linoleic acid was99.21%with RSD of0.41%, the average recovery of bound linoleic acid was98.91%with RSD of0.51%.3.Through the three indicators β-sitosterol, adenosine, linoleic acid in yam, free-sulfuryam was preferably obtained at65℃blast conditions after drying one hour, and thenchanged to45℃blast to dryness, the traditional yam drying process was that theamount of sulfur was100g/m3, the fumigation time was six hours, and every twohours to reignite the sulfur once.Conclusion: Through comparing of the three active ingredients content, in thegathering traditional and free-sulfur yam, the β-sitosterol, adenosine contents intradiontional yam were lower than free-sulfur yam, while the contents of the free typelinoleic acid and the bound linoleic acid in traditional yam has no significant difference with free-sulfur yam. It is found that after sulfitation β-sitosterol,adenosine, linoleic acid were all reduced by comparing the machining traditional andfree-sulfur yam. Sulfitation traditional methods of processing yam need to control theamount of sulfur, and strict practices to ensure the safety of traditional yam. Theestablished methods for the determination of β-sitosterol, adenosine and linoleic acidcontent had good repeatability, high precision, good stability, quickly and easily. |
