| State Bureau of Quality and Technical Supervision has formulated the Chinese National Standard "Product of Geographical Indication—Xuanwei Ham"(GB183572001) in2001and reformulated it in2008(GB183572008). As a guidance document, it clearly limits the Xuanwei ham quality detection and control of comprehensive indicators. However, the detection methods of related indicators are deficient. Therefore, according to the requirements of this standard, studying the related analysis methods turns into necessary. Based on the consideration above, this paper will study the detection of colorants, preservatives, peroxide value, heavy metal and microbiological in Xuanwei ham. The main contents of this paper are listed below:1. After the optimizing of the Xuanwei ham colorant (lemon yellow, amaranth, carmine, sunset yellow, allura red) extract, sample pretreatment and the separation and analysis of chromatography conditions, samples are greaded by diethyl ether, extracted by acid methanol, cleaned by C18SPE cartridge and asgradient elution separated by methyl alcohol and the mobile phase consisted of0.02mol/L acetic ammonium to build the invere high performance liquid chromatography method of synthesis colorants in Xuanwei ham. This method can makes five kinds of synthetic colorant elute within15minutes completely, and separated from each other completely. After taking this method into the practice, the relative standard deviation is between0.04%and0.37%and the standard recovery rate is between64.97%and109.69%.2. In order to built the liquid chromatographic separation to detect two frequently used preservatives (sorbic acid and benzoic acid) in Xuanwei ham, this study optimized the extraction solvent and methods and the separation and analysis of chromatography conditions of the sample. As results showed, after the greasing by N-hexane, extracting by methyl alcohol and cleaning by C18, using the Acclaim120C18as stationary phase and the mixed solution of methyl alcohol of volume ratio35:65and0.02mol/L acetic ammonium (PH4) as the mobile phase, the sorbic acid and benzoic acid in Xuanwei ham can be separated and detected effectively in16minutes. After taking this method into the practice, the relative standard deviation is between0.16%and0.23%and the standard recovery rate is between75%and108%, which conform to the analysis requirement of preservative in meat and meat product.3. In the condition of ZB-1701capillary-column chromatography, injector temperature is250℃, base temperature is250℃and FPD temperature is150℃, using30℃/min column temperature procedure as the rate of temperature increase to increase the temperature from50℃to270℃, the method of organophosphorus chromatographic analysis dipterex and dichlorvos and methamidophos in Xuanwei ham was built. This tree kinds of organophosphorus in Xuanwei ham can be separated and detected effectively in6minutes by this method. The detection limits are7ppb,4ppb and2ppb respectively. The sample standard recovery rate is between83.80%and105.09%, which conform to the analysis requirement of organophosphorus in meat and bacon product and the supervision of the Xuanwei ham.4. As the determination of peroxide value of fatty Xuanwei Ham is an important index, determination method of peroxide value in Xuanwei ham was studied. This method added the procedure of sample dehydration. After the sample dehydration, using the oxidated material from the animal fat in the oxidation process to make potassium iodide oxidized into free iodine, then using the sodium thiosulfate to titrate the production of free iodine, the animal fat peroxide value in the sample will be received.5. The analysis method of5heavy metals (Pb, As, Cd, Hg and Cu) in Xuanwei ham was studied. Instead of using the traditional sample pretreatment method (dry-ashing or wet digestion), the microwave digestion technology was used in this method. After the microwave digestion of Xuanwei ham, using the graphite furnace atomic absorption spectrometry to detect the content of Pb and Cd and the atomic fluorescence spectrometry to detect the content of Hg and As and the flame atomic absorption spectrometry to detect the content of Cu. The results showed that the content of these elements in sampling standard basically are below the national limited standard.6. After the homogeneity attenuation of the sample, three sample homogenate with appropriate dilution were choosed to inoculate in the agar plate, lauryl sulfate tryptone medium and the potato-glucose-AGAR medium respectively and cultivate for relevant time. The aerobic bacterial count and contents of coliforms, molds and yeast in Xuanwei ham were detected. The test results show that in the traditional food of Xuanwei ham, aerobic bacterial count is less than10CFU/g, coliforms are less than30CFU/g, the contents of molds and yeast are120CFU/g. |
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