Transfer Characteristics Of Metallic Elements During Production Of Luzhou-flavor Liquor

Metallic multi-elemental composition is essential to the quality of liquor products. Moderate amount of mineral elements is favorable to promote the nutrient value, but the presence of some heavy metal ions in overdosed concentration would not only impair the organoleptic evaluation and stability of liquors but also result in potential hazards to human health. In the meantime, there is an increasing interest in the relationship between the specific production techniques and multi-elemental composition, which might serve as a fingerprint to discriminate famous Chinese liquors produced in specific area from adulterated ones. Although a plethora of studies reported the detection of metal ions in raw materials, liquor products and intermediate products during liquor production, none of them presented investigation on the transfer and change of metallic multi-elemental compositions through the production process. In the present thesis, we endeavored to make some contribution to this research area. With a combination of inductively coupled plasma(ICP-MS) with microwave-assisted digestion, the concentration change of 17 kinds of metal elements were evaluated in Luzhou-flavor liquor in the entire production process including starter manufacturing, grain fermentation, distillation, filtration and also storage. The main contents include the following parts:The composition and concentration of 17 metallic elements including Na, K, As, Pb, Cd, Sn, Ti, Mg, Fe, Cu, Mn, Zn, Ca, Al, Ni, Cr and Ba, which might be introduce into Chinese liquors for raw materials, water, and manufacturing equipment, were measured in raw materials like sorghum, wheat, rice and corn. The results suggested that the detection method that combines inductively coupled plasma(ICP-MS) with microwave-assisted digestion provide an accurate and reliable tool with good linear range and low detection limits for the detection of related metallic elements raw materials. In view of the relative standard error less than 5%, it would be beneficial for following-up studies.17 kinds of common metal elements including Na, K, As, Pb, Cd, Sn, Ti, Mg, Fe, Cu, Mn, Zn, Ca, Al, Ni, Cr and Ba were measured in the starter for Luzhou-flavor liquor in the fermentation using ICP-MS coupled with microwave-assistant decomposition methods. With the employment of SPSS software, statistical analysis of the difference of related metal elements in the out-layer and center in the starter was applied by t-test. The results suggested that the majority of metal elements kept in relatively stable concentrations and showed no significant change after fermentation for 90 days. The amount of Cu and Fe in the center of starter significantly decreased upon increasing fermentation time, which is different to those in the out-layer starter. In the meantime, Zn concentration declined in the starter center but increased in the out-layer. We ascribe the time-dependent concentration change of Cu, Fe and Zn to the selective distribution of aerobic and anaerobic microbes in the starter.The concentration and change of 17 kinds of common metal elements including Na, K, As, Pb, Cd, Sn, Ti, Mg, Fe, Cu, Mn, Zn, Ca, Al, Ni, Cr and Ba were detected in wine lees(fermented grain) in the fermentation process using ICP-MS coupled with microwave-assistant decomposition methods. It suggested that the spatial distribution of the wine lees and the fermentation time exerted clear influence on the concentration of the metal elements in the samples. The concentrations were significantly higher in the mid-lower lees than those in the mid-upper ones, and increased with increasing fermentation time. The increasing rates were much fast in the mid-upper samples than the mid-lower, which reached to a balance after fermentation for 28~35 days while the former showed declined increase after 28 days. The difference in concentration and change pattern of metal elements in wine lees of different spatial distribution may be ascribed to the production and transfer of Huang-shui during fermentation.The composition of Na, K, As, Pb, Cd, Sn, Ti, Mg, Fe, Cu, Mn, Zn, Ca, Al, Ni, Cr and Ba were measured in fermented grains, liquor and related samples using ICP-MS coupled with microwave-assistant decomposition before and after distillation. SPSS was applied to analyze the origin of related elements in liquor samples by t-test. The results suggested that more than 94% of the overall metal elements remained in the wine lees after distillation, while less than 6% metal ions transferred into either Huang-shui or resultant liquor. Heavy metal ions like Pb, Mn and Cr showed relatively less altered ratio than Na, K, Ca and Mg, which significantly reduce the possibility of those hazardous components transfer from polluted raw materials into liquor. It was also found that Ca, Cu, K, Mg, Na, Zn and Ba in liquor samples mainly resulted from wine lees, and the equipment used in the distillation process would lead Fe, Ni, Al and Sn, and even Pb and Cr to the liquor.Change of multi-elemental composition in liquor product after storage in different containers was preliminarily investigated after storage for three months. It was found that the influence of container on the multi-elemental composition was varied. For all containers, significant increase of Cr and Pb was observed, which suggested that containers for liquor storage would likely introduce heavy metal ions contamination. Moreover, Using orthogonal design method, experiments were conducted to evaluate the impact of filtration parameter including amount of powdered activated carbon, immersion time and alcoholic strength of original liquor on the multi-elemental composition in liquor samples after filtration using powdered activated carbon/ diatomite as substrate, as well as that of substrate height, alcoholic strength and filtration speed using granular activated carbon as filtration substrate. It suggested that the filtration substrates not only absorb some metallic components from the liquor but also introduce contamination of several heavy metal ions. For instance, powdered activated carbon/ diatomite absorbed Ba, Cd and Cu but introduced As, Cr and Pb, while granular activated carbon led to contamination of Cr, Cu, Fe and Mg.