The importance of meat preservation and various reports on different types of packaging, and to compare the effects of modified atmosphere packaging （MAP） and vacuum packaging （VP） on shelf life of flesh bull meat...The importance of meat preservation and various reports on different types of packaging, and to compare the effects of modified atmosphere packaging （MAP） and vacuum packaging （VP） on shelf life of flesh bull meat, and microbiological tests on meat together with some chemical and sensory tests was on tight observation. It was an experimental study, 96 samples were randomly packaged in two groups of MAP and VP equally. The package consists of five layers which are Polyvinylidin Chloride （PVDC）, Ethyl Vinyl Alcohol （EVOH）, Poly Ethylene （PE）, Linear Low Density Poly Ethylene （LLDPE）, and poly Amid （PA）, respectively. MAP meat with 700 mL of CO2 per kg of meat. The packaging were made in at-ameh-pars factory and transported in chilled condition to a well prepared refrigerator in National Research Institute of Food Science （NRIFS） of Shahidbeheshti University of Medical Sciences. These samples tested weekly, since first day after packaging, and week 2, 3, 4, 5, 6, 7, and 8. Microbial tests include Total Microbial, Coliform, Lactic Acid Bacteria, Pseudomonas Counts, and Clostridium. Chemical and sensory tests also carried out. Total volatile bases （TVN）, TBA, and pH as chemical analyses and color, odor, and weep as sensory analyses are also added. Results revealed that total microbial count was in standard range within the 6 weeks for VP, and 5 weeks for MAP technique. Other microbial factors including coliforms, lactic acid bacteria are less and somehow in chemical and sensory tests emphasized the microbial figures. recommended for meat packaging. similar pattern to total count, and no clostridia were found. By the way, The results showed that according to our existing facilities, VP is展开更多
气候变暖已成为全球面临的严重问题,各国均积极应对。食品体系产生大量温室气体,其碳足迹已成为研究热点。本研究依据产品碳足迹全生命周期评价标准,从单元操作角度计算不同包装(真空、空气和气调包装)操作工艺碳足迹。主要研究结论如下...气候变暖已成为全球面临的严重问题,各国均积极应对。食品体系产生大量温室气体,其碳足迹已成为研究热点。本研究依据产品碳足迹全生命周期评价标准,从单元操作角度计算不同包装(真空、空气和气调包装)操作工艺碳足迹。主要研究结论如下:包装200 g熟食米饭,在真空包装和空气包装条件下,最终碳足迹为:34.05±0.01 g CO_2eq和57.94±0.01 g CO_2eq。气调包装条件为40%O_2+20%CO_2+40%N_2、50%O_2+20%CO_2+30%N_2、60%O_2+20%CO_2+20%N_2和70%O_2+20%CO_2+10%N_2时,最终碳足迹分别为:214.39±0.26 g CO_2eq,220.53±0.26 g CO_2eq,224.76±0.55 g CO_2eq和230.58±0.52 g CO_2eq。研究发现使用塑料制品带来的碳排放在最终碳足迹中占较高比例,并且气调包装中使用气体产生的最终碳足迹占比较高。敏感性分析显示,包装过程中碳足迹对塑料制品排放因子是敏感的;空气及气调包装过程中碳足迹对设备排放因子变化以及电力使用效率变化是稳定的,而真空包装过程对两者敏感。可通过减少使用塑料制品,降低产品最终碳足迹。展开更多
Waste heat recovery from the flue gas of gasfired boilers was studied experimentally by measuring the flow and heat transfer of air and water through six kinds of packing with saturated humid air as the simulated flue...Waste heat recovery from the flue gas of gasfired boilers was studied experimentally by measuring the flow and heat transfer of air and water through six kinds of packing with saturated humid air as the simulated flue gas.The experiments measured the effects of inlet air temperature, inlet air velocity and circulating water flow rate on the flow and heat transfer. The results show that higher inlet air temperatures and lower inlet air velocities lower the flow resistance and increase the heat transfer coefficient. The stainless steel packing had better surface wettability and larger thermal conductivity than the plastic packing, which enhanced the heat transfer between the water and the saturated moist air. When both the flow resistance reduction and the heat transfer enhancement were considered, the experimental results gave an optimal packing-specific surface area. A packed heat exchanger tower was designed for waste heat recovery from the flue gas of gas-fired boilers based on the experimental results which had better flow and heat transfer characteristics with lower pump and fan power consumption, more stable system operation and less thermal fluctuations compared with a non-packed heat transfer system with atomized water.展开更多
文摘The importance of meat preservation and various reports on different types of packaging, and to compare the effects of modified atmosphere packaging （MAP） and vacuum packaging （VP） on shelf life of flesh bull meat, and microbiological tests on meat together with some chemical and sensory tests was on tight observation. It was an experimental study, 96 samples were randomly packaged in two groups of MAP and VP equally. The package consists of five layers which are Polyvinylidin Chloride （PVDC）, Ethyl Vinyl Alcohol （EVOH）, Poly Ethylene （PE）, Linear Low Density Poly Ethylene （LLDPE）, and poly Amid （PA）, respectively. MAP meat with 700 mL of CO2 per kg of meat. The packaging were made in at-ameh-pars factory and transported in chilled condition to a well prepared refrigerator in National Research Institute of Food Science （NRIFS） of Shahidbeheshti University of Medical Sciences. These samples tested weekly, since first day after packaging, and week 2, 3, 4, 5, 6, 7, and 8. Microbial tests include Total Microbial, Coliform, Lactic Acid Bacteria, Pseudomonas Counts, and Clostridium. Chemical and sensory tests also carried out. Total volatile bases （TVN）, TBA, and pH as chemical analyses and color, odor, and weep as sensory analyses are also added. Results revealed that total microbial count was in standard range within the 6 weeks for VP, and 5 weeks for MAP technique. Other microbial factors including coliforms, lactic acid bacteria are less and somehow in chemical and sensory tests emphasized the microbial figures. recommended for meat packaging. similar pattern to total count, and no clostridia were found. By the way, The results showed that according to our existing facilities, VP is
文摘气候变暖已成为全球面临的严重问题,各国均积极应对。食品体系产生大量温室气体,其碳足迹已成为研究热点。本研究依据产品碳足迹全生命周期评价标准,从单元操作角度计算不同包装(真空、空气和气调包装)操作工艺碳足迹。主要研究结论如下:包装200 g熟食米饭,在真空包装和空气包装条件下,最终碳足迹为:34.05±0.01 g CO_2eq和57.94±0.01 g CO_2eq。气调包装条件为40%O_2+20%CO_2+40%N_2、50%O_2+20%CO_2+30%N_2、60%O_2+20%CO_2+20%N_2和70%O_2+20%CO_2+10%N_2时,最终碳足迹分别为:214.39±0.26 g CO_2eq,220.53±0.26 g CO_2eq,224.76±0.55 g CO_2eq和230.58±0.52 g CO_2eq。研究发现使用塑料制品带来的碳排放在最终碳足迹中占较高比例,并且气调包装中使用气体产生的最终碳足迹占比较高。敏感性分析显示,包装过程中碳足迹对塑料制品排放因子是敏感的;空气及气调包装过程中碳足迹对设备排放因子变化以及电力使用效率变化是稳定的,而真空包装过程对两者敏感。可通过减少使用塑料制品,降低产品最终碳足迹。
基金support extended by the National Basic Research Program of China(2013CB228301)is gratefully acknowledged
文摘Waste heat recovery from the flue gas of gasfired boilers was studied experimentally by measuring the flow and heat transfer of air and water through six kinds of packing with saturated humid air as the simulated flue gas.The experiments measured the effects of inlet air temperature, inlet air velocity and circulating water flow rate on the flow and heat transfer. The results show that higher inlet air temperatures and lower inlet air velocities lower the flow resistance and increase the heat transfer coefficient. The stainless steel packing had better surface wettability and larger thermal conductivity than the plastic packing, which enhanced the heat transfer between the water and the saturated moist air. When both the flow resistance reduction and the heat transfer enhancement were considered, the experimental results gave an optimal packing-specific surface area. A packed heat exchanger tower was designed for waste heat recovery from the flue gas of gas-fired boilers based on the experimental results which had better flow and heat transfer characteristics with lower pump and fan power consumption, more stable system operation and less thermal fluctuations compared with a non-packed heat transfer system with atomized water.
