Thermal blanching is an essential operation for many fruits and vegetables processing.It not only contributes to the inactivation of polyphenol oxidase(PPO),peroxidase(POD),but also affects other quality attributes of...Thermal blanching is an essential operation for many fruits and vegetables processing.It not only contributes to the inactivation of polyphenol oxidase(PPO),peroxidase(POD),but also affects other quality attributes of products.Herein we review the current status of thermal blanching.Firstly,the purposes of blanching,which include inactivating enzymes,enhancing drying rate and product quality,removing pesticide residues and toxic constituents,expelling air in plant tissues,decreasing microbial load,are examined.Then,the reason to why indicators such as POD and PPO,ascorbic acid,color,and texture are frequently used to evaluate blanching process is summarized.After that,the principles,applications and limitations of current thermal blanching methods,which include conventional hot water blanching,steam blanching,microwave blanching,ohmic blanching,and infrared blanching are outlined.Finally,future trends are identified and discussed.展开更多
The high content of alkali chlorides in municipal solid waste incineration(MSWI) fly ash limit its resource reuse due to the potential environmental risks.In this paper, with superheated steam as the gasifying agent a...The high content of alkali chlorides in municipal solid waste incineration(MSWI) fly ash limit its resource reuse due to the potential environmental risks.In this paper, with superheated steam as the gasifying agent and inducer, chlorides in fly ash were removed by thermal treatment within a moderate temperature range.Thermal treatment experiments were performed under different conditions: temperature(500–800℃), steam addition(mass ratio of steam to fly ash = 0.25–1) and residence time(0.5–3 hr).Iron and aluminum powders were added to fly ash to improve the chlorine removal efficiency.Water-soluble chlorides included Na Cl and KCl, and insoluble chlorides mainly included Ca(OH)Cl.The heating process with the addition of water steam was more efficient than that without steam in terms of the removal performance of water-soluble chlorides.The removal efficiency of soluble chlorides reached 75.25% for a mass ratio of 1:1 after 1-hr thermal treatment at 700℃.When the residence time was increased above 1 hr, the total dechlorination efficiency was not increased dramatically.Moreover, adding iron and aluminum powder into the fly ash improved the removal of water-insoluble chlorides, and the total dechlorination efficiency was increased by 11.41%–16.64%.展开更多
文摘Thermal blanching is an essential operation for many fruits and vegetables processing.It not only contributes to the inactivation of polyphenol oxidase(PPO),peroxidase(POD),but also affects other quality attributes of products.Herein we review the current status of thermal blanching.Firstly,the purposes of blanching,which include inactivating enzymes,enhancing drying rate and product quality,removing pesticide residues and toxic constituents,expelling air in plant tissues,decreasing microbial load,are examined.Then,the reason to why indicators such as POD and PPO,ascorbic acid,color,and texture are frequently used to evaluate blanching process is summarized.After that,the principles,applications and limitations of current thermal blanching methods,which include conventional hot water blanching,steam blanching,microwave blanching,ohmic blanching,and infrared blanching are outlined.Finally,future trends are identified and discussed.
基金supported by Major Science and Technology Program of China for Water Pollution Control and Treatment(No.2017ZX07202).
文摘The high content of alkali chlorides in municipal solid waste incineration(MSWI) fly ash limit its resource reuse due to the potential environmental risks.In this paper, with superheated steam as the gasifying agent and inducer, chlorides in fly ash were removed by thermal treatment within a moderate temperature range.Thermal treatment experiments were performed under different conditions: temperature(500–800℃), steam addition(mass ratio of steam to fly ash = 0.25–1) and residence time(0.5–3 hr).Iron and aluminum powders were added to fly ash to improve the chlorine removal efficiency.Water-soluble chlorides included Na Cl and KCl, and insoluble chlorides mainly included Ca(OH)Cl.The heating process with the addition of water steam was more efficient than that without steam in terms of the removal performance of water-soluble chlorides.The removal efficiency of soluble chlorides reached 75.25% for a mass ratio of 1:1 after 1-hr thermal treatment at 700℃.When the residence time was increased above 1 hr, the total dechlorination efficiency was not increased dramatically.Moreover, adding iron and aluminum powder into the fly ash improved the removal of water-insoluble chlorides, and the total dechlorination efficiency was increased by 11.41%–16.64%.
