During postmortem storage,fluoride in Antarctic krill can be enriched in the muscle.Trypsin,as the most important digestive enzyme in Antarctic krill with a high activity in low temperature,plays a potential role in t...During postmortem storage,fluoride in Antarctic krill can be enriched in the muscle.Trypsin,as the most important digestive enzyme in Antarctic krill with a high activity in low temperature,plays a potential role in this process.In this study,endogenous trypsin was purified and its properties were investigated.The involvement of trypsin in the generation of free fluoride from Antarctic krill cuticle was explored.Cuticle microstructure before and after hydrolysis was compared with scanning electron microscopy,and the ash samples of the hydrolyzed Antarctic krill cuticle were analyzed with X-ray diffraction,Fourier transform infrared spectroscopy,and electron dispersive spectroscopy,respectively.Mass spectrometry analysis and inhibition tests confirmed that the purified enzyme was endogenous trypsin.Results of the present study indicated that trypsin digestion caused the increases of the concentrations of both fluoride ions and free amino N simultaneously,while the protein coated on the cuticle surface was dissolved too.However,no compositional change was detected in the cuticle inorganic salts.These findings suggest that trypsin triggered free fluoride release from Antarctic krill cuticle.In addition,the kinetics of free fluoride release could be described by the equation C_(W)=(1-0.97^(-0.006t)-0.03e^(0.0558t))×337.53+10.50.The present study improved the understanding of the role of trypsin in free fluoride release from Antarctic krill cuticle,facilitating future studies aimed at reducing the fluoride content in krill protein during Antarctic krill processing.展开更多
The cause of the concentration of fluoride in Antaractic krill is studied by the analysis of the characteristics of fluoride change in the cuticle of the krill before and after moulting. Associated with other related ...The cause of the concentration of fluoride in Antaractic krill is studied by the analysis of the characteristics of fluoride change in the cuticle of the krill before and after moulting. Associated with other related information, the source and accumulating mechanism of fluoride in krill are also disscussed. Results show that as an inorganic medium the cuticle of krill has the second concentrating function and action to fluoride after moulting , which has nothing to do with the biological action of the krill. The fluoride is concentrated from seawater, which is prosecuted mainly in the form of ion exchange.展开更多
The aim of the study is to investigate the existing form and the partitioning pattern of fluoride in krill (Euphusia superba) by analysing the fluoride and other elements in various part of krill, primarily to approac...The aim of the study is to investigate the existing form and the partitioning pattern of fluoride in krill (Euphusia superba) by analysing the fluoride and other elements in various part of krill, primarily to approach the potential concentrating mechanism and the effect of fluoride in krill on the geochemical characteristics of fluoride in the Antarctic ecoenvironment. The results of the study show that the amount of flouride in various part of krill has a considerable difference. Most of fluoride is concentrated in the carapace, up to 4028 μg/g, and the head and legs, respectively 2724 μg/g and 2828 μg/g. The muscle contains the least flouride with amount of 226 μg/g. The amount of fluoride in whole freeze - dried krill is averagely 1232 μg/g, which indicates that the functional position of fluoride in krill is mainly located at the crust. Only a few of fluoride is found in the chitin of the carapaces (200 μg/g), which exhibits that fluoride in the carapaces exists mostly in the form of the nonchitious constitutent. In addition, the variation and concentration of flouride is related closely to some other elements such as P, Ca. Thus, fluoride in the carapaces is likely to exist as the form of the inorganic salt with P and Ca. It is also estimated frorn the study that a slightly higher concentration of fluoride in seawater and lower in sediment of the area relative to other oceans is possibly affected by the concentration of fluoride in the huge storage of krill in the area. The bioprocesses and precipitation with relation to the activity of krill should be very important and key sectoin to the geochemical cycling of the fluoride in Antarctic ocean.展开更多
Water-washing removes fluoride from Antarctic krill but produces large volumes of wash water containing water-soluble proteins and fluoride. The freeze concentration method was tested to determine if it could be used ...Water-washing removes fluoride from Antarctic krill but produces large volumes of wash water containing water-soluble proteins and fluoride. The freeze concentration method was tested to determine if it could be used to recover water-soluble proteins while leaving the fluoride in solution. After freezing and thawing the wash water, protein and fluoride contents of the thawed fractions were determined to explore the melting regularity of components in the wash water. The highest concentration factors of protein and fluoride were obtained after 80 min of thawing, such as 1.48 ± 0.06 and 1.35 ± 0.04 times, respectively. The free amino-nitrogen(FAN) content and sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern results revealed that the highest concentrations of all ingredients were obtained after 80 min of the process. The degree of hydrolysis of all fractions from the thawing process fluctuated in a narrow range around 12% during the entire process, indicating that the thawing order did not change with various proteins or time during the entire thawing course. These results demonstrate that the freeze concentration method can be used to concentrate protein solutions, even those with fluoride. It was concluded that condensation was achieved and no ingredient could be separated, regardless of fluoride, amino acids, or different proteins in the water.展开更多
基金supported by the Guangdong Provincial Key Laboratory of Aquatic Product Processing and Safety(No.GDPKLAPPS2005)the School Level Talent Project of Lingnan Normal University(No.ZL2021009)+2 种基金the Science and Technology Planning Project of Zhanjiang(No.2020A01040)the Study on the Preparation of Active Polypeptide from the Processing Waste of White Shrimp and its Fatigue Resistance(No.2021E05022)the Scientific Research Capacity Improvement Project of the Key Construction Discipline of Guangdong Province(No.2022ZD JS079).
文摘During postmortem storage,fluoride in Antarctic krill can be enriched in the muscle.Trypsin,as the most important digestive enzyme in Antarctic krill with a high activity in low temperature,plays a potential role in this process.In this study,endogenous trypsin was purified and its properties were investigated.The involvement of trypsin in the generation of free fluoride from Antarctic krill cuticle was explored.Cuticle microstructure before and after hydrolysis was compared with scanning electron microscopy,and the ash samples of the hydrolyzed Antarctic krill cuticle were analyzed with X-ray diffraction,Fourier transform infrared spectroscopy,and electron dispersive spectroscopy,respectively.Mass spectrometry analysis and inhibition tests confirmed that the purified enzyme was endogenous trypsin.Results of the present study indicated that trypsin digestion caused the increases of the concentrations of both fluoride ions and free amino N simultaneously,while the protein coated on the cuticle surface was dissolved too.However,no compositional change was detected in the cuticle inorganic salts.These findings suggest that trypsin triggered free fluoride release from Antarctic krill cuticle.In addition,the kinetics of free fluoride release could be described by the equation C_(W)=(1-0.97^(-0.006t)-0.03e^(0.0558t))×337.53+10.50.The present study improved the understanding of the role of trypsin in free fluoride release from Antarctic krill cuticle,facilitating future studies aimed at reducing the fluoride content in krill protein during Antarctic krill processing.
文摘The cause of the concentration of fluoride in Antaractic krill is studied by the analysis of the characteristics of fluoride change in the cuticle of the krill before and after moulting. Associated with other related information, the source and accumulating mechanism of fluoride in krill are also disscussed. Results show that as an inorganic medium the cuticle of krill has the second concentrating function and action to fluoride after moulting , which has nothing to do with the biological action of the krill. The fluoride is concentrated from seawater, which is prosecuted mainly in the form of ion exchange.
基金Project was supported by the State Antarctic Committeethe National Natural Science Foundation of China
文摘The aim of the study is to investigate the existing form and the partitioning pattern of fluoride in krill (Euphusia superba) by analysing the fluoride and other elements in various part of krill, primarily to approach the potential concentrating mechanism and the effect of fluoride in krill on the geochemical characteristics of fluoride in the Antarctic ecoenvironment. The results of the study show that the amount of flouride in various part of krill has a considerable difference. Most of fluoride is concentrated in the carapace, up to 4028 μg/g, and the head and legs, respectively 2724 μg/g and 2828 μg/g. The muscle contains the least flouride with amount of 226 μg/g. The amount of fluoride in whole freeze - dried krill is averagely 1232 μg/g, which indicates that the functional position of fluoride in krill is mainly located at the crust. Only a few of fluoride is found in the chitin of the carapaces (200 μg/g), which exhibits that fluoride in the carapaces exists mostly in the form of the nonchitious constitutent. In addition, the variation and concentration of flouride is related closely to some other elements such as P, Ca. Thus, fluoride in the carapaces is likely to exist as the form of the inorganic salt with P and Ca. It is also estimated frorn the study that a slightly higher concentration of fluoride in seawater and lower in sediment of the area relative to other oceans is possibly affected by the concentration of fluoride in the huge storage of krill in the area. The bioprocesses and precipitation with relation to the activity of krill should be very important and key sectoin to the geochemical cycling of the fluoride in Antarctic ocean.
基金supported by the Key Research and Development Project of Shandong Province (No.2015 GSF115005)the Huimin Special Fund of Qingdao Municipal Achievement Transformation Plan (No.15-9-2-120NSH)the National Natural Science Foundation of China (No.31101380)
文摘Water-washing removes fluoride from Antarctic krill but produces large volumes of wash water containing water-soluble proteins and fluoride. The freeze concentration method was tested to determine if it could be used to recover water-soluble proteins while leaving the fluoride in solution. After freezing and thawing the wash water, protein and fluoride contents of the thawed fractions were determined to explore the melting regularity of components in the wash water. The highest concentration factors of protein and fluoride were obtained after 80 min of thawing, such as 1.48 ± 0.06 and 1.35 ± 0.04 times, respectively. The free amino-nitrogen(FAN) content and sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern results revealed that the highest concentrations of all ingredients were obtained after 80 min of the process. The degree of hydrolysis of all fractions from the thawing process fluctuated in a narrow range around 12% during the entire process, indicating that the thawing order did not change with various proteins or time during the entire thawing course. These results demonstrate that the freeze concentration method can be used to concentrate protein solutions, even those with fluoride. It was concluded that condensation was achieved and no ingredient could be separated, regardless of fluoride, amino acids, or different proteins in the water.
