As a novel food quality monitoring technology,intelligent freshness indicator has received wide attention in recent years.However,its poor safety and stability are the main problems hindering its practical application...As a novel food quality monitoring technology,intelligent freshness indicator has received wide attention in recent years.However,its poor safety and stability are the main problems hindering its practical application.Hence a new pH-sensing indicator based on bromocresol green(BCG)was developed in this study for nondestructive and real-time monitoring the freshness of marine fishes.The indicator was designed with a three-layer structure,using the polytetrafluoroethylene(PTFE)membrane with high hydrophobicity and air permeability as the inner layer to isolate the moisture in the package,BCG-coated filter paper as the colorchanging layer to indicate the freshness of fish,and a transparent unidirectional permeable(TUP)membrane with moisture resistance as the out layer to isolate the moisture in the environment.This contributed to weaken the influence of humidity and prevent dye migration,so as to improve the accuracy and safety of the indicator.Therefore,a highly sensitive and distinguished color variation response to trimethylamine(TMA)standard solution with different concentrations was observed on the indicator.Additionally,the indicator showed a high color stability at different storage temperatures up to 14 days with total color differences(ΔE)less than 5.0.The indicator presented visible color variations from yellow to green then eventually to blue when applied to monitor the freshness of sea bass and salmon stored at 4℃,implying that fish was spoiled.Meanwhile,indicatorsΔE value was significantly positively correlated with total volatile basic nitrogen(TVB-N)and total viable count(TVC)in sea bass and salmon samples.Thus,the pH-sensing indicator can be applied as a cost-effective and promising intelligent indicator for monitoring fish freshness.展开更多
A multiwalled carbon nanotubes/poly(bromocresol green) modfied glassy carbon electrode (MWNTs-PBG/GCE) was used to investigate the electrochemical behavior of reduced glutathione(GSH). GSH showed an irreversible oxida...A multiwalled carbon nanotubes/poly(bromocresol green) modfied glassy carbon electrode (MWNTs-PBG/GCE) was used to investigate the electrochemical behavior of reduced glutathione(GSH). GSH showed an irreversible oxidation process on MWNTs-PBG/GCE with an oxidation peak at 0.77 V(vs. SCE) in a phosphate buffer solution(pH=4.0). The kinetic parameters of the electrochemical behavior of GSH on MWNTs-PBG/GCE were calculated. Under the optimal conditions and with the help of amperometric method, a linear relationship was obtained between the oxidation peak current and GSH concentration in the range from 2×10-7 mol/L to 5×10-6 mol/L with the detection limit as 1×10-8 mol/L(signal-to-noise ratio of 3). The current reached the steady-state current within about 5 s. The modified electrode surface had very good reproducibility and stability.展开更多
基金This work was supported by the National Key Research and Development Program(No.2019YFD0901705).
文摘As a novel food quality monitoring technology,intelligent freshness indicator has received wide attention in recent years.However,its poor safety and stability are the main problems hindering its practical application.Hence a new pH-sensing indicator based on bromocresol green(BCG)was developed in this study for nondestructive and real-time monitoring the freshness of marine fishes.The indicator was designed with a three-layer structure,using the polytetrafluoroethylene(PTFE)membrane with high hydrophobicity and air permeability as the inner layer to isolate the moisture in the package,BCG-coated filter paper as the colorchanging layer to indicate the freshness of fish,and a transparent unidirectional permeable(TUP)membrane with moisture resistance as the out layer to isolate the moisture in the environment.This contributed to weaken the influence of humidity and prevent dye migration,so as to improve the accuracy and safety of the indicator.Therefore,a highly sensitive and distinguished color variation response to trimethylamine(TMA)standard solution with different concentrations was observed on the indicator.Additionally,the indicator showed a high color stability at different storage temperatures up to 14 days with total color differences(ΔE)less than 5.0.The indicator presented visible color variations from yellow to green then eventually to blue when applied to monitor the freshness of sea bass and salmon stored at 4℃,implying that fish was spoiled.Meanwhile,indicatorsΔE value was significantly positively correlated with total volatile basic nitrogen(TVB-N)and total viable count(TVC)in sea bass and salmon samples.Thus,the pH-sensing indicator can be applied as a cost-effective and promising intelligent indicator for monitoring fish freshness.
基金Supported by the National Natural Science Foundation of China(No.20775044)the Natural Science Foundation of Shandong Province of China(No.Y2006B20)
文摘A multiwalled carbon nanotubes/poly(bromocresol green) modfied glassy carbon electrode (MWNTs-PBG/GCE) was used to investigate the electrochemical behavior of reduced glutathione(GSH). GSH showed an irreversible oxidation process on MWNTs-PBG/GCE with an oxidation peak at 0.77 V(vs. SCE) in a phosphate buffer solution(pH=4.0). The kinetic parameters of the electrochemical behavior of GSH on MWNTs-PBG/GCE were calculated. Under the optimal conditions and with the help of amperometric method, a linear relationship was obtained between the oxidation peak current and GSH concentration in the range from 2×10-7 mol/L to 5×10-6 mol/L with the detection limit as 1×10-8 mol/L(signal-to-noise ratio of 3). The current reached the steady-state current within about 5 s. The modified electrode surface had very good reproducibility and stability.
