An eco-friendly and visual pH indicator was developed based on cotton fabrics dyed with natural Lycium ruthenicum extract(LRE),whose color changed from red to purple,blue and green at pH of 2-10.Three methods for dyei...An eco-friendly and visual pH indicator was developed based on cotton fabrics dyed with natural Lycium ruthenicum extract(LRE),whose color changed from red to purple,blue and green at pH of 2-10.Three methods for dyeing cotton fabrics with LRE were attempted,namely pre-mordanting,simultaneous mordanting,and post-mordanting methods with different dyeing temperatures,dyeing times and dyebath pH values.The cotton fabrics exhibited the highest K/S value when they were dyed under a dyebath of pH 6 at 20℃for 90 min in the case of the simultaneous mordanting method.Meanwhile,the dyed cotton fabrics also showed reversible pH-dependent color changes.The developed flexible pH indicator based on renewable natural materials is suitable for multiple applications in environmental monitoring and smart textiles.展开更多
A simple method for rapid estimation of the enantioselectivity of lipase in resolution of chiral esters is described. The enantioselectivity of lipase can be estimated rapidly through comparing the difference of hydro...A simple method for rapid estimation of the enantioselectivity of lipase in resolution of chiral esters is described. The enantioselectivity of lipase can be estimated rapidly through comparing the difference of hydrolysis rates for the racemic ester and its slow reacting enantiomer under the same condition because the difference mainly depends on the enantioselective ratio（E values）. The higher the enantioselectivity of enzyme, the larger the difference of hydrolysis rate. The bromothymol blue（BTB） can be used as pH indicator for microplate reader to monitor the formation of acid in lipase-catalyzed hydrolysis of esters. This method has been successfully used to rapidly estimate the enantioselectivity of several lipases in the resolution of glycidyl butyrate.展开更多
A visual pH indicator through purple cabbage dye is selected to test the freshness of venison.Chitosan and cassava starch of an equal weight were used to prepare the film-forming matrix of the indicator.The crystalliz...A visual pH indicator through purple cabbage dye is selected to test the freshness of venison.Chitosan and cassava starch of an equal weight were used to prepare the film-forming matrix of the indicator.The crystallization of natural purple cabbage dyes with a weight ratio of 5%,10%,20%and 40%were added to the matrix,respectively.The pH color test showed that the natural purple cabbage lyophilized powder with a weight ratio of 40%was the best for the pH indicator,which was used to test the freshness of venison stored at 4℃.The total bacterial count,volatile basic nitrogen(TVB-N)and thiobarbituric acid(TBA)of venison were tested through an experiment.When stored at under 4℃,a significant color change of the indicator from pink to blue-green was shown when the total amount of volatile basic nitrogen(TVB-N)(22.78 mg/100 g)exceeded the critical value(20 mg/100 g).The test result showed that the indicator was very sensitive to pH value and it would help customers identify the freshness of venison.展开更多
Food safety is a worldwide public concern that has recently gained increased attention due to the emerging outbreaks of foodborne diseases.Therefore,there is a pressing need to make simple,cost-effective,and environme...Food safety is a worldwide public concern that has recently gained increased attention due to the emerging outbreaks of foodborne diseases.Therefore,there is a pressing need to make simple,cost-effective,and environmentally friendly methods for detecting food spoilage and to mitigate the impact of possible outbreaks.The aim of this study is to develop a biodegradable indicator film which was made by combining cellulose-nanofiber/chitosan dyed with methyl red synthesis(CCM)as a pH indicator film and followed by a single layer coating of polylactic acid(PLA)on its surface,named PLA/CCM film.The microstructural properties of PLA/CCM films were studied using scanning electron microscopy(SEM)and results showed that PLA effectively adhered to the surface of CCM film.The microbial response to PLA/CCM film was determined via a bacterial plating method.It was found that the contact of film with the microbes caused a substantial color change in the film.The coating of PLA upon the CCM film decreased the percentage of the water vapor transmission rate(WVTR).The color of the film vividly altered from slightly red to yellow in response to a pH change in the range of 4-8.The PLA/CCM film was applied to monitor the spoilage of beef and fish at room temperature(23℃)and revealed the onset of food spoilage by displaying the color change from red to yellow after 1 day.The total viable counts(TVC)of microorganisms and pH of the tested beef sample were determined,and the results revealed that both TVC and pH increased concurrently after beef spoilage.展开更多
With enormous amounts of food being wasted at every level of consumption,the future of food security is in jeopardy.The confusion aroused due to“best before”or“use by”can be eliminated by intelligent colorimetric ...With enormous amounts of food being wasted at every level of consumption,the future of food security is in jeopardy.The confusion aroused due to“best before”or“use by”can be eliminated by intelligent colorimetric indicators which communicate the quality of food.pH indicators have gained their attention because they are simple and visually informative.Using natural pigments to fabricate pH indicators can help reducing use of carcinogenic chemicals in packaging.In this work,anthocyanins extracted from a novel flower source named Ipomoea coccinea(ICE)were added to polyvinyl alcohol(PVA)and guar gum(GG)matrix in varying amounts and was applied as antioxidant and intelligent pH indicator film to monitor the freshness of chicken fillets and to visually communicate the quality of chicken.The pH indicator was characterized for halochromism,antioxidant activity,thermogravimetry,water solubility,water contact angle,surface morphology,colorimetry and X-ray diffractograms.The color change of the extract was observed from orange to red to yellow.Film with highest amount of anthocyanin extract has increased thickness of 150.5±17.86a(μm),decreased water vapor transmission rate of 4.95±0.29a(mg day1 cm^(-2))and has a crystallinity of 52.35%.Anthocyanins started to degrade at 65◦C according to thermogravimetric analysis.The film with 20%ICE showed an excellent color change in pH solutions and the highest antioxidant activity of~91%.The food study results suggested that the developed film has the potential to be employed as an active and intelligent visual indicator in poultry packaging.展开更多
To monitor the freshness of chicken,a pH-sensitive film based on sodium alginate,gelatin,and plum peel extract(SGPE)was created.Thickness,color,water contact angle,mechanical characteristics,water content,water vapor ...To monitor the freshness of chicken,a pH-sensitive film based on sodium alginate,gelatin,and plum peel extract(SGPE)was created.Thickness,color,water contact angle,mechanical characteristics,water content,water vapor transmission,light transmission,and pH sensitivity were used to evaluate the performance of the film sample.SEM and FTIR graphs demonstrated that adding plum peel extract made the SGPE film’s internal structure more denser and increased its mechanical property,while decreasing the water contact angle,water content,and WVP value.The color of the SGPE15 film clearly changed from red to yellow-green in various buffer solutions(pH=1-14),demonstrating more pH sensitivity than the SG,SGPE5,and SGPE10 films.On day 6,when checking the freshness of chicken kept at 4℃,the SGPE15 film’s color changed from orange-pink to yellow-green with TVB-N level beyond the allowable limit(15 mg/100 g).The result revealed that the SGPE film might be applied to monitor the freshness of chicken breast flesh.展开更多
In this study,intelligent,pH-responsive colorimetric films were prepared by encapsulating anthocyanins in nanocomplexes prepared from glutenin and carboxymethyl chitosan.These nanocomplexes were added to a corn starch...In this study,intelligent,pH-responsive colorimetric films were prepared by encapsulating anthocyanins in nanocomplexes prepared from glutenin and carboxymethyl chitosan.These nanocomplexes were added to a corn starch matrix and used in the freshness monitoring of chilled pork.The effects of anthocyanin-loaded nanocomplexes on the physical,structural,and functional characteristics of the films were investigated.The addition of anthocyanin-loaded nanocomplexes increased the tensile strength,elongation at break,hydrophobicity,and light transmittance of the films while decreasing their water vapor permeability.This is because new hydrogen bonds are formed between the film components,resulting in a more homogeneous and dense structure.The colorimetric film has a significant color response to pH changes.These films were used in experiments on the freshness of chilled pork,in which the pH changes with changing freshness states.The results show that the colorimetric film can monitor changes in the freshness of chilled pork in real time,where orange,pink,and green represent the fresh,secondary fresh,and putrefied states of pork,respectively.Therefore,the intelligent colorimetric film developed in this study has good application potential in the food industry.展开更多
In this study, we tried to develop the in situ coating methods of hydrophilic polymer solution containing water soluble dye on nonwoven sheet for the colorimetric film sensor. And color change of coated dye according ...In this study, we tried to develop the in situ coating methods of hydrophilic polymer solution containing water soluble dye on nonwoven sheet for the colorimetric film sensor. And color change of coated dye according to contact various gas samples (as strong acid and base, chloroform, ammonia and HF) of this dye-coated nonwoven film was examined for the application of chemically toxic materials detecting tools in the actual site of working place without aid of any kinds of detecting devices. By the addition of electron transfer agent (quinone derivatives), quick color change behaviors were observed within 10 seconds under the contact of various toxic gases in general condition(room temperature, 50% humidity).展开更多
基金Quanzhou City Science&Technology Program of China(No.2019C014R)Innovation and Entrepreneurship Training Program for College Students of Quanzhou Normal University,China(No.S202110399067)。
文摘An eco-friendly and visual pH indicator was developed based on cotton fabrics dyed with natural Lycium ruthenicum extract(LRE),whose color changed from red to purple,blue and green at pH of 2-10.Three methods for dyeing cotton fabrics with LRE were attempted,namely pre-mordanting,simultaneous mordanting,and post-mordanting methods with different dyeing temperatures,dyeing times and dyebath pH values.The cotton fabrics exhibited the highest K/S value when they were dyed under a dyebath of pH 6 at 20℃for 90 min in the case of the simultaneous mordanting method.Meanwhile,the dyed cotton fabrics also showed reversible pH-dependent color changes.The developed flexible pH indicator based on renewable natural materials is suitable for multiple applications in environmental monitoring and smart textiles.
基金Supported by the National Natural Science Foundation of China(Nos.20072011, 20272017)the Foundation of Research Program of Jilin University, China.
文摘A simple method for rapid estimation of the enantioselectivity of lipase in resolution of chiral esters is described. The enantioselectivity of lipase can be estimated rapidly through comparing the difference of hydrolysis rates for the racemic ester and its slow reacting enantiomer under the same condition because the difference mainly depends on the enantioselective ratio（E values）. The higher the enantioselectivity of enzyme, the larger the difference of hydrolysis rate. The bromothymol blue（BTB） can be used as pH indicator for microplate reader to monitor the formation of acid in lipase-catalyzed hydrolysis of esters. This method has been successfully used to rapidly estimate the enantioselectivity of several lipases in the resolution of glycidyl butyrate.
基金Basic Scientific Research Project 2572020DF01 of Northeast Forestry UniversityFundamental Research Funds for Higher Education Institutions of Heilongjiang Province(135309513,135309109).
文摘A visual pH indicator through purple cabbage dye is selected to test the freshness of venison.Chitosan and cassava starch of an equal weight were used to prepare the film-forming matrix of the indicator.The crystallization of natural purple cabbage dyes with a weight ratio of 5%,10%,20%and 40%were added to the matrix,respectively.The pH color test showed that the natural purple cabbage lyophilized powder with a weight ratio of 40%was the best for the pH indicator,which was used to test the freshness of venison stored at 4℃.The total bacterial count,volatile basic nitrogen(TVB-N)and thiobarbituric acid(TBA)of venison were tested through an experiment.When stored at under 4℃,a significant color change of the indicator from pink to blue-green was shown when the total amount of volatile basic nitrogen(TVB-N)(22.78 mg/100 g)exceeded the critical value(20 mg/100 g).The test result showed that the indicator was very sensitive to pH value and it would help customers identify the freshness of venison.
基金This research was supported by(1)North Central Regional Sun Grant Center at South Dakota State University through a grant provided by USDA NIFA(Grant No.SA2000386)the Hatch Project(No.3AR652,3AR692,3AH640 and 3AH658)funded by USDA NIFA through South Dakota Agriculture Experimental Station at South Dakota State University.All supports and helps were highly appreciated,however,only the authors are responsible for the opinions expressed in this paper and for any possible errors.
文摘Food safety is a worldwide public concern that has recently gained increased attention due to the emerging outbreaks of foodborne diseases.Therefore,there is a pressing need to make simple,cost-effective,and environmentally friendly methods for detecting food spoilage and to mitigate the impact of possible outbreaks.The aim of this study is to develop a biodegradable indicator film which was made by combining cellulose-nanofiber/chitosan dyed with methyl red synthesis(CCM)as a pH indicator film and followed by a single layer coating of polylactic acid(PLA)on its surface,named PLA/CCM film.The microstructural properties of PLA/CCM films were studied using scanning electron microscopy(SEM)and results showed that PLA effectively adhered to the surface of CCM film.The microbial response to PLA/CCM film was determined via a bacterial plating method.It was found that the contact of film with the microbes caused a substantial color change in the film.The coating of PLA upon the CCM film decreased the percentage of the water vapor transmission rate(WVTR).The color of the film vividly altered from slightly red to yellow in response to a pH change in the range of 4-8.The PLA/CCM film was applied to monitor the spoilage of beef and fish at room temperature(23℃)and revealed the onset of food spoilage by displaying the color change from red to yellow after 1 day.The total viable counts(TVC)of microorganisms and pH of the tested beef sample were determined,and the results revealed that both TVC and pH increased concurrently after beef spoilage.
文摘With enormous amounts of food being wasted at every level of consumption,the future of food security is in jeopardy.The confusion aroused due to“best before”or“use by”can be eliminated by intelligent colorimetric indicators which communicate the quality of food.pH indicators have gained their attention because they are simple and visually informative.Using natural pigments to fabricate pH indicators can help reducing use of carcinogenic chemicals in packaging.In this work,anthocyanins extracted from a novel flower source named Ipomoea coccinea(ICE)were added to polyvinyl alcohol(PVA)and guar gum(GG)matrix in varying amounts and was applied as antioxidant and intelligent pH indicator film to monitor the freshness of chicken fillets and to visually communicate the quality of chicken.The pH indicator was characterized for halochromism,antioxidant activity,thermogravimetry,water solubility,water contact angle,surface morphology,colorimetry and X-ray diffractograms.The color change of the extract was observed from orange to red to yellow.Film with highest amount of anthocyanin extract has increased thickness of 150.5±17.86a(μm),decreased water vapor transmission rate of 4.95±0.29a(mg day1 cm^(-2))and has a crystallinity of 52.35%.Anthocyanins started to degrade at 65◦C according to thermogravimetric analysis.The film with 20%ICE showed an excellent color change in pH solutions and the highest antioxidant activity of~91%.The food study results suggested that the developed film has the potential to be employed as an active and intelligent visual indicator in poultry packaging.
基金support from the National Natural Science Foundation of China(No.22268024,32060569,and 21576126).
文摘To monitor the freshness of chicken,a pH-sensitive film based on sodium alginate,gelatin,and plum peel extract(SGPE)was created.Thickness,color,water contact angle,mechanical characteristics,water content,water vapor transmission,light transmission,and pH sensitivity were used to evaluate the performance of the film sample.SEM and FTIR graphs demonstrated that adding plum peel extract made the SGPE film’s internal structure more denser and increased its mechanical property,while decreasing the water contact angle,water content,and WVP value.The color of the SGPE15 film clearly changed from red to yellow-green in various buffer solutions(pH=1-14),demonstrating more pH sensitivity than the SG,SGPE5,and SGPE10 films.On day 6,when checking the freshness of chicken kept at 4℃,the SGPE15 film’s color changed from orange-pink to yellow-green with TVB-N level beyond the allowable limit(15 mg/100 g).The result revealed that the SGPE film might be applied to monitor the freshness of chicken breast flesh.
基金funded by the Hainan Provincial Natural Science Foundation of China[Grant Number 2019RC031]National Natural Science Foundation of China[Grant Number 31460407].
文摘In this study,intelligent,pH-responsive colorimetric films were prepared by encapsulating anthocyanins in nanocomplexes prepared from glutenin and carboxymethyl chitosan.These nanocomplexes were added to a corn starch matrix and used in the freshness monitoring of chilled pork.The effects of anthocyanin-loaded nanocomplexes on the physical,structural,and functional characteristics of the films were investigated.The addition of anthocyanin-loaded nanocomplexes increased the tensile strength,elongation at break,hydrophobicity,and light transmittance of the films while decreasing their water vapor permeability.This is because new hydrogen bonds are formed between the film components,resulting in a more homogeneous and dense structure.The colorimetric film has a significant color response to pH changes.These films were used in experiments on the freshness of chilled pork,in which the pH changes with changing freshness states.The results show that the colorimetric film can monitor changes in the freshness of chilled pork in real time,where orange,pink,and green represent the fresh,secondary fresh,and putrefied states of pork,respectively.Therefore,the intelligent colorimetric film developed in this study has good application potential in the food industry.
文摘In this study, we tried to develop the in situ coating methods of hydrophilic polymer solution containing water soluble dye on nonwoven sheet for the colorimetric film sensor. And color change of coated dye according to contact various gas samples (as strong acid and base, chloroform, ammonia and HF) of this dye-coated nonwoven film was examined for the application of chemically toxic materials detecting tools in the actual site of working place without aid of any kinds of detecting devices. By the addition of electron transfer agent (quinone derivatives), quick color change behaviors were observed within 10 seconds under the contact of various toxic gases in general condition(room temperature, 50% humidity).
