Portable fluorogenic probe for monitoring of volatile amine vapour and food spoilage

There are urgent needs of volatile amine gas sensors with high-performance in food quality control,disease monitoring and environmental pollution.Thin-film fluorescent probe is suitable for amine vapour sensing due to its high sensitivity,high selectivity,and no polluting analyte.Herein,a novel fluorescent probe based on indacenodithiophene structure withπconjugated system was designed and synthesized.The experimental results show that the films prepared by this material exhibit rapid and distinct fluorescence quenching after being exposed to saturated vapours of primary amine,secondary amine and tertiary amine represented by n-propylamine,diethylamine and trimethylamine,respectively.The quenching of fluorescence is 84%,87%and 96%,respectively,within 10 s.The detection mechanism of probe for primary amine is based on specific chemical reaction,while the detection mechanism for secondary amine and tertiary amine is intramolecular charge transfer.Further experiments show that the detection limit of the fluorescent probe for trimethylamine,an important marker of food spoilage,could reach 4.610 ppt.On-site detection based on spoilage of small yellow croaker suggests the material possesses the potential for food freshness detection.This simple fluorogenic probe is an original approach to simplify real-time visual monitoring of volatile amine vapour.

New strategy to delay food spoilage:Application of new food contact material with antibacterial function

Frequent food poisoning and food-borne diseases outbreaking in recent years have caused people to attach great attention to food safety,especially the food contact materials that are essential in the food industrial chains and daily lives,ensuring their clean sanitation are of great importance in blocking microbial contamination and spread of food-borne pathogens.Stainless steel(SS)is one of the most accepted and widely used food contact material,and the Cu-bearing SS possesses excellent antibacterial performance and maintains the original mechanical properties of SS,maybe making it a better substitute for the conventional SS in the food area.Taking advantages of bactericidal and antifouling properties of Cubearing SS,this study simulated a variety of food contact scenarios,explored a new strategy for food preservation and food safety by using Cu-bearing SS as a food contact material.The results showed that the Cu-bearing SS could not only delay the spoilage of different foods by inhibiting the activity of microorganisms in foods,but also reduce the expressions of spoilage traits of bacteria as well as the formation of biofilms by quenching the quorum-sensing signals,and further creating a good bacteriostatic atmosphere for the contacted food and its surrounding environment.In addition,the remarkable antifouling property of Cu-bearing SS would give the material a self-cleaning feature for food applications,which can avoid secondary contamination of food as a source of contamination.This study well demonstrates that the Cu-bearing SS has broad application potentials and prospects in the food area.

A biopolymer-based pH indicator film for visually monitoring beef and fish spoilage

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.