| In recent years,with development of economic,the consumption of high-protein foods in the diet of residents has gradually increased.Such foods are prone to spoilage due to microbial activities during storage and transportation.The degradation of proteins will produce a large amount of biogenic amines.These volatile biogenic amines will make the surrounding environment of the food become weakly alkaline.The use of indicators sensitive to p H changes can indicate the p H changes,it will reflect the freshness of the food to a certain extent.Hydroxyanthraquinone derivatives are blue-violet or orange-red in alkaline aqueous solutions,which can be used to indicate changes in environmental p H.The hydroxyanthraquinone derivative is formed into a film in different ways to prepare biogenic amine response film,which is placed in food packaging box and can be used to monitor the freshness of the food.This research first studied the influence of different substituents of hydroxyanthraquinone on the p H response sensitivity,and then formed the film through different methods to find a more suitable film formation method to improve the safety while maintaining the sensitivity.The main research contents are summarized as follows:(1)A series of hydroxyanthraquinone derivatives were synthesized through alkylation reaction,and the inductive effect of carboxyl group,methyl group and chlorine atom on p H response sensitivity and biogenic amine response performance was explored.The results show that the electron-withdrawing substituent can increase the sensitivity to p H of hydroxyanthraquinone.The most sensitive molecule is 2-chloro-1,4-dihydroxy-6-carboxyanthraquinone(DCQ-Cl),which changes at p H 7.The changes can be discerned by the naked eye.(2)In order to apply DCQ-Cl to food safety testing,different film-forming methods are used to prepare biogenic amine response film.The film-forming materials of cellulose acetate(CA),ethyl cellulose(EA),and polyvinyl alcohol(PVA)are formed by solvent casting,and low-density polyethylene(LDPE)is formed by hot pressing.Test the response of biogenic amine response film prepared by different film-forming methods to volatile biogenic amine sensitivity,and test its mobility,swelling rate,water solubility rate and water contact angle in aqueous solution.The results showed that the biogenic amine responsive film material prepared by PVA has good p H response performance,and can be used to monitor the freshness of food and respond to the spoilage of food in real time.(3)In order to further improve the safety of biogenic amine response films,TEMPO oxidized crystal nanocellulose(TOCNC)is prepared,and the carboxyl groups on DCQ-Cl and TOCNC are cross-linked with aziraldehyde crosslinking agent.Fixed on TOCNC to obtain modified TOCNC,which was fully mixed with PVA aqueous solution and then used to form a film to prepare a biogenic amine responsive composite film,and tested its response sensitivity to butanediamine and food freshness monitoring performance.The results showed that after cross-linking DCQ-Cl and TOCNC,it was formed into a film with the PVA aqueous solution.With the increase in the amount of modified TOCNC,the swelling rate was gradually reduced,and the mobility was also reduced to a certain extent,but its response sensitivity to biogenic amines was also a certain degree of reduction has occurred.When the mass fraction of modified TOCNC is 0.25%,the overall performance is optimal,and the spoilage of food freshness can be monitored. |
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