Research On Rapid Detection Methods Of Formaldehyde In Squids

Although annual output of squid in China was about four hundred thousand tons,the annual Import of raw squid in China need three hundred thousand tons.Unfortunately,a severely situation happens incessantly in some countries that squids in the market are soaked in formaldehyde aqueous solution to preserve the squid appearance and extend the shelf-life,which hinders the survival and development of squid industry.Formaldehyde not only be carcinogenic,but also could damage DNA.Hence,formaldehyde has been banned to be added into food,especially aquatic product.Various countries in the world not only provided the maximum usage and residue limits of formaldehyde content in squid,but also developed various determination methods including spectrophotometry,electrochemistry and Chromatography.Although those methods are reliable and accurate,high expenses,and time-consuming complicated pre-treatment processes would hinder them for rapid determination.Due to massive output of squids in market,which has conventional detection methods complicated operations,high expenses,and time-consuming pre-treatment processes is not conducive to fast monitoring formaldehyde content in squids.A rapid quantitative analysis of formaldehyde concentration in squids for rapid screening of massive samples is urgently needed in practical process.Main results in this study were below.?1?A rapid and quantitative detection method of formaldehyde in squid for screening massive samples was established based on tri-step IR method.Firstly,the HPLC method for formaldehyde determination was established and optimized based on the standard method?SC/T 3025-2006?.Secondly,Tri-step infrared spectroscopy was employed to rapidly analyze the chemical profile variances of squids soaked in different formaldehyde concentrations,and then a quantitative prediction model was established.Finally,prediction accuracy of the model by t-TEST and HPLC was checked.The results were indicated that chemical profile variances of squids were rapidly analyzed by Tri-step infrared spectroscopy.Specifically,with increasing formaldehyde concentration,peak intensities of 2927 cm^-1(v_as?CH₂?),1081 cm^-1?glycogen?,1631cm^-1??-sheet?decreased while 1655 cm^-1??-helix?increased.Spectral curve-fitting results further disclosed that?-sheet proteins were transformed to?-helix and?-turn conformations.Furthermore,a quantitative prediction model based on IR spectra was established by PLS?R²:0.9787,RMSEC:5.51?.The developed method was applicable for rapid?c.a.5 min?and quantitative analysis of formaldehyde in squids with LOD of9.7 mg/kg.?2?The aim was to establish a rapid and quantitative detection method of formaldehyde in squid based on electronic nose for screening massive samples.Identification of volatile compounds in squid with different formaldehyde content by electronic nose were mainly depended on eight sensors.Besides,the diversities of volatile constituents in squids with increasing contents of aldehydes and aromatic compounds were validated by GC-MS results.Moreover,to build a qualitative discrimination model for estimating whether formaldehyde in squid over standard limit or not,DFA and SIMCA based on PCA were used to analyze data of electronic nose data for semi-quantitative determination of formaldehyde content in squid.Finally,a rapid quantitative prediction model based on electronic nose and PLS was established?R²=0.9266?.To verify the accuracy of quantitative model,t-test was employed and no significant difference between predicted values and true values was found.?3?Response surface methodology was employed to optimize parameters of ultrasonic extraction method,and then the phloroglucinol system were optimized,moreover,a rapid and quantitative detection method of formaldehyde in squid was established.The results were indicated that optimized parameters were ultrasonic power of 142 W,extraction time of 15.7 min,temperature of 54?and extract 1 time.Furthermore,the quantitative detection method based on optimized phloroglucinol system has great detection effect with R² of 0.9902 in the formaldehyde range of 0³3ppm.The aim was to establish a rapid and quantitative detection method of formaldehyde in squid based on ultrasonic extraction and chemical coloration method for screening massive samples.These rapid detection methods have different advantages.For example,detection method based on tri-step IR have more information about the chemical profile variances of squid,moreover,the pre-treatment of detection method based on electronic nose were more simple,and the detective time of detection method based on ultrasonic extraction method and chemical coloration method were more brevity.These detection methods could be employed to rapid analytical and quantitative evaluation of formaldehyde content in squid for screening massive samples.Furthermore,they approach showed well potentiality to provide a rapid,nondestructive and quantitative method for detecting chemical residue in food.Moreover,they could provide a reference for the quality evaluation and control of food safety at the stages of aquatic product storage and processing.