Species Identification And Quality Evaluation Of Surimi Based On The Spectrum And Its Imaging Techniques

Surimi as an important middle material in aquatic food processing,has become a worldwide extensive use of food raw materials because of its nutrition value and economic benefit.With people's growing consciousness of food safety and quality,the analysis and detection method of surimi quality is an urgent need to innovate.The most common used method is chemical analysis method,but there are many defects such as single index,time-consuming,laborious and unfriendly to environment.The infrared spectrum and its microscopic imaging technique can detect various forms samples with directly,fast,nondestructive and multicomponent detection at the same time,thus it obtain the spatial information and spectral information of sample with synchronization.In this paper,the characterization methods of infrared spectroscopy(IR)and its imaging combined with electronic sensory evaluation,low field nuclear magnetic resonance(NMR)and its imaging techniques were fully utilized.The whole IR macroscopic fingerprint of surimi nutrient component and the recognition mechanism of surimi species were obtained,at the same time the microscopic characteristics of surimi chemical composition distribution are also revealed.The qualitative and quantitative discriminant analysis of two common adulterated(soy protein,starch)in silver carp surimi can be detected by using the rapid identification of surimi species and quality.The results in this study are as follows:(1)Tri-step macro infrared spectroscopy(Fourier transform infrared spectroscopy(FT-IR)integrated with second derivative infrared(SD-IR)spectroscopy and two-dimensional correlation infrared spectroscopy(2DCOS-IR))combined with electronic sensory evaluation technology were used to identify the different species of marine fish surimi(red sea bream(Pagrosomus major)surimi,hairtail(Trichiurus haumela)surimi,gurnard(Lepidotrigla abyssalis)surimi and trash(large yellow croaker(Pseudosciaena crocea)and small yellow croaker(Larimichthys polyactis)mixed)surimi).For different species of surimi,the differences in chemical composition and structure(such as lipid,protein secondary structure)has different IR macroscopic fingerprint(amide ? band,amide ? band and lipid absorption band),namely the recognition mechanism.200 surimi samples(50 for each surimi)in the infrared spectrum PCA model were successfully distinguish,and the model's reliability was proved by external validation sample.Four species surimi can be effectively identified by electronic eyes and electronic nose fingerprint from the color and the smell,and distinguish index are respectively 98 and 82,thus distinguish effect is good.It has been demonstrated that the Tri-step infrared spectroscopy combined with electronic sensory evaluation analysis could be a scientific and powerful tool for rapid chemotaxonomic discrimination of surimi in a holistic manner.(2)Qualitative and quantitative analysis of soybean protein and starch in silver carp surimi was carried out by using Tri-step infrared spectroscopy combined with chemometric.With increase the content of adding starch and soybean protein in surimi,the characteristic peak of lipid and sugars in spectrum showed significant gradient.For specific wavenumber region of 1710~1500 cm-1 and 1200~900 cm-1(protein and sugar characteristic peak wavelengths),the second derivative spectrum showed apparent higher resolution.The results revealed that the soybean protein and surimi protein have an inner difference on IR fingerprint characteristics,and explored the detection limit of containing starch surimi at 1%~5% and containing soy protein surimi at 5 mg/g~10 mg/g in the macro spectrum infrared.The auto-peak relative strength of specific constituents(proteins,carbohydrates)wavenumber in two-dimensional correlation infrared spectrum can directly reveal the differences among pure surimi,pure adulterated sample and different concentration of adulterated one in surimi samples.The quantitative model of partial least squares method in infrared spectrum can accurately and fast predicted the content of soybean protein and starch in silver carp surimi,and correlation coefficient(R2)are above 0.99.The root mean square error correction of soybean protein and starch model were 4.64 and 5.23,furthermore prediction root mean square error(RMSEP)were 4.89 and 5.95.Their scaling effect and prediction accuracy are good.(3)T2 value in low field nuclear magnetic resonance NMR can reflect the moisture state,composition and relative content in different species surimi on a macro level.Combined with low field NMR technology,the proton density in surimi was determined,and it can reflect the moisture distribution in surimi.Thereby the composition,distribution and content of four species surimi moisture could be comprehensively analyzed.Compared with the traditional direct drying method,we found that the results of low field(NMR)technology were highly consistent with traditional technology.The distribution and the relative content of proteins in different species marine surimi and their imaging figure were obtained by IR microscopic imaging technology,and different species surimi also were characterized and identified successfully from micro spatial resolution angle.