Antioxidant and Antimicrobial Effect of Encapsulated Grape Extract inNanochitosan-TPP on Shelf life of Surimi (Clupeonella cultriventris) in 4º ± 1 C

In this study, the effect of an aqueous extract of grape microencapsulated in chitosan nanoparticles (0.5 / 1) was used to evaluate the shelf life of surimi prepared from Kilka fish by ionic gelation method.

Grape was extracted aqueously, and total phenol content was detected by spectrophotometry and phenolic acids of the extract by HPLC method.  Physical properties of nanoparticles including particle size, zeta potentia and PDI were determined with zeta-sizer, and microencapsulation efficiency was determined by spectrophotometer and loading capacity of nanoparticles by HPLC method. Antioxidant activity of free extract and chitosan nanoparticles with / without extract (by DPPH test) was determined.  The total count was determined by cryophilic, mesophilic, pseudomonas, mold, and yeast and inhibition capacity (MIC, MBC and IZ) of selected Gram positive and Gram negative bacteria and mold and yeast in different treatments days (0 , 1 , 3 , 6  and 9 ) at refrigeration temperature.

The data showed that the produced nanoparticles were in a favorable condition (particle size, zeta potential and PDI: 177.5 nm, +32.95 mV and 0.385 and the efficiency of microencapsulation and loading of nanoparticles were 48.95 and 6.19 percent, respectively). The phenolic content of the extract was 2896 ±18 mg/g and the extract in the loaded state showed a higher percentage of antioxidant activity (42.1%). Growth inhibition in microorganisms (gram positive and negative) is also increased and the overall amounts of bacteria and mold and yeast decreased, and the total values of cryophilic bacteria (6.35 ± 0.29 CFU/g), mesophilic bacteria (6.18 ± 0.27 CFU/g), Pseudomonas (5.41 ± 0.14 CFU/g), and mold and yeast (2.45 ± 0.26 CFU/ /g) in the last day of experiment, showed a significant decrease in the growth of microorganisms.   

According to the results, the use of chitosan nanoparticles containing extract in surimi of Kilka fish can delay microbial decay and increase the product resistance to free radicals and thus increase the shelf life of the product during the storage period in the refrigerator.