THE COMBINED EFFECT OF ROSEMARY OIL AND CHITOSAN COATING ON QUALITY OF CATFISH FINGERS DURING FROZEN STORAGE
Samya I. A. Hassanin
Processing and Quality Control Department, Central Laboratory for Aquaculture Research, Agricultural Research Center, Egypt
|Received 4/ 8/ 2013||
Accepted 28/ 8/ 2013
This study is attempts to explore the possibilities of utilization of catfish (Clarias gariepinus) by processing of its minced flesh with based value added products and evaluate the effect of rosemary oil in combined with chitosan (2% w/w) on the stability of fingers stored at -18±1ºC for six months. Minced catfish flesh with ingredients were mixed and preparation of fingers. The treatments were control (C1) fingers without treatment then packaging only in low density polyethylene (LDPE) bags, (C2) without rosemary oil and immersed in chitosan (2% w/w) solution in glacial acetic acid for 2 min (as primary edible packaging) then packaging in (LDPE) bags (as secondary packaging), (RO1) catfish fingers with rosemary oil without chitosan was packaging only in (LDPE) bags and (RO2) catfish fingers with rosemary oil and immersed in chitosan then packaging in (LDPE) bags. Some physico-chemical, microbial and sensory parameters of catfish fingers were evaluated during the storage period.
Results indicated that a slowly decrease was observed in moisture, crude protein and fat contents, while ash content was increased for all treatments at end of storage period. The moisture, protein, fat and ash % were higher in catfish fingers (RO2) followed by (C2) samples then (RO1) compared to (C1) catfish fingers. However, rosemary oil and chitosan + LDPE packaging reduced lipid oxidation as displayed in thiobarbituric acid values, chemical spoilage as reflected in pH, total volatile basic nitrogen and trimethylamine nitrogen values, inhibits microbial growth as indicated by total bacterial and psychrotrophic bacterial counts and improves sensory parameters compared to control samples during frozen storage. It was concluded that it can be added rosemary oil as natural preservatives and chitosan with LDPE in order to maintain the quality of fish product and thus prolong its validity.
Key words: Rosemary, Chitosan, Catfish fingers, Sensory quality.