(Oncorhynchus mykiss) (+ ºC) * (// : //: ).. (Oncorhynchus mykiss). ( C) Thiobarbituric acid (TBA) Free Fatty Acids (FFA) (TVC) Total Viable Count Total Volatile Basic Nitrogen (TVB-N)... TVC TVB-N TBA. ( ) TVB-N ( log cfu/g) TVC. (Oncorhynchus mykiss) : E-mail: zolfaghari.mz@gmail.com - : - : : *
....(Yildiz et al., 2004)..(Bremner, 2002) Arashisar et ).(al., 2004 Rezaei et al., ).(2008.. -...(FAO, 2009). (Oncorhynchus mykiss) Statistical Yearbook of Fisheries Organization of ).(Iran, 2008 -. Barat et al., ).(2006 Rezaei and Hosseini, ).(2008.(Gram and Dalgard, 2002) % Mahmoud ).(et al., 2006 (HUFA ) (EPA ) (DHA ).(Steffen, 1997) 1- High unsaturated fatty acids 2- Eicosapentenoic acid 3- Decosahexanoic acid
. ). ) ( (... FFA ) % FFA / ) (% / (. ). (. ( ) ml (/ N) NaOH =/ gr / / ( FFA ( ) = (TBA). (1997) Egan et al. HACH, DR/2000, ) (USA (MDA) (TBA). 1- Malonaldehid.. ( ± SD ±ºC)... - ) ( -. AOAC 2005; 938, ) ºC (08. (AOAC; 950, 46) (James, 1995) Vap 40 Kjeldtherm. Gerhardt / James, ). (1995 Gerhardt SE 416 Soxtec. ( ).. (FFA) Egan et al.. (1997).
... - Goulas and Kontominas. (2007).. -ºC ) (... - -.. Mann-Whitney U Kruskal-Wallis.. %.. SPSS 13 -. (TVB-N ) (1998) TVB-N. Parvaneh ( ). /. ( ) TVB-N= / / (TVC) ( - Siskos (2007). ) ( Seward -.. ( ) PCA. ( ). cfu/gr.. % 1- Total volatile basic nitrogen 2- Plate count agar
- TVC. TVC.. TVC -.... * - (Oncorhynchus mykiss) ( ) /±/ /±/ /±/ /±/. * - FFA.. FFA FFA FFA.(P</).(P>/) - TBA TBA.(P>/) (P</) TBA.(P>/). TBA - TVB-N. TVB-N. TVB-N TVB-N.(P</).
... 7 a درصد اسيد اولي يك 6 5 4 3 2 f e d c b b 1 (Oncorhynchus mykiss) ( ± SD) -..( ºC) ميلي گرم مالون آلدهيد در هر كيلوگرم نمونه 2.5 2 1.5 1 0.5 0 a b b b c e d (Oncorhynchus mykiss) ( ± SD) -..( ºC). ميلي گرم نيتروژن در 100 گرم فيله 65 60 55 50 45 40 35 30 25 20 15 10 5 0 g f e d c b a (Oncorhynchus mykiss) ( ± SD) - -..(ºC).
9 8 d a a a log cfu/g 7 6 5 f e 4 g 3 (Oncorhynchus mykiss) ( ± SD) -..(ºC). امتياز 12 10 8 6 4 2 0.(ºC) (Oncorhynchus mykiss) -. امتياز 12 10 8 6 4 2 0.(ºC) (Oncorhynchus mykiss) -.
... امتياز 12 10 8 6 4 2 0.(ºC) (Oncorhynchus mykiss) -. امتياز 12 10 8 6 4 2 0.(ºC) (Oncorhynchus mykiss) -. TVC. TVB-N. - TVC / ** (ºC) (Oncorhynchus mykiss) FFA / ** -/ ** TBA / ** / ** / ** TVB-N / ** / ** / ** / ** TVB-N TBA FFA TVC. **
Ramanathan and ).(Das 1992 Goulas and Kontominas ).(2007.. TBA.(Chouliara et al., 2004) TBA.(Bremner, 2002). TBA. TBA TBA Jeevanandam et ).(al., 2001; Goulas and Kontominas 2007.(Silva and Ammerman 1993) TBA - (Goulas and Kontominas, 2007) FFA. / Rezaei and Hoseeini (2008). Rezaei FFA et al. (2008). FFA.(Aubourg and Medina, 1999) FFA.(Bremner, 2002) FFA.(Lugasi et al., 2007) FFA.(Abourg, 2001) FFA. FFA.(Losada et al., 2004) TBA.
... / log cfu/g / log cfu/g. Venugopal, ) log cfu/g TVC (2006. TVC. TVC (Mahmoud et al., 2006) - (Rezaei et al., 2008) - (Arashisar et al., 2004) C.. log cfu/g.. TVB-N TVB-. N.. TVC TVC. TVB-N....(Huss, 1995) TVB-N.. Arashisar et ) TVB-N.(al., 2004. TVB-N (Gram and Huss, 1996) TVB-N... TVB-N.(Arashisar et al., 2004) ) TVB-N ( / TVB-N... 1- Lag phase
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119 Journal of Natural Environmental, Iranian Journal of Natural Resources, Vol. 64, No. 2, 2011, pp.107-119 Study of Trend of Chemical and Microbial Changes of Rainbow Trout (Oncorhynchus Mykiss) to Determine the its Optimum Shelf-Life During Storage in Refrigerator Temperature (4 C) M. Zolfaghari *1, B. Shabanpour 2 and S. Falahzadeh 3 1 M.Sc Graduated, Gorgan University of Agriculture and Natural Resources, Gorgan, I.R. Iran 2 Associate Professor of the Gorgan University of Agriculture and Natural Resources, Gorgan, I.R. Iran 3 a M.Sc Student, Gorgan University of Agriculture and Natural Resources, Gorgan, I.R. Iran (Received: 21 November 2009, Accepted: 7 Jun 2010) Abstract Nowadays, importance of keeping and presentation of fresh fish, with regard to consumer preference for fresh fish rather than frozen fish, is increasing. So, determination of fish shelf-life, to find its consumption time, due to high perishability of fish, is important. This study was aimed to investigate the process of spoil changes and determining the shelf-life of rainbow trout (Oncorhynchus mykiss) fillet during storage period in refrigerator (4 C). For this purpose, rainbow trout fillets were kept in refrigerator for 18 days and the changes of free fatty acids (FFA), tiobarbitoric acid (TBA), total volatile bases nitrogen (TVB-N), total viable count (TVC) and sensory evaluations were assessed. The results showed that the quantity of chemical indices increased during storage period. With regard to the standard quantity of TBA, TVB-N and TVC and also sensory evaluation of panel group, the samples were out of the specified standard on 5 day. Considering of correlation between chemical and microbial indices with total acceptability showed that the most precise indices for shelf-life determination of rainbow trout fillet is TVC (6 log cfu/g) indicator and TVB-N (about 25 mg in 100 g fillet). Accordingly, rainbow trout fillet can be kept in refrigerator for 5 days. Keywords: Rainbow trout (Oncorhynchus mykiss), Shelf-life determination, Microbial analysis, Chemical analysis, Sensory assessments refrigerator temperature *Corresponding author: Tel: +98 122 6253101,Fax: +98 122 6253499, E-mail: zolfaghari.mz@gmail.com