Changes in the proximate and fatty acid composition in carp meat during the semi intensive farming

Abstract

The aim of this study was to examine and evaluate the proximate composition and fatty acid profiles of carp (Cyprinus carpio) during rearing in the semi-intensive farming conditions, supplementary fed extruded feed. Carp at the age of two years was submitted to trials, from spring to autumn, at the fish farm 'Ečka' AD. Samples of carp were collected in April, June, September and October. The protein content in fish sampled in September was significantly different from the protein content in fish sampled in April, June and October (p lt 0.001), (17.48%, 17.27%, 18.28% and 17.26%, respectively). The quantities of total lipids slightly increased (2.25%, 2.37%, 3.02% and 4.72%, respectively) with the increase of the fish weight (598 g, 874 g, 1439 g and 1984 g, respectively), but significant increases occurred between September and October (p lt 0.001). The moisture content decreased (79.55%, 78.86%, 77.46% and 75.72%, respectively). Principal Component Analysis (PCA) and Linear Discrimination Analysis (LDA) indicated that there were significant changes in the fatty acid composition of carp during growth. Starting from April to October the quantities of fatty acids were as follows: SFA (saturated fatty acids) - 28.47%, 28.97%, 24.86% and 23.66%, respectively; MUFA (monounsaturated fatty acids) - 38.57%, 40.52%, 41.68% and 42.43%, respectively; PUFA (polyunsaturated fatty acids) - 32.53%, 30.49%, 31.53% and 32.55%, respectively. The additional feeding of carp with the extruded feed influenced the increase in quantities of MUFA and n-6 PUFA (24.98%, 22.86%, 26.96% and 27.99%, respectively), and the decrease in quantities of the nutritionally important n-3 PUFA (5.13%, 6.59%, 4.57% and 4.57%, respectively). The highest n-3/n-6 ratio was obtained in June (0.30) and the lowest in October (0.16), indicating that the applied extruded feed was rich in n-6 and poor in n-3 PUFA. PCA and LDA have shown that significant changes in the fatty acid composition of carp during the breeding occurred. Separation of the carp according to the sampling period was achieved by the LDA analysis, which is consistent with the type of ingested food.

Cilj ovog rada bio je ispitivanje osnovnog hemijskog i masnokiselinskog sastava šarana (Cyprinus carpio) u toku uzgoja u poluintenzivnom sistemu uz prihranjivanje ribe ekstrudiranom hranom, kao i statistička evaluacija dobijenih rezultata. Eksperiment je realizovan od proleća do jeseni, na ribarskom gazdinstvu 'Ečka'AD, a korišćen je dvogodišnji šaran u nasadu za dvogodišnji. Uzorci šarana su uzimani u toku aprila, juna, septembra i oktobra meseca. Sadržaj proteina u šaranu koji je uzorkovan u septembru značajno se razlikovao od sadržaja proteina u šaranu koji je uzorkovan u aprilu, junu i oktobru (p lt 0,001), (17,48%, 17,27%, 18,28% i 17,26%, respektivno). Količine ukupnih lipida su blago rasle (2,25%, 2,37%, 3,02% i 4,72%, respektivno) sa povećanjem mase ribe (598 g, 874 g, 1439 g i 1984 g, respektivno), a između septembra i oktobra došlo je do značajnog povećanja ukupnih lipida (p lt 0,001). Sadržaj vlage se smanjivao (79,55%, 78,86%, 77,46% i 75,72%, respektivno). Analiza glavnih komponenti (Principal Component Analysis, PCA) i diskriminaciona linearna analiza (Linear Discrimination Analysis, LDA) ukazuju da je u toku perioda rasta ribe došlo do značajnih promena u sastavu masnih kiselina. U periodu istraživanja, od aprila do oktobra, količine masnih kiselina su bile sledeće: ZMK (zasićene masne kiseline) - 28,47%, 28,97%, 24,86% i 23,66%, respektivno; MNMK (mononezasićene masne kiseline) - 38,57%, 40,52%, 41,68% i 42,43%, respektivno, PNMK (polinezasićene masne kiseline) - 32,.53% , 30,49, 31,53% i 32,55%%, respektivno. Prihranjivanje šarana ekstrudiranom hranom uticalo je na porast količina MNMK i n-6 PNMK (24,98%, 22,86%, 26,96% i 27,99%, respektivno), kao i na smanjenje količina nutritivno važnih n-3 PNMK (5,13, 6,59%%, 4,57% i 4,57%, respektivno). Najveći odnos n-3/n-6 masnih kiselina dobijen je u junu (0,30), a najmanji u oktobru (0,16), što ukazuje da je ekstrudirana hrana koja je na ribnjaku korišćena bila bogata sa n-6 i siromašna sa n-3 PNMK. PCA i LDA su pokazale da je došlo do značajnih promena u sastavu masnih kiselina šarana tokom uzgoja. LDA analizom postignuto je razdvajanje šarana prema periodu uzorkovanja, a što je u korelaciji sa vrstom unete hrane.