عنوان به زبان ديگر :
Effectiveness of fried in different plant oils including olive oil, corn oil and grape seed oil on fatty acid profile, lipid oxidation and sensory properties of grass carp (Ctenopharyngodon idella) fillet compared with raw fish
پديد آورندگان :
گل گلي پور، سارا دانشگاه علوم و فنون دريايي خرمشهر , خدانظري، آي ناز دانشگاه علوم و فنون دريايي خرمشهر - دانشكده منابع طبيعي دريا - گروه شيلات , غانمي، كمال دانشگاه علوم و فنون دريايي خرمشهر - دانشكده علوم دريايي - گروه شيمي دريا
كليدواژه :
Ctenopharyngodon idella , سرخ كردن عميق , روغن‌هاي گياهي , اسيد چرب , اكسيداسيون چربي , ارزيابي حسي
چكيده لاتين :
Introduction: Grass carp (Ctenopharyngodon idella, family Cyprinidae) is one of the main fresh water fish species and highly demanded aquaculture species in Iran. Among the cultivated fish, grass carp, also called farmed white fish, has received great attention because of its similarity to Caspian white fish in Iran. The muscle of fish contains important levels of macronutrient and micronutrient which are beneficial to health. Cooking method can lead to a loss of the nutritional value of foods. The proper cooking methods are important for preserving maximum nutritional value such as proximate, vitamin, mineral and the fatty acid composition. Fatty acid is one of the most important healthy aspects of fish consumption. The fatty acids in fish based on the number of double bonds are saturated fatty acid (SFA), mono unsaturated fatty acid (MUFA) and poly unsaturated fatty acid (PUFA), but it is clear that individual fatty acids within these groups have distinct biological properties and health effects. Seafood is the only excellent source of the long chain polyunsaturated fatty acids (LC-PUFAs) such as arachidonic acid (ARA), eicosapentaenoic acid (EPA, 20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3) which have markedly different biological functions and physiological properties compared to the shorter chain PUFAs such as α- linolenic acid and linoleic acid. The polyunsaturated fatty acids are considered to be susceptible to oxidation during heating compared with saturated fatty acids. However, in some studies, the EPA and DHA contents remained stable in different species of fish during different cooking methods. The nutritional quality index (NQI) of fatty acid profile and their biological functions are necessary health effects of fatty acids of fish. NQI is calculated by several indices of fatty acid composition including indices of atherogenicity (IA) and the thrombogenicity (IT); hypocholesterolemic/ hypercholesterolemic fatty acid ratio (HH); EPA+ DHA, PUFA/ SFA- stearic acid; PUFA/ SFA ratio; n-3/n-6 PUFA ratios and ARA/ EPA and UFA/ SFA ratios.
Material and methods: On arrival at the laboratory, fresh fish were washed with cold water and filleted and cut into slices with a thickness of 1 cm by hand, and then the fish samples were cooked using AOAC 976.16 procedure. Different cooking procedures were selected as common processing methods used by consumers. The fish fillet samples were placed in a wire mesh basket and immersed in olive oil in a deep fryer for 5 min at 180 ºC. After frying, the basket was shaken and the samples placed on absorbent paper towels. After the cooking process, the samples were cooled to room temperature and the skin and backbone of the samples were removed. All fish in each lot were homogenized using a kitchen blender and analyzed to determine proximate composition, fatty acid composition, minerals and vitamins contents. All assays were conducted on triplicate samples of the homogenates. Proximate composition of cooked and uncooked fish was measured in triplicate for moisture, protein, lipid and ash contents. The moisture content of fish was determined by drying the meat in an oven at 105 ºC until a constant weight was obtained. The crude protein was measured by converting the nitrogen content determined by Kjeldahl̕s method (6.25 × N). The lipid content was extracted by the AOAC (2002) method using the Soxhlet system. Ash content was determined gravimetrically in a muffle furnace by heating at 525 ºC for 24 h. Fatty acids were extracted from fish samples according to the method demonstrated by Folch et al., (1957) with modification. Fatty acids of the extracts were then converted to fatty acid methyl esters (FAMEs). FAMEs were analyzed using a Phillips GC-PU4400 (Phillips Scientific, Cambridge, UK) equipped with a fused silica capillary polar column (BPX70, 60 m×0.32 mm ID, 0.25-μm film thichness, SGM, Victoria, Australia) and a flame ionization detector (FID). The temperature of the injector and FID were 240 and 280 ºC, respectively. Thiobarbituric acid reactive substances (TBARS) and free fatty acid (FFA) value was determined. Significant differences between means were determined by one- way analysis of variance (ANOVA) using SPSS16.0 for Windows (SPSS Inc., Chicago, Illinois, USA). Duncanʼs test was used to compare the means. A significance level of p<0.05 was used.
Results and discussion: Fat and protein contents significantly increased during frying of grass carp fillet and moisture and ash contents significantly decreased (P<0.05). The moisture content of raw fillets was 74.33%, showing a decrease after cooking because of the denaturation of protein structure and evaporation of water during cooking. The fat content significantly increased in deep-frying cooking method compared with raw fillet, due to the oil penetration after water is evaporated during frying. The total lipid content of the fish samples was inversely related to the moisture content. The increase of protein, fat and ash content was found to reduce moisture content. A relative pattern of fatty acid content presented in raw fillet was MUFA>SFA>PUFA. Saturated fatty acid (SFA) of deep-frying samples significantly decreased, while monosaturated fatty acid (MUFA) content of frying samples with raw samples did not show (P>0.05). Polyunsaturated fatty acid (PUFA) content of frying samples with grapseed oil and corn oil was triplicate of raw samples approximately. The n-3/n-6 ratio in raw grass carp fish was 0.33. The n-3/n-6 ratio significantly decreased in samples fried with grapeseed oil (P<0.05). PUFA/SFA, UFA/SFA and HH index increased in fried samples with grapeseed oil and corn oil. Deep-fried of grass carp fillets caused a significant decrease of n-3 content due to the oil absorption during frying. TBA and FFA levels in samples of raw fish was determined 0/19± 0/01 mg malonaldehyde/kg of meat and 7/35± 0/37 % oleic acid. The TBA fried samples showed a significant increase (P<0.05). The highest of TBA content was fillet fried with grapseed oil. FFA content in fried samples showed a significant decrease. The results of sensory properties showed that texture, smell, taste, color and overall acceptability of different methods of deep frying oil is approved by Consumers.
Conclusion: Considering the overall nutritional quality indices and lipid oxidation showed that fried grass carp with corn oil is the best frying method among other plant oil.
