5. BIOCHEMICAL COMPOSITION AND FOOD VALUE OF RIBBON FISH L. SAVALA

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1 5. BIOCHEMICAL COMPOSITION AND FOOD VALUE OF RIBBON FISH L. SAVALA During present study, sixty specimens of fresh L. savala ranging from 200 to 600 mm of total length were collected from Baithkol, Majali and Karwar fish market at monthly intervals from January to December for biochemical estimation and for obtaining the food value. Five gram of fresh flesh from each specimen was taken in the marked watch glass and dried in hot air oven at 70 o C for six days, weighed twice to obtain the same weight. For subsequent estimations dried ground samples were used. The proximate composition was estimated on dry weight basis. Estimations were carried out in triplicate and mean values for every month were obtained statistically. Sekharan (1955) studied the relationship between feeding, maturity and fat content of the muscle of the Ribbon fish, T. haumela. Mohammad and Mahbuba (2011), studied the changes of nutritional value of L. savala. Material and methods Five grams of sample from each fish was taken accurately and blended thoroughly in mortar and pestle. Estimation of moisture Moisture was determined by drying of fine ground sample at o C in the oven for 24 hours duration until getting constant weight. Percentage of moisture was obtained by subtracting dry weight from wet weight X

2 Estimation of protein Protein estimation was done by Lowry et. al. (1951), 10 mg of dried fish tissue sample was taken to which 1 N NaOH was added (for extraction of protein, kept in the water bath for 30 minutes). Then it was cooled at room temperature and neutralized with 1 ml of 1 N HCl. The extracted sample was centrifuged for 10 minutes (2000 RPM); 1 ml aliquot of the sample was diluted with distilled water by taking 1: 9 volumes. From that 1 ml was taken and treated with 2.5 ml Carbonate- tartrate -copper reagent and 0.5 ml Folin s reagent (Kept it for 30 minutes). Then absorbency of sample was read by using spectrophotometer (750 nm). Obtained values were expressed in percentage. Estimation of fat Lipid estimation was done by Folch et.al, (1957) method. 10 mg of dried fish tissue sample was taken and homogenized in 10 ml of chloroform-methanol mixture by taking 2:1 volumes. The homogenate was centrifuged (2000 RPM). The supernatant was washed with 0.9% saline solution in order to remove nonlipids and were separated. The upper layer was discarded by siphoning and lower layer was dried in the oven and weighed. Lipid content was expressed in percent as weight of lipid (mg) / weight of sample (mg) X 100. Carbohydrate estimation Dubois et. al. (1956), method was used for the estimation of carbohydrate (Phenol-sulphuric method). 10 mg dried fish tissue sample was taken and treated with 2 ml of 80% sulphuric acid (It was kept at room 129

3 temperature for about hours for digestion). In the digested sample, 2 ml of 5% phenol reagent was added which was followed by 5 ml conc. H 2 SO 4 (Kept for cooling). Then absorbency of sample was read by using spectrophotometer (490 nm). Obtained values were expressed in percentage. Estimation of calorific content Food value was estimated for the entire Ribbon fish, L. savala, using the calorific equivalents (protein, 5.65 k.cal / g; fat, 9.45 k.cal / g and carbohydrate, 4.2 k.cal / g). Constituents in the sample were expressed as percent then calorific value of sample can be calculated as follows (Phillips, 1969): Calorific value of L. savala = Where: P = protein F = fat C = carbohydrate Results and discussion... K.cal / g Variation in the biochemical composition may be related to the feeding, maturation and spawning of the fish. Study of biochemical composition of L. savala and its food value are the important aspects, as this fish is consumed by only the coastal poor people. It is worthwhile knowing, how far this fish can be made popular as a class protein food to meet the requirements of all classes of people. 130

4 Moisture content In L. savala average highest and lowest values were recorded in the months of June 81.16% (varied between %) and November 89.23% (varied between %) respectively. Moisture content has shown increase in the month of May, average value recorded was 87.23% (varied between %). In rest of the months moisture values showed somewhat similar trend, (Fig.29). Protein content Protein content in the body of L. savala was expressed as percentage of dry weight. Comparatively higher protein values were recorded in the months of January. Average value was (73.12%, varied between %), February (73.62%, varied between %), and in July (74.28%, varied between %), August (74.31%, varied between %) and September (73.44%, varied between %) showed increasing trend, coincided with pre-spawning period in rest of the months values were comparatively lower. Lowest value was recorded during May (71.61%, varied between %), (Fig.30). According to Mohammad and Mahbuba (2011), values of protein content in L. savala during different storage periods were; in fresh fish (71.90%), after six month storage (71.01%), after one year sample storage (69.07%) and after two year sample storage duration (67.22)%. As storage period increased values showed decrease. During present study the values obtained for protein 131

5 showed closely similar results even though different method was used for estimation of protein. Fat content In the month of April comparatively high fat content value was observed. Average fat content was (6.99%, varied between %) followed by sudden decrease in the month of May (6.04%, varied between %) thereafter fat values showed progressive rise from June (6.19%, varied between %) to December (7.71%, varied between %). The highest values were observed in the month of December. Increase in the fat content in the body, was coincided to the pre-spawning period. Lowest fat content values were observed during spawning season in the months of January (6.01% varied between %) and February (6.04%, varied between %) as mentioned above fall in fat content was observed in the month of May too, (Fig.31). According to Mohammad and Mahbuba (2011), values of fat content in L. savala during different storage periods were; in fresh fish (7.79%), after six month storage (7.48%), after one year sample storage (7.21%) and after two year sample storage duration (6.66)%. During present investigation, for the fresh fish sample the fat content values found to be closer to these results. Carbohydrate estimation In L. savala average highest and lowest values for carbohydrate, were recorded in the months of March 0.95% (varied between %) and 132

6 December 0.72% (varied between %) respectively. In rest of the months carbohydrate values showed somewhat similar trend, (Fig.32). According to Mohammad and Mahbuba (2011), values of carbohydrate content in L. savala during different storage periods were; in fresh fish (1.64%), after six month storage (1.28%), after one year sample storage (1.06%) and after two year sample storage duration (0.98)%. During present study carbohydrate values were lying in between %. Ash estimation The average estimated values for ash were comparatively higher (5.42% Varied between %) in the month of August and lower in the month of November (4.31% varied between %). In rest of the months ash content values were closely related to the higher and lower values of ash content, (Fig.33). According to Mohammad and Mahbuba (2011), values of ash content in L. savala during different storage periods were; in fresh fish (4.86%), after six month storage (4.74%), after one year sample storage (4.71%) and after two year sample storage duration (4.64%). During present study lowest and highest ash content values were % respectively. Calorific value of L. savala Calorific value of L. savala was calculated by following formula: Calorific value of L. savala =... K.cal / g 133

7 Where: P = protein F = fat C = carbohydrate. Calorific value of L. savala = = k cal/g Average values of January to December were taken for computing the food value of L. savala. Little Information is available on the biochemical composition and nutritive value of L. savala thus the present attempt has been made. 134

8 90 Moisture % Moisture Jan 12 Feb 12 Mar 12 Apr 12 May 12 Jun 12 Fig.29: Percentage moisture content in the tissues of L. savala from January-2012 to December-2012 % Protein Jan 12 Feb 12 Mar 12 Apr 12 May 12 Jun 12 Fig.30: Percentage protein content in the tissues of L. savala from January-2012 to December-2012 Jul 12 Months Protein Jul 12 Months Aug 12 Aug 12 Sep 12 Sep 12 Oct 12 Oct 12 Nov 12 Dec 12 Nov 12 Dec

9 Fat % Fat Jan 12 Feb 12 Mar 12 Apr 12 May 12 Jun 12 Jul 12 Months Aug 12 Sep 12 Oct 12 Nov 12 Dec 12 Fig.31: Percentage Fat content in the tissues of L. savala from January- % Carbohydrate to December-2012 Carbohydrate Jan 12 Feb 12 Mar 12 Apr 12 May 12 Jun 12 Jul 12 Aug 12 Sep 12 Oct 12 Nov 12 Dec 12 Months Fig.32: Percentage Carbohydrate content in the tissues of L. savala from January-2012 to December

10 Ash % Ash Jan 12 Feb 12 Mar 12 Apr 12 May 12 Jun 12 Jul 12 Months Aug 12 Sep 12 Oct 12 Nov 12 Dec 12 Fig.33: Percentage Ash content in the tissues of L. savala from January-2012 to December

4. Determination of fat content (AOAC, 2000) Reagents

4. Determination of fat content (AOAC, 2000) Reagents 94 ANALYTICAL METHODS 1. Determination of moisture content (AOAC, 2000) 1. Dry the empty dish and lid in the oven at 105 C for 3 h and transfer to desiccator to cool. Weigh the empty dish and lid. 2. Weigh