Product characteristics, amino acid and fatty acid profiles of milkfish ( Chanos chanos ) with different cooking methods

Different cooking methods would produce different product characteristics. The aim of this study was to identify product characteristics (sensory analysis, texture, color, yield, and proximate analysis), amino acid profile, and fatty acid profile of cooked milkfish. Milkfish were boiled (18 mins, 100°C), steamed (30 mins, 100°C), and pressure steamed (120 mins, 121°C with a pressure of 1 atm). Based on the sensory value, the most preferred milkfish by the panelists was pressure steamed milkfish. Pressure steamed milkfish had the highest a* and b* values and produced the hardest texture. The highest yield was obtained from steaming. The proximate composition showed that boiled milkfish had the highest moisture, ash, protein, and fat content. Different cooking methods had different effects on amino acids and fatty acids because cooking time plays a role in determining changes in the amount of amino acids and fatty acids. Glutamic acid, aspartic acid, lysine, and leucine were the dominant amino acids. The dominant fatty acid profiles were palmitic acid, oleic acid, docosahexaenoic acid (DHA), and linoleic acid. Pressure steaming was the process that took the longest time, so that the proximate and amino acid content in it was lower than boiled and steamed, which had a shorter cooking time. However, pressure steamed cooking resulted in the most preferred product by the panelists.


Introduction
Milkfish belongs to the Chanidae family which is mostly found in the Indo-Pacific as consumption fish.Milkfish (Chanos chanos) is one of the potential commodities of aquaculture that has important economic value.Milkfish production in Central Java, Indonesia from 2018 to 2019 has increased, from 956,944.76 tons to 985,006.27 tons (Statistics and Information Center for Data of the Ministry of Maritime Affairs and Fisheries Republic of Indonesia, 2022).This amount was higher than catfish (149,702.28 tons), carp (17,178.13 tons), and common carp (11,697.53tons) (Statistics and Information Center for Data of the Ministry of Maritime Affairs and Fisheries Republic of Indonesia, 2022).Milkfish cultivation is often found in tropical countries, especially Indonesia, due to the availability of abundant food, fast growth, disease resistance, and tolerance to a wide range of environmental conditions (Vasava et al., 2018).
Most of the milkfish in Semarang, Central Java, Indonesia was processed into products such as softed bone milkfish, smoked milkfish, grilled fish cake, meatballs, sausage, nuggets, fish crackers and other value added products.Tourists are usually use softed bone milkfish as typical gifts from Semarang city.The effect of cooking or processing on milkfish meat components could cause changes in product characteristics and chemical composition of milkfish meat.Several studies have shown that the cooking process that involves heat affects the water content, ash, fat, protein, fatty acids, and amino acids contained in fish (Oluwaniyi et al., 2010;Oluwaniyi et al., 2017;Yu et al., 2017).Cooking or processing is one of the important methods where the purpose of processing is to get the desired quality and effect.The processing also plays a role in flavor formation, provides a lasting effect, and also improves nutritional components.According to Ma et al. (2015), thermal processes significantly affect the flavor and taste of food products.Different cooking methods such as steaming and boiling affect the appearance and texture of the meat, which had a different texture with different humidity (Jiao et al., 2020).
Milkfish were classified as high protein and low-fat fish.Based on the research results of Malle et al. (2019), FULL PAPER the protein content of milkfish originating from Pangkep, Indonesia was 24.18%, with fat content of 0.87%.According to Murthy et al. (2016), milkfish originating from Narasapur, India had protein content of 20.37% with fat content of 3.84%.Proteins are composed of amino acids.The quality of protein was determined by the type and amount of constituent amino acids.Specifically, amino acids were divided into two types, namely, essential amino acids and non-essential amino acids.The higher the levels of essential amino acids in a food, the better the quality of the protein in the food.Different cooking methods in fish affect the physical, chemical, and nutritional content.In addition, the cooking method affects Polyunsaturated Fatty Acids (PUFA) and product acceptance by consumers (Abraha et al., 2018).
This study aimed to determine the product characteristics, amino acid profile, and fatty acid profile of milkfish using different cooking methods.

Sample preparation
Fresh milkfish (Chanos chanos) was obtained from a fish seller at a local market in Sayung District, Demak, Central Java, Indonesia.Fish transportation uses styrofoam boxes, which contain ice cubes to maintain freshness.

Experimental procedure
Fresh fish were removed from the visceral in the laboratory with knives, then cleaned and washed.Cooking methods were used in this study including boiling, steaming, and pressure steaming.The sample was boiled in 5 L water using a temperature of 100°C for 18 mins.Milkfish was steamed in 2.5 L water using a temperature of 100°C for 30 mins.Next, the fish was put into an autoclave which had been filled with water and then cooked using a temperature of 121°C, a pressure of 1 atm with a cooking time of 120 mins.

Sensory analysis
Sensory analysis was carried out using a hedonic assessment sheet based on the Indonesian National Standard (2015) SNI 2346:2015.The hedonic scale ranges from 1 to 9. The samples were divided into three groups depending on three different cooking methods.Each group was taken in triplicate, and then the panelists were given a hedonic scoresheet, descriptive test file, water, and tissue.The panelists were six undergraduate students of Fisheries Products Technology, Universitas Diponegoro, Semarang City, Indonesia.

Yield
The yield was calculated by dividing the weight of the final product (ripe product) by the weight of the whole fish product (raw product) (Hafiluddin, 2014).The calculation of the yield percentage uses the following formula:

Texture (hardness)
The texture (hardness) was analyzed by the Texture Analyzer tool.Whole fish samples were divided into two parts and then analyzed for texture (hardness).The probe was installed and then positioned close to the sample.After the probe was close to the sample, the computer operated to run the probe.This method was according to the procedure described by Untoro et al. (2012).

Color
Fish color was determined by measuring the values of L (lightness), a* (component (+) red to (-) green) and b* (component (+) yellow to (-) blue).Taking pictures using a Logitech camera connected to a PC and Logitech Camera software.Color testing was measured using the Software smartphone "Color Grab" (Loomatix).The picture was taken using a styrofoam box in the form of a cube with size (30×30×30 cm).The sample was placed in a box with a white background and sufficient lighting.The captured image was entered into the application.Then, the selected image was locked and picked as a color sample.

Proximate analysis
The moisture or water content of milkfish was analyzed using the Association of Official Analytical Chemists method at a temperature of 105°C to constant weight (AOAC, 2005).The ash content of milkfish was analyzed using the Association of Official Analytical Chemists method at a temperature of 550°C (AOAC, 2005).Milkfish protein content was analyzed using the Kjeldahl method (AOAC, 2005).Fat content in milkfish was analyzed using the soxhlet (National Standardization Agency of Indonesia, 2017).

Amino acid profile
Amino acid profile analysis using UPLC (Ultra Performance Liquid Chromatography) method.The sample of about 0.1-1.0g was put into a 20 mL headspace vial.The sample was added with 5-10 mL of 6 N HCl solution and hydrolyzed in an oven at 110°C for 22 hrs.The hydrolyzed sample was transferred to a 50 mL volumetric flask, and aquabides were added to the mark and then homogenized.The solution was filtered  (Waters, 2012).

Fatty acid profile
Analysis of the fatty acid profile using the GC method refers to the AOAC (2005) with modification.The preparation of a standard solution of a mixture of 1 point concentration of FAME (Fatty Acid Methyl Ester) in hexane solvent.The sample was put into a 50 mL falcon tube.For the oil matrix, 0.5 M KOH was added.The sample was added with isopropanol and then vortexed.After being vortexed, the sample was added with hexane and then shaken with a mechanical shaker.The sample was then mixed with distilled water and vortexed again, after which it was centrifuged.Take the top layer (organic phase) into a 10 mL screw tube.Evaporate with N 2 gas.Methylation was processed by adding a solution of KOH in methanol into a 10 mL screw tube that already contains oil or fat extract and then vortexed.Heat the solution in a water bath, then cool the solution to room temperature and add a solution of BF 3 in methanol, and then vortex.After that, the solution is heated again in a water bath.After the cold solution was shaken and added with saturated NaCl solution and hexane, then shaken again.After forming two layers, transfer the top layer (organic phase) to a 2 mL tube containing anhydrous Na 2 SO 4 .The solution was let stand at room temperature for 1 hr and then put into a 2 mL vial.The solution was injected into the GC FID system.

Sensory analysis
Panelist acceptance of the appearance, aroma, taste, and texture of milkfish with boiled, steamed and pressure steamed methods was shown in Table 1.This assessment is based on a hedonic scale of 1-9.The scores for the acceptance of the boiled sample were 6.50-7.17which were evaluated as "like".The acceptance score of the boiled sample was 6.50-7.17,which was rated as "like."The acceptance score of the steamed fish sample was 6.77-7.33,which indicates that the sample has a "like" rating.The acceptance evaluation on the pressure steamed sample had an acceptance score of 8.00-8.33,this was evaluated as "very much like".The results of the sensory evaluation showed that the pressure steamed milkfish sample was preferred by the panelists.These results revealed that different cooking methods significantly affected the appearance, aroma, taste, and texture of milkfish.The difference was caused by the cooking method, cooking time, and temperature used (Fabre et al., 2018).The composition of volatile flavor compounds in fishery products affects the taste and smell of fishery products.They come from aldehydes, alcohols, ketones, and hydrocarbons (Liu et al., 2009).
A descriptive analysis method involves detection (discrimination) and description of both qualitative and quantitative sensory aspects of a product and is carried out by 5-100 trained panelists.These qualitative aspects were combined to define a product that includes the appearance, aroma, taste, texture, or nature of a product that distinguishes it from other products (Meilgaard et al., 2007).Table 2 shows the results of the descriptive test and the physical appearance of milkfish with different cooking methods.
Different cooking methods give different characteristics of milkfish which include appearance, aroma, taste, and texture.The temperature difference used and the length of cooking time affect the appearance of milkfish meat and its external appearance.The appearance of the fish after pressure steamed treatment is golden yellow or brownish flesh and skin.The yellowish color of the pressure steamed milkfish caused a Maillard reaction.This reaction was caused by reducing sugars (ketone groups or aldehydes) and amino components (amine groups).Maillard reaction rate increases with increasing temperature and decreasing water content.Based on Ayub and Ahmad (2019)  The processed fish produces a distinctive odor.Fatty acids found in fishery products were a major source of the emergence of volatile compounds.This compound affects the aroma of a commodity.The main volatile components in fish and fishery products come from aldehydes, alcohols, ketones, and hydrocarbons (Liu et al., 2009).According to Liu et al. (2021), the main fishy odor substances from fish originating from freshwater fish and seawater fish are different.The main compounds found in freshwater fish are geosmin and 2methylisobomeol.In seawater fish, aldehydes, alcohols, and ketones were the most common compounds found.Odor components also come from the environment, such as water, feed and algae, enzymeolysis, and oxidative reactions of proteins and lipids.
The differences in the cooking methods used affect the taste of meat products, especially the volatile components contained in meat (Cui et al., 2020).The dominant flavor of boiled milkfish was sweet and less savory, whereas steamed milkfish was more savory and slightly less sweet.Pressure steamed fish had a very savory and salty taste.The glutamic acid content was responsible for the savory taste of fish.Glutamic acid was a source of savory or umami taste that gives a perfect taste to food.Glycine and alanine were active flavor components that were known to give sweet characteristics to aquatic foods.The amino acids glycine, alanine, and arginine contribute to sweetness, although the contribution of alanine does not have a significant effect.The amino acid arginine also contributes to the bitter taste that gives it its characteristic sweet taste (Risso and Carelli, 2017).

Yield
The results of the measurement of the yield of milkfish showed the pressure steamed method was significantly different (p<0.05) from the boiled and steamed cooking methods.The treatment of the boiled cooking method and the steamed cooking method was not significantly different.The highest product yield was found in milkfish with the steam cooking method, which was 77.09%.The yield of steamed and boiled products has a difference of 0.09%, while the yield of pressure steamed milkfish is the lowest (57.33%).This followed the research conducted by Yoon et al. (2018) on skipjack tuna, where the yield of steamed tuna (24.4%) was higher than that of boiled tuna (22.4%).Table 3 shows the yield of milkfish using different cooking methods.

Texture (hardness)
The texture (hardness) of boiled, steamed, and pressure steamed milkfish was shown in Table 3.Based on the results of the analysis of the texture (hardness) of milkfish with different cooking methods, it could be concluded that the different cooking methods have a significant effect on the texture (hardness) of milkfish.
Cooking Methods Descriptions Boiling Appearance White, whole, and the flesh was slightly pale and slightly brownish.Texture Dense, slightly runny, slightly mushy, and the meat was cooked well.Aroma Specific boiled fish and fragrant volatile aroma.Taste Dominantly sweet and slightly savory.
Steaming Appearance Whole, yellowish-white, bright, and flesh was brownish white.Texture Dense, compact, and the meat was cooked well.Aroma Specific to steamed fish, fragrant, and prominent volatile aroma.Taste Sweet and savory.
Pressure Steaming Appearance Golden yellow, whole, and bright.
Texture Dense, compact, the meat was cooked well, and the milkfish bones were tender.Aroma Specific pressure steamed fish and prominent volatile aroma.Taste Salty and strong savory.

FULL PAPER
The results of the measurement of the hardness level of milkfish showed the pressure steaming method treatment had the highest hardness value of 741.33 gf.This means that the force to break the product was higher, so the product was harder.The value of the hardness or texture of Atlantic salmon increased along with the high pressure during the cooking process (Yagiz et al., 2009).
The pressure steam process could cause higher protein denaturation than other cooking methods.The lowest level of hardness was found in milkfish with boiled cooking method treatment (575.46 gf), which means that the force for breaking the product was lower, so the product is not too hard.Suryaningrum and Syamdidi (2013) reported that the boiled carp "pindang" (7.63) has a lower texture (less dense) than steamed carp "pindang" (8.13).This is because the amount of protein in steamed fish meat is higher, so it can affect the compact and dense texture.

Color analysis
Table 4 shows that the different cooking methods have a significant effect on color analysis, both the L, a*, and b* values of each treatment.Testing the value of L on milkfish aims to determine the level of brightness.The L value ranges from 0-100, where the closer the value to 100 the milkfish will be brighter or whiter in color.The highest L value was obtained in milkfish with the boiled cooking method, which was 53.7, while the lowest L value was obtained in milkfish with the pressure steamed method, which was 45.2.This means that the color of pressure steamed milkfish tends to be dark because the L value was close to 0. Temperature and pressure could affect color change, where high pressure would reduce the brightness of the product (Schubring et al., 2003).The pressure steamed process that uses high pressure would cause the L value to decrease.The decrease in the value of L was due to the Maillard reaction process in pressure steamed fish.Due to high temperatures and long processing time would form a brown pigment.
The notation or a* value interprets the mixed redgreen chromatic color.The +a* (positive) value was the interpretation of the red color from 0 to +80.The value -a* (negative) is the interpretation of the green color from 0 to -80.Based on the results obtained, it could be concluded the different cooking methods affect the a* value of milkfish.The highest a* value was obtained in milkfish with the pressure steaming method treatment, which was 6.9, while the lowest a* value was obtained in milkfish with the boiled cooking method treatment, which was 1.8.Because the result was positive and close to zero, the color of the pressure-steamed milkfish tends to be close to red.The concentration and chemical composition of myoglobin would affect the color of the meat (Sen et al., 2014).The use of high temperatures for a long time in the pressure steaming process increases the intensity of the reddish color level in fish.Amino acids in protein contain iodine.The formation of a red color occurs when iodine reacts with glycogen in fish.The myoglobin content in pressure steamed fish would undergo oxidation due to the heating process.According to Singh et al. (2022), during the cooking process, myoglobin would undergo oxidation from ferrous (Fe 2+ ) to ferric (Fe 3+ ) and form metmyoglobin, which gives the meat a brownish color.
The value of b* is an interpretation of the mixed blue -yellow chromatic color.Value +b* (positive) from 0 to +70 for yellow.Value -b* (negative) from 0 to -70 for blue.Based on the results obtained, it can be concluded that the different cooking methods affect the b* value of milkfish.The highest b* value was obtained in milkfish with the pressure steaming method treatment, which was 19.0, while the lowest b* value was obtained in milkfish with the boiled cooking method treatment, which was 9.4.The result of an increasing b* value or positive value, causes the color of milkfish to become closer to yellow.According to the research results of Sen et al. (2014), the b* value in mutton cooked using an increase in endpoint temperature leads to yellowness and the b* value increases.The yellow pigment in processed fish appears due to the presence of carotenoid compounds present in fish.Carotenoid compounds give yellow, orange to bright red colors (Sefc et al., 2014).Carotenoid compounds are antioxidants that easily react with oxygen and are unstable at high temperatures.The yellow color formed in processed fish is also caused by the Maillard reaction which is a reaction that occurs between amino acid groups and reduces sugars as a result of the heating process (Murata, 2021).

Proximate analysis
Changes in moisture content, ash content, protein content, and fat content were expressed on a dry basis and shown in Table 5.Based on the analysis of the water content of milkfish with different cooking methods, the average total water content was obtained in the range of .The results of the measurement of the water content of milkfish showed the treatment of boiled, steamed, and pressure steamed methods were significantly different (p<0.05).The water content of boiled milkfish was highest when compared to other fish, except fresh fish.Generally, the water content of foodstuffs after undergoing the cooking process will decrease.The results of the analysis showed the water content decreases after milkfish was boiled, steamed, and pressure steamed.Cooking is a process that could reduce the water content of food.The research of Pratama et al. (2019), showed that the water content of steamed milkfish decreased when compared to fresh fish.The water content of grouper fish fillet, Spanish mackerel, pompano, and red snapper was reduced after the cooking process (Gall et al., 1983).
Ash content is an inorganic residue obtained by ashing organic components in food.Based on the analysis of the ash content of milkfish with different cooking methods, the average total ash content on a dry basis was 3.46-3.80%.The results of the measurement of the ash content of milkfish showed the steamed cooking methods were not significantly different from the boiled and pressure steamed treatments, but the pressure steamed treatment was significantly different from the boiled treatment.The ash content of boiled milkfish was highest when compared to steamed and pressure steamed milkfish.Based on Zhang et al. (2013), the ash concentration decreased in boiled grass carp fillet samples because some minerals might have come out of the fillets due to the washing process.
Based on the analysis of the protein content of milkfish with different cooking methods, the average total protein content was obtained in the range of 73.97-83.98% on a dry basis.The results of measuring the protein content of milkfish showed the treatment of boiled, steamed, and pressure steamed methods were significantly different.The protein content of boiled fish was highest when compared to the protein content of steamed and pressure steamed fish.According to Asghari et al. (2013), the protein content increased in boiled rainbow trout fillets when compared with fresh fillets.Food processing affects the damage that occurs to proteins.The high temperature and length of processing time caused major protein damage in food ingredients.This means that the nutritional value of protein in fish will also decrease.Abraha et al. (2018), reported that time and temperature were factors that affected protein quality during the heating process.If time and temperature increased, protein denaturation would be large enough so that it would also cause a loss of minerals, vitamins, essential amino acids, and other nutrients.
Based on the analysis of the fat content of milkfish with different cooking methods, the average total fat content expressed on a dry basis is 10.19-12.31%.The results of measuring the fat content of milkfish showed the treatment of boiled, steamed, and pressure steamed methods were significantly different.The fat content of boiled milkfish was highest than steamed and pressure steamed milkfish.The process of processing food would cause damage to the fat contained in it.The degree of fat breakdown depends on the temperature used and the length of the processing time.The higher the temperature used, the greater the fat damage.Based on Devi and Sarojnalini (2012), the fat concentration decreased in steamed mola carplet (Amblypharyngodon mola) fish when compared with fresh fish.The boiling process results in a decrease in fat content.Fat has heat-resistant properties, so it makes the fat content decrease.Another component that arises as a result of fat melting and evaporating during the cooking process is flavor.According to Koubaa et al. (2012), an increase in fat content would lead to an increase in the energy value of fish fillets.

Amino acid profiles
Amino acid profiles of raw fish and their cooked products were expressed as (%/100 g) dry base.Compositions of the amino acid profiles of fresh, boiled, steamed, and pressure steamed milkfish were shown in Table 6.The amino acids that dominated the entire sample were glutamic acid (11.80%, 11.22%, 11.81% and 11.56%), followed by aspartic acid, lysine, and leucine.According to Murthy et al. (2016), the dominant essential amino acids in milkfish were leucine, lysine, phenylalanine, and histidine.In milkfish, glutamic acid was the most abundant non-essential amino acid.This is also confirmed by the research of Malle et al. (2019) FULL PAPER namely leucine.Sphyraena jello fish contains the highest non-essential amino acids, namely glutamic acid and aspartic acid, and the highest levels of essential amino acids, namely lysine and leucine (Aberoumand and Baesi, 2021).
The highest total content of essential amino acids and non-essential amino acids was found in boiled milkfish samples (42.21%, 37.93%).Meanwhile, the total essential amino acids (EAA) and non-essential amino acids (NEAA) of fresh fish were not significantly different from steamed fish and pressure steamed fish.Both essential and non-essential amino acids increased in milkfish that were given boiled treatment, except lysine.After steaming, lysine, valine, and isoleucine were increased.Essential amino acids are amino acids that cannot be synthesized by the body, so they can be obtained from food.All essential amino acids were decreased after pressure steaming.This was by the research of Gómez-Limia et al. (2020), who reported that the sterilization treatment caused the histidine and phenylalanine content in canned eels to decrease.Arginine content decreased after months of storage with sterilization treatment.
Non-essential amino acids are amino acids that can be synthesized by the body.The non-essential amino acids in steamed milkfish that had increased when compared to fresh fish were glutamic acid and aspartic acid.The pressure steamed treatments reduced the levels of all non-essential amino acids.Serine and tyrosine levels increased in boiled fish but not in steamed or pressure steamed fish.Three cooking temperatures (60°C , 100°C and 140°C) affect the thermal stability of three aromatic amino acids in meat: tryptophan, phenylalanine, and tyrosine.The amino acid proline contains active sulfur atoms which are oxidized to varying degrees (Xia et al., 2021).In the study by Bressani et al. (1978), the amino acid content of tyrosine in Cannavalia spp. with the pressure steaming method decreased, in which the amount of tyrosine content of Cannavalia spp.after the cooking process is 0.197 g/gN and the tyrosine content in Cannavalia spp.without the cooking process is 0.219 g/ gN.
Heating affected the amino acid content of the material.Differences in cooking methods and cooking times applied to fish affect the amino acid composition of fish, so it would cause a loss or decrease in amino acids.The heating process of the material would reduce the water content, and this would cause the amino acid content to significantly increase.Heating causes chemical changes in amino acid residues, and as a result of this, heating could change the structural, digestibility, and functional properties of proteins.This depends on the thermal treatment and the processing or processing conditions applied (Deng et al., 2015).

Fatty acid profiles
The fatty acid profile of raw and cooked milkfish was expressed as %/100 g dry base.Based on Table 7, the fatty acid profile of milkfish with different cooking methods could be seen to have a lower content of omega 3 than omega 9, except in pressure steamed milkfish.
SFA are fatty acids that contain single bonds in the hydrocarbon chain.The highest component of SFA was palmitic acid, and palmitic acid was found in fresh milkfish (7.10%), boiled milkfish (5.20%), steamed milkfish (7.37%), and pressure steamed (4.11%).Steamed milkfish had higher palmitic acid than milkfish with other cooking methods.Based on research by Malle et al. (2019), the highest SFA in fresh milkfish was palmitic acid.The same results were found in Memon et al. (2011), who reported the most abundant saturated fatty acids were palmitic acid and stearic acid.The abundance of palmitic acid in the SFA component was found in carp (73.46% in Labeo rohita, 71.76% in Cirrhinus mrigala and 69.54% in Catla catla) of the total SFA.Unsaturated fatty acids are fatty acids that have double bonds in the hydrocarbon chain.Unsaturated fatty acids are divided into two types, namely MUFA and PUFA.MUFA has one double bond in its molecule.PUFA contains two or more double bonds.Because the body cannot synthesize PUFA, they are considered essential fatty acids.The MUFA component was dominated by oleic fatty acid.The content of oleic acid in fresh, boiled, steamed, and pressure steamed milkfish is sequentially 2.84%, 1.72%, 2.52% and 0.89%.Based on research by Paul et al. (2018), oleic acid was the primary component of MUFA.The total oleic acid in fresh Catla was 16% of total fatty acids.The highest component PUFA was docosahexanoic acid with a value of 0.21% in fresh milkfish, boiled milkfish at 0.44%, steamed milkfish at 0.55%, and pressure steamed milkfish at 1.06%.In the research of Weber et al. (2008), the content of boiled silver catfish docosahexanoic acid was around 4.89% of total fatty acids.

Conclusion
Differences in cooking methods had a significant effect on product characteristics, amino acid content, and fatty acid content of milkfish.In terms of proximate composition, L value (lightness), and amino acid composition, milkfish with boiled treatment obtained higher yields when compared to steamed and pressure steamed.The highest amino acids contained in fresh, boiled, steamed, and pressure steamed milkfish were glutamic acid, aspartic acid, lysine, and leucine.The highest fatty acid profiles identified were palmitic acid, oleic acid, docosahexanoic acid, and linoleic acid.Panelists preferred pressure steamed milkfish because of FULL PAPER color of the meat turns brown because of the Maillard reaction and caramelization.The reaction takes place during the cooking process using high temperatures.

Table 1 .
, the Sensory value of milkfish with different cooking methods.
Values are presented as mean±SD of three replicates.Values with different superscripts are statistically significantly different (p<0.05).

Table 2 .
Sensory descriptions test of milkfish with different cooking methods.

Table 5 .
, milkfish contains the highest essential amino acid, Proximate analysis of fresh milkfish and milkfish with different cooking methods.Values are presented as mean±SD of three replicates.Values with different superscripts are statistically significantly different (p<0.05).

Table 6 .
Amino acid content (%, db) in fresh milkfish and milkfish with different cooking methods.

Table 7 .
Fatty acid content (%, db) in fresh milkfish and milkfish with different cooking methods.