Abdul Rahman, Russly

Ahmad, Nurul Izzah

Bakar, Jamilah

Che Man, Yaakob

Selamat, Jinap

Yusoff, Anida

Universiti Putra Malaysia Institutional Repository

Agricultural SciencesThe Effect of Alkaline and Acid Washings on The Quality Attributes of TilapiaMuscleJamllah·, Jlnap, 5., RU661y, AB., Nurullzzah, A., Anlaa, Y. ana Che Man, Y.B.Faculty of Food Science and BiotechnologyUniversiti Putra Malaysia43400 UPM, Serdang, SelangorMalaysiaTelephone Number of Corresponding Author: 03-89468396E-mail olCorrespondingAuthor:jamilah@putra.upm.edu.myKey words: acid washing, alkaline washing, quality attributes, tilapiaIntroductionTilapia occupies an important place in freshwater fish trade in Malaysia. However. one of the major problems associated withmarketing of tilapia, in particular black tilapia, is their poor acceptability due to the presence of earthy odour and flavour.Geosmin and 2-methylisobomeol are the principle compounds responsible for the earthy odour and flavour in fish. Theirpresence in the black tilapia muscle cultured in the ex-mining pool in Malaysia was also confirmed by a GCMS study of thevolatile flavour and off-flavour components of the tilapia muscle carried out in our laboratory. Washing can reduce the earthyodour and flavour in fish. Washing of freshwater fish with tamarind pulp. lemon juice. vinegar or a mixture of them to removethe earthy odour and flovour is a common practice in Malaysia and its effectiveness has been proven in breaded tilapia. TheIndian continent practices washing with alkali solutions for the removal of such properties. Since those juices contain organicacids as one of their main constituents, therefore, for industrial purposes these practices can be translated into washing withdilute organic acids. No report on the removal of the earthy odour and flavour by acid washing such as acetic. citric andtartaric acid is found. Hence, the effects on these treatments on the physico-chemical and the sensory properties of the fishmuscle need to be looked into. Therefore, studies were conducted to determine effect of selected organic acids and alkaliwashings on the muddy characteristic removal and their effects on the physico-chemical properties of the tilapia muscle.Materials and MethodsBlack tilapia (Oroechromis mossambicus), weighing 150 to 300g. 15 to 20cm long was obtained from local farm. Live fishwas killed by a blow. They were then dressed and filleted. The fillets were then rinsed with chilled water (3-5°C) to removeblood, slime and other unwanted materials. The fillets were drained to remove excess water before been washed in therespective acids or alkaline solutions. The ratio of alkaline/acid solutions to fillet was 4: I. Several quality indices weredetermined. They were pH of muscle, color (sensory and instrumental). rancidity. protein stability, thermal properties ofmuscle (DSC) to name a few. Two separate trials were carried out to determine seasonal variations.Results and DiscussionSodium and potassium hydroxide solutions were the alkali used for washings. KOH was found to have more significant effectin majority of the quality indicators determined. Both the alkali showed slightly different trends on their influence on thequality attributes of the fish muscle. This is perhaps due to their different diffusibility rates. KOH treatments resulted in asignificant reduction in the muddy odour of the muscle.The effectiveness of the acid washing treatments in the removal of the muddy component varies with the acid used. The acidsalso had the ability to camouflage the muddy characteristics as commented by the panelists. Unlike the alkali washingtreatment, the reduction of the muddy odour and flavour works through a different mechanism whereby the apparent absenceof geosmin (since through GCMS analysis) can be due to the conversion of the geosmin into an odourless compound i.e.argosmin beside the possibility that it is leached into the washed water. Increasing the concentration of all acids above 0.125Mseems to result in negative effects to the fish muscle characteristics. Texture of the fish muscle becomes fibrous and increasein opacity unlike in alkali washings where the muscle turned into gel-like translucent substance. Increase in the yellowness ofthe samples were also observed. All quality indicators monitored tend to indicate that acid washings may be superior to alkaliwashings, however, the main drawback is the depth of penetration of the acid into the muscle. The outer muscle layers werefound to denature and thus formed a distinct outer zone preventing futher penetration of the acids from the washed solutioninto the interior layer. Hence decreasing the effectiveness of the treatment since the denatured layer will also prevent theleaching of the geosmin and 2-methylisobomeol (MIB). Electron microscopy also showed that the muscle had differentpattern of denaturing upon exposure to different acids.ConclusionsThe acid washings' of the fish muscle are effective in reducing the muddy flav our and odour of the fish muscle. It also has theability to camouflage the muddy character. The effectiveness of the acid washings varies. Washings should not be carried outwith acid concentration above 0.125 M when the contact time is for 10 min. The noticeable textural degradation is differentfrom that observed in alkali washings. Both acid and alkali washings can produce positive quality attributes. but they were tobe used at different contact time and concentrations.295UPM Research Report 1997-2000. Vol II. Section 2-Extended AbstractsBenefits from the studyDevelopment of procedures for the reduction of muddy flavor and odor in freshwater fish, which is applicable for industrialapplication. This will increase the value of the fish either as minimally processed products or an raw materials for processedproducts.Patent(s), if applicable:Not applicable for time beingStage of Commercialization, if applicable:Have potential, but requires the interest of the private sector.Project Publications in Refereed JournalsI. Nurul lzzah, A., Ahmad, F.B.H .• Jamilah, B. and Yusoff, S. 2000. Volatile flavour and off-flavour components in blacktilapia (O.mossambica) cultured in ex-tin mines. Research Journal of Chemistry and Environment. 4(3): 67-72.2. Jamilah, B., Nurul Izzah, A., Yusoff, S. and Ahmad, F.B.H. 2001. The flavour and earthy characteristics of black tilapia(Oreochrornis mossambica) identified through sensory evaluation. Pertanika Journal of Tropical Science 24(2)95-100.3. Nurul, lA. Ahmad. F.B.H, Jamilah, 8.and Yusoff, S. 2002. Contamination of volatile aromatic hydrocarbons in wild blacktilapia. Journal a/Physical Science. (in press)4. Nurul lzzah, A, F.B.H., Ahmad, Jamilah, B. and Y, Salmah. Geosmin and isoborneol in black tilapia. Journal of Agricultureand Food Chemistry (submitted)5. Anida, Y., Jamilah, 8., Jinap, S. and Y.B. Che Man. The detection of rancidity in alkali treated fillets of tilapia by FTIR.European Journal of Lipid Science and Technology (submitted)Project Publications in Conference ProceedingsI. Jamilah, B. 1997. The removal of off-odourlflavour in freshwater fish. Presented at the National Conference on FoodIndustry 2000: Technology and opportunities, 5-7 May, 1997. Kuala Lumpur.2.. Md. Mohsin, B. Jamilah, B.A. asbi, and Jinap, S. 1997. Effect of supernatant from banana (Musa sp) leaf ash inremoving the muddy odourlflavour of blaek tilapia (Oreochromis mossambicus). Presented at the National Conference onFood Industry 2000: Technology and opportunities, 5-7 May, 1997. Kuala Lumpur.3. Mohsin, Md., Jamilah, B. and Jinap, S. 1998. Sodium hydroxide - its ability to remove the muddy odour of black tilapia.Presented at the International Sci. Conference, 7-9 May, 1998. Universiti Pertanian Malaysia, Serdang, Selangor.4. Mohsin, Md., Jamilah, B. and Jinap, S. 1998. Removing the muddy odour from cooked black tilapia fillet using sodiumhydroxide. In: Proceedings of the Malaysian Science and Technlogy Congress 98- update of R&D findings andcommercialisation. 7-9 Nov., 1998. Kuala Terengganu, Terengganu, Malaysia. p 10-17.5 Jamilah, B. Fang, L.S. and Che Man, Y.B. 1999. The differential scanning calorimetry (DSC) of KOH washed black tilapiamuscle. In: Proceedings of the Malaysian Science and Technology Congress '99 - research and development priorities in thenew millennium. 25-27 Oct., 1999, Kuala Lumpur. p 185-185.6 Yusoff, A., Jarnilah, B. and Che Man, Y.B. 1999. Effect of potassium and sodium hydroxide washing on the lipid oxidationin black tilapia (O.mossambicus) muscle. In: Proceedings of the Malaysian Science and Technology Congress '99 - researchand development priorities in the new millennium. 25-27 Oct., 1999, Kuala Lumpur. p 120-126.7. Nurul Izzah, A., Jamilah, 8., Yusof, S. and Ahmad, F.8.H. 1999. Volatile flavour and off-flavour components in blacktilapia (O.mossambicus) from different water environments. Presente4d at the 4th Princess Chulabhom Institute ScienceCongress: Chemicals in the 21 sI century. 28 Nov.-2 Dec. 1999, Bangkok, Thailand.8. Nurul lzzah, A., Jamilah, B., Yusof, S. and Ahmad, F.B.H. 1998. Earthy odourlflavour in black tilapia (O.mossambicus)fillet and the effect of acid washings for the removing the off-flavour and other sensory attributes. Presented at the firstseminar of the National Institute of Health. 30-31 Oct., 1998. Institute of Medical Research, Kuala Lumpur.9. Nurul Izzah, A., Jamilah, 8., Yusof, S. and Ahmad, F.B.H. 1998. Volatile flavour components in black tilapia. Presentedat the IMR's monthly research and development session. 13 Aug., 1998. IMR, Kuala Lumpur.10. Yusoff, A. Jamilah, B., Che Man, Y.B. and Jinap, S. 2000. Monitoring the lipid oxidation in black tilapia(O.mossambicus) muscle by Fourier Transform Infra-red (FTIR) spectroscopy. In: Oils and fats International Congress 2000.4-8 September, 2000, Kuala Lumpur.11. Nurul Izzah, A., Jamilah, B., Yusof, S. and Ahmad, F.B.H. 1999. Determination of volatile aromatic hydrocarbons inblack tilapia (0. mossambicus). Presented at the 36th Annual Scientific Seminar of the Malaysia Society of Parasitology andTropical Medicine. 24-25 Feb., 2000, Kuala Lumpur.12. Jamilah, B. and Lim, K.H. 2000. The effect of organic acid washings on the protein denaturation in black tilzpia 10.rnossambicus) muscle. Presented in Asia Pacific Symposium on Food Science and Nutrition 2000. 18-20 Oct, :00;. KOlaKinabalu, Sabah.13. Abu Bakar, F., Jamilah, B., Hassan, Z. and Ali, A.R. 2000. Effect of acid washings on the microbiological characteristicsof red tilapia (Mossambicus nilotica) fillets during storage. Proc. of the 23th Microbiology Symposium., Aseania Resort,Langkawi, 19-21 Nov., 2000. P 241-244.296Agricultural SciencesGraduate Research--------Name of Graduate Research Topic Field of Expertise Degree Awarded Graduation YearNurullzzah Extraction, Food Processing MSc completedAhmad characterization and and chemistryremoval of muddycharacteristics intilapia filletsAnida Yusoff Effect of alkaline Food processing MSc Completedwashings on the and preservationranciditydevelopment intilapia filletsAzelina Shaari Development offish Food processing MSc Draft thesischips with treated and preservations submittedtilapia filletsIRPA Project number03-02-04-0088UPM Research Cluster:AFFProject Leader Assoc. Prof. Dr Jamilah Bakar297

The effect of alkaline and acid washings on the quality attributes of tilapia muscle

http://psasir.upm.edu.my/42723/1/the%20effect%20of%20alkaline%20and%20acid.pdf

The effect of alkaline and acid washings on the quality attributes of tilapia muscle

Abstract

Similar works

Full text

Available Versions

Universiti Putra Malaysia Institutional Repository