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Abstract
Abstract
The objectives of this research were to study the effect of fish and flour formulation as well as centre point temperature on the thermal diffusivity and shelf life of pempek lenjer. The parameters observed were the temperature of pempek at several position: i.e. (r0) = 0 cm, r1 = 1 cm, r2 = 2 cm, cooking time, change of textural value, total volatile nitrogen and total microbes of pempek during storage. Data temperature
distribution was analyzed by using diffusivity at center point model, and random diffusivity models through computer program of Engineering Equation Solver (EES) Ver 8.91. The shelf life data was analyzed by using
linear regression to determine the relationship between storage time and the measured variables which was followed by calculating using Arrhenius method to compare the decrease of pempek lenjer quality. The results showed that thermal diffusivity coefficient of pempek lenjer for formula 1 was in the range of 0.321 to 1.515 .10-7 m2/s, for formula 2 was in the range of 0.297 to 1.389.10-7 m2/s, for formula 3 was in the range
of 0.378 to 1.471 . 10-7 m2/s and for formula 4 was in the range of 0.2778 to 1.620.10-7 m2/s.The research results showedthat longerstorage time results in lower values of texture, but produced higher value of
total volatile nitrogen and total microbes. The lowest Eavaluefrom the measured variablewas totalmicrobes which can be used as the main parameter of deterioration for pempek lenjer during storage. The shelf life
of pempek lenjer based on total microbes value was in the range of 27 to 33 hours
Keywords : thermal diffusivity, shelf life, pempek
Abstrak
Tujuan penelitian inimempelajari pengaruh formula ikan dan tepung, serta suhu terhadap difusivitas panas dan umur simpan pempek lenjer. Variabel yang diukur adalah suhu sampel pempek pada titik pusat (r0) = 0 cm, r1 = 1 cm, r2 = 2 cm,lama pemasakan pempek, perubahan nilai tekstur, total volatil nitrogen dan total mikroba selama penyimpanan. Data distribusi suhudianalisis menggunakan model difusivitas panas pada titik sebarang, dan model difusivitas panas pada titik pusat dengan program computer Engineering Equation Solver (EES) Ver 8.91. Data umur simpan dianalisismenggunakan regresi linier untuk melihat hubungan antara lama penyimpanan dengan tekstur, total volatil nitrogen, dan total mikroba yang diukur, dan dilanjutkan dengan perhitungan cara Arrhenius untuk membandingkan penurunan mutu pempek lenjer. Hasil penelitian menunjukkan bahwa koefisien difusivitas panas pempek lenjer pada formula 1 adalah interval 0,321 - 1,515. 10-7 m2/s, pada formula 2 adalah 0,297 – 1,389.10-7 m2/s, pada formula 3 adalah 0,378 – 1,471. 10-7 m2/s, dan formula 4 adalah 0,2778 – 1,620.10-7 m2/s.Semakin lama penyimpanan, tekstur semakin menurun, tetapi total volatil nitrogen dan total mikroba semakin meningkat. Nilai Ea terendah pada total mikroba, sehingga dapat dijadikan parameter kunci kerusakan pempek lenjer selama penyimpanan. Umur simpan pempek “lenjer” berdasarkan total mikroba selama 27 - 33 jam.
Kata kunci : difusivitas panas, umur simpan, pempek
Diterima: 17 Juni 2013; Disetujui: 26 September 2013
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