Kinetics of Quality Deterioration Based on Metabolic Responses of Fruits Stored in the Modified Atmospheric

HARTANTO, Rofandi, Promotor Prof.Dr.Ir. Suprodjo Pusposutardjo, M.Eng

2004 | Disertasi | S3 Ilmu Pertanian

Penelitian mengenai kinetika kemunduran mutu berdasarkan respon-respon metabolik buah-buahan yang disimpan dalam atmosfir termodifikasi bertujuan untuk menghasilkan model kemunduran mutu yang dinyatakan dalam model laju respirasi, model laju emisi etilen, dan model laju perubahan kandungan malat, tanin, pektin, sukrosa, glukosa dan fruktosa. Laju respirasi dan laju kemunduran mutu dimodelkan berdasarkan kinetika enzim Michaelis-Menten. Parameter mutu fisik yaitu laju perubahan kelunakan dan laju perubahan warna masing-masing dimodelkan dengan persamaan reaksi orde pertama dan persamaan eksponensial. Dipilih dua macam buah yaitu buah salak Pondoh (Salacca zalacca cv. Pondoh), yang mewakili buah non-klimakterik, dan buah pisang Raja (Musa sp.), yang mewakili buah klimakterik. Masing-masing buah disimpan dalam atmosfir termodifikasi dengan konsentrasi oksigen sebesar 2, 4, 6 dan 8%, karbon dioksida sebesar 1, 2, 3, dan 4% dan sisanya nitrogen, dengan suhu 12, 20 dan 24 oC. Model laju respirasi buah salak Pondoh dan buah pisang Raja yang disimpan dalam atmosfir termodifikasi mengikuti persamaan kinetika enzim Michaelis-Menten, dengan O2 sebagai substrat terbatas dan CO2 sebagai inhibitor uncompetitive. Model dapat digunakan untuk menduga laju respirasi buah salak Pondoh dan buah pisang Raja yang disimpan dalam atmosfir termodifikasi. Pemberian konstanta faktor transpirasi dapat memperbaiki pendugaan nilai laju respirasi baik pada buah salak Pondoh maupun buah pisang Raja. Model laju emisi etilen buah pisang Raja yang disimpan dalam atmosfir termodifikasi mengikuti persamaan kinetika enzim Michaelis-Menten, dengan CO2 sebagai inhibitor competitive terhadap etilen. Model dapat digunakan untuk menduga laju emisi etilen buah pisang Raja yang disimpan dalam atmosfir termodifikasi. Model laju perubahan kandungan malat, tanin, pektin, sukrosa, glukosa dan fruktosa baik pada buah salak Pondoh maupun pada buah pisang Raja yang disimpan dalam atmosfir termodifikasi tidak jitu untuk menduga laju perubahan mutu kimiawi tersebut. Model laju perubahan tekstur dengan persamaan reaksi orde pertama cukup baik untuk menduga laju perubahan tekstur buah pisang Raja yang disimpan dalam atmosfir termodifikasi. Model laju perubahan warna dengan persamaan eksponensial cukup baik untuk menduga laju perubahan warna kulit buah pisang Raja yang disimpan dalam atmosfir termodifikasi.

The research of quality deterioration kinetic based on metabolic responses of fresh fruit stored in the modified atmosphere aims to obtain the quality deterioration behavior expressed in the model of respiration rate; the model of ethylene emission rate; and the model of malate, tannin, pectin, sucrose, glucose and fructose content change rate. The respiration rate as well as the quality deterioration rate were modeled based on the Michaelis-Menten enzyme kinetic theory. Physical parameter of quality such as texture change rate and color change rate were also modeled, each with the first order equation and the exponential equation, respectively. It was chosen two kinds of fruit samples that is salak Pondoh (Salacca zalacca cv. Pondoh) representing the non-climacteric fruit and 'Raja' banana representing the climacteric one. Each sample was stored in the modified atmosphere condition with oxygen concentration of 2, 4, 6 and 8%, carbon dioxide concentration of 1, 2, 3 and 4% and nitrogen as the rest, with temperature treatment of 12, 20 and 24 oC. The model of respiration rate of both salak Pondoh and 'Raja' banana fruit stored in the modified atmosphere followed the Michaelis-Menten enzyme kinetic, with O2 as a limited substrate and CO2 as an uncompetitive inhibitor. The models were satisfied to predict the respiration rate of salak Pondoh and 'Raja' banana fruit stored in the modified atmosphere condition. Additional transpiration factor constant improved prediction values of respiration rate of both salak Pondoh and 'Raja' banana fruit. The model of ethylene emission rate of 'Raja' banana fruit stored in the modified atmosphere followed the Michaelis-Menten enzyme kinetic, with CO2 as competitive inhibitor towards ethylene. The model was satisfied to predict the ethylene emission of 'Raja' banana fruit stored in the modified atmosphere condition. The models of malate, tannin, pectin, sucrose, glucose and fructose content change rate of both salak Pondoh fruit and 'Raja' banana fruit were not satisfied to predict each quality parameter. The first order model of texture change rate was satisfied to predict the texture change rate of 'Raja' banana fruit stored in the modified atmosphere condition. The exponential model of color change rate was satisfied to predict the color change rate of the peel of 'Raja' banana fruit stored in the modified atmosphere condition.

Kata Kunci : Teknologi Pangan,Respirasi Buah Salak,Kinetika Kemunduran, carbon dioxide, enzyme kinetic, inhibitor, modeling, modified atmosphere storage, moisture, oxygen, quality deterioration, respiration.