ANALISIS PERPINDAHAN PANAS DAN MASSA PADA PENGERINGAN BUAH SALAK, NANAS, DAN PEPAYA MENGGUNAKAN PENGERING KABINET DENGAN PERLAKUAN DEHIDRASI OSMOTIK

FATIKA ANISA, Dr. Joko Nugroho WK, STP, M.Eng.

2013 | Skripsi | TEKNIK PERTANIAN

Tujuan penelitian ini adalah menentukan kinetika pengeringan buah dengan berbagai perlakuan awal. Pengering kabinet dengan pemanas listrik digunakan dalam penelitian. Pengeringan dilakukan dengan suhu pengeringan 50oC, 60oC, dan 70oC. Potongan buah nanas, pepaya, dan salak digunakan sebagai bahan penelitian. Perlakuan blansir dan perendaman dalam larutan gula diberikan pada setiap perlakuan awal. Perendaman dalam asam sitrat dan sodium metabisulfit, dalam asam sitrat, sodium metabisulfit, dan kalsium klorida, dalam asam sitrat saja, dan dalam asam sitrat dan kalsium klorida digunakan untuk perlakuan S1, S2, S3, dan S4. Satu variasi kontrol digunakan sebagai buah tanpa pemberian perlakuan awal dengan notasi perlakuan S0. Hasil penelitian menunjukan bahwa dehidrasi osmotik menurunkan kadar air buah salak, nanas, dan pepaya masing-masing sebesar 10 – 13%, 11 – 18%, dan 10 – 16%. Waktu yang dibutuhkan untuk mengeringkan buah pada suhu pengeringan 50oC, 60oC, dan 70oC masing-masing adalah 24 jam, 15 - 16 jam, dan 12 - 13 jam. Laju pengeringan dalam analisis basis kering pada periode konstan buah salak, nanas, dan pepaya masing-masing berkisar antara 23,97%/jam - 74,20%/jam, 28,85%/jam - 143,07%/jam, dan 38,34%/jam - 143,84%/jam, sedangkan pada periode menurun masing-masing berkisar pada 0,19/jam - 0,65/jam, 0,16/jam - 0,52/jam, dan 0,22/jam - 0,65/jam. Koefisien perpindahan panas konveksi buah salak, nanas, dan pepaya masing-masing berkisar pada 0,15 W/(m2.oC) - 3,32 W/(m2.oC), 0,08 W/(m2.oC) - 1,65 W/(m2.oC), dan 0,003 W/(m2.oC) - 2,33 W/(m2.oC). Nilai energi aktivasi periode konstan buah salak, nanas, dan pepaya masing-masing berkisar pada 23,95 kJ/mol – 28,91 kJ/mol, 20,29 kJ/mol – 27,92 kJ/mol, dan 6,66 kJ/mol – 27,71 kJ/mol, sedangkan nilai energi aktivasi periode menurun masing-masing berkisar pada 39,63 kJ/mol – 56,38 kJ/mol, 39,23 kJ/mol – 45,89 kJ/mol, dan 27,82 kJ/mol – 47,23 kJ/mol. Perendaman buah dalam larutan osmotik berpengaruh dalam menurunkan laju pengeringan. Penggunaan kalsium klorida tidak berpengaruh secara signifikan terhadap kualitas buah kering. Penggunaan sodium metabisulfit berpengaruh secara signifikan terhadap warna buah salak untuk mencegah proses pencoklatan dan tidak berpengaruh secara signifikan terhadap warna buah nanas dan pepaya. Pengeringan buah dengan pengering kabinet memberikan produk akhir yang baik dan banyak disukai apabila buah dikeringkan pada suhu pengeringan 50oC dan sebelum dikeringkan buah direndam dalam larutan sodium metabisulfit dan asam sitrat, diberi perlakuan blansir, serta direndam dalam larutan gula.

The objective of this research was to determine the kinetic of drying on sliced fruit with various pretreatments.The cabinet dryer with electric heater was used in this research. The drying temperatures were 50oC, 60oC, and 70oC. The sliced of pineapple, papaya, and snake fruit were used as samples. Blanching process and sugar solution dipping were used for all variations. Citric acid and sodium metabisulphite dipping, citric acid, sodium metabisulphite, and calcium chloride dipping, citric acid only dipping, and citric acid and calsium chloride dipping were noted as S1, S2, S3, and S4 variations respectively. One controlled variation was noted as S0 which was fruit that was not given the pretreatments variation. The result showed that the osmotic dehydration had effect on reducing the moisture content of snake fruit, pineapple, and papaya for 10 – 13%, 11 – 18%, and 10 – 16% respectively. The time needed for drying fruit process at 50oC, 60oC, and 70oC was 24 hour, 15 – 16 hour, and 12 – 13 hour respectively. The drying rates in dry basis analysis at constant period of snake fruit, pineapple, and papaya were 23,97%/hour – 74,20%/hour, 28,85%/hour – 143,07%/hour, and 38,34%/hour – 143,84%/hour respectively, while the drying rates at falling period were 0,19/hour – 0,65/hour, 0,16/hour – 0,52/hour, and 0,22/hour – 0,65/hour respectively. The coefficients of convective heat transfer of snake fruit, pineapple, and papaya were 0,15 W/(m2.oC) - 3,32 W/(m2.oC), 0,08 W/(m2.oC) - 1,65 W/(m2.oC), and 0,003 W/(m2.oC) - 2,33 W/(m2.oC) respectively. The activation energies of snake fruit, pineapple, and papaya were 23,95 kJ/mole – 28,91 kJ/mole, 20,29 kJ/mole – 27,92 kJ/mole, and 6,66 kJ/mole – 27,71 kJ/mole respectively at constant period and 39,63 kJ/mole – 56,38 kJ/mole, 39,23 kJ/mole – 45,89 kJ/mole, and 27,82 kJ/mole – 47,23 kJ/mole respectively at falling period. The dipping on osmotic solution process for the fruit had effect on reducing drying rate. The using of calsium chloride had no significant effect to the quality of dried fruit. The using of sodium metabisulphite had only effected the color of snakefruit significantly to prevent browning process while it hadn’t effected the color of pineapple and papaya significantly. The fruit drying process using cabinet dryer gave the best result and produced the dried fruit that many people liked if the fruits were dried at 50oC for drying temperature and before they put on the dryer, they’re dipped on sodium metabisulphite and citric acid solution, given the blanching treatment, and dipped on sucrose solution (sugar solution).

Kata Kunci : Buah, pengeringan, pengering kabinet, osmotik, bahan aditif