i
ABSTRAK
SYAHDIAN LESTARI : Pengaruh metode perlakuan awal (pre-treatment) dan suhu pengeringan terhadap mutu fisik, kimia, dan fungsional tepung ubi jalar ungu, dibimbing oleh ELISA JULIANTI dan RIDWANSYAH
Tujuan peneitian ini adalah untuk mengetahui pengaruh metode perlakuan awal dan suhu pengeringan terhadap mutu fisik, kimia, dan fungsional tepung ubi jalar ungu. Penelitian ini menggunakan rancangan acak lengkap dengan dua faktor, yaitu metode perlakuan awal (P): (ubi tidak dikupas dan diiris, ubi dikupas dan diiris, ubi tidak dikupas lalu diiris dan perendaman sodium metabisulfit (Na2S2O5) 0,5 %, ubi dikupas lalu diiris dan perendaman sodium metabisulfit
(Na2S2O5) 0,5 % dan suhu pengeringan (T): (50 oC, 55 oC, 60 oC, 65 oC).
Parameter yang dianalisa meliputi nilai warna, densitas kamba, organoleptik warna dan aroma, indeks pencoklatan, kadar air, daya serap air dan minyak,
swelling power, kelarutan, dan baking expansion.
Hasil penelitian menunjukkan bahwa perlakuan awal memberikan pengaruh berbeda sangat nyata terhadap nilai warna, kadar air dan antosianin, dan memberikan pengaruh berbeda tidak nyata terhadap densitas kamba, organoleptik aroma, organoleptik warna, indeks pencoklatan, daya serap air, daya serap minyak, swelling power, kelarutan, dan baking expansion. Suhu pengeringan memberikan pengaruh berbeda sangat nyata terhadap densitas kamba, organoleptik aroma dan organoleptik warna, dan memberikan pengaruh berbeda tidak nyata terhadap nilai warna, indeks pencoklatan, antosianin, daya serap air dan minyak, swelling power, kelarutan, dan baking expansion. Interaksi antara kedua faktor memberikan pengaruh berbeda nyata terhadap kadar air dan memberikan pengaruh berbeda tidak nyata terhadap nilai warna, densitas kamba, organoleptik aroma dan warna, indeks pencoklatan, daya serap air dan minyak,
swelling power, kelarutan, dan baking expansion. Tepung dengan mutu terbaik adalah tepung dengan metode umbi utuh yang dikupas dan perendaman sodium metabisulfit (Na2S2O5) 0,5 % dan suhu pengeringan 65 oC.
Kata kunci: perlakuan awal, kulit ubi, sodium metabisulfit, suhu pengeringan, tepung ubi jalar ungu
ii
ABSTRACT
SYAHDIAN LESTARI: The effect of pre-treatment method and drying temperature on physical, chemical, and functional quality of purple flesh sweet potato flour, supervised by ELISA JULIANTI and RIDWANSYAH
The purpose of this research was to find the effect of pre-treatment method and drying temperature on physical, chemical, and functional of purple flesh sweet potato flour. This research was using randomized design with two factors, namely the method of pre-treatment (P): (sweet potato unpeeled and sliced, sweet potato peeled and sliced, sweet potato unpeeled then sliced and soaking in 0,5% sodium metabisulfite (Na2S2O5), sweet potato peeled then sliced and soaking in
0,5% sodium metabisulfite (Na2S2O5) and the drying temperature (T): (50 o
C, 55
o
C, 60 oC, 65 oC). The parameters analyzed were the color values, bulk density, organoleptic test of color and aroma, browning index, moisture content, and water and oil absorption, swelling power, solubility, and baking expansion.
The results showed that the pre-treatment had highly significant effect on the value of the color, moisture content and antocianin, had no significant effect on bulk density, organoleptic test of color and aroma browning index, water absorption, absorption of oil, swelling power, solubility, and baking expa nsion. The temperature of drying had highly significant effect on the bulk density, organoleptic test of color and aroma, had no significant effect on the value of the color, browning index, antocianin, water and oil absorption, swelling power, solubility, and baking expansion. The interaction between the two factor s had significant effect on moisture content and had no significant effect on the value of the color, bulk density, organoleptic test of color and aroma, browning index, water and oil absorption, swelling power, solubility, and baking expansion. The flour with the best quality was using pre-treatment of peeled tuber and soaking in 0,5% sodium metabisulfite (Na2S2O5) and the drying temperature of 65 °C. Ash
content, protein content, fat content, crude fiber content, starch content, amylose and amylopectin, total sugar, reducing sugar, dextrose equivalent, and the degree of polymerization of the best flour were analyzed.
Keywords: pre-treatment, tuber skin, sodium metabisubh, drying temperature, the purple flesh sweet potato flour
