Thesis Supervisors: Dr. Suyanto Pawiroharsono; Prof. Dr. Indrawati Gandjar
SUMMARY
Food deterioration is often due to lipid oxidation, excluding bacterial and
enzymatic spoilage. The end-products of lipid oxidation, such as aldehydes,
ketones, and alcohols are responsible for unacceptable off-tiavors and off-
odors in food. Lipid oxidation can be inhibited by antioxidants.
Soybean tempe is the most popular indigenous fermented food in
Indonesia. Soybeans are known to contain isotiavones. Four major forms are
known respectively as acetylglycosides, malonylglycosides, glycosides, and
aglycones.
Tempe were produced from soybean fermentation by Rhizopus oryzae
UICC 524 and Rhizopus microsporus var. chinensis UICC 521. The tempe
samples were extracted with methanol and the extraction defatted with hexa»
ne. The isoflavone aglycones were isolated using column chromatography,
and then anaiyzed using a gradient elution reverse phase of high-pressure
liquid chromatography (HPLC). After HPLC analysis, isotiavone aglycones
were evaporated to dryness and added to soybean oil at the 100, 200, 300,
iii ' and 400-ppm concentration in test tubes, then heated at 170°C for 30 minu-
tes. The oxidation of soybean oil was measured using the thiobarbituric acid
(TBA) test. The result, called thiobarbituric acid reactive substances
(TBARS) value, was expressed as pmolll and compared to the synthetic
antioxidant, buthylated hidroxytoluene (BHT), at the same concentration.
The profile of isoflavone aglycones isolated contains daidzein and
genistein. No factor-2 (6,7,4'-trihidroxyisoflavone) and glycitein were detec-
ted. Daidzein resulted from biotransformation of daidzin was dominant in
both tempe samples. The isoflavone biotransformation was much greater by
R. microsporus var. chinensis UICC 521 than by R. oryzae UICC 524, except
for the 24 hours incubation. After 72 hours of incubation, the total isoflavone
aglycones in tempe using R. microsporus var. chfnensis UICC 521 was
721.6 pglg and when using R. oryzae UICC 524, 268.2 p.glg.
The oxidized soybean oil without any antioxidants had a TBARS value of
327.32 1 20.31 pmol/1. Addition of the antioxidants showed a decreased
TBARS value following increasing concentration for both. For concentration
until 300 ppm, the TBARS values of oxidized soybean oil added with isofla-
vone aglycones were greater than when added with BHT, respectively
55.40 zl: 2.77 pmol!! and 45.20 i 2.63 pmolll. However at concentration of
400 ppm, the TBARS values of oxidized soybean oil added with isoftavone
aglycones and added with BHT did not show a significant difference.
ix + -51 pp; 6 append; 5 plates; 3 tables.
Bilb 35 (1964-1999).
iv
T5748-Biotransformasi.pdf :: Unduh