4
2.2 Tempe
Tempe is a product made from fermented soybean with Rhizopus spp. mould having compact solid form, grey-white color, and specific aroma of tempe
BSN 2009. The main mold used for the preparation of tempe in Indonesia is Rhizopus oligosporus Feng 2006. More strains identified in tempe, including
Rhizopus formosaensis and Rhizopus oryzae Babu et al. 2009. Various microorganisms, including filamentous fungi, yeasts and bacteria, are found in the
traditional tempe. The growth of lactic acid bacteria LAB, coexisting with R. oligosporus, is performed to improve the safety and could inhibit the growth of
pathogenic bacteria Ashenafi and Busse 1991, Feng et al. 2005. Table 2 shows the requirements of tempe quality regulated by National Standardization Agency
of Indonesia BSN.
Table 2 Requirements of tempe quality based on Indonesian national standard SNI 3144:2009.
Parameters Unit
Requirements Conditions
Aroma Color
Taste -
- -
normal, specific normal
normal
Moisture ww max. 65
Ash ww max. 1.5
Lipid ww min. 10
Protein N × 6.25 ww min. 16
Crude fiber ww min. 2.5
Metal poisoning Cd
Pb Sn
Hg As
mgkg mgkg
mgkg mgkg
mgkg max. 0.2
max. 0.25 max. 40.0
max. 0.03 max. 0.25
Microorganisms Coliform
Salmonnella MPNg
- max. 10
negative25 g
Tempe is made by soaking soybeans in water, removal of the seed coat, boiling the cotelydons, cooling, inoculating them with pure or traditional mixture
of starters, and incubating as a solid bed at 25-30
o
C for 24-72 h Nout and Kiers 2005. During fungal fermentation the enzymes degrades some substrates leading
to an increase of free amino acids, water-soluble nitrogen compounds, free fatty acids, and the development of specific flavor
Jeleń et al. 2013. Anti nutritional factors, such as trypsin inhibitors, tannin, and phytic acids, were also leached out
during cooking, dehulling, and fermentation. Besides, tempe processing eliminated almost stachyose, the most flatulent oligosaccharide in soybean
Egounlety and Aworh 2003.
5 In addition to being a source of proteins, tempe has several interesting
functional properties from its bioactive compounds. Soy isoflavones are recognized for their benefits to human health, reducing menopause symptoms and
lowering the risk of chronic diseases, such as cardiovascular ones, osteoporosis, and breast, prostate and colon cancer
Matsuo et al. 1997, Alekel et al. 2000, Badger et al. 2005, Lee et al. 2005, Ma et al. 2008, Dong and Qin 2011. Tempe also
contains g
amma amino butyric acid GABA which has antihipertensive effects Aoki et al. 2003,
Tsai et al. 2006
.
2.3 Antioxidant in Tempe
An antioxidant is any substance that significantly delays or inhibits the oxidation of an oxidizable substrate Halliwell and Gutteridge 1989, Sies 1993,
Halliwell 1995. Antioxidant compounds can scavenge free radicals and increase shelf life by retarding the process of lipid peroxidation, which is one of the major
reasons for deterioration of food products during processing and storage Halliwell 1997. Antioxidants protect the human body from free radicals and
ROS effects that can retard the progress of many chronic diseases as well as lipid peroxidation Gülçin 2012.
Natural antioxidants are found in almost all plants, microorganisms, fungi, and animal tissues Pokorny 1999. Phenolic compounds are secondary plant
metabolites that are thought to be an integral part of both human and animal diets Gülçin 2006. The predominant of natural antioxidants are phenolic compounds
such as tocopherols, flavonoids, phenolic acids, and lignans, as well as carotenoids and ascorbic acid Ames et al. 1993, Chen et al. 1996, Gülçin 2012.
Nitrogeneous compounds such as oligopeptides, proteins, and melanoidins also have antioxidative activity Chen et al. 1996.
According to Hoppe et al. 1997, tempe is reported to be antioxygenic. Fermentation of tempe causes increased antioxidative capacity Chang et al. 2009.
The antioxidant components of soybean flour have been shown to be isoflavones, phospholipids, tocopherols, amino acids, and peptides
Gyӧrgy et al. 1964, Naim et al. 1974, Naim et al. 1976, Hayes et al. 1977, Murakami et al. 1984. The
predominant isoflavones in tempe were genistein 5,7,4 ’-trihydroxyisoflavone
and daidzein 7,4 ’-dihydroxyisoflavone, produced by digesting genistin and
daidzin with β-glucosidase during fermentation Murakami et al. 1984.
Isoflavones contributed only one-thirds of the antioxidative capacity in tempe and the other two-thirds were contributed by the peptides derived from proteolyzing
soy proteins Sheih et al. 2000. Esaki et al. 1996 found 3-hydroxyanthranilic acid HAA as another antioxidative substance formed in tempe.
2.4 Antioxidant, Phenolics, and Flavonoids in Food
The terms of antioxidant activity and antioxidant capacity have different meanings. Activity refers to the rate constant of a reaction between a specific
antioxidant and a specific oxidant. Capacity is a measure of the amount as a mole of a given free radical scavenged by a sample MacDonald-Wicks et al.
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