PhD Student, University of Massachusetts Amherst
The first research that links solid-state fermentation with changes on food "ignored" antioxidants
Tempeh has been a staple protein source in Indonesia since the 1700s. It is made of soybeans bound together by molds through fermentation. The fermentation increases its protein content, decreases fat content, added Vitamin B12 (which makes Indonesian tempeh the only plant-based food with Vit. B12), eliminates anti-nutrient phytate that blocks iron absorption, and created delicious flavors with a unique meaty texture. With its affordable price (starting from $1.99 for 40 g of protein in the US), tempeh has the potential to be an important choice for nutritious, sustainable, and affordable protein source world-wide.
Recent research showed that tempeh fermentation also increased the antioxidant activities by 12-fold. Antioxidants in general are some factors to decrease the risk of chronic diseases e.g. cancer, obesity, and diabetes. In soybean, antioxidants include those which are responsible in ameliorating lung and prostate cancers in various populations.
However, there is no published research that analyzes how tempeh fermentation affects the "non-extractable polyphenols" (NEP). NEPs are antioxidants that have been ignored due to limitations of old analytical methods. For example, after the NEPs of banana were analyzed, its NEPs/"ignored antioxidants" turned out to be 100-fold more than the regular "free" antioxidants, showing how banana's anti-oxidative capacity might had been underestimated.
Thus, this research aims to analyze the NEPs before and after tempeh fermentation. The main data this research would obtain are:
By being the first research to inform those data above, the impacts this research would contribute are:
Abstract: Antiradical and total antioxidant activities of extracts from raw, prepared for inoculation, fermented (tempeh) and cooked seeds of grass pea (Lathyrus sativus Krab and Derek cultivars) were measured. Tempeh fermentation with Rhizopus oligosporus resulted in higher scavenging activity towards DPPH and ABTS(+) radicals which correlated well with the content of total phenols. In Derek cultivar, fermentation caused a significant inhibition of linoleic acid oxidation by methanol extracts. In buffer extracts the highest TAA values were observed in raw seeds. Cooking of seeds lowered RSA values as compared to fermentation, especially for the DPPH assay. Methanol and buffer extracts from cooked seeds showed prooxidant activity towards linoleic acid.
Pub.: 15 Jul '08, Pinned: 29 Nov '17
Abstract: Biogenic amines in foods may pose a public health problem. Therefore, histamine, tyramine, putrescine, cadaverine, spermine, and spermidine concentrations were measured in selected food items commonly consumed in Egypt. Foods examined were dairy products (blue cheese and Mesh cheese), meats (fermented and smoked cooked sausage), and fish (smoked and salted fermented fish [Feseekh], salted sardines, and anchovies). Egyptian fermented sausage had the highest concentration of total biogenic amines (2,482 mg/kg), followed by Mesh cheese (2,118 mg/kg) and blue cheese (2,084 mg/kg). The lowest concentration was found in smoked cooked sausage (111 mg/kg). Histamine was found at a high level (521 mg/kg) in Feseekh, and tyramine was highest (2,010 mg/kg) in blue cheese. These results indicate that some traditional Egyptian foods may pose a health risk due to the concentration of biogenic amines, especially histamine.
Pub.: 12 Apr '11, Pinned: 29 Nov '17
Abstract: Soybean and its fermented products are the most common source of isoflavones in human food.The present study quantifies the major glycosides and aglycones in soybean and its fermented product tempeh isoflavone extracts. The comparision of antioxidant effects and BACE1 inhibitory activity between the isoflavones of soybean and tempeh were also established.The major isoflavones such as daidzein and genistein (aglycones), and their sugar conjugates (glycosides) daidzin and genistin in soybean and tempeh isoflavones were quantified using HPLC analysis. Comparative studies on BACE 1 (β-site amyloid precursor protein cleaving enzyme 1 or β-secretase 1) inhibition and free-radical scavenging activities (diphenyl-1-picrylhydrazyl (DPPH) and ferrous ion chelating ability) were conducted.The amount of actives (mg/100 g) in soybean isoflavone compared with tempeh isoflavone is as follows: daidzein 16.72 mg/100 g versus 38.91 mg/100 g, genistein 11.10 mg/100 g versus 24.03 mg/100 g, daidzin 6.16 mg/100 g versus 0.69 mg/100 g, and genistin 24.61 mg/100 g versus 6.57 mg/100 g. The IC50 values of soybean and tempeh isoflavones against BACE1 were 10.87 and 5.47 mg/ml, respectively. The tempeh isoflavone had a more potent DPPH free-radical scavenging activity (IC50 = 2.67 mg/ml) than the soybean isoflavone (IC50 = 10 mg/ml). The ferrous ion chelating ability of the isoflavones was practically similar (IC50 = 10.40 mg/ml, soybean and 11.13 mg/ml, tempeh).The present study indicates that tempeh is a healthy supplement to alleviate oxidative stress through the enrichment of aglycones.
Pub.: 11 Mar '15, Pinned: 29 Nov '17
Abstract: Sufu is a solid-state fermented product made from soya beans. For the sake of quality control and regulation purposes, it is essential to be able to identify key odorants of various commercial sufus. To identify the aroma-active compounds in sufus, gas chromatography-olfactometry/aroma extract dilution analysis (GC-O/AEDA) was performed, and odour activity value (OAV) was estimated. The correlations between aroma profiles and identified aroma-active compounds were also investigated by principal component analysis. Results showed that 35 aroma-active compounds were detected through OAV calculation, while 28 compounds were identified by using GC-O/AEDA. Quantitative descriptive analysis revealed that aroma recombination model based on OAV calculation was more similar to original sufu in terms of aroma comparing to aroma recombination model based on GC-O/AEDA. Omission experiments further confirmed that the aroma compounds, such as ethyl butanoate, ethyl 2-methylbutanoate, ethyl hexanoate, (E,E)-2,4-decadienal and 2,6-dimethylpyrazine, contributed most significantly to the characteristic aroma of a commercial sufu.
Pub.: 20 Mar '15, Pinned: 29 Nov '17