A pinboard by
Amadeus Ahnan

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:

  1. Does tempeh fermentation increase or decrease NEP content?
  2. Does tempeh fermentation increase or decrease NEP antioxidative capacity?
  3. Does tempeh fermentation affect the capacity of NEPs to inhibit cancer cell growth and development in cell culture?
  4. Does tempeh fermentation affect the capacity of NEPs to inhibit cancer cell growth and development in animal models?

By being the first research to inform those data above, the impacts this research would contribute are:

  1. The prospect of tempeh as an affordable and sustainable functional food/protein source in terms of cancer risk
  2. The prospect of fermentation technology that increases antioxidative capacity in foods, which can lead to potential antioxidant production biotechnology
  3. More understanding of the mechanism in which mold and soybeans interact in changing antioxidative property

Enhancement of β-secretase inhibition and antioxidant activities of tempeh, a fermented soybean cake through enrichment of bioactive aglycones.

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