Is durian and tapai a bad combo?

CONTENT

1. Introduction
2. What is tapai
3. - Fermentation process of tapai
4. - What happens in the fermentation process of tapai?
5. - Nutritional values of tapai
6. Durian
7. - Chemical components of durian
8. - Nutritional values of durian
9. Metabolism of tapai and durian in the body
10. What happens when both tapai and durian consumed together?
11. Conclusion

1. Introduction

Durian and tapai are one of the most popular local foods consumed in Malaysia and as other parts of South-East Asia such as Vietnam, Thailand and Indonesia.
There is a myth believed by many locals until now that when eating both durian and tapai together will give an adverse effect of increase body temperature, indigestion and bad breath. Can this myth be considered as a fact? By observing the nutritional, chemical components of both durian and tapai and their metabolism pathways in the body, we can obtain a clear and logical understanding how these two foods interact together to give an adverse effect.

2. What is Tapai?

For those who are not aware what tapai is, tapai can also be called as tapai pulut or ragi tapai in Malaysia and Indonesia, lao-chao or chiu-niang in China, Bhattejaanr in India.
Therefore, tapai is an alcoholic product directed by the fermentation process commonly made from glutinous rice, certain moulds and yeasts. Common moulds used are rhizopus oryzae, amylomyces rouxii or mucor sp. and yeasts such as sacchromyces cerevisiae and saccharomycopsis fibuliger and endomycopsis burtonii.

3. Fermentation Process of Tapai

The main ingredient to make tapai are cooked glutinous rice, moulds and yeasts as mentioned above.

• Glutinous rice is cooked and cooled to room temperature at 28C to 30C.
• Moulds and yeasts are added and mixed with the glutinous rice
• Traditionally the mixtures are wrapped with banana leaves. Commercially, the mixture are place in a small container.
• It is then incubated at room temperature for 30-36 hours or sometimes longer as such incubation can take for days.

Usually after 3 days, tapai can be consumed. If incubation is left for a longer duration, the higher the concentration of alcohol and acidity of tapai. The product is soft textured and have a sweet-sour alcoholic taste and smell to it depending on the concentration. Tapai can be kept refrigerated until needed.

4. What Happens in the Fermentation Process of Tapai?

The moulds and yeasts have a special role when it is added and mixed with the glutinous rice. The moulds breaks down the glutinous rice into simpler sugars and these are then being oxidized to ethanol and carbon dioxide by yeasts.

5. Nutritional Values of Tapai

Since tapai major component is glutinous rice, it is therefore high in simple carbohydrates, with a small value of protein and fat. It has a very high glycaemic index of 98. It has a few micronutrients such as calcium, iron and vitamin B.

6. Durian

Durian is a stone fruit wrapped with edible, yellow custurdy flesh and is covered in a thorny shell.

7. Chemical Component of Durian

The edible flesh of the durian consist of many volatile compounds such as 7 sulfur compounds (responsible for giving the durian its yellow color and the distinctive odor), 12 aliphatic esters, 2 aldehydes, 4 alcohols and 1 aromatic compound.

8. Nutritional Values of Durian

Durian's major nutrient is high in simple carbohydrates and then fats, and small amount of protein, vitamin C, potassium and serotonergic amino acid tryptophan. It has high calories such as 100g can give 124-18805 kcal.

9. Metabolism of Tapai and Durian

Since both tapai and durian contains high in simple carbohydrates and have a glycaemic index that can raise blood sugar at a fast rate, both of these foods also share similar metabolic pathways.

• Simple sugars are broken in the body to glucose and is converted to pyruvate in the glycolysis process:

C6H12O6 ----------> CH3COCOO- + 2H+

• Pyruvate is then converted to acetyldehyde and CO2 by an enzyme called pyruvate decarboxylase. The acetyldehyde is subsequently reduced to ethanol by the NADH from the previous glycolysis which is returned to NAD+:

CH3COCOO- + H+ ----------> CH3CHO + CO2

CH3CHO + NADH ---------> C2H5OH + NAD

The ethanol in tapai will be metabolized in the liver to acetyldehyde and is converted to the less toxic form which is acetate by acetyldehyde dehydrogenase.

It is the acetyldehyde that gives a toxic effect in the brain causing behavioural changes and acetyldehyde is known to inhibit certain metabolic activities in the body.

10. What Happens When Both Tapai and Durian are consumed together?

As the nutritional, chemical and metabolic pathways of tapai and durian are observed, we can conclude the myth believed by the locals of giving a warming properties of the body, bad breath and indigestion are some what can be accepted as a fact. Adhering to the observations above, tapai and durian are high caloric foods and when consumed too much, energy is produced and accumulated in the body, therefore will make an individual feel hot. Since durian's flesh has a 124-18805 kcal per 100g and tapai caloric value of 100g is almost 400kcal.

Ethanol in tapai and one of the sulfur compound in durian such as hydrogen sulfide are combined together when these two foods are consumed together, excess hydrogen is build up in the blood plasma and this however can lead to metabolic acidosis:

CH3COOH + H2S ---> CH3COO- + H+ + H+ + S2-

The sulfur compound when combined with ethanol gives a disulfram-ethanol compound and this compound rises and accumulates in the blood and becomes toxic to the body as disulfram-ethanol compound inhibits the enzyme aldehyde dehydrogenase and therefore becomes unable to remove this compound out of the body.

The toxicity level depends on how much tapai and alcohol is consumed. The ethanol in tapai can precipitate the sulfur compound in durian which cannot be digested as we mention earlier that the enzyme is inhibited to remove a disulfram-ethanol compound. Therefore the build up of disulfram-ethanol is circulated in the blood system which can lead to unconsciousness and other effects such as abdominal pain, nausea, vomiting and sulfur or garlic odor breath.

11. CONCLUSION

As observed above of tapai and durian, it is not just a warming property that is an adverse effect towards the body, excess consumption of tapai (ethanol) and durian (sulfur compounds) when combined together can lead to acidosis, unconsciousness, nausea, vomiting and bad breath as ethanol and sulfur compound can give an accumulation of disulfram-ethanol compound leading to toxicity effect in the body.