Papaya may be yet another instance of the biology of butyric acid

(writing in progress)

Recently, I posted about butyric acid.

I pointed out that this substance, despite its unpleasant odour, may be a previously unrecognised vitamin for the human species. I also mentioned how butyric acid crops up in a strange assortment of situations, from smelly socks and delectable cheeses, through the defensive substances of certain animals, to various fleshy fruits such as that of the street tree Ginkgo biloba (most notorious in New York).
 
I have just spotted yet another instance of butyric acid contributing to a familiar experience.
 
The fleshy fruit Carica papaya (common name ‘pawpaw’ or ‘papaya’) will be familiar to most readers.

This fruit has a faintly ‘sickly smell’ and ‘vomitous aftertaste’. The yellow variety (called ‘Richter gold’) most commonly cultivated here in Australia, and found nowhere else, is particularly known for ‘its musty, rotten smell and sickly, bitter flavour’.
 
What just occurred to me is that this typical odour and taste is probably butyric acid. I.e. papaya is yet another example of a familiar item with the biological ambiguity of a smell/taste that is simultaneously repulsive and strangely healthy for the human body.
 
It seems I may be the first person to notice the occurrence of butyric acid in papaya. Please see the detailed analysis of this fruit below, which lists all sorts of vitamins and mineral nutrients but does not mention mention butyric acid or butyrate.
 
As an aside, please note from the analysis below that papaya is yet another example of a pattern familiar in fleshy fruits generally: the main mineral nutrient is potassium, the concentration of which is about an order of magnitude greater than those of the next most concentrated elements (calcium and magnesium).
 
I infer that butyric acid was originally offered naturally in the ripe fruit of the ancestral plant in the genus Carica.

This occurred in tropical central America, and was later domesticated by the indigenous Americans to produce the cultivated species (C. papaya). I.e. I infer that the healthy qualities of butyric acid for fruit-eating but seed-defecating animals were part of the ‘reward’ naturally offered by this genus of wild plants to the animals performing the service of dispersing and sowing the plant.

As a natural adaptation, this would be in line with Ginkgo in particular, despite the great botanical differences between ginkgo (which is a woody plant native originally to China) and papaya. I wonder if anyone has previously noticed this connection between papaya and ginkgo?
 
Papaya seems to be yet another source of an underrated fatty acid which acts effectively as a ‘strangely stinky vitamin’, namely butyric acid.

“Unusually for a fruit, Papaya contains butyric or butanoic acid (1.2 mg/kg). (1) This is a fatty acid also found in butter and used in the manufacture of plastics”

http://www.phadia.com/en/Products/Allergy-testing-products/ImmunoCAP-Allergen-Information/Food-of-Plant-Origin/Fruits/Papaya/

1. Idstein H, Bauer C, Schreier P. Volatile acids in tropical fruits: cherimoya (Annona cherimolia, Mill.), guava (Psidium guajava, L.), mango (Mangifera indica, L., var. Alphonso), papaya (Carica papaya, L.). [German] Z Lebensm Unters Forsch 1985;180(5):394-7.

The main components of the smell of pawpaw are carboxylic esters and butyl esters:
http://pubs.acs.org/doi/abs/10.1021/jf00076a024?journalCode=jafcau

Most persons prefer smooth, sweet pawpaw. However, the strong-smelling varieties may be more beneficial.

Most of the fruits and vegetables that people eat today have been bred over centuries or even millennia, and their toxins have mostly been bred out, whilst retaining nutrients and increasing sugar.

Considering that the fruit-pulp of ripe papaya is about 90% water, I infer that the concentration on a dry matter basis of butyric acid is about 0.12%. This is a small value compared with that in butter, which seems to be about 3.5% on a fresh matter basis.

I do not see the breeding of ever more bland, flavourless, intensely sweet fruits as beneficial. For me, papaya without its distinctive flavours just becomes a ‘generic fruit’. Ripe papaya is already rather bland to start with (in great contrast to the unripe fruit, which tastes intense and is good medicine), and catering to the consumer’s whims by removing its healthy stinkiness is unfortunate. What should be done is the educate the consumer instead.

I would like to taste the form of papaya originally cultivated by the Aztecs. Perhaps, like cacao, it really packed a punch in terms of taste and was correspondingly more healthy than the ever more bland and sweet product towards which we are heading today.

 Let me illustrate how the butyric acid in papaya could hypothetically act as a vitamin.

Normally in the human species, the main source of butyric acid is fermentation of fibre in the colon. One eats fibrous material such as tubers, and the gut bacteria in the colon convert some of this to volatile fatty acids including butyric acid.

These fatty acids are then absorbed into the blood. On a normal plant-based diet, there is no problem, because there is plenty of fermentation going on in the colon.

Now imagine a situation where, for whatever reason, no plant matter other than fruit-pulp is available. The person in question eats only animal matter, such as eggs or muscle meat, which contains no cellulose or resistant starch, and thus produces negligible butyric acid in the colon.

Under such circumstances, the only supply of butyric acid is that already contained in food itself; and most animal matter contains none to speak of.

In this situation, it would make all the difference just to eat some ripe papaya daily. Although there is not much butyric acid in papaya, there is some, and perhaps just enough to make all the difference. This is the concept of a vitamin.

Viewed in this context, what it amounts to when the horticultural industry breeds Carica papaya to be ‘stink-free’ is the deliberate impoverishment of a food in terms of its vitamin content. And many persons on modern ‘junk’ diets are indeed likely to be subclinically deficient in butyric acid, because a) they avoid dairy products such as butter and b) eat only processed forms of carbohydrate (e.g. white bread or white rice) in which the fibre has been removed.

https://en.wikipedia.org/wiki/Papaya

 
http://www.theaustralian.com.au/news/nation/pawpaw-dreaming-try-it-then-love-it--and-the-skys-the-limit/news-story/61d892a575f4e5f402a4fb6e6d42b203

(writing in progress)

Publicado el julio 27, 2022 09:40 MAÑANA por milewski