operation oaxaca: group bonding.

mango pectins. (026)

Carlos Manuel Jarquín Sánchez
5 min readMar 9, 2024

this is carlos.

time to move quickly.

there’s a lot of distractions.

youtube, late nights, music, girls, what else?

the world that i wanna see and where i am right now is on me.

so the further i get away from these things…

the closer i’ll get to the vision.

and by default, i’ll get everything else for free as a reward (including the distractions).

the longer it takes for “x” thing to happen, the harder it hits.

time to hit the internet.

and speak about the last of the chemical groups to consider for mango adsorption.

and the metal ion selection for this wet lab.



for our purposes…

pectin is a carbohydrate molecule that’s in the mango pulp.

and its properties can be used as a gelling material.

the pectins create the fruit texture (on the surface).

pectin rises in the fifth week of mango fruit.

then the de-esterification occurs.

de-esterification → splitting/cleaving ester groups to remove ester bonds on the mango peel into hydroxyl groups. (aka hydroxide ions specifically)

this is done to create additional anionic functional groups for the cationic metal ions (for adsorption).

pectin groups - source
(OH) → hydroxyl groups || (COOH) → carboxyl groups

but the de-esterification occurs when the mango ripens.


the mango fruit pulp consists of parenchymatous (functional groups) tissues containing calcium salts of pectin located in the cell wall during early cell growth stages.

and the de-esterification of pectins (including the loss of calcium ions) is a characteristic of ripening fruit due to the cell wall breakdown and dissolution of the middle lamella.

the middle lamella in mangoes is a structure primarily made of pectin, a type of carbohydrate polymer.

it plays a crucial role in regulating fruit softening by controlling cell separation. (aka it makes the fruit surface smooth)

it does so by utilizing its pectin groups to ‘glue’ (or maintain the cellular structure) the cells from sliding over each other or separating from the mango fruit.

this contributes to the mango’s smoothness on the surface.

and on the surface lies the pectin groups.

these pectin groups have the hydroxyl and carboxyl groups we’re looking for.

the reason emphasis is placed on hydroxyl (-OH) & carboxyl (-COOH) groups is due to their anionic ability to adsorb cationic ions/particles.

partial involvement is due to the electronegativity between oxygen and hydrogen in the hydroxyl group…

and the carbonyl (C=O) in the carboxyl group.

carbon electronegativity: 2.5

oxygen electronegativity: 3.44

hydrogen electronegativity: 2.2

the electronegativity difference is 1.24 for the hydroxyl group.

and the electronegativity difference is 0.94 for the carboxyl group.

both numbers fall within a range known as “polar covalent bonding”.

this means that the negative electric charge will prefer to be ‘located’ around the element with the higher electronegativity number.

this is formally known as a ‘dipole moment’:

where two covalently-bonded nonmetal elements will tend to have either a positive or negative charge.

the pectin in mango peels is primarily composed of methyl esters of galacturonic acid, resulting in a high methoxyl content.

see where it says “ester group”? that’s the methyl esters.

ester → a chemical compound formed by the reaction between an alcohol and an acid. this results in the elimination of water.

for pectin groups:

  • the acid component is pectic acid.
  • the alcohol component is methyl alcohol.

pectin is the methyl ester of pectic acid and pectic acid is a complex of galacturonic acid molecules.

this includes other compounds like arabinose and galactose.

and those methyl esters are created when methanol reacts with the carboxyl groups of galacturonic acid.

this results in the formation of methyl ester groups along the pectin chain.

methyl esters are characterized by their specific chemical structure.

a methyl group (-CH3) is attached to the oxygen atom of the carboxyl group.

esterification is a chemical reaction involving the formation of an ester compound by combining an alcohol with an acid.

for pectin, esterification occurs when galacturonic acid reacts with methanol to form methyl ester groups.

and galacturonic acid is a sugar acid derived from d-galactose and is a major component of pectin.

d-galactose only has hydroxyl groups, btw.

the galacturonic acid contains carboxyl groups that can undergo esterification to form methyl esters in the presence of methanol.

galacturonic acid in mangoes.

and the final functional group is gallic acid.

gallic acid is a polyphenolic compound found in various plants, including mangoes.

polyphenols → groups of chemicals containing multiple hydroxyl (phenolic) groups.

the structure of gallic acid contains three hydroxyl groups and one carboxyl group.

gallic acid structure.

these are the pieces to consider before lab work.

there were some concerns raised.

but because the functional groups are part of the peel, they will not dissolve when they are boiled.

i’ll speak about our metal ion selection for this proof-of-concept for the lab.

catch you, boyz.

© 2024–2100 by Carlos Manuel Jarquín Sánchez. All Rights Reserved.