Study of presence
of Oxalate ions in
Guava Fruit
At different stages of ripening
Made by :
XII-A
CERTIFICATE
ACKNOWLEDGEMENT
DECLARATION
INDEX
Page
S.No Topic
1. Acknowledgment
2.
Introduction
3. Plant chemicals
4. Oxalic Acid
5. Experiment
6. Observations
7. Calculations
8.
9.
INTRODUCTION
Family: Myrtaceae
Genus: Psidium
Species: guajava
Common names: Guava, goiaba, guayaba, djamboe,
djambu, goavier, gouyave, goyave, goyavier, perala,
bayawas, dipajaya jambu, petokal, tokal, guave,
guavenbaum, guayave, banjiro, goiabeiro, guayabo,
guyaba, goeajaaba, guave, goejaba, kuawa, abas,
jambu batu, bayabas, pichi, posh, enandi
Part Used: Fruit, leaf, bark
Guava is a common shade tree or shrub in dooryard
gardens in the tropics. It provides shade while the
guava fruits are eaten fresh and made into drinks, ice
cream, and preserves. In the richness of the Amazon,
guava fruits often grow well beyond the size of tennis
balls on well-branched trees or shrubs reaching up to
20 m high. Cultivated varieties average about 10
meters in height and produce lemon-sized fruits. The
tree is easily identified by its distinctive thin, smooth,
copper-colored bark that flakes off, showing a greenish
layer beneath.
Guava fruit today is considered minor in terms of
commercial world trade but is widely grown in the
tropics, enriching the diet of hundreds of millions of
people in the tropics of the world. Guava has spread
widely throughout the tropics because it thrives in a
variety of soils, propagates easily, and bears fruit
relatively quickly. The fruits contain numerous seeds
that can produce a mature fruit-bearing plant within
four years
PLANT CHEMICALS
Guava is rich in tannins, phenols, triterpenes,
flavonoids, essential oils, saponins, carotenoids, lectins,
vitamins, fiber and fatty acids. Guava fruit is higher in
vitamin C than citrus (80 mg of vitamin C in 100 g of
fruit) and contains appreciable amounts of vitamin A as
well. Guava fruits are also a good source of pectin - a
dietary fiber. The leaves of guava are rich in flavonoids,
in particular, quercetin. Much of guava's therapeutic
activity is attributed to these flavonoids. The flavonoids
have demonstrated antibacterial activity. Quercetin is
thought to contribute to the anti-diarrhea effect of
guava; it is able to relax intestinal smooth muscle and
inhibit bowel contractions. In addition, other flavonoids
and triterpenes in guava leaves show antispasmodic
activity. Guava also has antioxidant properties, which
is attributed to the polyphenols found in the leaves.
Guava's main plant chemicals include: alanine, alpha-
humulene, alpha-hydroxyursolic acid, alpha-linolenic
acid, alpha-selinene, amritoside, araban, arabinose,
arabopyranosides, arjunolic acid, aromadendrene,
ascorbic acid, ascorbigen, asiatic acid, aspartic acid,
avicularin, benzaldehyde, butanal, carotenoids,
caryophyllene, catecholtannins, crataegolic acid, D-
galactose, D-galacturonic acid, ellagic acid, ethyl
octanoate, essential oils, flavonoids, gallic acid,
glutamic acid, goreishic acid, guafine, guavacoumaric
acid, guaijavarin, guajiverine, guajivolic acid,
guajavolide, guavenoic acid, guajavanoic acid,
histidine, hyperin, ilelatifol isoneriucoumaric acid,
isoquercetin, jacoumaric acid, lectins, leucocyanidins,
limonene, linoleic acid, linolenic acid, lysine,
mecocyanin, myricetin, myristic acid, nerolidiol,
obtusinin, octanol, oleanolic acid, oleic acid, oxalic
acid, palmitic acid, palmitoleic acid, pectin,
polyphenols, psidiolic acid, quercetin, quercitrin,
serine, sesquiguavene, tannins, terpenes, and ursolic
acid.
GUAVA PLANT SUMMARY
Main Preparation Method: decoction
Main Actions (in order):
antidysenteric, antiseptic, antibacterial, antispasmodic,
cardiotonic (tones, balances, strengthens the heart)
Main Uses:
1. for dysentery (bacterial and amebic), diarrhea, colic,
and infantile rotavirus enteritis
2. as a broad-spectrum antimicrobial for internal and
external bacterial, fungal, candidal, and amebic infections
3. to tone, balance, protect and strengthen the heart (and
for arrhythmia and some heart diseases)
4. as a cough suppressant, analgesic (pain-reliever), and
febrifuge (reduces fever) for colds, flu, sore throat, etc
5. as a topical remedy for ear and eye infections
Properties/Actions Documented by Research:
amebicide, analgesic (pain-reliever), antibacterial,
anticandidal, antidysenteric, antifungal, antimalarial,
antioxidant, antispasmodic, antiulcerous,
cardiodepressant, cardiotonic (tones, balances,
strengthens the heart), central nervous system depressant,
cough suppressant, gastrototonic (tones, balances,
strengthens the gastric tract), hypotensive (lowers blood
pressure), sedative, vasoconstrictor
Other Properties/Actions Documented by Traditional Use:
anti-anxiety, anticonvulsant, antiseptic, astringent, blood
cleanser, digestive stimulant, menstrual stimulant, nervine
(balances/calms nerves), vermifuge (expels worms)
Cautions: It has a cardiac depressant effect and is
contraindicated in some heart conditions.
OXALIC ACID
It is the chemical compound formula H2C2O4. This
dicarboxylic acid is better described with the formula
HO2CCO2H. It is a relatively strong organic a cid,
being about 10,000 times stronger than acetic acid.
The dianion, known as oxalate, is also a reducing agent
and a ligand in coordination chemistry. Oxalic acid and
oxalates are abundantly present in many plants, most
notably in sour grass, and sorrel (including Oxalis),
roots and leaves of rhubarb and buckwheat
. At high concentrations, it is a dangerous poison, but
such immediately toxic levels are not found in
foodstuffs but rather in manufactures, such as some
bleaches, some anti-rust products, and some metal
cleaners (among other things). It is also a naturally
occurring component of plants, and is found in
relatively high levels in dark-green leafy foods
In the human body, ingested oxalic acid is not a useful
nutrient; so, like all such unneeded components of diet,
it is processed by the body to a convenient form and
that byproduct is then excreted-- in this case, in the
urine. In the course of being processed by the body,
oxalic acid combines with other substances to form
various salts, called oxalates; usually, those salts are in
solution, but in high concentration some may
precipitate out in crystalline form.
Such tiny crystals can cause damage to human tissue,
especially to the stomach, the kidneys, and the
bladder. It is commonly believed that oxalates
contribute to the formation of kidney and bladder
stones; one common nutrient with which oxalic acid
combines is calcium, making the salt calcium oxalate,
and calcium oxalate is found in kidney stone
To study the presence of Oxalate Ion
content in Guava Fruit at different
stages of ripening
Requirements:100 ml measuring flask, pestle and
mortar, beaker, titration flask, funnel, burette, weight
box, pipette, filter paper, dilute H2SO4, KMnO4, and
guava fruits at different stages of ripening.
Theory:Oxalate ions are extracted from the fruit by
boiling pulp with dil. H2SO4 . Then Oxalate ions are
estimated volumetrically by titrating the solution with
standard KMnO4 solution.
End Point: Appearance of permanent pink colour.
Procedure:
1. 50.0g of fresh guava was weighed and crushed to a
fine pulp using pestle-mortar.
2. The crushed pulp was transferred to a beaker and
about 50ml dil. H2SO4 was added. The contents were
boiled for about 10 minutes.
3. The contents were filtered and cooled in 100ml
measuring flask. The volume was made up to 100ml by
adding distilled water.
4. 20ml of this solution was taken into a titerating flask
and 20ml of dil. H2SO4 was added to it. The mixture
was heated to about 60C and titerated against the
standard KMnO4 solution taken in a burette
5. The process was repeated with different samples of
guava.
OBSERVATION
Weight of guava taken = 50.0 g
Volume of guava extract taken = 20.0 ml
Normality of KMnO4 solution = 1/20
Calculations
N1V1 = N2V2
(guava extract) (KMnO4 solution)
N1 x 20 = 1/20x V
Normality of oxalate, N1 =
Strength of oxalate = Normality x Eq. mass of oxalate
ion
= v/400* 44 g/litre of the diluted
extract.
CONCLUSION
Oxalic acid and oxalates are abundantly present in
many plants, most notably in sour grass, and sorrel
(including Oxalis), roots and leaves of rhubarb and
buckwheat.
After doing this experiment we can conclude that
unripe guava has a high content of Oxalate ions. The
concentration of oxalate ions decreases with the
ripening of fruit.
BIBLIOGRAPHY
In order to complete this project, I took help from:
My chemistry teacher
Comprehensive Practical Chemistry (Lab Manual) of
Laxmi Publication
Different internet sites:
www.google.com
www.rain-tree.com
www.wikipedia.com
