This document presents a comparative study of the water, mineral, and biochemical content of three common edible shellfish varieties found in South Kerala: white prawn, mud crab, and clam. The study aimed to determine the moisture content, total ash content, acid insoluble ash, calcium, and magnesium content of each variety. The results showed that all three varieties contained high moisture levels between 75-85%, with white prawn having the highest at 83.85%. Mud crab had the highest total ash and acid insoluble ash, indicating higher mineral content. White prawn and mud crab both had higher calcium and magnesium levels than clam. The study concludes that all shellfish varieties provide good nutrient value and

1. A COMPARATIVE STUDY OF WATER AND
MINERAL CONTENT OF EDIBLE SHELL
FISH VARIETIES COMMONLY FOUND IN
SOUTH KERALA
Saneesh Kumar N
Assistant Professor
Department of Chemistry And Industrial Chemistry
T.K.Madhava Memorial College
Nangiarkulangara
Haripad, Alappuzha

2. FISH AS FOOD
Biochemical constituents

3. SHELL FISH
 Fishes without a skelton but
covered with some type of hard
shell
 Different variety of shell fish are
available in kerala
 Shell fish allergy is not common in
kerala

4. SHELL FISH
BROAD TERM FOR CRUSTACEANS AND MOLLUSKS SEA FOOD
CRUSTACEANS
CRUSTACEANS
MOLLUSKS
(BIVALVES)

5. WHITE PRAWN (Penaeus indicus)

6. MUD CRAB (Scylla serrata)

7. CLAM (Meretrix meretrix)

8. OBJECTIVES OF THE STUDY
 To determine the following in edible shell fish
verieties such as crab, prawn and clam
available in south kerala
 Moisture content
 Total ash content
 Acid insoluble ash
 Calcium and Magnesium

9. NEED,IMPORTANCE AND
SCOPE OF THE STUDY
 Need to know the proximate composition of
fish food to estimate the intake of principal
nutrients in human diet
 Requirement of regular updating of fish
nutrition table because of changes in nature
and source of raw materials in manufacturing
process
 Quality Control -Requirement of simple and
rapid methods applicable to fish and fish
products
 To ensure that fish products meet the

10. PREPARATION OF THE SAMPLES
 After removing the shell, samples in
the form a homogeneous paste was
produced and was kept in air tight
containers at low temperature to
prevent loss of moisture

11. DETERMINATION OF MOISTURE CONTENT
 Oven Drying Method
 5g of well mixed sample in a silica
crucible was kept in an air oven at 1000c-
1050c for 6- 12 hours and was weighed
after cooling in a desicator for 30 minutes
Deciding shell life, texture of food
material

12. DETERMINATION OF ASH CONTENT
 Total Ash Procedure
 5g of well mixed sample was dried and
charred the portion by igniting with meker
burner and heated at 5500c-6000c in a
muffle furnace for 3 hour, a whitish grey ash
obtained was weighed.
Mineral content of fish

13. DETERMINATION OF ACID INSOLUBLE ASH
 Total ash after evaporating with 3M HCl
was suspended in50 ml dil.HCl was boiled
and fitered through an ashless filter paper
and the total ash procedure was repeated
Indication of contamination in fish

14. PREPARATION OF SAMPLE SOLUTION
 The filtrate obtained from the process
of determination of acid insoluble ash
was made up to 250ml. 100ml of the
sample solution were used for Ca2+ and
Mg2+ estimations.
Mg2+ ions necessary requirements
Activation of phosphate transfer enzymes
carbohydrate metabolism.
Mg2+ and Ca2+ responsible for the transmission of
electrical impulses along the nerve fibre and for the
contraction of muscles

15. ESTIMATION OF TOTAL CALCIUM AND
MAGNESIUM
 COMPLEXOMETRIC TITRATION METHOD
 100 ml of the sample solution(with 2ml NH3-
NH4Cl buffer,pH=10) was titrated against
EDTA (standardised with std. MgSO4
solution) using Erichrome black T
indicator(end point wine red to blue)

16. ESTIMATION OF CALCIUM
 COMPLEXOMETRIC TITRATION METHOD
 100 ml of the sample solution(with NaOH
,pH=12) was titrated against EDTA(0.02N)
using ammonium purpurate
(murexide)indicator(end point pink to purple)
 The percentage composition of magnesium was
obtained from the estimated value of total calcium and
magnesium and that of calcium.

17. Percentage composition of moisture
Sl.
No.
Variety Scientific name Moisture percentage
1. Prawn Penaeus indicus 83.85
2. Mud crab Scylla serrata 75.70
3. Clams Meretrix meretrix 77.35
70.00%
72.00%
74.00%
76.00%
78.00%
80.00%
82.00%
84.00%
86.00%
white prawn mud crab clams

18. Percentage composition of acid insoluble ash
Sl.
No.
Variety Scientific name Acid insoluble ash %
1. Prawn Penaeus indicus 0.98
2. Mud crab Scylla serrata 1.02
3. Clams Meretrix meretrix 0.49
0.00%
0.20%
0.40%
0.60%
0.80%
1.00%
1.20%
White prawn Mud crab Clam

19. Percentage composition of total
ashSl.
No.
Variety Scientific name Ash percentage
1. Prawn Penaeus indicus 3.23
2. Mud crab Scylla serrata 11.16
3. Clams Meretrix meretrix 5.72
0.00%
2.00%
4.00%
6.00%
8.00%
10.00%
12.00%
White prawn Mud crab Clams

20. Composition of Magnesium
Sl.
No.
Variety Scientific name magnesium content
1. Prawn Penaeus indicus 205.90mg/100g
2. Mud crab Scylla serrata 246.51mg/100g
3. Clams Meretrix meretrix 36.5mg/100g
0
50
100
150
200
250
White prawn Mud carb Clam

21. Composition of Calcium
Sl.
No.
Variety Scientific name calcium content
1. Prawn Penaeus indicus 192.21mg/100g
2. Mud crab Scylla serrata 178.03mg/100g
3. Clams Meretrix meretrix 36.45mg/100g
0
20
40
60
80
100
120
140
160
180
200
White prawn Mud crab Clam

22. CONCLUSION
 All the experimented shellfish contain
higher nutrient value that are not less
than the larger fish
 All the three varieties consisting white
prawn, mud crab and clam contains
75-85% of moisture
 Maximum total ash content suggest
high mineral contents in mud crab

23.  High acid insoluble ash content in
mud crab may be due to the siliceous
impurities present in the edible portion.
 Low value of calcium and magnesium
contents of clam may be due to the
loss of minerals during the recovery of
the fish from its shell.
 Species-specific physiological
characteristics and changes in
environmental conditions might

24. SUGGESTIONS
 Loss of minerals in clams during the
recovery of the fish from its shell can
be prevented by steaming the clams
before opening their shell.
 Cheap shell fishes may be included
regularly in our diet to decrease the
nutrient deficiency as they are good
source of proteins and minerals .

25. THANK YOU