1. Fresh fish quality is assessed using sensory and non-sensory methods to determine freshness and detect spoilage. Sensory methods rely on human panels while non-sensory methods include biochemical, biological, and physical tests. 2. Processing fresh fish prevents spoilage through methods like removal of scales, filleting, and packaging. Common fish products include fish sauce, fish paste, fish oil, and fish protein concentrate created through various extraction and fermentation processes. 3. Fish protein concentrate is created through a multi-step extraction process using solvents to remove oils and concentrate proteins from fish or fishery waste to over 85% protein content.

1. QUALITY OF FRESH FISH
SUBMITTED BY
SAKSHI THAKUR
1732065
M.Sc. FOOD SCIENCE AND TECHNOLOGY

2. INTRODUCTION
• Freshness describes the presence and absence of deterioration.
• Fish is highly perishable food.
• Spoilage in fish starts as soon as the fish dies after fishing.
• Freshness makes major contribution to the quality of fish or fishery products.
• The detection of freshness of foods has become an important routine in the fields of food industry.
• There are different methods used for the assessment of fish quality

3. METHODS FOR QUALITY OF FISH
SENSORY METHOD
• Based on changes in appearance, odour, colour, flavour and texture.
• Fast, simple, sensitive and objective.
• It rely on human judgment and proper training of panels.
• Instrument like Instron, Bohlin Rheometer for measuring texture and other rheologic properties are used and articial
nose to evaluate odour.
• Some sensory methods used are
QUALITY INDEX METHOD (QIM)
TORRY SENSORY ASSESMENT SCHEME

5. NON SENSORY METHOD
• Can be cheaper and often quicker.
• Can appear more reliable and objective.
• Courts of law may find it much easier to accept the results of physical and chemical tests.
• There are different non sensory methods :
• BIOCHEMICAL METHOD
A variety of chemical compounds accumulate post-mortem fish muscles and these chemical are either intermediate or end products
of biochemical changes occurring in muscles after death.
a. Proximate Composition : For the determination of moisture, ash, lipid, protein of fish sample. It varies with species, age, sex, season etc. So
conclusive result are difficult to obtain
b. Histamine content: Histamine develops in freshly caught fish after 40-50 hrs of death, if fish is not properly iced. Histamine content over 20
mg/100g in canned fish is prohibited by US. FDA.
c. pH: Changes in fish muscle is a good index for freshness assesement.
d. Ammonia: Bacteria can generate small amount of ammonia in spoiling fish, mainly from free amino acid. There are several chemical and
enzymatic method for measuring ammonia.
e. Peroxide value: Use to determine oxidative rancidity in fish tissue. Good quality fish have value less than 10.

6. • BIOLOGICAL METHOD
a. Total Plate Count: Total number of microbial flora is changed with the time in fish or fish products. The
number per grams of fish and fish products or per square centimetre of surface area indicate quality of fish
from microbiological point of view.
• PHYSICAL METHOD

7. PROCESSING OF FISH
• The purpose of processing and preserving fish is to get fish to an ultimate consumer in good, usable
condition.
• Fish that becomes spoiled is obviously unusable.
• The aim of fish processing and preservation is to slow down or prevent the enzymatic, bacterial, and
chemical deterioration, and to maintain the fish flesh in a condition as near as possible to that of fresh
fish.
• Steps include in the processing of fish are:

8. HANDLING THE CATCH
REMOVAL OF SCALES
CUTTING
FILLETING OF FISH

9. FISH PRODUCTS
• There are different products of fish:
• FISH SAUCE
• FISH PASTE
• FISH OIL
• FISH PROTEIN CONCENTRATE

10. FISH PASTE (BAGOONG)
• Bagoong is undigested residue of partially hydrolysed fish or shrimp.
• It has salty and slightly cheese-like odour.
WASHED AND DRAINED
MIXING OF SALT AT DIFFERENT PROPORTIONS
MIXTURE IS ALLOWED TO FERMENT
• Bagoong is eaten raw or cooked.
• Used as flavouring or condiment in many traditional recipies.
• As an appetizer it is sautéed with onion and garlic and served with tomatoes or green mangoes.
• Main source of protein in the diet.

11. FISH SAUCE (PATIS)
• The raw material used is similar to that of fish paste.
• They differ only with respect to the period of fermentation.
• To obtain fish sauce the fermentation is continued until liquid forms on top of the mixture, after
which it is drained and filtered.
• Fish sauce may be obtained either from fish or shrimp bagoong after 1-2 years of fermentation.
• The longer the digestion period, the better.
• The total bacterial counts decreased rapidly upto 6 month and declined slightly until the end of
fermentation.

12. FISH PROTEIN CONCENTRATE (FPC)
• FPC usually refers to fish meal intended for human consumption.
• It can be prepared from any type of fish or fishery waste.
• It is prepared from fish by extracting out the oil, screening or settling out the bones and drying, so
that the resultant product (Fish Protein Concentrate) is higher in protein *85% to 95 % and lower in
ash content than fish meal.
• The Food and Agriculture Organization of the United Nations defines three types:
•
Type A: a virtually odourless and tasteless powder having a
maximum total fat content of 0·75 per cent.
Type B: a powder having no specific limits as to odour or
flavour, but definitely having a fishy flavour and a
maximum fat content of 3 per cent.
Type C: normal fish meal produced under satisfactorily
hygienic conditions

13. 1. Fresh whole fish are rinsed with fresh water soon after landing, weighed and fed
to a mincer by conveyor.
2. First extraction: the minced fish are fed to extractor 1 which dehydrates the fish;
it is an unheated vessel in which the mince is agitated for about 50 minutes
together with the liquid recovered from extractor 2, which contains some
isopropanol.
3. Centrifuging: the contents of extractor 1 are fed to a continuous centrifuge,
where the slurry separates into a solid known as wet cake, and a liquid. The wet
cake is conveyed to extractor 2, and the liquid to a still for recovery of solvent and
fat.
4. Second extraction: extractor 2 is jacketed, and the temperature is about 75°C.
Here the liquid recovered from extractor 3 is added to the wet cake from extractor
1 and the mixture is agitated for 90 minutes. At the beginning of this stage the cake
is almost completely dehydrated, but has a fat content of about 5 per cent, which is
reduced to about 1 per cent during the extraction.

14. 5.Centrifuging: the contents of extractor 2 are centrifuged, the wet cake is conveyed to
extractor 3, and the liquid is returned to extractor 1 for the next batch of raw material.
6.Third extraction: extractor 3 is jacketed, and the temperature is again about 75°C.
Fresh isopropanol is added to the wet cake and agitated for about 70 minutes. During
this stage the fat content is reduced to about 0·3 per cent.
7. Centrifuging: the contents of extractor 3 are centrifuged and the wet cake is washed
with pure isopropanol for about 50 minutes. The liquid is returned to extractor 2 for
the next batch.
8. Solvent removal: the wet cake is heated in a rotating vacuum dryer to evaporate the
solvent; the vapours are drawn off, condensed and used again.
9. Grinding and packing: the dried material is conveyed to a hammer mill, where it is
ground to a fine powder and sieved. The FPC is typically packed in 50-lb fibreboard
containers and sent to store ready for shipment.

15. REFERENCES
• www.ncbi.nlm.nih.gov.in
• www.fao.org
• Solanki J, et al., (2016), Freshness evaluation of fish by quality index method (QIM) and instrumental
method at Veraval Fish Landing Centre, International Journal of Processing and Post Harvest
Technology, 42-46.
• Bremner, H.A., (2002), Safety and quality issues in fish processing, Woodhead Publishing Limited,
607-625.
• Nwaigwe U.V., (2017), Fish preservation and processing, Journal of food.