MEATAND FISH

PROCESSING

Presented byKarthik,S.K.

M.Tech (Agri. Engg)PALB 3310

MEAT PROCESSING

INTRODUCTION

• The word meat comes form the old English word mete, in general which referred to food.

• Meat is those animal tissues which are suitable for use as food by the man.

• Technically it is the muscle portion of the animals body that is consumed as food.

• It is composed of numerous types oftissues like muscle tissues, epithelialtissues and nervous tissues but the majorcomponent of meat is muscle.

• The muscle and connective tissues are themajor compositional components andcontributes towards qualitative andquantitative characteristics of meat.

Cont.,

MUSCLE

S

Striated muscles Smooth

muscles

1. Striated muscles have transverse band

pattern as in skeletal and cardiac muscle.

2. Smooth muscles do not show such pattern an

mainly found as a component of blood vessels.

• Skeletal Muscle: The muscles have direct attachment with

bones but some of them are also attached with ligaments,

fascia, cartilage and skin. Muscle fiber is a structural unit of

skeletal muscle tissue and constitutes 75-92% of total muscle

volume.

• Smooth Muscle: It has little contribution to meat and found

mainly in wall of arties, lymph vessels, gastrointestinal and

reproductive tracts. Smooth muscle fiber is a single nucleus

cell located mainly at the centre of the cell.

STRUCTURE OF MEAT MUSCLE

Nutritional Composition of Meat

Carbohydrates: glycogen, glucose and glucose-

6-phosphate is in meat.

Protein: Meat is rich in proteins and provides all

the essential amino acids.

15-20% of good quality protein, the percentage is

higher in lean meat 20-22%.

On dividing the total nitrogen content of meat we

get 95% as protein and remaining 5% as smaller

peptides and amino acids.

Fat: Variable 5-40% depends on age, breed,

feed and type of source animal.

Vitamins and minerals: found in the lean portions of

meat.Meat are excellent sources of some vitamin B12, the liver is an

excellent source of Vitamin A.

Calcium and magnesium are the main minerals with important

roles to play in the contraction of muscles.

Iron as the component of the red pigment and zinc in enzymes.

Hydrolysing enzymes: The enzymes help in the process

of denaturation of the muscle proteins which in turn makes

meat tender.

Pigments: Meat contain to pigments myoglobin and

haemoglobin.

Water: it is the largest single component of muscles by

weight.

CLASSIFICATION OF

MEAT1. Mutton

a) Lamb.

b) Yearling Mutton.

c) Mature Mutton.

2. Pork

3. Organs Meats

4. Sausages

AGIN

G

• The term ageing or ripening of meat, which implies the changes brought about by the resolution of rigor.

• Resolution of rigor means improvement in flavour as well as juiciness, in cold conditions.

• The method used for ageing is to keep the meat in a cold room with temperature between 0.50c to -20c for 1-4 weeks. Meat aged for 2-4 weeks has been found to be of best flavour and good tenderness.

• Events:– Tenderization of meat.– Development of better flavour and juiciness.– Denaturation of proteins and their mild hydrolysis.– Breakdown of the connective tissues present between muscle

fibres by the action of cathepsins.

TENDERISATION OF

MEAT

The most important sensory qualities of meat is

its tenderness and soft chewy feel.

Some meats are tender while others are hard to

chew. This is due to the type of animal, its age,

level of activity and the part of the animal eaten.

It can be improved by either natural methods or

artificial methods, Mechanical action, Chemical

action, Hydration and Cooking.

Natural

Method

Natural method implies the natural ripening and

tenderisation brought about by cathepsins present

inside the meat.

They cause the denaturation and hydrolysis of

muscle proteins and make the meat tender.

Cold room storage is effective in the natural ripening

process.

Over tenderisation of meat is undesirable as it

changes the texture of meat and results in loss of

flavour and juiciness.

Artificial MethodsMany artificial methods have been developed to tenderise meat. They are

1. MECHANICAL ACTION: Tenderness is improved by reducingthe length of muscle fibres or breaking them. This is achieved by:

1. Pounding: This tears and breaks the surface meat fibres andconnective tissues. This method is used for individual portionedcuts, steaks not whole joints.

2. Grinding: Breaks and cuts all muscle fibres and connective tissues.Meat is put through a chopper, grinding machine to break upconnective tissue and muscle tissue into small pieces.

3. Ultrasonic vibrations break the meat fibres.

4. Insertion of needles/blades into the meat has also been observed toincrease meat tenderness.

2. Chemical Action

• Salt increases tenderness because it softens the connective tissue.

• Vegetable enzymes such as papain, bromelin, trypsin, ficin and fungal enzymes also tenderize meat

• The tenderizing effect acts mainly at the surface, so a marinade or powder works better in small, thin cuts of meat.

• Vegetable enzymes are limited though in that their action is sometimes restricted to the surface of the meat

Hydration: ◦ An acidic, alkaline or salt solution can increase the water

holding capacity of meat and make it tenderer.

◦ Salts like sodium chloride, sodium bicarbonate and

sodium/potassium phosphate used for solubilizes the

meat proteins.

◦ Acid like lemon juice are often used to marinate meat

before cooking.

• Cooking:

o Tough cuts generally need a long, slow, moist method of

cooking, such as casseroling.

o On heating, muscle fibres begin to shrink. A around 770c,

shrinkage ceases and there are colour changes and loss of

liquid. This liquid is mixture of meat extracts, water and fat.

SMOKING

The process of curing refers to the treatmentsmeted out to meat which helps in preserving meatas well as imparting it the unique flavour, colourand tenderness.

Curing is a traditional art practised primarily topreserve meat and retard spoilage.

Curing agents are salt, sugar, nitrite and spices.

Occasionally cured meat is dried and smoked to

impart a better flavour and cause protein

coagulation.

Smoking helps in destruction of microorganisms

and prevents rancidity in meats. The sawdust

from hardwood is the fuel for smoking.

CURING

Meat Cookery or Cooking

It is the art of preparing food for the

nourishment of the body.

Objectives of cooking meat are:a) Develop or improve flavour, colour, aroma.

b) Make it delicious/appetising to eat.

c) Make it tenderer.

d) Make it easier to digest.

e) Make it safe to eat i.e., kill any harmful bacteria it

may have picked up during handling.

During the process of cooking many chemical

changes occur, affecting the appearance, taste

and texture of meat.

1. Muscle proteins shrink and moisture is lost

2. Changes in colour

3. Connective tissue softens

4. Fat melts, browning occurs and flavour develops.

Cooking Methods

Dry heat methods: In this methods do not use liquid,

but can use fat or oil. Dry heat suits tender or medium-

tender meat cuts.

a) Roasting

b) Grilling (fan-grilling, pan-grilling)

c) Shallow frying (pan-frying, stir-frying)

d) Deep frying

Moist heat methods:

a) Braising

b) Pot-roasting

c) Stewing

d) Simmering

e) Poaching

f) Steaming

g) Pressure-cooking

The cooking method chosen depends on

1. Natural tenderness of meat cut.

2. The amount and type of connective tissue.

3. The leanness of the meat.

4. Size and thickness of the cut of meat.

CHILLING• After slaughter many biological changes take place in the

muscle that convert it to meat.

• Chilling is used to prevent spoilage.

• If chilling occurs rapidly the result is cold shortening

– Occurs when the muscle is chilled to less than 150cbefore rigor mortis(Contraction and stiffening of themuscle) is complete.

• If the carcass is frozen before rigor is complete the resultis “thaw rigor” and the result is extremely tough meat

• Before freezing, beef or lamb should be sufficiently aged, as meat does not continue to tenderise while frozen.

• Frozen large cuts will keep better and longer, with less flavour change, than frozen smaller cuts, thin slices or mince.

• It is important to make sure temperature don’t fluctuate by more than 0.50c.

• Big temperature changes can mean a partial thaw which damages the structure of the meat.

Freezing

Thawing• The best way to maintain quality of frozen meat is by slow thawing in the

refrigerator.

• Thawing meat at room temperature is not recommended. The surface of themeat may reach warm temperatures which encourages spoilage.

• If thawing is needed urgently there are some options. Leave the meat in itssealed freezer wrap or vacuum-pack for all the following “speed-thaw” methods.

1) Place meat on a tray in a relatively cool room for 1-2hr before completingthawing in the refrigerator.

2) Use a microwave oven set on defrost.

3) Place sealed vacuum-pack in a sink of cold running water.

Storage

Dried TVP should be kept cool, in an air-tight container away from direct sunlight. Tofu, tempeh and myco-protein should be kept in a refrigerator or freezer unit until needed.

FISH PROCESSING

Introduction

O Fish is found abundantly in all natural

waters.

O It is a valuable source of food and has

been used by man from antiquity.

O Its popularity can be gauged by the

umpteen numbers of dishes with fish as

their base made in these states.

Although there are over 25,000 species of fishes.

Edible fishes are divided in two categories.

1) Fin fish

2) Shell fish

a) Mollusks (oysters, clams, scallops and mussels)

b) Crustaceans (lobsters, shrimps, crabs and cray fish)

• Classification of fish on the basis of their fat content

1) Lean: <2% (Bombay duck, halibut, cod perch and sole)

2) Medium: 2 – 5% (Generally fishes are white fleshed)

3) Fat: >5% and so the flesh is more pigmented and they

appear reddish. (Tuna, salmon, sardine and mackerel)

Nutritive

Value

Protein: Fish is an excellent source of good quality

protein with about 20% protein. The main amino acids

are lysine and histidine. Methionine and tryptophan are

also present.

Fats: variable and dependent on many factors like age,

season, sex and stage of maturity.Fish type N-3 PUFA content (g/100 g

edible muscle)

Fresh water fish 0.07 – 0.28

Fish murrel 0.28

Marine fish 0.26 – 0.28

Fresh water fish (fat 1.7 g%) 0.26

Marine fish (1.8 g% fat) 0.39

Carbohydrate: Fishes are not good sources of energysince their fat and carbohydrate content is insignificant.The main carbohydrate present in fish is glycogen frommuscles (3 – 5 % in shell fish).

Vitamins: Fish oils are the richest sources of vitamins Aand D. They are fairly rich in thiamine, but due to thepresence of thiaminase in raw fish. Niacin is a vitaminabundant in both fresh water and salt water fish.

Minerals: The major minerals fishes contribute are iron,copper, iodine, sulphur and phosphorus.

Iodine content of marine fishes( 0.01 – 0.5 mg/100 g offish meat) is much better (30%) than fresh water fishes.

Oysters are good sources of copper and iron.

Fishes are specially rich in calcium, particularly smallfishes eaten with bones.

SELECTI

ON

Observed part Identifying characters

Skin Bright and shiny skin. No wrinkles and shrunken skin.

Eyes Convex eyes with black pupil and translucent cornea.

Bright, clear and bulging eyes.

Gills Bright red, not brown or with mucous.

Backbone Firmly attached backbone to the skin on splitting it

open

Surface Clean, free of dirt and grime

Flesh Firm to touch and not dry or brown.

Odour Absent

Taste Fresh and not sour as rancidity causes sour taste to

develop.

Yellow spots on

surface

Rancid fish so not to be selected

SHELL FISH

SELECTION

Shell fish Characters for good quality

Prawns Fresh and firm

Scallops Pinkish or pale yellow in colour, with firm flesh and clear liquid

oozing out.

Clams Tightly closed with no entry points left open. Heavy to lift and no

foul odours emitting out.

Oysters Tightly closed with no entry points left open. Heavy to lift and no

smell of deterioration.

Mussels Difficult to open as the lids are tightly closed. The mussels

should be heavy to confirm no microbial spoilage and intact

flesh. No off odours should be coming out.

Spoilage

Microbial spoilage: Till the time fishes are alive theyare sterile(microbiologically), but a number of microbes arepresent on the body surface in the form of slime and in theirdigestive tracts.

Physiological spoilage: If there is no glycogen availablefor conversion into lactic acid, pH does not decrease, thiscondition accelerates spoilage.

Biochemical spoilage: Odour is developed due to theproduction of the compound tri-methyl amine formed whenbacteria react on phospholipids and choline of the fish cells.

Oxidative rancidity also is a major cause forundesirable smell since the unsaturated fats undergooxidation.

Preservation Methods

1. Drying: Drying was done by exposure to sun or thetechnique which resists bacterial and enzymeputrefaction.

2. Pickling/salting: It is another primitive method whichuses salt as preservative (dry salting and wet salting).

3. Canning:

Popular preservation method (John Eppurt). Salmon andTuna are the most popular varieties of canned fish.

Canning is done by putting cleaned, dressed and cut fishinto a saline solution.

Sterilize the cans at 1210c for 90 minutes, under steampressure.

Sterilization is followed by cooling of the cans undernormal room temperature by running water.

4. Low temperature treatment

For the effective preservation, very low temperature to

the tune of -400c and maintained at -230c approved. Freezing

is done rapidly and has to be properly maintained. This way,

fish stays in food condition for about 6 – 7 months.

Freezing causes some undesirable changes in the

quality of fish. It is the major reason for denaturation of fish

protein and desiccation of fish.

5. Denaturation: When water crystals are formed, salt

concentration of the muscle tissues goes on increasing. This

high salt concentration causes the denaturation of muscle

proteins and makes the flesh tough to chew and eat.

6. Desiccation: Implying drying, this is another

problem with freezing fish. The loss of moisture due to

the fact that the air close to the fish in the storage area

is not as cold as that in the refrigeration pipes. As a

result it absorbs large amounts of moisture form the

surface of the fish.

The facet of desiccation is the evaporation of

water from flesh of the frozen fish to the air cavities

between muscle fibres. This can be avoided and

controlled by letting a weak saline solution to fill these

cavities prior to any evaporation.

7. Oxidation changes: Another aspect of freezing is

the development of oxidative rancidity. This is more

marked in fatty fish than lean ones. It can be avoided by

proper wrapping of the fish and adequate storage.

Fish Cookery

With any food stuff the most important part comes

when it has to be cooked for consumption.

Lot of factors like time, seasonings, cooking

method, additives etc. have to be considered to

make the perfect dish.

Generally dry heating methods like broiling,

baking and frying are used to cook fish.

Moist heating methods are also used as they

are effective in protecting the delicate flavour of

the fish.

Some times a combination of both methods also

used.

Storage

Fresh fish have 3 – 6 hours they are considered well enough for consumption. But from the sixth hour their journey to spoilage accelerates.

It should be stored at frozen temperature(-180c or less) to preserves the colour, texture, flavour and nutritive value of fish. (max. 2 days)

Canned fishes, pre-packed fish can keep well for a short time.

Cold storages are a viable storage option.

If fish are kept with crushed ice they remain good for 2 days. Additionally, if stored in freezer with crushed ice, the self-life increases to a week.

For further long storage a media of crushed ice with salt is good enough.