What is spoilage?

Changes in food, through physical, chemical, enzyme deterioration or micro-organisms

growth, that lead to the food becoming damaged, inedible or unsafe if eaten.

Signs of spoilage:

off odor- off flavorsoff odors such as sweet and fruity, putrid, Sulphur and cheese are

characterized in aerobically stored meat. Species which are involved

Pseudomonas, and pseudomonas fragi

discoloration

the bacterial production of hydrogen sulphide converts the muscle pigment to

green sulphemoglobin

gas production

Clostridium species are involved in this gas production. Gas production

by lactic acid bacteria

contaminants may be already present in food e.g. salmonella in chicken

or transferred to the food by humans, pests etc.

What is microbial spoilage:

Microbes are responsible for spoilage of food, when they breakdown the food, acids and

other waste products are created in this process. While the microbe itself may or may

not be harmful, the waste products may be unpleasant to taste or may be harmful to

one’s health.

How it occurs?

Normal slaughtering techniques

External sources during bleeding, handling, cutting and processing

Intestinal tract of animal, exterior of anima (hides, hooves and hairs) knives, cloth, air, hands, and clothing of workers

depends on methods of slaughtering such as mechanical, physical, chemical and

electrical.

What Is meat?

Meat is a nutritious, protein-rich food which is highly perishable and has a short

shelf-life unless preservation

methods are used. It is the first-choice source of animal protein for many people all

over the world. Consumption

of meat is continuously increasing worldwide. Although consumption of meat is

increasing worldwide the

significant portion of meat and meat products are spoiled every year.

Slaughtering of meat:

Different technical operations are involved in slaughtering:

stunning,

o bleeding,

o skinning

o evisceration

o carcass splitting.

Constituents of meat:

• Fat,

• protein,

• minerals,

• carbohydrate and water are the constituents of meat

quality of meat:

The quality of meat and meat products degrade as a result of digestive enzymes,

microbial spoilage and fat oxidation). Lipid oxidation, protein degradation and the

loss of other valuable molecules are the consequence of meat spoilage process.

Spoilage of meat:

• raw is subjected to change by its own enzymes and microbial action and its fat

may be oxidized chemically

• autolysis changes include some proteolytic action on muscle and connective and

slight hydrolysis of fats.

• The defect caused by excessive autolysis has been called souring.

Invasion of tissue by micro-organism

• Upon the death of animal, invasion of tissue by contaminating micro-organism

takes place.

Factors:

• load In the gut of animal

• physical condition of animal

• method of killing and bleeding

• the rate of cooling

Growth of micro-organism in meat and meat product

Meat is an ideal culture for many microbes because it is high in moisture, rich in

nitrogenous foods, filled with minerals and accessory growth factor

Also It usually has some fermentable carbohydrate (glycogen) is at favorable

ph. for most micro-organism.

Growth factors:

Physical properties of meat

Chemical properties of meat

Availability of oxygen

Temperature

Conditions:

1. Aerobic 2. Anaerobic

Aerobic condition 1. Surface slime

It is caused by species of Pseudomonas, Acinetobacter, Moraxella, Streptococcus, Leuconostoc, Bacillus and Micrococcus

it is early stage of spoilage

2. change in pigment: the red color of meat is called bloom, may be changed to shades of green,

grey as a result of the production of oxidizing compound. e.g. hydrogen

peroxide and hydrogen sulfide.3. Lactobacillus and leuconostoc are basically responsible

4. Changes in fats: The oxidation of unsaturated fats

5. Pseudomonas and achromobacter are responsible for oxidative

rancidity or by yeast.

6. Phosphorescence: This is caused by luminous bacteria example photobacterium spp. Grows on the

surface of meat

Achromobacter

pseudomonas

7.Various surface colors due to pigmented bacteria:

Serratia Marcescens (red color) Pseudomonas (impart blue color) Syncyanea (impart blue color) Micrococcus or flavobacterium (black spot) Chromo bacterium lividum (black spot)

8.off odors and off taste:

Taints are undesirable taste or smell that appear in meat.

Souring is the term applied to almost any defect that gives the sour odor that may

be due to volatile acids. e.g formic, butyric, propionic acids

9. Actinomycetes may be responsible for musty or earthy flavor

Aerobic molds may cause:

1. StickinessSurface become sticky

2. WhiskersMycial growth may take place without sporulation when meat is placed at freezer

3. Black spotCladosporium cause black spot

4. White spotSporotricum cairns may cause white spot

5. Green patches

Penicillin such as P. oxaclium and p. expansum

Serratia marcesence

penicillin

Sporotricum on meat

Types of spoilage and microorganisms

Meat spoilage depending upon oxygen

oxygen Microbialagents

Symptoms

present Aerobic bacteria

Surface slime Discoloration Gas production Change in odor Fat decomposition

Present Yeasts Surface slime Discoloration Change in odor and taste Fat decomposition

Present Molds Sticky and "whiskery" surface Discoloration Change in odor Fat decomposition

Absent Anaerobic bacteria Putrefaction and foul odors Gas production Souring

Spoilage under anaerobic condition

Facultative and anaerobic bacteria can able to grow with the meat under anaerobic

conditions and cause spoilage.

Following changes occurs in such conditions:

Souring:It imparts sour taste to meat such as formic, propionic acid, acetic acid etc.

Putrefaction:True putrefaction is the anaerobic decomposition of proteins with the production

of foul smelling compound such as hydrogen, sulphide, indole, ammonia, amines

due to species clostridium.

Taintit is undesirable smell that appears in meat.

Salmonella poisoning:

• Salmonella Food Poisoning is a pretty disabling and annoying pathological

condition that normally occurs due to eating contaminated food.

• The food that the affected individual eats is usually contaminated by animal or

human feces which tend to carry the bacteria called as Salmonella.

• Salmonella Food Poisoning are normally found when people eat foods made of

poultry items like eggs or meat.

• Some of the common food items that can be infected by the bacteria Salmonella

and cause Salmonella Food Poisoning are undercooked eggs, raw milk, contaminated

water, and raw meat.

Lab test for spoiled meat:

In the simplest way of sensory testing, the meat processor, possibly assisted by other

staff, will test a product’s color, smell, taste and texture upon manufacture. In a more

sophisticated approach a team of trained panelists can be used in order to make the

results as objective as possible. For this purpose, it is useful to have an appropriate

testing room available with lights, temperature and seating arrangements with individual

testing compartments so as not to distract the members of the pane.

Sense of sight is used to evaluate the general appearance of the product such

as color, size, shape etc.

Sense of smell for the odor

Sense of taste for the flavor which includes the four basic tastes sour, sweet,

bitter and salty

Sense of touch for the texture either by mouth feel or finger feel.