Food Handling And Spoilage

Food handling and spoilage

Food spoilage refers to the damage or distortion of food . So as to make it undesirable for human consumption such spoilage may be due to

• Physical damage caused by cutting ,brushing, freezing etc.
• Mechanical damage is caused by insects , birds, animals etc.
• The growth of spoilage microorganism in food .
• The activity of food enzyme itself .
• Improper environment conditions during harvesting ,transport storage and marketing .
• The spoilage food may be transferred the spoilage organism to the fresh food and result in the spread of spoilage .Spoilage increased the number of wastages.

Egg

Contamination :Freshly laid egg is sterile t the egg cell soon become contaminated by and faecal matter of hand , by other material in which is stored. The total no.of microorganisms per shell of hens egg has been reported to range from 100 to 10000000 with an average of 100000 Salmonella species may be found on the shell or inside the egg .

preservation : Egg has been a way of protecting itself from microbial spoilage shell and underlying membrane serve of microorganisms.In addition to a physical barrier , the egg is not suitable growth medium and discourage the growth of many microorganisms.Characteristics of egg albumin that discourage microbial growth include pH( 9-10) level of simple nitrogen compound lysozyme that hydrolyzes peptidoglycan of bacteria . Avidin that binds biotin and lipoprotein that binds riboflavin . Despite physical barrier and other antimicrobial factors, the microorganism can invade and cause spoilage of egg .therefore ,following method ae employed for its preservation .

Asepsis :Great care should be taken to reduce the contamination of the outside of the shell by hand faeces and dirt from the nest.Contamination during cleaning and from equipment must be reduced or sanitised

Use of heat :Heating egg shell in oil for 10 min at 60°c or in water for 30 min at 54.5c. Heating egg content of egg in not the detergent-sanitizer solution( 43.3°c -54.4°c). The sanitizer solution can be quarterly ammonium compound. The egg should be pasteurized but before pasteurization egg should be stabilised by the addition of aluminium.

Removal of the organism : Various methods can be employed to remove dirt and faecal matter from egg spray .Dry cleaning by sandblasting( to spray with fast moving solid grain such as sand) removes dirt and bloom and part of microorganism but encourage the penetration of bacteria into the egg through the pores in the shell . Use of disinfectant in washing solution reduced the number of microorganisms.

• Chilling : Egg is commercially stored fors6 months or longer at a temperature of -1.7 to - 0.55c and a relative humidity of(70-80%). The higher the relative humidity, the more likely the microbial spoilage of the egg.Similarly ,higher the temperatures,the more rapid the penetration of most into the egg and grown here and the greater the physical and chemical changes .eg, thinning of the egg white and weakening of the yolk membrane special treatment like impregnation of egg shell with colourless and odourless mineral oil keeps out moisture,shows desiccation (dry) and air penetration during chilling.freezing: Egg are first washed with 200-500ppm chloride solution and broken on automatic.
• freezing: Egg are first washed with 200-500ppm chloride solution and broken on automatic breaking machine .egg yolk and egg whites are separated and they are frozen separately at -17c to -20.5c.
• preservation by drying:Egg is first washed with chloride solution and broken on automatic breaking machine and then yolk and white are separated lipid egg is then dried by drum drying or spray drying method.
• preservation by chemical preservatives :Preservation may be used on shells of egg in the atmosphere around them and on containers for the egg.Some of them are;waxing and oiling of shell dry ,reduce penetration of oxygen into the egg and reduce passage of co2 and moisture out . Immersion of whole egg in the solution of sodium silicate is also a food preservative. Use of zone and co2 in storage environment improves the quality of the egg.
• Use of irradiation :Ionizing radiation can be used in egg to kill pathogen like salmonella

Spoilage

Nonmicrobial effect: They include loss of moisture and hence loss of weight during long-term strong.Chang physical state of egg content also occurs during long storage .They include thinning of egg white and breaking of yolk membranes weaken and break yolk become flat and homogenously mixed in egg white.

Microbial spoilage :In order to cause spoilage of shell penetrate the pores in the shell and inner membrane reach the egg white and yolk and grow there.Some microorganisms can not grow in egg white but can grow rapidly in egg yolk change in storage temperature facilitate penetration of organism through the cell and hence facilitate microbial spoilage.

• Bacterial spoilage : Bactria is more common spoilage organism than mold . Bacteria cause "rot" in egg , they decompose the content and from the product . This results in characteristics ,odour, appearance ,or colour from white various rotacquire their name.

1. Green rot: Itis caused by pseudomonas fluorescence .The rot is a show named because of the bright green colour of the white during early of development .Green egg white shows fluorescence when exposed to light .
2. Colourless rot: It may be caused by pseudomonas ,acinetobacter,alkalines and cold from
3. Pink rot: It is caused by pseudomonas usually at a later stage of green rot .They are similar to colourless rot except that colourless occurs in yolk and white .
4. Black rot: It is caused by proteus and sometimes pseudomonas and Aeromonas egg content have a muddy appearance and odour are petrified to hydrogen sulphide production .
5. Red rot:It is caused by Serratia marcescent .Their eggs are distinguished by a red discolouration of egg white and the surface of the yolk
6. Custard rot : It is caused by proteus vulgar and proteus Vulgaris and proteus intermedium . The albumin becomes than with orange colouration.

• fungal spoilage : Fungal spoilage goes through following stage .

1. Pink spot molding : In this case small compact colonies of mold appearance on the shell and usually just inside the shell . The colour of pin varies with the type of mold. For example, Cladosporium gives black spot and Sporotrichum gives a pink spot.
2. superficial fungal spoilage : This occurs if the egg is stored in an atmosphere of high humidity . In this case, mold grows on the shell in the form of "Whiskers".
3. fungal rotting :It is the final stage of spoilage by mold . during this jellying of the white result and coloured rot may be produced. For example, fungal red rot caused by spirotrich and black rot caused by Cladosporium.

Reference

Frazier, WC and Westhoff DC. Food Microbiology. 3rd. New Delhi: Tata McGraw-Hill Publishing Company Limited, 1986.

Jay, MJ. Moderen Food Microbiology. Ed. India. 3rd. Delhi: CBS Publications and Distributions, 1987.