Egg storage is an essential aspect of egg handling. The main goal is to preserve important egg quality characteristic, since there is now year round egg production, long term storage, to keep egg quality at a level acceptable for table eggs, is no longer essential as it was. Barbosa et al., (2004), evaluating the effect of temperature and storage time (0,7,14,28 and 35) on egg quality, Verified that the increase of storage time caused reduction in Haugh unit and the egg weight. They also reported that storage time affects the quality of eggs, exerting a negative influence on the Haugh unit.

          Egg lose weight due to evaporation of water form the albumen. As long as relative humidity (RH) in the atmosphere around the eggs is less than 99.6% water evaporates through the shell pores. Leandro et al., (2005) and Menezes et al., (2009). The rate of evaporation increases linearly with the difference in relative humidity inside and outside of the egg. It can be described in the equation: L =p(1-R) where
L       =        Loss in weight
P        =        permeability of the shell
R       =        atmosphere relative humidity. This formular hold for single
egg fully surrounded by an atmosphere with a certain relative humidity.
In a pile of packed eggs, other condition occurs depending on the rate of ventilation through the pile. Pile eggs usually are not well ventilated in the centre. This is the reasons why in the centre, the relative humidity (RH) reaches equilibrium with the interior of egg. At that point, an atmosphere has risen with a relative humidity of about 99% and weight loss has been reduce to zero. Under this condition, mould growth often occur and care should be taken that no where in the pile does the relative humidity exceed 85%. This can be achieved by frequent collection of eggs, rapid storage in the cold room separated from other products. (miles and Henry, 2004). A rule of thumb is that under correct conditions, egg lose about 1% of their weight each week, proper storage means that some loss in weight must be allowed. Weight loss is restricted by oiling of the shell which decreases the permeability of the shell by closing the pores.
          In the first stage of storage, egg lose carbon dioxides causes cloudy white which is a characteristics of newly laid eggs. Due to the low content of carbon dioxide in the atmosphere, eggs lose it in a few days. This phenomenon gives rise to an increase in PH of the white.
          Ageing of eggs causes a reduction in the amount of thick albumen with it’s conversion into thin albumen. Eggs of several days old show weak and watery albumen (Awosanya et al.,1998). Since this is a chemical process, progress depends on temperature, the lower the temperature ,the slower the conversion of thick albumen proceeds.
          High temperature above 16.50c cause rapid decrease in internal quality via increasing humidity loss (Samli et al., 2005). storage temperature should be adjusted carefully to the ambient temperature and relative humidity. immediately the surface temperature is low, the dew point of the air around it water vapour will condense on the shell. This phenomenon of water condensation on the shell is called “sweating” and should be prevented as it is very harmful since an egg is never sterile, micro organisms will start to develop in the moist environment. They will again access through the pores and continue to grow on the membranes. When microbial growth reaches the yolk, the egg will spoil.
          The yolk absorbs water due to osmotic activity during storage. At the same time the strength of the vitelline membrane decreases. These factors are responsible for the difference in appearance between yolk from the stored eggs and those form fresh eggs. The colour of the yolk also varies with the type of feed given to the chicken but does not affect the nutritional content (Choprakem et al., 1998). When eggs that has been stored for long period are boiled, the surface of the yolk will have a greenish colour. This is caused by chemical interaction between iron present in the yolk and sulphur coming from decomposition in the albumen.
          Other factors that may cause loss of quality include disease. New castle disease and infectious bronchitis produce. Watery albumen which may persist for long after the diseases has been controlled (Aldene, 1996). Relative humidity of 70-780h reduces the egg weight losses by decrease in egg water losses to keep albumen fresh for long period of time (Keener et al., 2004).

Internal and external egg quality
          Egg quality is a general term that relate to various standards that are imposed on the eggs (USDA, 2000). Egg quality is a general term which refers to several standards which define both internal and external egg quality. External quality is focused on the shell cleanliness, texture and shape. Whereas internal quality refers to egg white (albumen) cleanliness and viscosity size of he air cell, yolk shape and strength. Internal egg quality also involves functional aesthetic and microbiological properties of the egg yolk and albumen. (Akbas, 1996).
          The white is formed by four structures. Firstly the chalalziterous layer or chalazae, immediately surrounding the yolk accounting for 3% of the white .Next is the inner thin layer, which surround the chalazae and account for 18% of the white. Third is the firm or thick layer which provide an envelope or jacket that holds the inner thin white and the yolk. It adheres to the shell membrane at each end of the egg and accounts for 57% of the albumen. Finally, the outer thin layers lies just inside the shell membranes except where the thick white is attached to the shell, and accounts for 23% of the egg white (USDA, 2000).
          Egg yolk from a newly laid egg is round and firm. As the egg gets older, the yolk absorbs water from the egg white, increasing the size. This provides an enlargement and weakness of the vitalize membrane, the yolk looks flat and show spots.
         As soon as egg is laid , the internal quality starts to decrease, the longer the storage time, the more the internal egg quality deteriorates. However, the chemical composition changes much.
          In a newly laid egg the albumen ph lies between 7.6 and 8.5.
 During storage, the albumen pH increases at a temperature dependent rate to a maximum value of about 9.7 (Lichan et al., 1995), after three days of storage at 30C. In oiling of the shell the albumen pH of 8.3 did not change over a 7 days period of storage at 220c. In oiled egg stored at 70C, albumen pH dropped form 8.3 t 8.1 in 7 days (Li-chan et al 1995).
          Increase in albumen pH are due to the carbondioxide(CO2) loss through the shell spores and depend on dissolved Co2 bicarbonate ions.
          In a newly land eggs, the yolk pH is in general close to 6.0 however, during storage it gradually increases to reach 6.4 to 6.9. Egg quality preservations through handling and distribution is dependent on constant care from all personnel involved in this activities. The quality of an egg once it is laid cannot be improved so effort to maintain it’s quality must start right at this moment. (Cotterill et al.,1995).
          To minimize egg quality problems, the following are important;
*        keep the birds confined
*        gather eggs frequently at least three times a day
*        if egg must be cleaned, clean them immediately after gathering
*        dry clean slightly dirty eggs
*        cool eggs as quickly as possible
*        maintain an egg storage room temperature of 10-130C and relative humidity of 75%
*        the packing material should be clean and odorless
*        the storage room should be cleaned regularly with odourless sanitizer and fee form staining material.
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