KENYA STANDARD  KS 2296:2022  
ICS 67.140.10  
Second  Edition  
  
 © KEBS 2022   
  Chicken eggs — Methods for evaluation 
of quality    
 
 
KS 2296 : 2022  
ii © KEBS 2022  – All rights reserved  
 TECHNICAL COMMITTEE REPRESENTATION  
The following organizations were represented on the Technical Committee:  
Ministry of Health - food safety unit  
Kenya Industrial Research and Development Institute  
National Public Health Laboratory  
Government Chemist’s Department  
Farmer’s Choice (K) Ltd.  
University of Nairobi — Department of Food Science, Nutrition and Technology  
Consumer Information Network  
Kenchic (K) Ltd.  
Kenya Meat Commission  
Directorate of Livestock Production  
Directorate of Veterinary Services  
Kenya Nut Company - Morendat farm  
Meat Tr aining institute  
Choice Meats limited  
XXX 
Kenya Bureau of Standards — Secretariat  
REVISION OF KENYA STANDARDS  
In order to  keep abreast of progress in industry, Kenya Standards shall be regularly reviewed.  Suggestions for 
improvements to published standards, addressed to the Managing Director, Kenya Bureau of Standards, are 
welcome.  
© Kenya Bureau of Standards, 2022  
Copyrigh t. Users are reminded that by virtue of Section 25 of the Copyright Act, Cap. 130 of 2001 of  the Laws of Kenya, copyright subsists 
in all Kenya Standards and except as provided under Section 25 of this Act, no Kenya Standard produced by Kenya Bureau of Sta ndards 
may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in writing f rom the 
Managing Director.   KENYA STANDARD  KS 2296 :2022  
ICS 67.140.10  
Second  Edition  
 
© KEBS 2022  – All rights reserved  iii 
  Chicken eggs — Methods for evaluation of  
quality   
 
Kenya Bureau of Standards,  Popo Road, Off Mom basa Road,  
P.O. Box 54974 - 00200,  Nairobi, Kenya  
 +254 020 6948000, + 254 722202137, + 254 734600471  
 info@kebs.org  
 @KEBS_ke  
 kenya bureau of standards (kebs)  
  
KS 2296 : 2022  
iv © KEBS 2022  – All rights reserved  
 Foreword  
This Kenya Standard was prepared by the Meat  and Poultry  products  Technical Committee under the guidance 
of the Standards Projects Committee, and it is in accordance with the procedures of the Kenya Bureau of 
Standards  
This standard specifies methods of sampling and test necessary to determine quality of fresh eggs. It  
includes external quality factors as they appear under direct examination and internal quality factors as they  
appear before candling light or when the egg is broken out and measured by Haugh units plus visual  
examination of the yolk portions.   
During the preparation of this standard, reference was made to the following documents:  
Regulations governing the voluntary grading of shell eggs , 7 CFR Part 56, Effective March 30, 2008.  
United States Standards, grades, and weight classes for shell eggs, AMS 56, Eff ective July 20, 2000.  
IS 9810:1981(R2000), Methods for evaluation of quality of chicken eggs.  
Codex Alimentarius website: http://www.codexalimentarius.net/mrls/vetdrugs/jsp/vetd_q -e.jsp.  
USDA Foreign agricultural service website: http://www.mrldatabase.com . 
USDA Agricultural marketing service website: http://www.ams.usda.gov/AMSv1.0/Standards.  
European Union: http://ec.europa.eu/enterprise/sectors/pharmaceuticals/veterinary -use/maximumresidue - 
limits/index_en.htm.  
XXXXXXXX  
Acknowledgement is hereby made for  the assistance derived from this (these) source (s)  
 KS 2296 :2022    
 
© KEBS 2022 – All rights reserved   
  Chicken eggs — Methods for evaluation of quality  
1 Scope  
This Kenya Standard specifies methods of sampling and test necessary to determine quality of fresh eggs. It  
includes external quality factors as they appear under direct examination and internal qua lity factors as they  
appear before candling light or when the egg is broken out and measured by Haugh units plus visual  
examination of the yolk portions.  
2 Normative references  
The following referenced documents referred to in the text in such a way that s ome or all of their content 
constitutes requirements of this document. For dated references, only the edition cited applies. For undated 
references, the latest edition of the referenced document (including any amendments) applies , see ISO/IEC 
Directives, P art 2). 
I. AOAC Official Method 931.06:1931, Phosphorus (Total) (P2O5) in Eggs  
II. CAC/RCP 1, Recommended international code of practice — General principles of food hygiene  
III. EAS 39, Hygiene in the food and drink manufacturing industry — Code of practice  
IV. EAS 123, Distilled water — Specification  
V. ISO 4831, Microbiology of food and animal feeding stuffs — Horizontal method for the detection and  
enumeration of coliforms — Most probable number technique  
VI. ISO 4832, Microbiology of food and animal feeding stuffs — Horizontal method for the enumeration of  
coliforms — Colony -count technique  
VII. ISO 4833, Microbiology of food and animal feeding stuffs — Horizontal method for the enumeration of  
microorganisms — Colony -count technique at 30 degrees C  
VIII. ISO 6491, Animal feeding st uffs — Determination of phosphorus content — Spectrometric method  
IX. ISO 6579, Microbiology of food and animal feeding stuffs — Horizontal method for the detection of  
Salmonella spp.  
X. ISO 13730, Meat and meat products — Determination of total phosphorus conten t — Spectrometric 
method  
XI. ISO 21527 -1, Microbiology of food and animal feeding stuffs — Horizontal method for the enumeration 
of yeasts and moulds — Part 1: Colony count technique in products with water activity greater than 0.95  
XII. ISO 21527 -2, Microbiology o f food and animal feeding stuffs — Horizontal method for the enumeration 
of yeasts and moulds — Part 2: Colony count technique in products with water activity less than or 
equal to  0.95 
XIII. KS EAS 38, Labelling of pre -packaged foods  
XIV. KS EAS 39, Hygiene in the f ood and drink manufacturing industry — Code of practice   
© KEBS 2022  – All rights reserved  iii 
  XV. CAC/RCP 1 -1969, Rev. 4 -20031:  Recommended International Code of Practice General Principles of 
Food Hygiene  
3 Terms and definitions  
For the purposes of this document, the following terms and definitions apply.  
3.1 Description of shell condition and its cleanliness   
 
3.1.1 sound shell is unbroken  
3.1.2  checked  
shell having a crack in the shell but shell membranes intact  
3.1.3 The leaker   
egg showing leakage through the shell and shell membranes allowing the contents to come out. Area of shell  
missing from the surface is more than 6 mm square.  
3.1.4  smashed  
an egg the shell of which is smashed, crushed  or scattered allowing the contents to come out  
3.1.5  clean  
free from foreign material, stain or other visual discolouration  
3.1.6  slightly stained  
a shell surface which is almost free from adhering dirt, but has slight stains without appreciably detractin g its 
appearance limited to 1/16th of the shell surface  
3.1.7  moderately  
a shell that is free from adhering dirt but has stains covering to a moderate degree and limited to ¼ of the  
shell surface  
3.1.8  dirty  
egg shell having adhering dirt and stains coveri ng more than ¼ of the shell surface  
3.1.9  roughness/smoothness of the shell.  
The shell shall not be overly rough nor smooth  
3.2 Description of air cell  
3.2.1  practically regular  
an air cell which maintains practically a fixed position inside the egg and presents an even outline with not  
more than 6 mm movement in any direction when it is turned  
3.2.2  free air cell  
an air cell that moves freely towards the uppermost point inside the egg as it is rotated slowly. The shell   
iv © KEBS 2022  – All rights reserved  
 membranes are intact allowing the a ir cell to move freely in any direction between them  
3.2.3  bubbly air cell  
a ruptured air cell consisting of one or more small separate air bubbles floating beneath the main air cell  
3.3 Description of yolk shadow outline  
3.3.1  outline slightly defined  
a yolk outline which is distinctly visible and blends into the surrounding white as the egg is rotated in front of  
the candler  
3.3.2  outline fairly well defined  
a yolk outline which is discernible but cannot be outlined clearly when twirled in front of a candler  
3.3.3  outline well defined  
outline of the yolk clearly visible as it casts a dark shadow when twirled in front of a candler  
3.4 Description of yolk defect s 
3.4.1  practically free from defects  
a yolk that shows no germ development, meat or blood spots  
3.4.2  definite but not serious defects  
a yolk may show definite meat or blood spots on the surface with slight indications of germ development but  
without any pronounced or serious defects  
3.4.3  definite and serious defects  
yolk showing development of germ spot on the yolk, visible as a definite area with no blood ring  
3.5 Description of egg white  
3.5.1  clear  
egg white which is free from discolourations and pres ence of any free floating foreign bodies on it  
3.5.2  firm 
egg white which is sufficiently thick or viscous and thus makes the outline of yolk slightly or indistinctly visible  
when twirled in front of a candler  
3.5.3  reasonably firm  
egg white which is reasonably thick or viscous but enough to allow casting of the outline of the yolk when  
twirled and candled  
3.5.4  weak and watery  
egg white which is thin and lacks in viscosity. It permits the yolk to approach the shell closely on candling,   
© KEBS 2022  – All rights reserved  v 
  making yolk out line clearly visible on twirling.  
4 Sampling and testing  
4.1 Sampling  
Twenty eggs should be drawn from a lot at random for estimating the breakout quality of eggs.  
4.2 Testing  
Carry out the following tests to determine the egg quality.  
4.2.1 External quali ty 
Determine the external quality of egg for the parameters given in 3.1 and 3.2.  
4.2.2 Internal quality  
Determine the internal quality of eggs for the parameters given in 3.3, 3.4 and 3.5 by candling and breaking  
out tests.  
4.3 Candling  
4.3.1 Hold the egg before a beam of 60 watt light in such a way that the light rays penetrate and illuminate  
the interior of the egg for inspection. Note any internal defects.  
4.3.2 Measure the aircell height by means of aircell gauge while candling prior to bre aking.  
4.4 Shell thickness  
After breaking the egg, boil the shell in 2.5 % sodium hydroxide solution f or 5 min. Wash and dry in a  
thermostatically controlled oven at 100 °C to 105 for 24 h. Determine the thickness of the shell by screw  
gauge at three diffe rent longitudinal points and take the average of the readings.  
4.5 Haugh Unit (HU)  
4.5.1 Haugh unit can be measured by using the interior egg quality calculator. The following precautions  
should be followed while estimating the same:  
i) The internal temper ature of eggs should not be lower than 7 °C or higher than 15 °C at the time of  
performing the breakout test.  
ii) Care should be exercised to see that the thick white is not punctured while breaking.  
iii) One egg at a time should be broken since it is important to measure the albumen height immediately  
after breaking.  
iv) Measurement of height of thick albumen should be made with the help of a spherometer or Haugh  
meter or micrometer as given in Figure 1.  
v) Care should be taken to avoid measuring the a lbumen height in an area where there is a chalaza for   
vi © KEBS 2022  – All rights reserved  
 air bubble.  
4.5.2 Eggs removed from the refrigerator should be kept for three hours at ambient temperature of 23 °C ±  
2 °C. Determine the Haugh unit reading of the eggs by the following procedure:  
a) Ch eck the zero reading by placing the instrument on a flat surface and lowering the plung until the  
point touches the surface. The pointer should be at zero. If not, slacken the clamp and turn the bezol  
so that the zero mark coincides with the pointer. Retra ct the point upwards to its full extent.  
b) Open the egg on to a flat glass plate of sufficient size to contain it, place the instrument over the egg,  and 
lower the point until just touches the albumen. The height is then indicated on the dial.   
 
 
Figure  1 — Gauge for egg quality  
The HU can then be calculated from the following equation:  
HU = 100log 10H + 7.57 - 1.7 M 
where  
HU = Haugh units of interior quality whose numerical value equals the quality value of the egg;  
H = height, mm; and  
M = mass, g.  
NOTE An alignment chart for finding Haugh units without having to make calculation from the above formula is given in Figure 2.  
 
© KEBS 2022  – All rights reserved  vii 
  4.6 Albumen index  
Albumen index can be determined by measuring the height of the thick albumen by spherometer or  
micrometer and avera ge width of the thick albumen by using vernier calipers:  
 
 
Figure 2 — Alignment chart  
4.7 Yolk index  
Yolk index can be determined by measuring the height or width of the yolk after it has been separated from  
the albumen or of the yolk in its natural position when the egg is broken out on a flat surface.  
 
 
 
viii © KEBS 2022  – All rights reserved  
 Bibliography  
[1] ISO ##### -#, General title — Part #: Title of part  
[2] ISO ##### -##:20##, General title — Part ##: Title of part  
A Biblio graphy , if present, shall appear after the last annex.  
The bibliography may include  
— documents that are not publicly available,  
— documents which are only cited in an informative manner, and  
— documents which have merely served as bibliographic or backgr ound material in the preparation of the 
document.  
For online referenced documents, information sufficient to identify and locate the source shall be provided. 
Preferably, the primary source of the referenced document should be cited, in order to ensure tra ceability. 
Furthermore, the reference should, as far as possible, remain valid for the expected life of the document. The 
reference shall include the method of access to the referenced document and the full network address .