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The Effect of Washing, Oiling, Holding and Temperature of Eggs on Shell Strength
The Effect of Washing, Oiling, Holding and Temperature of Eggs on Shell Strength R.
F . B A L L , J. F . H I L L , V . LOGAN AND J. LYMAN
Babcock Poultry Farm, Inc., Box 280, Ithaca, New York 14850 (Received for publication May 20, 1975)
POULTRY SCIENCE 55: 335-340,
INTRODUCTION
T
HE monetary losses from cracked and broken eggs continue to plague the poultry industry. Frequently cited factors associated with shell damage are mechanical handling, higher rate of egg production, inadequate nutrition, use of cages and age of the hen. Basic studies of egg shell structure and the development of devices for measuring shell strength have revealed less obvious factors affecting shell strength and damage. For example, Tyler and Geake (1964) demonstrated that water weakens shell strength. The removal of the cuticle was also shown by these workers to decrease shell strength. Further evidence of the role of the cuticle in shell strength was obtained by Tyler and Thomas (1966). Simon and Wiertz (1966) using electron microscopy found that water of 40° C. or higher temperature or detergent wash water removed much of the cuticle from eggs. That shell strength increases from the time of oviposition for several days thereafter was demonstrated by Tyler and Geake (1964) and again by Talbot and Tyler (1974).
1976
The oiling of eggs with a liquid paraffin containing silicone is a common commercial practice to preserve interior quality. The possibility that oiling may also contribute to shell strength, directly or indirectly, does not appear to have been studied. Indirect evidence that oiling may improve shell strength may be seen in the report of Hutchison (1955) who demonstrated that silicone coated bottles have less breakage. Grotts et al. (1957) also observed that some egg coating materials made egg breakouts more difficult. Meyer and Spencer (1973) found increased shell strength in eggs coated with six different materials. Bragg (1971) however, found more breakage of oiled than unoiled eggs during the washing process. Froning (1973) reported significant weakening of shell strength when eggs were heated above 13° C. for 15 minutes. In commercial egg washing, eggs are exposed briefly to temperatures of 46° C. or greater during the washing, rinsing and drying process. The importance of these less obvious influences on shell strength in present day commercial egg handling is unknown. The purpose of this study was to measure under 335
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on June 14, 2015
ABSTRACT The effect of washing, oiling, holding and egg temperature on shell strength was studied in a series of five experiments. Washing was shown to reduce shell strength from 180 to 380 grams per egg in two trials. Eggs oiled after lay and washed were significantly stronger than unoiled, washed eggs. Eggs oiled after lay and not washed were also stronger than unoiled, unwashed eggs. In a single trial, oiling after washing did not improve shell strength. No significant changes in shell strength from one to nine hours after oviposition were observed. Eggs were found to be significantly stronger at two days than one day and four days than three days of storage. No significant change in shell strength occurred between four and eight days. By the eleventh and thirteenth day, egg shell strength was significantly weaker than at four days of age. Eggs, either wet or dry, exposed for fifteen minutes to temperatures of 13° C , 24° C , 35° C. and 46° C. had a reduction of shell strength at each increment of temperature. However, the wetting of eggs at these temperatures was not found to reduce shell strength as reported by Froning (1973).
336
R. F. BALL, J. F. HILL, V. LOGAN AND J. LYMAN
MATERIALS AND METHODS All measurements of shell strength were made with an Allo-Kramer shear press using a 45.4 kilogram proving ring. Eggs were placed in a verticle position with large end up for crushing. Only whole eggs were measured. Eggs were washed in a commercial type egg washer 1 which provided a wash temperature of 46° C. and a rinse water temperature of 49° C. Eggs were oiled by spraying a liquid paraffin with silicone 2 over eggs placed large end up in filler flats. Trial 1. Two cases of eggs (709) from the
1. Model Super 80, Kuhl International Corp., Remington, New Jersey 08822. 2. Sta-Good, manufactured by Mattox and Moore, Indianapolis, Indiana 46202.
morning laying of a large flock of White Leghorns were randomly divided into 4 nearly equal groups and treated as follows: A. washed and held for one day; B. washed and held for two days; C. unwashed and held for one day; and D. unwashed and held for two days. Eggs were stored at 17° C. Trial 2. Eight cases of eggs (2880) from the morning pickup of a large flock of White Leghorns were divided into four groups and treated as follows: A. unwashed, B. washed, C. sprayed with oil after gathering and then washed, and D. washed and then sprayed with oil. All egg washing was done one day after laying. One hundred or more whole eggs from each group were stored at 17° C. for 3, 4, 6, 8, 11 and 13 days before measuring shell strength. Trial 3. Four cases of eggs (1440) from the morning pickup of a large flock of White Leghorns were divided into two groups and treated as follows: A. sprayed with oil after laying, and B. untreated. One hundred or more eggs from each group were stored at 17° C. for 1, 2, 3, 4, 5 and 6 days before measuring for shell strength. Trial 4. Over nine hundred White Leghorn eggs which were laid between 7:30 and 8:30 A.M. on one day were divided into five groups to be measured for shell strength at intervals of 1, 3, 5, 7 and 9 hours after laying. Trial 5. Whole eggs from a case of White Leghorn eggs were divided into 16 lots of 20 eggs each. Following the procedure of Froning (1973), lots 1 and 2 were heated for 15 minutes in a water bath at 13° C , lots 3 and 4 at 24° C , lots 5 and 6 at 35° C. and lots 7 and 8 at 46° C. The eggs in the remaining lots were individually wrapped in tightly fitting plastic freezer bags before immersing in the water baths for 15 minutes. Breaking strength was measured immediately after re-
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on June 14, 2015
commercial conditions the effect of washing, oiling, aging and temperature on shell strength. It is appropriate here to give the reader some means of relating the figures for egg shell breaking strength cited in the following report to the amount of egg shell damage that might be expected during normal commercial egg handling. In our experience, a breaking strength of 2.72 kilograms is the lower limit beyond which excessive shell damage occurs in normal commercial egg handling. For example, the average breaking strength of eggs from a 29 week old flock of White Leghorns was 4.35 kilograms with a range for individual eggs of 2.27 to 6.35 kilograms. Only one percent of the eggs were below 2.72 kilograms and the incidence of damaged eggs was negligible. The eggs from a second flock, 56 weeks old, had an average breaking strength of 3.40 kilograms with a range of 1.36 to 4.99 kilograms. Fifteen percent of the eggs were below 2.72 kilograms breaking strength and the incidence of damaged eggs was excessive.
337
EGG SHELL STRENGTH
moval of the eggs from the baths. The same procedure was used with three cases of eggs and was designed to measure the effect of wet and dry heat on shell strength. RESULTS AND DISCUSSION
TABLE 1.-—Shell
Trial 2. Data for this trial are presented in Fig. 1. The shell strength of unwashed eggs was consistently greater (P < 0.01) than that of washed eggs at all days of storage thus confirming the observations in Trial 1. Eggs that were oiled and then washed were also consistently stronger (P < 0.01) than washed eggs over the storage period. However, those eggs which were washed and then oiled had lower shell strength than unwashed or oiled and washed eggs at the time of each measurement. The average shell strength in kilograms for all eggs of each treatment was as follows: A. unwashed 4.545, B. washed 4.200, C. oiled
strength of washed and unwashed eggs held for 1 and 2 days at 17" C. Held 1 day
Unwashed Washed
Held 2 days
# Eggs
Shell strength
180 180
kg. 4.52 4.34 -.18*
Difference
Difference significant at 1% level.
# Eggs
Shell strength
Difference
180 169
kg. 4.77 4.39
kg. + .25* + .05*
-.38*
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on June 14, 2015
Trial 1. The results of this trial are summarized in Table 1. Washed eggs had significantly lower shell strength than unwashed eggs when held for one and two days. These differences were statistically significant at the 1 percent level. That washing weakened shell strength is consistent with the findings of Tyler and Geake (1964) who demonstrated that water weakens the shell and that cuticle removal weakens the shell. Simon and Wiertz (1966) demonstrated by electron microscopy that washing eggs in detergent solutions causes a flattening and disappearance of the cuticle. Ball et al. (1975) by use of a cuticle stain, Edicol Supra Pea Green H, also demonstrated that washing removes the cuticle primarily by the abrasive action of the brushes. Froning (1973) reported that temperatures above 13° C. reduced shell strength and wetting coupled with high temperatures significantly reduced shell strength. From this study it is apparent that washing weakens shell strength. This loss in shell strength would appear to be due to the loss of cuticle because of abrasion and high water temperature as well as high temperature effects on the shell itself. A preliminary study of shell strength of washed and unwashed eggs indicated a possible source of error in using eggs from flocks
with poor shell strength. Unwashed eggs from such a flock had only 6 percent cracked eggs and 23.9 percent of the whole eggs measured had less than 2.72 kilograms of shell strength. Washed eggs from the same flock gave 10.8 percent cracked eggs and only 15.3 percent of the eggs measured less than 2.72 kilograms of shell strength. The washing process appeared to have damaged more of the weaker eggs, thus eliminating them from measurement of shell strength. The significance of the findings in Trial 1 is that washing of eggs does more than crack and break eggs but also lowers the strength of those eggs that remain intact. A small but statistically significant increase in shell strength was observed in two day-old eggs compared to that of one day-old eggs (Table 1). This finding is in agreement with Tyler and Geake (1964) and Talbot and Tyler (1974).
338
R. F. BALL, J. F. HILL, V. LOGAN AND J. LYMAN
5.00 r UNWASHED WASHED
4.90 -
iiiimiiliiniliii OILED AND WASHED WASHED AND OILED
4.80 to
S
4.70 -
CD O
2
4.60 •
i
4.50 h
|
4.40 -
i— to
_. 4.30 •
_J LU
^
4.20 •
4.10 1
'
i
i
i
i
4.00 0
'
•
•
t
.1
10
11
12
13
14
DAYS OF STORAGE FIG. 1. Data from Trial 2. and washed 4.513 and D. washed and oiled 4.249. The effect of oiling on shell strength is not certain from this trial. Since oiling before but not after washing improved shell strength, the results suggest that oiling may have merely been protecting the cuticle in the washing process. Tyler and Geake (1964) have shown that removal of the cuticle decreases shell strength. It will be shown in Trial 3 however, that oiling did add to shell strength since oiled, unwashed eggs were stronger than unoiled, unwashed eggs. Data for all treatments were pooled to study the effect of age on shell strength. Eggs were found to have significantly greater shell strength (P < 0.05) at four days than at three days of age. No significant differences in shell strength were observed in eggs from four to six or eight days of age. By the
eleventh day of storage, eggs were significantly (P < 0.01) weaker than those measured at three and four days. No significant difference was found between eggs held eleven and thirteen days. The data of this trial and Trial 1 suggest that during the first four days after oviposition the shell slowly strengthens. From four to eight days, there is little change but by the eleventh and thirteenth days shell strength declines slightly. Evaporation after the eighth day, resulting in a smaller internal egg mass and reduced internal support of the shell, may account for the decline in shell strength after eight days of age. Trial 3. The shell strength of oiled eggs stored over a six day period was found to be significantly greater (P < 0.01) than that of unoiled eggs (Table 2). Although the rela-
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on June 14, 2015
i— CD
339
EGG SHELL STRENGTH
TABLE 2.—Shell strength of oiled and unoiled eggs measured over a 6 day storage period at 17" C. Treatment Age of eggs—days
Oiled shell strength—kg.
Unoiled shell strength—kg.
Difference
1 2 3 4 5 6
4.354 4.513 4.336 4.576 4.626 4.495
4.390 4.245 4.367 4.263 4.408 4.304
-.036 + .268 -.031 + .313 + .218 + .191
Average
4.486
4.331
Difference
+ .154*
tionship of oiling to shell strength in Trial 2 was equivocal, the results of this trial indicate that the spraying of oil does add to shell strength. It should be pointed out that no eggs were washed in this trial as was done in Trial 2. It is hypothesized that the protective coating of oil may slow the normal deterioration of cuticle that occurs with age, Ball et al. (1975). An analysis of variance indicated no significant effect on shell strength of aging over a six day period although there is a slight indication that 5 and 6 day eggs are stronger than those only 1 and 2 days old. Trial 4. The data for shell strength of eggs crushed 1, 3, 5, 7 and 9 hours after laying are shown in Table 3. Although the shell strength was lowest at 1 and 3 hours after oviposition, no statistically significant change in shell strength could be demonstrated over the 1 to 9 hour period. The ability to measure an improvement in shell strength soon after lay may require a larger sample size and TABLE 3.—Shell strength of eggs crushed from 1 to 9 hours after laying Age of egg—hrs.
#Eggs
Shell strength—kg.
1 3 5 7 9
161 150 157 145 154
3.387 3.346 3.523 3.460 3.505
shorter intervals between measurements. At oviposition, egg temperature is approximately 39° C. and the egg is moist. Almost immediately, drying and cooling take place. Based on the work of Froning (1973) this cooling and drying should be accompanied by a strengthening of the shell. This was not demonstrated in this trial. Trial 5. The data for this trial are shown in Table 4. In both wet and dry treatments, egg shell strength decreased as shell temperatures increased from 13° C. to 25° C , 35° C. and 46° C. The decrease in shell strength from the coldest (13° C.) to the hottest temperature (46° C.) was 510 grams for wet eggs and 490 grams for dry eggs or approximately 10 percent for both. No significant effect of wetting of eggs could be demonstrated. Froning (1973) reported a depressing effect on shell strength of both higher temperatures and wetting. Washing has been shown in Trials 1 and TABLE 4.—The effect of temperature and moisture on the breaking strength of the egg shell Breaking strength—kg. Egg shell temperature °C. Wet Dry 13° 4.78 4.78 25° 4.46 4.61 35° 4.38 4.54 46° 4.27 4.29 -.49* Diff. 13°-46° -.51* *Difference significant at 1% level.
Difference 0.0 + .15 + .16 + .02
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on June 14, 2015
*Significant at 1% level. Over 100 eggs measured for each treatment each day.
340
R. F . B A L L , J. F . H I L L , V. LOGAN AND J. LYMAN
2 to decrease shell strength. Washing has also been shown to remove cuticle by the abrasive action of brushing, Ball et al. (1975). In this trial, temperatures of 46° C. but not wetting, decreased shell strength by 10 percent. From this it would appear that under commercial egg washing conditions the loss of shell strength is primarily due to the high temperature effects on the shell and the loss of cuticle due to brushing.
Ball, R. F., V. Logan and J. F. Hill, 1975. Factors affecting the cuticle of the egg as measured by intensity of staining. Poultry Sci. 54: 1479-1484. Bragg, D. D., 1971. Effect of egg oiling on thoroughness of cleaning and breakage during processing. Poultry Sci. 50: 1556. Froning, G. W., 1973. Effect of temperature and moisture on breaking strength of the egg shell. Poultry Sci. 52: 2332-2333.
NEWS AND NOTES (Continued from page 324) Products Company, the agricultural marketing of Eli Lilly and Company. He has been serving as Director of Agrichemicals Marketing Planning since 1973. Max S. Crowder has been named Manager, Marketing Communications for Animal Products. He joined Elancoin 1966 as Manager, Greenfield®Sales, became Agricultural Marketing Advisor in 1974, and earlier this year was named Manager, Marketing PlanningCoban®.
Cooking Contests on Wayne Farms Flavor Best fryers. Chickens from Wayne Farms will carry recipes on the back of the wing tag and will include such tantalizing dishes as Blushing Chicken, Chicken Tarragon Champignon, and Sweet 'n' Smokey Oven Barbequed Chicken. H&N NOTES
At the 1975 fall avian science get-acquainted luncheon at Colorado State University, the $750 Hubbard Scholarship was presented to Donald W. Jackson. He is working on his Ph.D. in animal nutrition and hopes to have a career as a nutritionist with a commercial feed company or integrated poultry farm. The Scholarship is made available by Hubbard Farms, Walpole, New Hampshire.
Dr. Richard H. Towner has been appointed to the genetic staff of H&N Inc., Redmond, Washington. A recent graduate of the University of Wisconsin, he will work primarily with H&N's "Nick Chick" Leghorn. Glenn Nicolls has been appointed Company Comptroller. He comes to H&N from Pfizer's headquarters where he was Senior Planning Analyst in the Corporate Controller's Division. He was with Haskins and Sells, New York, before joining Pfizer Inc. in 1969.
WAYNE NOTES
SOUTH DAKOTA NOTES
Wayne Poultry Company, a division of Allied Mills, is putting 10 tested recipes from the National Chicken
Dr. C. Wendell Carlson, Head of the South Dakota University's Poultry and Meat Section in the Depart-
COLORADO NOTES
(Continued on page 358)
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REFERENCES
Grotts, R. E., J. V. Spencer, M. H. George and D. W. Miller, 1957. Effect of preserving shell eggs by coating with plastics and other compounds. W.S.C. Poultry Council Proceedings, Exp. No. 2-56, p. 144-146. Hutchinson, F. S., 1955. Silicone-coated bottles live longer. Am. Glass Rev. 75: 40-58. Meyer, R., and J. V. Spencer, 1973. The effect of various coatings on shell strength and egg quality. Poultry Sci. 52:703-711. Simmons, P. C. M., and G. Wiertz, 1966. The ultrastructure of the surface of the cuticle of the hen's egg in relation to egg cleaning. Poultry Sci. 45: 1153-1162. Talbot, C. J., and C. Tyler, 1974. A study of the fundamental cause of artificial translucent areas in egg shells. British Poultry Sci. 15: 205-215. Tyler, C , and F. H. Geake, 1964. The effect of water on egg shell strength including a study of the translucent areas of the shell. British Poultry Sci. 5: 277-284. Tyler, C. and H. P. Thomas, 1966. A study of the snapping strength of egg shells and the effect of various factors on it. British Poultry Sci. 7: 227-238.
F . B A L L , J. F . H I L L , V . LOGAN AND J. LYMAN
Babcock Poultry Farm, Inc., Box 280, Ithaca, New York 14850 (Received for publication May 20, 1975)
POULTRY SCIENCE 55: 335-340,
INTRODUCTION
T
HE monetary losses from cracked and broken eggs continue to plague the poultry industry. Frequently cited factors associated with shell damage are mechanical handling, higher rate of egg production, inadequate nutrition, use of cages and age of the hen. Basic studies of egg shell structure and the development of devices for measuring shell strength have revealed less obvious factors affecting shell strength and damage. For example, Tyler and Geake (1964) demonstrated that water weakens shell strength. The removal of the cuticle was also shown by these workers to decrease shell strength. Further evidence of the role of the cuticle in shell strength was obtained by Tyler and Thomas (1966). Simon and Wiertz (1966) using electron microscopy found that water of 40° C. or higher temperature or detergent wash water removed much of the cuticle from eggs. That shell strength increases from the time of oviposition for several days thereafter was demonstrated by Tyler and Geake (1964) and again by Talbot and Tyler (1974).
1976
The oiling of eggs with a liquid paraffin containing silicone is a common commercial practice to preserve interior quality. The possibility that oiling may also contribute to shell strength, directly or indirectly, does not appear to have been studied. Indirect evidence that oiling may improve shell strength may be seen in the report of Hutchison (1955) who demonstrated that silicone coated bottles have less breakage. Grotts et al. (1957) also observed that some egg coating materials made egg breakouts more difficult. Meyer and Spencer (1973) found increased shell strength in eggs coated with six different materials. Bragg (1971) however, found more breakage of oiled than unoiled eggs during the washing process. Froning (1973) reported significant weakening of shell strength when eggs were heated above 13° C. for 15 minutes. In commercial egg washing, eggs are exposed briefly to temperatures of 46° C. or greater during the washing, rinsing and drying process. The importance of these less obvious influences on shell strength in present day commercial egg handling is unknown. The purpose of this study was to measure under 335
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on June 14, 2015
ABSTRACT The effect of washing, oiling, holding and egg temperature on shell strength was studied in a series of five experiments. Washing was shown to reduce shell strength from 180 to 380 grams per egg in two trials. Eggs oiled after lay and washed were significantly stronger than unoiled, washed eggs. Eggs oiled after lay and not washed were also stronger than unoiled, unwashed eggs. In a single trial, oiling after washing did not improve shell strength. No significant changes in shell strength from one to nine hours after oviposition were observed. Eggs were found to be significantly stronger at two days than one day and four days than three days of storage. No significant change in shell strength occurred between four and eight days. By the eleventh and thirteenth day, egg shell strength was significantly weaker than at four days of age. Eggs, either wet or dry, exposed for fifteen minutes to temperatures of 13° C , 24° C , 35° C. and 46° C. had a reduction of shell strength at each increment of temperature. However, the wetting of eggs at these temperatures was not found to reduce shell strength as reported by Froning (1973).
336
R. F. BALL, J. F. HILL, V. LOGAN AND J. LYMAN
MATERIALS AND METHODS All measurements of shell strength were made with an Allo-Kramer shear press using a 45.4 kilogram proving ring. Eggs were placed in a verticle position with large end up for crushing. Only whole eggs were measured. Eggs were washed in a commercial type egg washer 1 which provided a wash temperature of 46° C. and a rinse water temperature of 49° C. Eggs were oiled by spraying a liquid paraffin with silicone 2 over eggs placed large end up in filler flats. Trial 1. Two cases of eggs (709) from the
1. Model Super 80, Kuhl International Corp., Remington, New Jersey 08822. 2. Sta-Good, manufactured by Mattox and Moore, Indianapolis, Indiana 46202.
morning laying of a large flock of White Leghorns were randomly divided into 4 nearly equal groups and treated as follows: A. washed and held for one day; B. washed and held for two days; C. unwashed and held for one day; and D. unwashed and held for two days. Eggs were stored at 17° C. Trial 2. Eight cases of eggs (2880) from the morning pickup of a large flock of White Leghorns were divided into four groups and treated as follows: A. unwashed, B. washed, C. sprayed with oil after gathering and then washed, and D. washed and then sprayed with oil. All egg washing was done one day after laying. One hundred or more whole eggs from each group were stored at 17° C. for 3, 4, 6, 8, 11 and 13 days before measuring shell strength. Trial 3. Four cases of eggs (1440) from the morning pickup of a large flock of White Leghorns were divided into two groups and treated as follows: A. sprayed with oil after laying, and B. untreated. One hundred or more eggs from each group were stored at 17° C. for 1, 2, 3, 4, 5 and 6 days before measuring for shell strength. Trial 4. Over nine hundred White Leghorn eggs which were laid between 7:30 and 8:30 A.M. on one day were divided into five groups to be measured for shell strength at intervals of 1, 3, 5, 7 and 9 hours after laying. Trial 5. Whole eggs from a case of White Leghorn eggs were divided into 16 lots of 20 eggs each. Following the procedure of Froning (1973), lots 1 and 2 were heated for 15 minutes in a water bath at 13° C , lots 3 and 4 at 24° C , lots 5 and 6 at 35° C. and lots 7 and 8 at 46° C. The eggs in the remaining lots were individually wrapped in tightly fitting plastic freezer bags before immersing in the water baths for 15 minutes. Breaking strength was measured immediately after re-
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on June 14, 2015
commercial conditions the effect of washing, oiling, aging and temperature on shell strength. It is appropriate here to give the reader some means of relating the figures for egg shell breaking strength cited in the following report to the amount of egg shell damage that might be expected during normal commercial egg handling. In our experience, a breaking strength of 2.72 kilograms is the lower limit beyond which excessive shell damage occurs in normal commercial egg handling. For example, the average breaking strength of eggs from a 29 week old flock of White Leghorns was 4.35 kilograms with a range for individual eggs of 2.27 to 6.35 kilograms. Only one percent of the eggs were below 2.72 kilograms and the incidence of damaged eggs was negligible. The eggs from a second flock, 56 weeks old, had an average breaking strength of 3.40 kilograms with a range of 1.36 to 4.99 kilograms. Fifteen percent of the eggs were below 2.72 kilograms breaking strength and the incidence of damaged eggs was excessive.
337
EGG SHELL STRENGTH
moval of the eggs from the baths. The same procedure was used with three cases of eggs and was designed to measure the effect of wet and dry heat on shell strength. RESULTS AND DISCUSSION
TABLE 1.-—Shell
Trial 2. Data for this trial are presented in Fig. 1. The shell strength of unwashed eggs was consistently greater (P < 0.01) than that of washed eggs at all days of storage thus confirming the observations in Trial 1. Eggs that were oiled and then washed were also consistently stronger (P < 0.01) than washed eggs over the storage period. However, those eggs which were washed and then oiled had lower shell strength than unwashed or oiled and washed eggs at the time of each measurement. The average shell strength in kilograms for all eggs of each treatment was as follows: A. unwashed 4.545, B. washed 4.200, C. oiled
strength of washed and unwashed eggs held for 1 and 2 days at 17" C. Held 1 day
Unwashed Washed
Held 2 days
# Eggs
Shell strength
180 180
kg. 4.52 4.34 -.18*
Difference
Difference significant at 1% level.
# Eggs
Shell strength
Difference
180 169
kg. 4.77 4.39
kg. + .25* + .05*
-.38*
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on June 14, 2015
Trial 1. The results of this trial are summarized in Table 1. Washed eggs had significantly lower shell strength than unwashed eggs when held for one and two days. These differences were statistically significant at the 1 percent level. That washing weakened shell strength is consistent with the findings of Tyler and Geake (1964) who demonstrated that water weakens the shell and that cuticle removal weakens the shell. Simon and Wiertz (1966) demonstrated by electron microscopy that washing eggs in detergent solutions causes a flattening and disappearance of the cuticle. Ball et al. (1975) by use of a cuticle stain, Edicol Supra Pea Green H, also demonstrated that washing removes the cuticle primarily by the abrasive action of the brushes. Froning (1973) reported that temperatures above 13° C. reduced shell strength and wetting coupled with high temperatures significantly reduced shell strength. From this study it is apparent that washing weakens shell strength. This loss in shell strength would appear to be due to the loss of cuticle because of abrasion and high water temperature as well as high temperature effects on the shell itself. A preliminary study of shell strength of washed and unwashed eggs indicated a possible source of error in using eggs from flocks
with poor shell strength. Unwashed eggs from such a flock had only 6 percent cracked eggs and 23.9 percent of the whole eggs measured had less than 2.72 kilograms of shell strength. Washed eggs from the same flock gave 10.8 percent cracked eggs and only 15.3 percent of the eggs measured less than 2.72 kilograms of shell strength. The washing process appeared to have damaged more of the weaker eggs, thus eliminating them from measurement of shell strength. The significance of the findings in Trial 1 is that washing of eggs does more than crack and break eggs but also lowers the strength of those eggs that remain intact. A small but statistically significant increase in shell strength was observed in two day-old eggs compared to that of one day-old eggs (Table 1). This finding is in agreement with Tyler and Geake (1964) and Talbot and Tyler (1974).
338
R. F. BALL, J. F. HILL, V. LOGAN AND J. LYMAN
5.00 r UNWASHED WASHED
4.90 -
iiiimiiliiniliii OILED AND WASHED WASHED AND OILED
4.80 to
S
4.70 -
CD O
2
4.60 •
i
4.50 h
|
4.40 -
i— to
_. 4.30 •
_J LU
^
4.20 •
4.10 1
'
i
i
i
i
4.00 0
'
•
•
t
.1
10
11
12
13
14
DAYS OF STORAGE FIG. 1. Data from Trial 2. and washed 4.513 and D. washed and oiled 4.249. The effect of oiling on shell strength is not certain from this trial. Since oiling before but not after washing improved shell strength, the results suggest that oiling may have merely been protecting the cuticle in the washing process. Tyler and Geake (1964) have shown that removal of the cuticle decreases shell strength. It will be shown in Trial 3 however, that oiling did add to shell strength since oiled, unwashed eggs were stronger than unoiled, unwashed eggs. Data for all treatments were pooled to study the effect of age on shell strength. Eggs were found to have significantly greater shell strength (P < 0.05) at four days than at three days of age. No significant differences in shell strength were observed in eggs from four to six or eight days of age. By the
eleventh day of storage, eggs were significantly (P < 0.01) weaker than those measured at three and four days. No significant difference was found between eggs held eleven and thirteen days. The data of this trial and Trial 1 suggest that during the first four days after oviposition the shell slowly strengthens. From four to eight days, there is little change but by the eleventh and thirteenth days shell strength declines slightly. Evaporation after the eighth day, resulting in a smaller internal egg mass and reduced internal support of the shell, may account for the decline in shell strength after eight days of age. Trial 3. The shell strength of oiled eggs stored over a six day period was found to be significantly greater (P < 0.01) than that of unoiled eggs (Table 2). Although the rela-
Downloaded from http://ps.oxfordjournals.org/ at East Tennessee State University on June 14, 2015
i— CD
339
EGG SHELL STRENGTH
TABLE 2.—Shell strength of oiled and unoiled eggs measured over a 6 day storage period at 17" C. Treatment Age of eggs—days
Oiled shell strength—kg.
Unoiled shell strength—kg.
Difference
1 2 3 4 5 6
4.354 4.513 4.336 4.576 4.626 4.495
4.390 4.245 4.367 4.263 4.408 4.304
-.036 + .268 -.031 + .313 + .218 + .191
Average
4.486
4.331
Difference
+ .154*
tionship of oiling to shell strength in Trial 2 was equivocal, the results of this trial indicate that the spraying of oil does add to shell strength. It should be pointed out that no eggs were washed in this trial as was done in Trial 2. It is hypothesized that the protective coating of oil may slow the normal deterioration of cuticle that occurs with age, Ball et al. (1975). An analysis of variance indicated no significant effect on shell strength of aging over a six day period although there is a slight indication that 5 and 6 day eggs are stronger than those only 1 and 2 days old. Trial 4. The data for shell strength of eggs crushed 1, 3, 5, 7 and 9 hours after laying are shown in Table 3. Although the shell strength was lowest at 1 and 3 hours after oviposition, no statistically significant change in shell strength could be demonstrated over the 1 to 9 hour period. The ability to measure an improvement in shell strength soon after lay may require a larger sample size and TABLE 3.—Shell strength of eggs crushed from 1 to 9 hours after laying Age of egg—hrs.
#Eggs
Shell strength—kg.
1 3 5 7 9
161 150 157 145 154
3.387 3.346 3.523 3.460 3.505
shorter intervals between measurements. At oviposition, egg temperature is approximately 39° C. and the egg is moist. Almost immediately, drying and cooling take place. Based on the work of Froning (1973) this cooling and drying should be accompanied by a strengthening of the shell. This was not demonstrated in this trial. Trial 5. The data for this trial are shown in Table 4. In both wet and dry treatments, egg shell strength decreased as shell temperatures increased from 13° C. to 25° C , 35° C. and 46° C. The decrease in shell strength from the coldest (13° C.) to the hottest temperature (46° C.) was 510 grams for wet eggs and 490 grams for dry eggs or approximately 10 percent for both. No significant effect of wetting of eggs could be demonstrated. Froning (1973) reported a depressing effect on shell strength of both higher temperatures and wetting. Washing has been shown in Trials 1 and TABLE 4.—The effect of temperature and moisture on the breaking strength of the egg shell Breaking strength—kg. Egg shell temperature °C. Wet Dry 13° 4.78 4.78 25° 4.46 4.61 35° 4.38 4.54 46° 4.27 4.29 -.49* Diff. 13°-46° -.51* *Difference significant at 1% level.
Difference 0.0 + .15 + .16 + .02
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*Significant at 1% level. Over 100 eggs measured for each treatment each day.
340
R. F . B A L L , J. F . H I L L , V. LOGAN AND J. LYMAN
2 to decrease shell strength. Washing has also been shown to remove cuticle by the abrasive action of brushing, Ball et al. (1975). In this trial, temperatures of 46° C. but not wetting, decreased shell strength by 10 percent. From this it would appear that under commercial egg washing conditions the loss of shell strength is primarily due to the high temperature effects on the shell and the loss of cuticle due to brushing.
Ball, R. F., V. Logan and J. F. Hill, 1975. Factors affecting the cuticle of the egg as measured by intensity of staining. Poultry Sci. 54: 1479-1484. Bragg, D. D., 1971. Effect of egg oiling on thoroughness of cleaning and breakage during processing. Poultry Sci. 50: 1556. Froning, G. W., 1973. Effect of temperature and moisture on breaking strength of the egg shell. Poultry Sci. 52: 2332-2333.
NEWS AND NOTES (Continued from page 324) Products Company, the agricultural marketing of Eli Lilly and Company. He has been serving as Director of Agrichemicals Marketing Planning since 1973. Max S. Crowder has been named Manager, Marketing Communications for Animal Products. He joined Elancoin 1966 as Manager, Greenfield®Sales, became Agricultural Marketing Advisor in 1974, and earlier this year was named Manager, Marketing PlanningCoban®.
Cooking Contests on Wayne Farms Flavor Best fryers. Chickens from Wayne Farms will carry recipes on the back of the wing tag and will include such tantalizing dishes as Blushing Chicken, Chicken Tarragon Champignon, and Sweet 'n' Smokey Oven Barbequed Chicken. H&N NOTES
At the 1975 fall avian science get-acquainted luncheon at Colorado State University, the $750 Hubbard Scholarship was presented to Donald W. Jackson. He is working on his Ph.D. in animal nutrition and hopes to have a career as a nutritionist with a commercial feed company or integrated poultry farm. The Scholarship is made available by Hubbard Farms, Walpole, New Hampshire.
Dr. Richard H. Towner has been appointed to the genetic staff of H&N Inc., Redmond, Washington. A recent graduate of the University of Wisconsin, he will work primarily with H&N's "Nick Chick" Leghorn. Glenn Nicolls has been appointed Company Comptroller. He comes to H&N from Pfizer's headquarters where he was Senior Planning Analyst in the Corporate Controller's Division. He was with Haskins and Sells, New York, before joining Pfizer Inc. in 1969.
WAYNE NOTES
SOUTH DAKOTA NOTES
Wayne Poultry Company, a division of Allied Mills, is putting 10 tested recipes from the National Chicken
Dr. C. Wendell Carlson, Head of the South Dakota University's Poultry and Meat Section in the Depart-
COLORADO NOTES
(Continued on page 358)
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REFERENCES
Grotts, R. E., J. V. Spencer, M. H. George and D. W. Miller, 1957. Effect of preserving shell eggs by coating with plastics and other compounds. W.S.C. Poultry Council Proceedings, Exp. No. 2-56, p. 144-146. Hutchinson, F. S., 1955. Silicone-coated bottles live longer. Am. Glass Rev. 75: 40-58. Meyer, R., and J. V. Spencer, 1973. The effect of various coatings on shell strength and egg quality. Poultry Sci. 52:703-711. Simmons, P. C. M., and G. Wiertz, 1966. The ultrastructure of the surface of the cuticle of the hen's egg in relation to egg cleaning. Poultry Sci. 45: 1153-1162. Talbot, C. J., and C. Tyler, 1974. A study of the fundamental cause of artificial translucent areas in egg shells. British Poultry Sci. 15: 205-215. Tyler, C , and F. H. Geake, 1964. The effect of water on egg shell strength including a study of the translucent areas of the shell. British Poultry Sci. 5: 277-284. Tyler, C. and H. P. Thomas, 1966. A study of the snapping strength of egg shells and the effect of various factors on it. British Poultry Sci. 7: 227-238.