Electronic Journal of Polish Agricultural Universities (EJPAU) founded by all Polish Agriculture Universities presents original papers and review articles relevant to all aspects of agricultural sciences. It is target for persons working both in science and industry,regulatory agencies or teaching in agricultural sector. Covered by IFIS Publishing (Food Science and Technology Abstracts), ELSEVIER Science - Food Science and Technology Program, CAS USA (Chemical Abstracts), CABI Publishing UK and ALPSP (Association of Learned and Professional Society Publisher - full membership). Presented in the Master List of Thomson ISI.
Volume 7
Issue 2
Food Science and Technology
Available Online: http://www.ejpau.media.pl/volume7/issue2/food/art-05.html


Semih Otles, Yasar Hisil



The aim of this work was to study coating variables which may effect on vitamin B2 (riboflavin) concentrations when eggs are stored at or above refrigeration temperature. Two duplicate experiments were conducted to determine: (1) the effects of strains of hens (white or brown shelled eggs) on vitamin B2 levels of eggs; (2) the relationship between storage conditions (storage temperature and humidity); and (3) the effects of coating methods (waterglass, lime and 90 mg/kg paraffin) on vitamin B2 levels of eggs.

Key words: vitamin B2, egg preservation, paraffin, waterglass, lime..


The regular use of hen eggs by many families in various countries and numerous questions which have been raised concerning the overall contribition of this food to the nutritional soundness of the human diet have been responsible for the conducting of this study. Hen eggs are considered to be one of the good sources of vitamin B2 (riboflavin)in the human nutrition [4, 6, 20, 33, 34]. Vitamin B2 is required by the body to use oxygen and the metabolism of amino acids, fatty acids, and carbohydrates. Vitamin B2 is further needed to activate vitamin B6 (pyridoxine), helps to create niacin and assists the adrenal gland. It is used for red blood cell formation, antibody production, cell respiration, and growth. Vitamin B2 is stable to oxygen and acid pH, but is unstable in alkaline medium and is very sensitive to light. Deficiency is often associated with alcoholism, cataracts, and sickle cell anemia [3].

Factors associated with extent of shell egg loss are storage time, temperature, humidity and handling. Several methods of altering the environmental condition of the egg have been used to prolong its storage life. Refrigeration, cold storage and freezing of egg and egg products are widely practised for the preservation of eggs in developed countries [7, 8]. However, these methods are expensive and hence are not suitable in developing countries because of the lack of electric power in rural areas. To retard the deteriorative changes in the internal quality characteristics of eggs, various shell treatments such as coating with vegetable and mineral oils, waterglass and lime sealing have been suggested. Oil coating of the shell has been documented as a method of preserving egg quality and is an accepted practice. In coating, the shell pores are sealed reducing evaporation and carbon dioxide escape, thus much of the original carbon dioxide is retained and the albumen pH increases less rapidly. It is generally agreed that coating within a few hours of lay is best for optimal preservation. Coating agents such as various vegetable oils, paraffin, acrylic acid resins, waterglass, polyvinyl alcohol, zein and sodium carboxymethyl cellulose have been reported in the literature. Few data have been published on possible changes and losses of vitamins from shell eggs coated with different agents during short- and long-term storage [1, 9, 11, 14, 15, 21, 22, 25, 26, 27].

The work described in this paper was undertaken in an attempt to obtain further information on the effects of the strains of hens on vitamin B2 levels of eggs and the effectiveness of coating with paraffin, waterglass and lime in maintaining vitamin B2 of albumen and yolks of freshly laid table shell eggs for short- and long-term storage at refrigeration and room temperature.



Table eggs were collected for all experiments within 6 h after lay from commercially-bred brown-Hisex and white-Weblein exotic hens of the same age (28-30 weeks-old), housed in pairs in battary cages. After sorting to eliminate cracks, dirties, thin shells etc., all eggs with interior quality below grade A were discarded. A total of 2114 eggs weighing between 60-65 g for two duplicate experiments were included [11, 21, 22, 25, 26] . Thirteen eggs were used in each of the 77 treatment combinations (28 for experiment 1, Fig. 1; 37 for experiment 2, Fig. 2; 12 for experiment 3, Table 1). Each treatment combination was run twice, thus involving a grand total of 2114 (112 eggs for the proximate composition in Table 2). Some components of fresh table eggs are presented in Table 2.

Table 1. Vitamin B2 levels of shell eggs stored at room temperature +31±1°C (mg/kg in fresh matter)

Coating method






Time (d)



loss (%)



loss (%)



loss (%)



loss (%)








































aWhite-shelled eggs
bBraun-shelled eggs
Values are shown as mean ± standard deviation

Table 2. Some components of fresh table eggs (mg/kg)

Brown-shelled eggs

White-shelled eggs































n.d. : not determined
aProtein = N x 6.70 for albumen, N x 6.62 for yolk
Values are shown as mean ± standard deviation

Coating methods

Eggs treated by means of three different coating agents (waterglass, paraffin and lime) were packed, small-end down, in egg cartons. After coating within a few hours of lay some of the eggs was placed in 4 ± 1°C, 0.85-0.86 relative humidity environment for a 10-month storage period and the rest were stored at 31 ± 2°C, 0.48-0.52 relative humidity for a 30-d storage period. Untreated eggs were stored in the same manner as the shell-treated eggs and were used as controls. For waterglass coating the eggs were placed in gallon jars for 1 h and covered with a mixture of one part sodium silicate (colourless, acidic and density 1.34) to nine parts distilled water. For lime treatment the eggs were dipped into lime solution (1.26 g/L calcium hydroxide with 1 g/L salt) for 1 h. For paraffin (wax) coating the eggs were immersed for 2 min in food-grade paraffin (90 g/kg) at a temperature of 38-43° C. After immersion the eggs were allowed to drain, repacked and stored at various conditions [11, 16, 21, 22, 25, 26].

Statistical Analysis

Data were analysed by student’s t-test, analysis of covariance, Duncan’s new multiple range test and LSD as outlined in the literature [32].

Vitamin analysis

Vitamin B2 in the egg samples after separation of yolk and albumen was analysed by both fluorimetric and high pressure liquid chromatographic (HPLC) methods. As described in the previous papers on HPLC method, vitamin B2 was extracted by digestion of homogenized albumen or yolk with with 0.05 mol/L H2 SO4 followed by enzymic digestion with Takadiastase and papain, adjusting to pH 4.5. After incubation in an oven at 35 ± 1°C overnight, the solution was injected and separated on a Waters 3.9 mm i.d. x 30 cm µ-Bondapak C18 column, isocratically at 25°C with a mobile phase prepared by mixing 220 mL of methanol with 780 mL of water containing 0.05 mol/L PIC B6 (hexane sulphonic acid, Waters Associates 84282) at a flow rate of 0.3 mL/min at 254 nm wavelenght [10, 16, 17, 18, 19, 23].


Vitamin B2 in fresh egg yolk and albumen

Changes in vitamin B2 of industrially-produced control and treated eggs during long- and short-term storage are presented in Table 1 and Figure 1. Albumen of braun-shelled eggs contained 3.58 mg/kg and albumen of white-shelled eggs 3.83. Yolk of braun-shelled eggs contained 4.24 mg/kg and yolk of white-shelled eggs 4.33. Although some investigators have found a statistically significant hen difference in vitamin B2 content of albumen, yolks and whole egg contents, vitamin B2 concentrations found in our study were not significant by strain (P ≤ 0.01). Most values reported in the literature fall within this range [2, 4, 5, 6, 27, 31, 32, 34]. It was found that the vitamin B2 concentration in the egg is proportional to the vitamin B2 concentration of the hen’s diet. Variation in the vitamin B2 content of albumen and yolks reported by different investigators would, therefore, be exp ected because of different diets used. In addition, modern hybrids are more efficient at depositing vitamins in eggs than those of 20 or 30 years ago when many similar researches were done.

Figure 1. Vitamin B1 loss in white-shelled eggs stored in a refrigerator (+4±1°C)

Storage of hen’s egg in various conditions

Storage conditions for foods are chosen with regard to their properties. Surface evaporation of moisture during storage depends upon the nature of the food and its packaging. Temperature, relative humidity and flow of air are considered the main parameters in determining the technological conditions of storage [3, 12, 28, 29, 35]. Vitamin retention during storage and processing of foods has been studied some in the case of vitamin B2. Results of the vitamin B2 measurements made on the yolk and albumen of the fresh and variously treated white-shelled eggs stored in a refrigerator for 6 months are shown in Figure 1. As expected, there was a gradual decrease in the levels of vitamin B2 during storage. The average loss of vitamin B2 of white-shelled eggs was 1.79 mg/kg for 1 month, 4.15 mg/kg for 3 months, 6.22 mg/kg for 5 months and 6.78 mg/kg for 6 months. The effect of storage length on vitamin B2 was significant at t he 0.01 level of probability. Clearly, the results of the two duplicate experiments were in conformity with the earlier reviewed reports on the effect of length of storage on vitamin B2 level of stored eggs.

Changes in vitamin B2 of control and treated brown-shelled eggs during 1 to 10 months of storage in a refrigerator are presented in Figure 2. As indicated by the data for yolk and albumen from control and treatments groups, there was an irregular decrease in vitamin B2 content of all the albumen and yolk samples. It is seen that the main loss of vitamin B2 of braun-shelled eggs was 0.18 mg/kg after 1 month of storage, 0.34 mg/kg after 3 months of storage, 0.85 mg/kg after 5 months of storage and 1.41 mg/kg after 10 months of storage. The vitamin B2 concentrations X storage time, and the hen strain X storage time interaction were significant (P ≤ 0.01). The data are in agreement with results in the literature [2, 6, 27, 30, 31]. Some investigators also showed that there was a disorderly decrease of vitamin concentration as the length of storage increased. The reasons for such variable losses of vitamin B2 activi ty in stored eggs is not known. The strain X length of long-term storage of eggs interaction was also significant (P ≤ 0.01). The average loss of vitamin B2 in white-shelled eggs after 6 months of storage (6.78 mg/kg) was slightly higher (P ≤ 0.01) than that (1.11 mg/kg) in brown-shelled eggs.

Figure 2. Vitamin B1 loss in brown-shelled eggs stored in a refrigerator (+4±1°C)

Table 1 represents the data on the effects of short-term storage of eggs at room temperature on vitamin B2 content of albumen and yolk. As expected, there was a significantly (P ≤ 0.01) higher concentration of vitamin B2 in eggs stored in a refrigerator. The data are in close agreement with the results in the literature [2 ,6, 27, 30, 31].

The main loss of vitamin B2 of white-shelled eggs was 6.90 mg/kg after 15 d of storage, 7.21 mg/kg after 30 d of storage, and that of braun-shelled eggs was 1.33 mg/kg after 30 d of storage.

Coating of shell eggs

Table 1 and Figures 1 and 2 represent the results of vitamin B2 analysis made on the albumen and yolk of fresh and variously treated eggs. As expected, the interaction between the effects of coating and temperature was important, but not statictically significant (P ≤ 0.01), indicating that the decrease in vitamin B2 loss produced by coating was greater at room temperature than in the refrigerator. No statictically significant differences were noted between control and coated eggs in vitamin B2 decline during the studies of short and long storage periods and various temperature conditions described in experiments and outlined in Table 1 and Figures 1 and 2. Corresponding losses of vitamin B2 of eggs coated with paraffin stored at room temperature were lower than the control and other treatment groups. The main loss afte r 30 d of storage was 4.52 mg/kg, 4.24 mg/kg, 4.44 mg/kg and 3.89 mg/kg, respectively, for control, waterglass, lime and paraffin treatments. It is evident from the data that the losses of vitamin B2 of eggs during long-term storage are generally maximum for the control groups compared with the other treatment groups. This was due to the fact that there are several thousand minute pores in the egg shell and the positive pressure with eggs at higher temperature opens pores and allows more carbon dioxide and water to escape.

When both white- and braun-strains stored in a refrigerator are considered, the amount of vitamin B2 in eggs coated with paraffin superior; the eggs preserved lime come next, while those coated with waterglass had the lowest vitamin B2 concentrations of any of the treated eggs. The average loss of vitamin B2 from any of the coated eggs after 6 months of storage (3.93 mg/kg, 3.92 mg/kg and 3.82 mg/kg, respectively, for waterglass, lime and paraffin treatments), was considerably less than that of the untreated control eggs (4.10 mg/kg). In this respect, food-grade paraffin coating of brown- and white shelled eggs appeared preferable to untreated control, lime and waterglass coatings in preserving vitamin B2 in freshly laid shell eggs, even under the room temperatures.


It is apperent from the foregoing evidence and also from many other sources that naturally clean unwashed eggs, whether treated or untreated, can be cold-stored for appreciable periods without the risk of undue spoilage taking place, and prevent the contents of the contents of vitamin B2 in yolk and albumen. On the other hand, it is very important and highly essential to retain the freshness in the fresh eggs by suitable methods of treatment prior to storage both from industrial and nutritional point of view. As a result of this study, there were no significant difference in vitamin B2 levels by hen strains, but the storage conditions and lengths effected significantly. In addition, the levels of vitamin B2 in eggs coated with food-grade paraffin stored in refrigerator were superior, followed by the lime-, waterglass coated eggs, and the untreated control eggs.


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Semih Otles, Yasar Hisil
Food Engineering Department
Ege University, Bornova
35100 Izmir, Turkey
Fax: (90)23237414 01
e-mail: otles@bornova.ege.edu.tr

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