THE VITAMIN B₂ CONTENT OF FRESH AND STORED HEN EGGS

Semih Otles, Yasar Hisil

ABSTRACT

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..

INTRODUCTION

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.

MATERIALS AND METHODS

Materials

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.

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].

RESULTS AND DISCUSSION

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.

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.

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.

CONCLUSIONS

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.

REFERENCES

1. Alvi A., Arshad M., Afzal M., 1979. Preservation of shell eggs with different coating agents. Pakist J. Sci. Ind. Res. 22, 341-345.

2. Calet C., Blum J., 1970. Les vitamines de l’ceuf. Ann. Nutr. Alim. 24, 201-226.

3. Colakoglu M., Otles S., 1985. Factors affecting the degradation and methods of preservation of vitamins. J. Eng. Fac. B 3 (2), 71-84.

4. Cotterill O., Marion W., Naber E., 1977. A nutrient re-evaluation of shell eggs. Poult. Sci. 56, 1927-1934.

5. Evans R., Butts H., Davidson J., 1952. The riboflavin content of fresh and stored shell eggs. Poult. Sci. 31, 269-273.

6. Everson G., Souders H., 1957. Composition and nutritive importance of eggs. J. Am. Diet. Ass. 33, 1244-1254.

7. Furukawa N., Yamanaka Y., Yokokawa Y., 1983. Effects of coating and storage conditions on the quality of chicken eggs. Jap. J. Dairy Food Sci. 32 (1), 21-30.

8. Health J., Owens S., 1978. Effect of oiling variables on storage of shell eggs at elevated temperatures. Poult. Sci. 57, 930-936.

9. Hill A., Hall W., 1980. Effects of various combinations of oil spraying, washing, sanitizing, storage time, strain, and age of layer upon albumen quality changes in storage. Poult. Sci. 59, 2237-2242.

10. Hisil Y., Otles S., 1989. Methods of vitamin analysis in foods and related problems. J. Eng. Fac., B 7 (1), 69-77.

11. Hisil Y., Otles S., 1997. Changes of vitamin B1 concentrations during storage of hen eggs. Lebensmitt. Wiss. Technol. (Food Sci. Technol.) 30, 320-323.

12. Maurer A., 1975. Refrigerated egg storage at two air movement rates. Poult. Sci. 54, 409-412.

13. Nash S., Mayfield H., Odland L., 1953. Physical, chemical and cooking qualities of eggs as effected by five methods of home preservation. Poult. Sci. 32, 275-284.

14. Neelekathan S., Shanthy A., 1979. Studies on the development of an emulsion for the preservation of shell eggs. Ind. Food Packer 33, 44-48.

15. Obanu Z., Mpieri A., 1984. Efficiency of dietary vegetable oils in preserving the quality of shell eggs under ambient tropical conditions. J. Sci. Food Agric. 15, 1311-1317.

16. Otles S., 1991. Vergleichende Vitamin-B₁ -und B₂-Bestimmungen mit verschiedenen Enzympraparaten in Lebensmitteln. Z. Lebensmitt. Untersuch. Forsch. 193, 347-350.

17. Otles S., 1999. High performance liquid chromatography of water-soluble and fat-soluble vitamins. Chrom. Sep. Technol. 10 (6), 20-24.

18. Otles S., 2000. Applications of HPLC and GC to vitamin and lipid analysis. LC.GC Europe, 13 (12), 905-908.

19. Otles, S. (2000). High pressure liquid chromatographic analysis of water and fat-soluble vitamins. J. Oil, Soap, Cosmetics 49 (1), 20-24.

20. Otles S., Colakoglu M., 1987. Die reiche Quellen der Vitamine. J. Eng. Fac. B 5 (2), 119-131.

21. Otles S., Hisil Y., 1989. Changes in Haugh units of braun shelled chicken eggs (Gallus domesticus) coated by different materials during the storage at different conditions. J. Eng. Fac. B 7 (2), 71-82.

22. Otles S., Hisil Y., 1991. Anderung des Vitamin-B₆-Gehaltes bei der Lagerung von Hühnereiern (Gallus domesticus). Mitteil. Gebiete Lebensmitt. Hygiene 82, 296-302.

23. Otles S., Hisil Y., 1992. Analysis of water soluble vitamins using mobile phase modifiers in reserve phase liquid chromatography. J. Eng. Fac. B 10 (1), 57-68.

24. Otles S., Hisil Y., 1993. High pressure liquid chromatographic analysis of water soluble vitamins in eggs. Ital. J. Food Sci. 5 (1), 69-73.

25. Otles S., Hisil Y., 1993. Effects of strain, coating agents and storage conditions on the vitamin A content of hen eggs (Gallus domesticus). Sci. Technol. Food Feed 1 (4), 27-32.

26. Otles S., Hisil Y., 1994. Der Einfluss der Lagerungsbedingungen und konservierender Flüssigkeiten auf die Qualität von Hühneiern (Gallus domesticus) aus unterschidlicher Herkunften während langfrissiger Lagerung. J. Vet. Fac. 20 (2-3), 177-182.

27. Partmann W., Wedler A., 1979. Untersuchungen zur Haltbarkeit von hartgekochten Eiern. Z. Ernährungswiss. 18, 191-208.

28. Sabrani M., Payne C., 1978. Effect of oiling on internal quality of eggs stored at 28 and 12°C. Brit. Poult. Sci. 19, 567-571.

29. Scholtyssek S., Raber A., Deissler E., 1979. Der Einfluss der Lagerung auf die Qualitat von Konsumeiern. Arch. Geflügelk. 43, 11-17.

30. Sebecic B., Balint L., Momirovic-Culjat J., 1984. Effect of layer management on carotene value in eggs. Nahrung 28 (4), 335-340.

31. Sebecic B., Momirovic-Culjat J., Balint L., 1981. The influence of food on the content of thiamin and riboflavin in eggs. Hrana I Ishrana 22, 1-2.

32. Steel R., Torrie J., 1960. Principles and procedures of statistics. New York: McGraw-Hill Book Co.

33. Tarhay S., Buss E., Clagett C., 1975. Avian riboflavinuria. Poult. Sci. 54, 562-571.

34. Vitamins in eggs. 1988. Poul. Int. 27, 28.

35. Yamanaka Y., Furukawa N., Yokokawa Y., 1980. Egg shell surface coating with edible material: effects on the quality of chicken eggs. J. Agric. Sci. Tokyo Univ. Agric. 25 (1), 10-17.

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