Carnauba Wax Applied to the Shell Surface of Chicken Eggs Improved the Shelf Life and Internal Quality of the Eggs

Special Article: Psychological Disorders

Austin J Nutri Food Sci. 2023; 11(2): 1174.

Carnauba Wax Applied to the Shell Surface of Chicken Eggs Improved the Shelf Life and Internal Quality of the Eggs

Piazentin MO¹; Mangili ELM¹; Correia DC¹; Martins EH¹; Nobre JAS¹; Córdoba GMC¹; Veríssimo CJ²; Katiki LM²; Rodrigues L¹*

¹Department of Food Sciences and Technology, FAM (Faculdade de Americana), Americana - SP, Brazil

²Department of Veterinary Parasitology, Instituto de Zootecnia, Nova Odessa - SP, Brazil

*Corresponding author: Rodrigues L Department of Food Sciences and Technology, FAM (Faculdade de Americana), Americana - SP, Brazil. Email: [email protected]

Received: November 06, 2023 Accepted: December 14, 2023 Published: December 21, 2023


The egg is a nutrient-rich food, essential for human health, containing proteins, vitamins, and minerals. However, it is perishable and begins to lose internal quality shortly after being laid. The quality of eggs deteriorates due to the loss of water and carbon dioxide, which is more pronounced at higher temperatures. Therefore, the aim of this study was to investigate the effect of coating eggs with a semi-solid product formulated with carnauba wax on the preservation and internal quality of eggs during a 28-day storage period at room temperature. 144 white eggs from 50-week-old hens were used, divided into three groups: eggs coated with carnauba wax, eggs coated with mineral oil (positive control), and a control group without coating (negative control). The results were subjected to analysis of variance (ANOVA), followed by the comparison of means through the Tukey test at a significance level of 5% (p<0.05), using the statistical program SISVAR. Eggs coated with carnauba wax showed less weight loss throughout the storage period, lower pH in both the yolk and albumen, higher yolk index and higher Haugh Unit compared to uncoated eggs and eggs coated with mineral oil. This suggests a significant improvement in the quality of coated eggs. Therefore, the use of carnauba wax coating can be an effective solution for extending the shelf life and preserving the quality of eggs, especially in regions where refrigerated storage cannot be guaranteed.

Keywords: Albumen; Carnauba wax; Coating; Haugh Unit; Yolk


Eggs stand out as a food with high nutritional value. Their composition includes essential nutrients such as lipids, proteins, and trace elements, as well as a variety of vitamins, including vitamin A, iron, vitamin B12, riboflavin, choline, zinc, and calcium, in addition to several biologically active components [1]. In addition to being a moderately calorie source, with approximately 140 kcal per 100g, eggs are accessible to society due to their low economic cost. The structure of eggs comprises the shell, membranes, egg white, yolk, chalaza, and an air sac. In terms of nutrient distribution, both the egg white and yolk are rich in proteins, with an average of 12.5g in 100g of raw fresh egg. The total lipid content in the egg is relatively stable, ranging from 8.7g to 11.2g in 100g of whole egg, with most of these lipids concentrated in the yolk and low carbohydrate content [1].

According to the Food and Agriculture Organization of the United Nations (FAO) estimate in 2016, global egg production reached 1.387 billion units, roughly equating to nearly one egg for every two individuals daily. According to the International Egg Commission (IEC) in 2018, the average consumption was reported at 161 eggs per person per year [2,3].

The quality of eggs is influenced by various factors, both extrinsic and intrinsic. Key elements associated with egg deterioration include environmental conditions such as temperature and relative humidity. Handling and storage also play a role in compromising egg quality. During the storage period, it's observed that certain characteristics of the egg white, yolk, and membrane can be altered, leading to a decline in egg quality [4]. The internal quality deterioration of eggs occurs due to the gradual loss of water and carbon dioxide over the storage period, with this degradation being directly impacted by rising temperatures. In Brazil, it is common for the majority of commercially available eggs to be stored at room temperature, which reduces their shelf life and, consequently, shortens their shelf life. This is a common practice in the marketing of low-quality eggs. The average temperature in Brazil can vary from 10°C to 30°C or more, depending on the region and time of the year [5]. The pursuit of alternative methods to extend the shelf life of eggs has been under study for some time. There is a growing interest in the development of effective methods to preserve the internal quality of eggs. In this context, edible coatings have emerged as a technology used and applied in various products to control moisture, gas exchange, and oxidation processes [6].

Carnauba wax is derived from the leaves of the Brazilian palm tree, known as Copernicia prunifera (Miller) H.E. Moore, which is abundant in the arid regions of northeastern Brazil. This wax is renowned for its highly hydrophobic nature, making it a suitable choice as a coating for fruits and vegetables, imparting a shine and safeguarding against water loss [7]. This attribute contributes to the extension of the shelf life of perishable foods. It is essential to emphasize that carnauba wax is regarded as safe for food use and is widely employed as an edible coating on fruits with peels [8]. In the food industry, wax is employed as a coating agent, acidity regulator, carrier, and anti-caking agent in surface treatments, as highlighted by Freitas et al. [9].

Although some studies have demonstrated the effectiveness of these coatings in preserving perishable products deemed safe for human consumption, there is still a significant research gap regarding their application to eggs. Therefore, the objective of this study is to evaluate the effectiveness of a semi-solid product formulated with carnauba wax (applied to the surface of chicken eggshells) in preserving the internal quality and prolonging the shelf life of these eggs during a four-week storage period at room temperature. In addition to contributing to the economic sector, the environment, and the scientific community, this study aims to assess the physical-chemical quality (through weekly evaluations of weight loss, yolk and albumen pH, yolk and albumen percentages, yolk index, and Haugh Unit) of eggs coated with carnauba wax, with the goal of minimizing food waste.

Materials and Methods


Unwashed white eggs from laying hens of the same commercial batch (Hisex White lineage, at 50 weeks of age, fed with a specific balanced diet for laying hens based on corn, soybean meal, and vegetable oil) were used. A total of 96 fresh, unfertilized whole eggs (no more than one day from laying) were utilized for the experiment. The eggs were acquired from a commercial farm (Brambilla) located in the city of Americana, SP, Brazil. The experiment took place at the Food Technology Laboratory of FAM – Faculdade de Americana, (550 meters of altitude, 22°42' South latitude and 47°18' West longitude), Americana, SP, Brazil.


The treatments consisted of a control group with no treatment (negative control); a group treated with mineral oil (positive control), and a group treated with a semi-solid product containing carnauba wax. The formulation of the semi-solid product involved the dissolution of 30% pure carnauba wax flakes (100%) (purchased from the industry PolyStar Comércio de essencias Ltda - manufactured in Brazil), 20% of solid vaseline (pharmaceutical grade Needs®), and 50% of liquid mineral oil (pharmaceutical grade Needs®), under constant stirring at a temperature of 80°C. On the same day as laying, all eggs were transported to the laboratory. On day zero (same day as egg collection), these eggs were weighed, numbered and their weight was noted on the shell with a pencil.

The eggs were divided between the three treatments according to their average weight, and after cooling, the semi-solid carnauba wax-based product was applied individually to the surface of each eggshell, manually, with the aid of a brush, forming the film of coating. The same procedure was performed with the positive control, mineral oil. An average of 170 mg of the product was applied per egg. Following the coating, the eggs were placed in cardboard trays, each capable of holding 30 units (one tray per treatment) and stored at room temperature. The production cost of 100 g of the product was $ 1.05 sufficient to treat 588 eggs (using approximately 170 mg of product per egg), resulting in a cost of $ 0.0018 per treated egg.

The temperature and relative humidity in the environment were monitored daily during the storage period using a digital thermo-hygrometer (Incoterm®).

The average maximum and minimum temperatures varied within the range of 27.8°C±2.9°C and 20.4°C±3.1°C, respectively. The variation in average maximum and minimum humidity was 70.8%±6.5% and 53.7%±7.6%, respectively.

The eggs were distributed in a completely randomized design with twelve eggs per treatment, divided into three replicates of four eggs each.

Assessment of Egg Quality

The analyses to assess the internal quality of the eggs were conducted at 7, 14, 21, and 28 days, corresponding to the storage duration of the eggs at room temperature. The variables under study included: egg weight loss (%), yolk percentage, egg white percentage, yolk pH, egg white pH, yolk index, and Haugh unit.

The weight of whole eggs was measured on a digital electronic scale (AG200 Gehaka). The weight of the eggs was assessed on day 0 (the day of coating) and subsequently on days 7, 14, 21, and 28 of storage at room temperature. The percentage weight loss of both control eggs (uncoated and coated with mineral oil) and the group coated with carnauba wax was calculated using the following equation described by Yüceer et al. [10].

% weight loss of egg = ([initial whole egg weight (g) after coating at day 0 - whole egg weight (g) after storage] / initial whole egg weight (g) after coating at day 0) x100)

The Haugh Unit (HU) was calculated according to the equation described by Haugh [11]: HU=100 log (h+7.57-1.7w 0.37), where h corresponds to the height of the egg white in millimeters, and w is the weight of the egg in grams.

The yolk index was calculated as the ratio of the height (mm) to the diameter of the yolk (mm). To do this, the eggs were cracked on a flat glass surface, and using a micrometer, the height of the dense egg white and the yolk diameter were measured. The yolks were manually separated from the egg whites, and the eggshells were washed and dried at room temperature for 7 days and then weighed.

The egg yolks were weighed to determine the percentage of yolk in relation to the egg's weight. The weight of the egg white was determined by the difference between the weight of the whole egg and the weights of the yolk and shell after drying, and its percentage in the total weight was estimated. The pH of the yolk and egg white was measured with a digital pH meter (Mpa-210A).

Egg classification: The egg quality was classified based on the United States Individual Shell Egg Quality Standards as follows: AA (albumen and yolk firmness = Haugh unit above 72); A (reasonably firm = 71 to 60); and B (weak and watery = below 60) [12].

Statistical Analysis

The eggs were distributed in a completely randomized design with twelve eggs per treatment, divided into three replicates of four eggs each. For each treatment there was a surplus of 15 eggs in case of accidental breakage. Statistical analysis was conducted using analysis of variance (ANOVA), considering each egg an experimental unit; followed by the comparison of means through the Tukey test at a significance level of 5% (p<0.05) using the statistical program SISVAR as described by Ferreira [13]. Information was collected in 12 eggs per treatment. Statistical models included the effects of treatments (coating types) (P<0.05), storage periods (weeks) (P<0.05) and interaction (treatments by storage periods) (P<0.05).

Results and Discussion

In general, on almost every storage day, there was a significant difference (p=0.05) between the group treated with carnauba wax when compared to the negative control (untreated) and positive control (mineral oil) for the variables under study, such as egg weight loss (%), yolk pH, albumen pH, yolk index, and Haugh Unit. There were no significant differences (p>0.05) observed in the evaluated parameters of albumen percentage and yolk percentage between the control group and the treated group during the 4-week storage period (Table 1).

Citation: Piazentin MO, Mangili ELM, Correia DC, Martins EH, Nobre JAS, et al. Application of a 30% Semisolid Carnauba Wax Product on the Surface of Hen Eggshells Improved the Shelf Life and Quality of the Eggs. Austin J Nutri Food Sci. 2023; 11(2): 1174.