A Comparative Study of the Internal and External Quality Characteristics of Table Eggs and the Effect of Storage Periods and Layer Strain on them under Summer Conditions

Table eggs are the cheapest animal protein and a full food with 75 kcal per egg. High digestibility and well-balanced amino acids make it a good human protein source (Nys and Sauveur, 2004). Changes in eating habits and rising pulse costs have led to an increase in demand for protein-rich foods such as fowl products. Given the rate of population increase and the surge in demand for chicken products such as eggs, the country must expand its supply (Chaudhari and Tingre, 2015). So, it’s a basic food product eaten worldwide (Gautron et al., 2022; Nys et al., 2022). About 150 eggs are consumed on average by each person across the globe every single year (Nys et al., 2022). The storage traits of eggs play an important role in their acceptability to consumer preferences (Sapkota et al., 2020). Therefore, eggs are a low-cost, low-calorie source of high-quality protein and other nutrients (Ruxton 2013; Zaheer 2015). Eggs are an important food item for humans because they contain animal protein, fats, mineral salts, essential amino acids, saturated fats, yeasts and enzymes that are only available in a few foods. One egg can constitute a complete meal for the consumer, which can be obtained at all times and places (Sahar and Rahman, 2018).
       
Genotype and storage periods have been proven to influence egg quality traits (Anderson et al., 2004; Alsobayel and Albadry, 2011). External and internal egg quality features have a genetic basis, as is well known. The qualitative, chemical, functional and microbial characteristics of table eggs are affected by environmental variables such as age of the bird, feeding, season, temperature, transportation, storage period and exposure to heat. Farm-produced eggs may be of high quality, but inefficient farm handling, storage and marketing practices may result in a decline in egg quality (Al-Obaidi et al., 2011). The loss of weight owing to the evaporation of water is the single most important factor that determines whether an egg’s quality is compromised on the inside or the outside during the course of storage or when it is handled (Samli et al., 2005; Calik, 2013). There is rise in hydrogen power of albumin and yolk, reduced Haugh unit values and carbon acid dissociation (Mohiti-Asli et al., 2008; Monira et al., 2003). These variations are the result of water movement through the vitelline membrane from albumin to yolk due to the weakness of the vitelline membrane (Jones, 2007; Kralik et al., 2014). Fresh eggs contain the highest quality characteristics and specifications and over time they begin to deteriorate and become corrupted and are susceptible to the factors of the surrounding environment as a result of storage and exposure to heat, drought and others. In many cases, the production of eggs is greater than the ability to market them in a short time, forcing the product to be stored for the longest possible period so it can retain its specifications (Johanning et al., 1996). Commercial table eggs are predominantly sold in supermarkets, poultry markets and grocery shops in Saudi Arabia. Saudi families buy eggs in trays of 30 eggs, keep them in the refrigerator and consume them within two to three weeks. In the meantime, there is relatively little information available on the quality features of locally produced commercial eggs. The current study sought to assess egg quality by assessing the internal and exterior characteristics and the effect of the storage period on commercial table eggs sold in Riyadh during the summer. Consequently, the research was carried out to compare and evaluate the influence of storage duration on external and internal quality traits of brown and white-shell eggs produced by commercial farmers raised under local conditions and marketed in the Riyadh region.

Experimental area and the eggs administration
 
This experiment was completed in the Animal Production Department of the College of Food and Agriculture Sciences-King Saud University, during the duration from (6/7/2022 – 6/10/2022). In this investigation, 480 brown and white shell eggs were used. Eight fresh egg dishes made up of two trays with 30 eggs each were chosen at random from the supermarket four times, at various intervals. They contained 240 brown-shelled eggs and 240 white-shelled eggs. The eggs of each species were separated into four treatments, with 30 eggs in each treatment and stored for 0, 10, 20 and 30 days at 4±1 °C and 50 -70% prorated humidity. The eggs of each treated collection were randomly portioned into four treatments, each replicate contained 20 eggs. The different egg treatments were individually weighed to the nearest 0.01 g. Eggs treatments that were stored for 10, 20 and 30 days were reweighed and the depth of egg air cell (AC) was measured in millimeters for each replicate utilizing a candling light and a thin plastic ruler.
 
Evaluation of the external adjectives of egg quality
 
Before being stored, each of the different egg-weighted groups were separately weighed. To determine the percentage of egg weight loss (WL), egg groups that were kept for 10, 20 and 30 days were reweighed and the candling lamp, a thin plastic ruler and the egg test equipment were utilized to measure the depth of the air chamber in millimeters for each of the eggs in duplicate. This was done for all of the eggs in each replicate. The cleanliness of the shell (CL) and the absence of any cracks or fractures in it were both factors that were evaluated. Using the inserted ruler and an egg test device were determine the depth of the air chamber using the inserted ruler and an egg test device. The egg was placed with the device from its wide end and the air chamber measured, other shell characteristics including shell thickness (ST), shell density (SD), shell surface area (SA) and shell weight (SWUSA). The specific density was determined by submerging an egg in water to determine the volume of water that was displaced and then calculating the specific density (SG), based on the equation that is presented below:

 
 

 
       
Calculating the egg’s coefficient (EI) by measuring the length and width of the egg > (width/length) * 100.
       
Egg surface area (SA) in cm² was calculated for each egg using the following equation suggested by Nordstrom and Qusterhout (1982): 
 

 
According to the following equation:

 
 
                                                                                                               (North and Bell, 1990)

Evaluation of traits Internal egg quality
 
After eggs were removed from each replication of each egg shell color and placed on a specialized glass table with a mirror on the bottom, the contents of the egg could be observed from both above and below using the mirror. Optical inspection was used to analyze the contents of the inner egg for the presence or absence of meat (MS) and blood (BS) spots, as described in the following. The Roch Color Scale (Hoover Man La Roche), which is graded to the degrees of yellow of 1-15 color gradations from extremely pale to deep yellow (North and Bell, 1990), was used to measure the degree of yolk color (YC). These color gradations range from very pale to deep yellow. The Haugh unit value was directly established by using a micrometer that is adjustable to egg weight and gives the Haugh unit value (USDA, 2000). The Haugh unit was measured using the Haw device (Haugh, 1937), which measures the height of the heavy whites at a distance of half a centimeter from the yolks. After entirely separating the yolk from the white using a specialized funnel, the yolk was placed on a scale and given its weight in grams after being thoroughly cleaned of any remaining traces of whiteness. After the albumin had been removed from the shell, it was thoroughly cleaned, allowed to dry at temperatures between 21 and 24 degrees Celsius for twenty-four hours and then it was weighed (SW) to the nearest 0.1 g increment. Each egg with a membrane was given three separate measures of its shell thickness (ST) using a dial touch micrometer. These measurements were taken in the middle of the egg as well as on both of its sides.
       
The qualitative characteristics of eggs were estimated using the following formula:
Weight of the egg =
Weight of the egg after storage - (Yolk weight + Shell weight)

 
 

 
 

 

 

 

 
Haugh unit = 100 leu (e + 7.57 - 1.7 f - 37)
 
Statistical analysis
 
Using the SAS program (2005), the data were statistically analyzed to verify the presence of significant differences between the average levels of each factor and the ability to overlap between the studied traits for each strain, using the following statistical model:

Y_ijk = µ + B_i + S_j + BS_ij + e_ijk 
 

Y_ijk = k^th observation of the i^th breed (B), j^th storage period. BS_ij = Interaction between breeding and storage time.

The results showed that faster rates of change in trait scores were associated with longer storage periods. According to the findings of the study, egg storage duration (10, 20 and 30 days) resulted in a significant (p≤0.05) decrease in some egg parameters.
       
Table 1 shows significant differences in weight between brown and white-shell eggs, yolk and white and shell. Whilst, not significant changes were seen in yolk (0.43) to whiteness (0.42) and egg weight loss (0.57), (1.10), respectively. With an increase in storage time, the weight of the yolk and white and the ratio of yolk and albumin between brown eggs and white-shell eggs changed, while the weight of eggs, loss and shell weight did not change. The interaction did not affect the previously mentioned traits except for egg weight. Large eggs had more albumin than small eggs (Cunningham et al., 1960; Attia, 2014). Silverides and Scott (2001) and Zeta et al., (2009) found statistically significant differences in these parameters between breeds and strains. Increasing storage time greatly lowers albumin and increases yolk (Akyurek and Okur, 2009).
 

       
The given percentages show statistically significant differences between eggs of all breeds held for different times, however, strain and storage period do not interact. Scott and Silversides (2000) found no significant effect of strain-storage period interaction on the studied traits, as well as an increase in yolk color grade, yolk albumin ratio and air cell depth. Shape index and shell density were unaffected by storage length (Alsobayel and Albadry, 2011; Alshaikhi et al., 2021). Research indicates that storage length (10, 20 and 30 days) days) and strain genotype significantly (p≤0.05) reduce yolk weight ratio to shell weight per unit surface area and Haugh unit values (Fig 1-4). Several studies found similar storage length effects for Haugh unit values and the yolk index. Samli et al., (2005), Alsobayel and Albadry (2011), Khatun (2016) and Monira et al., (2003) measured specific density, air cell depth and shell thickness. Unlike us, other researchers found no effect of storage duration on yolk color grade, yolk albumin ratio, shell thickness, or shell surface area. Some researchers found that increasing storage duration increased shell density, thickness and weight per unit of surface area (Lee et al., 2016; Alsobayel and Albadry, 2011) and decreased yolk color grade.
 

 

 

 

       
Brown eggs scored substantially higher (p<0.01) than White Lohmann eggs. According to Hassanin and Gabal (1990), this is true. Local Iraqi chickens were compared to imported breeds and those researched utilizing multiple breeds (Monira et al., 2003; Zita, 2009; Murshed et al., 2023). When stored for 0, 10, 20 and 30 days, egg weight reduced considerably (Table 2). Meijerhof (1994) showed no significant influence of storage time on egg weight. Storage has a substantial effect on white and brown shell eggs in terms of egg weight loss, yolk weight, white weight and shell weight. Other than egg weight reduction, the storage period affected all the other features. The interaction did not affect all attributes.
 

       
Table 3 indicates significant differences between white and brown shell eggs in yolk color (YC), shell integrity (BR), meat and blood stains (MS, BS) and shell cleanliness. We found that storage increased blood spots in the yolk color, but it did not affect the rest of the characteristics, as the interaction model predicted that the significant effects of the HU unit and yolk color did not affect the shell. This contradicted (Samil et al., 2005), who observed no significant strain-storage duration interaction on egg weight. Many researchers say the mean HUF is 0.173 (Stadelman and Cotterill, 1995). The investigation found a significant effect (P<0.01) of the HOF measurement unit for strains (71,40) (75,30) brown and white. Issa Brown (83) measured HU, which was equivalent to White Livorno, University of Baghdad (Al-Nedawi, 2006). White leghorn’s value is the same as before (Monira et al., 2003; Scott and Silversides, 2000). In earlier research, longer storage periods considerably reduced Hof units in different breeds (Akyurek and Okur, 2009). Interaction between strain and storage duration significantly impacted the HU unit (P<0.01). The storage dropped gradually in the Haugh unit with extended storage time (P<0.05) (Alsobayel and Albadry, 2011).
 

       
Fig 1 indicates no significant differences in the breed (brown and white) for shell weight per unit of surface area (SWUSA). While in significant differences between white and brown shell eggs in HU units (Fig 2). The results showed that there were statistically significant differences between storage duration (0, 10, 20 and 30 days) on shell weight per unit of surface area (SWUSA) and HU units (Fig 3, 4). The results in Fig 5 and 6 showed a significant significance between storage duration (0, 10, 20, 30 days) on egg yolk weight loss (YW) and albumin weight (AW). There were no significant variations between brown and white-shell eggs in egg weight, weight loss, weight percentage and shell weight percentage (Fig 7, 8 and 9). It is significant differences with increased storage time by 0-10 and 20-30 days. The figures’ traits are unaffected by interference (G*S). Several researchers (Scott and Silversides, 2000; Silversides and Scott, 2001; Hermiz et al., 2012) demonstrated a statistically significant link between egg weight and components. Genetic factors like breed, environmental changes during herd raising, chicken age, food, egg size and heat stress may cause these variances. Poor farm handling, marketing routes and storage practices also affect egg quality. The study found that storage length, strain and temperature greatly affect table egg quality. Storage of brown and white eggs at 5±2°C and 50-75% relative humidity for 30 days maintains internal quality and safety for human consumption. Eggs should be stored in their carton to protect their fragile shell, avoid refrigeration drying and prevent smells until 35 days. Salmonella and other bacteria can be killed by cooking eggs to 160°F. Pasteurized eggs eliminate disease transmission.
 

 

 

 

 

In conclusion, storage period, strain and temperature all have a significant impact on the quality of table eggs. Additionally, brown and white eggs held at 35°C and 50-75% relative humidity maintain quality and are acceptable for human consumption until 30 days. Keep eggs in their cartons to safeguard their fragile shell, avoid refrigerator drying and prevent smells. Never exceed 35 days. To destroy salmonella and other pathogens, boil eggs to 160°F. Pasteurized eggs prevent disease.