Oil Coating Affects Internal Quality and Sensory Acceptance of Selected Attributes of Raw Eggs during Storage

Quality characteristics, lysozyme activity, and albumen viscosity of fresh hatching duck eggs after a week's storage at various temperatures

The study aimed to analyze the qualitative features of Cherry Valley duck' hatching eggs during storage at different temperatures. Eggs were divided into 3 equal groups with 30 eggs each: fresh egg and stored at 7 °C and 17 °C within one week. Qualitative analyses of duck eggs were carried out, considering the morphological composition, physicochemical characteristics, lysozyme activity, and albumen viscosity. The highest weight of yolk and its percentage was found in the 17 °C group. The weight and percentage of albumen were significantly the highest in the group of fresh eggs. Higher egg weight loss was observed in the group stored at higher temperatures. Higher thick albumen height and Haugh units were found in fresh eggs and eggs stored at 7 °C. Different temperatures of egg storage did not affect lysozyme activity in thick and thin albumen. Stored eggs were characterized by lower albumen viscosity only at a shear rate of 10 rpm. The higher viscosity of thick albumen compared to thin ones was demonstrated at 10 and 20 rpm shear rates. The presented research results indicate a large diversity of selected qualitative indicators of hatching duck eggs, which may affect their storage and suitability for incubation.

Evaluation of Physicochemical Changes in Hard-Boiled Eggs Stored at Different Temperatures

Eggs that have been hard-boiled are frequently used as ready-to-eat food. Refrigerated and frozen storage of hard-boiled eggs causes issues, such as customer rejection owing to textural changes. The objective of this research is to ascertain how storage temperature affects hard-boiled eggs' alteration in texture over time. Medium-sized brown shell eggs were acquired from a local market, boiled at 100°C for 15 min, and then stored at room temperature (25°C), refrigeration (4°C), and freezing (-18°C) conditions for 0, 12, 24, and 48 h. Fourier transform infrared spectroscopy (FTIR), texture profile, visual observation using a gemological microscope, free amino acid content, and color were measured. Freezing had a substantial impact on the eggs' hardness, gumminess, chewiness, and cohesiveness (p<0.05). The FTIR spectrums confirmed the textural changes in bonds of amide A (3,271 cm-1), amide I (1,626.2 cm-1), amide II (1,539.0 cm-1), C=O stretch of COO- (1,397 cm-1), asymmetric PO2- stretch (1,240 cm-1). Microscopic images confirmed structural changes in eggs stored at -18°C. The free amino acid content was lower in fresh and frozen eggs than in the rest (p<0.05). However, there was no discernible variation in the egg white's color when eggs were kept at 4°C (p>0.05). Salmonella spp. was found exclusively in eggs kept at room temperature. In conclusion, hard-boiled eggs did not exhibit structural or chemical changes when stored at 4°C for up to 48 h compared to freezing and room temperature conditions.

Combination of sensory evaluation with conventional physiochemical analyses to evaluate quality changes during long-term storage and estimate the shelf life of chicken eggs

1. This study developed a comprehensive sensory evaluation system that consisted of descriptions corresponding to United States Department of Agriculture photos to evaluate overall acceptability, albumen and yolk appearances and odours. It determined physiochemical parameters of eggs stored at 7°C (7W12 and 7U12 for washed and unwashed, respectively) for 12 weeks and stored at 25°C (25W4 and 25U4 for washed and unwashed, respectively) for four weeks.2. Throughout storage, there was a general downward trend in Haugh units (HU) and yolk index and an upward trend in air cell size, weight loss and S-ovalbumin content were observed (P < 0.05). The 25W4 and 25U4 egg quality rapidly deteriorated from grade AA (HU 81.7) to grade B after two weeks (HU 46.5 and 49.6), whereas 7W12 and 7U12 eggs remained grade A after 12 weeks (HU 67.3 and 66.9). High correlations were observed between the sensory and physiochemical parameters (i.e., R2 = 0.93, 0.93, 0.88 and 0.94 for albumen appearance, yolk appearance, sensorial odour and overall acceptability, respectively, with HU in 25W4 eggs).3. Eggs stored at 25°C and classified into 'premium', 'class I', and 'class II' on the basis of their HU had estimated shelf life of 0.5, 1.5 and 2.5 weeks, while shelf lives of 4, 9 and 15 weeks were estimated for 7°C-stored premium, class I and II eggs, respectively.4. In conclusion, distinct HU requirements for eggs of different quality classes under two storage temperatures need to be established. Incorporating sensory evaluation with conventional physiochemical analyses is promising to assess and estimate egg quality changes. Further research work about the influences of different storage temperatures and possible temperature fluctuations during storage on egg quality changes is needed.

Combination of cassava starch biopolymer and essential oils for coating table eggs

This work aimed to evaluate the eggshell microbiota and the internal egg quality after coatings with cassava starch biopolymer enriched with different essential oils during 35 days of storage at 20°C. A total of 369 brown table eggs were used and distributed in the following treatments: uncoated eggs, coated with cassava starch + Ginger essential oil (CS+GIN), cassava starch + Lemongrass essential oil (CS+LEM), and cassava starch + Tahiti lemon essential oil (CS+TAH). The count of total aerobic mesophilic bacteria on coated eggshells at 0 and 35 days of storage were similar to each other (mean 0.70 ± 0.37 and 0.91 ± 0.22 log10 CFU/mL) and significantly lower compared to uncoated eggs (2.21 ± 0.17 and 3.17 ± 0.22 log10 CFU/mL), in that order. On the 35th day, coated eggs showed similar Haugh unit (HU) values between them (mean 70.61 ± 5.35; classified as A - high quality) and significantly higher than uncoated eggs (51.60 ± 4.28; classified as B - average quality). Cassava starch coatings added with essential oils preserved the internal quality of the eggs during storage for 5 weeks at 20°C, reducing the eggshell microbiota and effectively keeping it at low levels during storage.

Potential Implications of Natural Antioxidants of Plant Origin on Oxidative Stability of Chicken Albumen during Storage: A Review

Enhanced albumen quality is reflected in increased thick albumen height, albumen weight, and Haugh unit value, while the antimicrobial, antioxidant, foaming, gelling, viscosity, and elasticity attributes are retained. Improved albumen quality is of benefit to consumers and to the food and health industries. Egg quality often declines during storage because eggs are highly perishable products and are most often not consumed immediately after oviposition. This review provides insights into albumen quality in terms of changes in albumen structure during storage, the influence of storage time and temperature, and the mitigation effects of natural dietary antioxidants of plant origin. During storage, albumen undergoes various physiochemical changes: loss of moisture and gaseous products through the shell pores and breakdown of carbonic acid, which induces albumen pH increases. High albumen pH acts as a catalyst for structural changes in albumen, including degradation of the β-ovomucin subunit and O-glycosidic bonds, collapse of the ovomucin-lysozyme complex, and decline in albumen protein–protein interactions. These culminate in declined albumen quality, characterized by the loss of albumen proteins, such as ovomucin, destabilized foaming and gelling capacity, decreased antimicrobial activity, albumen liquefaction, and reduced viscosity and elasticity. These changes and rates of albumen decline are more conspicuous at ambient temperature compared to low temperatures. Thus, albumen of poor quality due to the loss of functional and biological properties cannot be harnessed as a functional food, as an ingredient in food processing industries, and for its active compounds for drug creation in the health industry. The use of refrigerators, coatings, and thermal and non-thermal treatments to preserve albumen quality during storage are limited by huge financial costs, the skilled operations required, environmental pollution, and residue and toxicity effects. Nutritional interventions, including supplementation with natural antioxidants of plant origin in the diets of laying hens, have a promising potential as natural shelf-life extenders. Since they are safe, without residue effects, the bioactive compounds could be transferred to the egg. Natural antioxidants of plant origin have been found to increase albumen radical scavenging activity, increase the total antioxidant capacity of albumen, reduce the protein carbonyl and malondialdehyde (MDA) content of albumen, and prevent oxidative damage to the magnum, thereby eliminating the transfer of toxins to the egg. These products are targeted towards attenuating oxidative species and inhibiting or slowing down the rates of lipid and protein peroxidation, thereby enhancing egg quality and extending the shelf life of albumen.

Effects of storage temperature on the quality of eggs coated by cassava starch blended with carboxymethyl cellulose and paraffin wax

A blend of cassava starch (CS), carboxymethyl cellulose (CMC), and paraffin was prepared as a coating material to maintain the quality of eggs during 4 wk of storage at different temperatures. The efficacy of the CS/CMC/paraffin (6/1/0.5% w/v) coating was investigated in terms of the Haugh unit (HU), weight loss, pH, and microbial load at the end of storage. The best egg storage temperature was 4°C, which maintained an HU of grade AA in coated and uncoated eggs for 4 wk. Lower weight loss (2.14%) was observed in coated eggs at 4°C storage than at 30°C storage (3.26%). The pH in the albumen of coated and uncoated eggs at 4°C increased from 6.84 to 6.88 and 7.01 to 7.03, respectively, after 4 wk of storage. No microbes were detected in the coated and uncoated eggs at 4°C. The maximum microbial count was 728 ± 35 cfu/mL in uncoated eggs at 30°C storage. Egg coating prevented microbial contamination of eggs stored at 30°C for 4 wk. The freshness of the eggs did not affect the nutrient content. The egg-coating material effectively maintained egg quality, prevented microbial contamination of eggs, and increased the shelf life of eggs at storage temperatures of 25 and 30°C.

Preservation of duck eggs through glycerol monolaurate nanoemulsion coating

Duck eggs have a short storage life. In this study, water-washed duck eggs and glycerol monolaurate (GML) coated duck eggs were stored at 25 °C for 70 days (away from light). The water-washed duck eggs started to lose weight from the 4th week. At the same time, Haugh unit and egg yolk index of the water-washed duck eggs started decreasing. The normal GML coating solution (NGML), the higher concentration GML diluent (HGML), and the lower concentration GML diluent (LGML) showed different preservation effects. Among them, NGML showed the strongest protection effect against spoilage of duck eggs. After 70-days storage, the weight loss rate of the NGML coated duck eggs was <6%, which was 4 times lower than that of the water-washed duck eggs; the Haugh unit and the surface morphology were also better than that of the water-washed duck eggs. Furthermore, the total colonies in NGML coated sample was >4 log CFU/g less than that was found in the water-washed samples (Control). The HGML and LGML coating agents were less effective but they might be suitable for the short storage of duck eggs due to the lower cost. Overall, this study provides a sound basis for the preparation and utilization of GML coating solution. The GML coating method is able to extend the shelf life of duck eggs by more than 6 weeks.

Effect of Egg-Coating Material Properties by Blending Cassava Starch with Methyl Celluloses and Waxes on Egg Quality

An egg-coating material was developed to extend the shelf-life and freshness of eggs by blending cassava starch (CS) with gelling agents and waxes. The effects of the properties of this egg coating on egg quality were investigated. Hydroxypropyl methylcellulose (HPMC), carboxymethyl cellulose (CMC), beeswax, and paraffin wax were used. CS blended with low-molecular-weight paraffin (Paraffin(L)) and CMC coating material displayed a tensile strength of 4 MPa, 34% elongation at break, 0.0039 g day⁻¹ m⁻² water vapor permeability, and a water contact angle of 89° at 3 min. Eggs coated with CS/CMC/Paraffin(L) solutions had a Haugh unit value of 72 (AA grade) and exhibited a weight loss of 2.4% in 4 weeks. CMC improved the compatibility of CS and Paraffin(L). This improvement and the hydrophobicity of Paraffin(L) provided suitable mechanical and water-resistance properties to the coating material that helped to maintain the quality of the coated AA-grade eggs with low weight loss for 4 weeks.

The effect of resin coating on the quality characteristics of chicken eggs during storage

In this study, after washing, changes in the quality characteristics of chicken eggs coated with apricot, almond, and sour cherry tree resins were examined during two different temperatures (4 °C and 22 °C) storage for 60 days. While air cell height, weight loss, albumen and yolk pH and a* (redness) values increased in all samples during storage, Haugh unit, albumen and yolk index, shell fracture and vitelline membrane strength, albumen and yolk L* (lightness) and b* (yellowness) values decreased (P < 0.05). The lowest weight loss (0.54 g) and air cell height (2.89 mm), highest Haugh unit (73.95 HU), albumen index (8.81%), and yolk index (40.37%) were found in the samples coated with sour cherry wood resin stored at 4 °C. The shell breakage and vitelline membrane strength of the coated samples were determined to be higher than the control samples and the samples stored after washing. Higher weight loss, air cell height, and pH values, while lower Haugh unit, Albumen and yolk index were found in samples stored at 22 °C (P < 0.05). At the end of storage, the maximum increase in the counts of total aerobic mesophilic and psychrophilic bacteria was found in the albumin and egg yolk of washed samples stored at ambient temperature. As a result, the coating materials prepared with the resin of apricot, almond, and sour cherry trees were suitable for eggshell's shelf life extension. PRACTICAL APPLICATION: The consumers demand the eggs be in their freshest condition, but the currently available storage conditions are not sufficient to maintain freshness in many regions of Turkey. The physical, chemical and, microbiological qualities of the eggs coated with wood resins were determined to be superior compared to other samples. Because resins have good barrier properties, it is recommended to conduct extensive studies on their applicability in different products.

Citric acid as a factor limiting changes in the quality of table eggs during their storage

The aim of the experiment was to evaluate the potential use of citric acid as a modifier of quality changes in table eggs during their storage. About 780 table hen eggs were collected on the same day. They were numbered individually and placed on trays 30 pcs on each. Control group (CA0) consisted of eggs unmodified with any additional substances. In experimental groups CA10 and CA15, eggshells were sprayed with the aqueous solution of citric acid (10 and 15% concentration, respectively). At the start of the experiment, only quality traits of eggs from the control group were analyzed. The remaining eggs were stored at 14°C and 70% RH (typical storage conditions). Their quality was evaluated after 7, 14, 21, and 28 d. The depth of the air cell, egg weight and specific gravity, traits of shell (permeability, strength, weight, thickness, density), and egg content (pH of yolk and albumen, Haugh units, yolk weight and color) were evaluated each time. The use of citric acid decreased the severity of qualitative changes. Citric acid–treated eggs demonstrated smaller weight loss, shallower air cell, higher structural albumen, less-intensive water diffusion from albumen to yolk indicating the improved resistance of the vitelline membrane. Owing to the fact that citric acid is accepted and recognized as a safe food preservative is a relatively cheap and available substance, it seems that it can be used to inhibit quality changes in table eggs during their storage.

Preliminary study: Health and performance assessment in broiler chicks following application of six different hatching egg disinfection protocols

As part of a Germany-wide project that evaluates strategies for the reduction of multi-resistant bacteria along the poultry production chain, the impact of different hatching egg disinfectants on hatchability and health of the broiler chicks was evaluated. Animal trials were conducted with extended-spectrum beta-lactamase- (ESBL) producing Escherichia (E.) coli contaminated hatching eggs and six disinfection protocols that used formaldehyde, hydrogen peroxide, low-energy electron irradiation, peracetic acid and an essential oil preparation. Each protocol was tested on a group of 50 chicks. Equally sized positive and negative control groups were carried along for each trial. Hatchability, mortality and body weight were recorded as performance parameters. During necropsy of half of the animals in each group on day 7 and 14 respectively, macroscopic abnormalities, body weight, weights of liver and gut convolute were recorded and a range of tissue samples for histological examination were collected as part of the health assessment. A decrease in hatchability was recorded for spray application of essential oils. Body weight development was overall comparable, in several groups even superior, to the Ross308 performance objectives, but a reduced performance was seen in the hydrogen peroxide group. Histologically, lymphoid follicles were regularly seen in all sampled organs and no consistent differences were observed between contaminated and non-contaminated groups. Significances were infrequently and inconsistently seen. In conclusion, remarkable findings were a decrease in hatchability caused by the essential oils spray application and a reduced body weight development in the hydrogen peroxide group. Therefore, the essential oils preparation as spray application was deemed inappropriate in practice, while the application of hydrogen peroxide was considered in need of further research. The other trial results indicate that the tested hatching egg disinfectants present a possible alternative to formaldehyde.

Effects of rice protein coating enriched with essential oils on internal quality and shelf life of eggs during room temperature storage

The effectiveness of rice protein coatings enriched with essential oils on maintaining interior quality of fresh eggs was evaluated during storage at 20°C for 6 wk. Egg quality was assessed by weight loss, Haugh unit (HU), albumen pH, and yolk index (YI) in uncoated eggs (control treatment) and eggs coated with rice protein concentrate at 8% enriched or not with different essential oils (1%): tea tree (Melaleuca alternifolia), copaíba (Copaifera langsdorffii), or thymo (Thymus vulgaris). The HU and YI were higher in coated eggs (P < 0.001). Data were submitted to variance analysis, and the statistical models included the effects of treatments (coating types), storage periods (weeks), and interaction (treatments by storage periods). Weight loss increased (P < 0.001) during long-term storage. Uncoated eggs showed the highest weight loss (5.43%), whereas coatings of rice protein alone (4.23%) or enriched with tea tree (4.10%), copaíba (3.90%), and thymo (4.08%) solutions were effective in preventing weight lost (P < 0.001). The coating use preserved the internal quality of the eggs for up to 3 wk longer than uncoated eggs in terms of HU, YI, and pH. Uncoated eggs had the worst (P < 0.001) HU (58.46), albumen pH (9.48), and YI (0.33) after 6 wk of storage. In conclusion, the use of coatings based on rice protein concentrate enriched with different essential oils influences the internal quality of eggs during storage and may be an effective alternative for increasing the shelf life of commercial eggs.

Rice protein coating in extending the shelf-life of conventional eggs

The effectiveness of rice protein coatings or mineral oil on maintaining interior quality and eggshell breaking strength of fresh eggs was evaluated during storage at 20°C for 8 wk. Egg quality was assessed by weight loss, Haugh unit (HU), albumen pH, yolk index (YI), shell strength, and scanning electron microscopy in uncoated eggs (control treatment) and eggs coated with mineral oil or rice protein concentrate at 5, 10, or 15%. The HU and YI were higher in coated eggs (P < 0.001). Weight loss increased (P < 0.001) during long-term storage. Uncoated eggs showed the highest weight loss (8.28%), whereas mineral oil (0.87%) and rice protein at 5% (5.60%), 10% (5.45%), 15% (5.54%) solutions were effective in preventing weight lost (P < 0.001). The use of the coatings preserved the internal quality of the eggs for up to 4 wk longer than uncoated eggs (HU, YI, and pH). Uncoated eggs had the worst (P < 0.001) HU (54.45), albumen pH (9.18), and YI (0.28) after 8 wk of storage. Among the coated eggs, the mineral oil had the best values of HU (70.54), pH (8.48), and YI (0.35) after storage. The eggs coated with 5, 10, and 15% of rice protein presented results with similar intern quality between them and intermediary quality in relation to the others treatments during all the storage period. Scanning electron microscopy demonstrated a lower surface porosity in coated eggshell, indicating that the use of the coating may provide a protective barrier against the transfer of gases and moisture. In conclusion, the use of coatings based on rice protein concentrate or mineral oil influences the internal quality of eggs during storage and may be an effective alternative for increasing the shelf-life of commercial eggs.

Application of Transglutaminase Crosslinked Whey Protein–Pectin Coating Improves Egg Quality and Minimizes the Breakage and Porosity of Eggshells

It is well known that an effective way to improve the quality attributes of food is the use of coatings. Moreover, there is evidence of the use of dairy byproducts to design coatings to improve the shelf life of food products. This study was conducted to explore the effectiveness of a film forming solution containing whey protein–pectin complex enzymatically reticulated by transglutaminase (TGase) applied as a coating on eggshells to preserve the internal quality of eggs stored under environmental conditions (25 ± 1 °C and 35% HR) during 15 days storage. Eggs properties tested included yolk index, albumen and yolk pH, albumen CO2 content, water loss, shell strength, and microbial permeability through the shell. The results showed that the coating maintained a higher yolk index and albumen carbon dioxide content, reduced the weight loss and increased both albumen and yolk pH values with respect to the uncoated eggs. All coated eggshells showed greater strength than those of uncoated eggs. Moreover, by using Blue Lake dye penetration method we demonstrated that the coating reduced the Blue Lake dye penetration confirming the effectiveness of the coating on the reduction of post-wash bacterial penetration. These results suggest that the studied coating can be useful to preserve internal egg quality but also to reduce the breakage of eggshell and egg microbial contamination. Based on this result we can conclude that the coating made with whey protein–pectin crosslinked by TGase could be an effective strategy to increase the shelf life of eggs preserved in environmental conditions and to reduce economic losses due to the eggs breakage during their marketing.

Effects of Chitosan Coating Structure and Changes during Storage on Their Egg Preservation Performance

To explore the influences of chitosan coating structure and structure changes during storage on egg preservation, eggs coated by chitosan solution for single time (CS1), two times (CS2), and three times (CS3) were prepared separately and stored with untreated eggs (CK1), eggs washed by water (CK2) and eggs treated by acetic acid solution (CK3) at 25 °C, 80% RH. The weight loss, Haugh unit, yolk index, albumen pH, eggshell morphologies and infrared (FTIR—Fourier Transform Infrared) spectra of all the samples were monitored. CS2 and CS3 presented the lowest weight loss, highest Haugh unit and yolk index, stabilized pH, and the highest thickness of chitosan coating layers (>2 μm) among all the groups, which extended egg shelf life for 20 days longer compared to CK1 and CK2. CS1 with very thin chitosan coating showed similar egg qualities with CK3, which are second only to CS2 and CS3. Furthermore, destructions were found on chitosan coatings during storage as revealed by the eggshell morphologies and FTIR spectra, which caused the quality deterioration of eggs. The results demonstrated that eggs with the thickest coating showed the best qualities during storage, while destructions on coating layers led to the quality drop of eggs.

Effect of egg freshness on their automatic orientation

BACKGROUND

High-quality eggs in unified packaging are desired by egg production enterprises. Automatic orientation apparatus is frequently used to orient eggs uniformly to pointed-end-down position for packaging. However, such apparatus may not work accordingly if the eggs are stored under improper methods or for excessive storage time. To study the effect of egg freshness on the efficiency of automatic orientation process, the relationship between egg freshness and its orientation motions was investigated under different storage conditions.

RESULTS

The results showed that as the storage time increased, centroid position and pointed-end-down turnover ratio decreased; other parameters such as eggs' obliquity at stationary state, horizontal deflection angle, speed, acceleration of axial motion, side-slip angle and rolling distance increased. However, the effects of storage time on the guiding distance of the guide rod were not apparent. In addition, the higher the storage temperature, the greater the changes of the final orientation states of eggs on the conveyor line. If the eggs were to be oriented uniformly, they should be stored for less than 25, 16, 10 and 7 days at 10 °C, 18 °C, 26 °C and 34 °C, respectively, under a relative humidity of 75%.

CONCLUSION

The experimental results presented in this paper are very useful for quality control and quality assurance in egg production enterprises. © 2017 Society of Chemical Industry.

Preservation of Quality of Table Eggs Using Vegetable Oil and Shea Butter

The poultry industry in Nigeria keeps expanding on a daily basis and it is faced with the problem of egg glut almost yearly. Most of the poultry are raised in rural environments where there is no available and avoidable power supply for egg preservation. The study was aimed at using locally available and cheap materials for preservation of eggs quality under the hot ambient temperature. The eggs were divided into three groups of 80 eggs each. The first and second groups were treated with vegetable oil (soybean oil) and shea butter, respectively, while the third group served as control. The eggs were stored under the ambient conditions and assessed for their physical and nutritional qualities on days 1, 8, 15, 22, 29, 36, 43 and 50. The physical quality was assessed by determining the albumen height and the Haugh’s unit, while the nutritional quality was appraised through the protein concentration of the albumen. Based on the values of Haugh’s unit, eggs treated with vegetable oil produced excellent results; good quality eggs were obtained up to 50th day of storage. Treatment with shea butter maintained quality eggs up to the 29th day, while with untreated eggs good physical quality was maintained up to 22nd day of storage. Protein concentrations of eggs in the three groups studied decline with duration of storage, however the protein concentrations of eggs treated with vegetable oil were significantly higher than the other groups (p<0.001). The eggs treated with shea butter recorded a comparative higher protein concentrations than the untreated eggs (p=0.002).

Preservation of Quality of Table Eggs Using Vegetable Oil and Shea Butter

The poultry industry in Nigeria keeps expanding on a daily basis and it is faced with the problem of egg glut almost yearly. Most of the poultry are raised in rural environments where there is no available and avoidable power supply for egg preservation. The study was aimed at using locally available and cheap materials for preservation of eggs quality under the hot ambient temperature. The eggs were divided into three groups of 80 eggs each. The first and second groups were treated with vegetable oil (soybean oil) and shea butter, respectively, while the third group served as control. The eggs were stored under the ambient conditions and assessed for their physical and nutritional qualities on days 1, 8, 15, 22, 29, 36, 43 and 50. The physical quality was assessed by determining the albumen height and the Haugh’s unit, while the nutritional quality was appraised through the protein concentration of the albumen. Based on the values of Haugh’s unit, eggs treated with vegetable oil produced excellent results; good quality eggs were obtained up to 50thday of storage. Treatment with shea butter maintained quality eggs up to the 29thday, while with untreated eggs good physical quality was maintained up to 22ndday of storage. Protein concentrations of eggs in the three groups studied decline with duration of storage, however the protein concentrations of eggs treated with vegetable oil were significantly higher than the other groups (p<0.001). The eggs treated with shea butter recorded a comparative higher protein concentrations than the untreated eggs (p=0.002).

Effect of dietary protein sources and storage temperatures on egg internal quality of stored shell eggs

This study was conducted to evaluate the effects of various protein sources (soybean meal, SBM; cottonseed protein, CSP; double-zero rapeseed meal, DRM) on the internal quality (Haugh unit, yolk index, albumen pH, yolk hardness and yolk springiness) of eggs when stored at either 4 or 28°C for 28 d. A total of 288 laying hens (32 wk of age) were randomly allotted to 6 treatment groups (4 replicates per treatment) and fed diets containing SBM, CSP, or DRM individually or in combination with equal crude protein content (SBM-CSP, SBM-DRM, and CSP-DRM) as the protein ingredient(s). A 6 × 2 factorial arrangement was employed with dietary types and storage temperatures (4 and 28°C) as the main effects. After 12 wk of diet feeding, a total of 216 eggs was collected for egg internal quality determination. The results showed as follows: 1) lower egg quality was observed in the DRM group compared with the other groups when stored at 4 and 28°C for 28 d (P < 0.05), while there was no difference in egg internal quality among the other groups. 2) The CSP diet resulted in higher yolk hardness compared with the other diets when eggs were stored at 4°C for 28 d (P < 0.05). Lower Haugh unit was observed in the DRM and SBM-DRM groups compared with the other groups when eggs were stored for 28 d at 4°C (P < 0.05). 3) Yolk breakage occurred in the DRM group and eggs could not be analyzed for egg internal quality when stored at 28°C for 28 d. The overall results indicated that CSP or DRM as the sole dietary protein source for laying hens may adversely affect the internal quality of stored eggs as compared with the SBM diet, and half replacement of CSP combined with SBM may maintain similar egg quality to SBM diet alone for eggs stored under refrigerated conditions.

Dietary Protein Sources Affect Internal Quality of Raw and Cooked Shell Eggs under Refrigerated Conditions

This study was conducted to evaluate the effects of various protein sources (soybean meal, SBM; cottonseed protein, CSP; double-zero rapeseed meal, DRM) on the internal quality of refrigerated eggs. A total of 360 laying hens (32 wk of age) were randomly allotted to six treatment groups (five replicates per treatment) and fed diets containing SBM, CSP, or DRM individually or in combination with equal crude protein content (SBM-CSP, SBM-DRM, and CSP-DRM) as the protein ingredient(s). A 6×3 factorial arrangement was employed with dietary types and storage time (0 d, 2 wk, and 4 wk) as the main effects. After 12 wk of diet feeding, a total of 270 eggs were collected for egg quality determination. The egg Haugh unit (HU) in the CSP, SBM-DRM, and DRM groups were significantly lower than those in the SBM and SBM-CSP groups. The hardness and springiness of the cooked yolk in the CSP group were significantly higher than those in the other treatment groups. A lower HU, lower yolk index and higher albumen pH were observed in the DRM group compared to the SBM and SBM-CSP groups when the eggs were stored to 4 wk, and the HU was improved in the CSP-DRM group compared to the DRM group (p<0.05). Higher yolk hardness was observed in the CSP group compared to the other groups during storage (p<0.05), but the hardness of the cooked yolk in the SBM-CSP and CSP-DRM groups showed no difference in comparison to the SBM group. In conclusion, CSP may ameliorate the negative effects of DRM on the HU of refrigerated eggs, and SBM or DRM may alleviate the adverse effects of CSP on yolk hardness.