The 10, 20 and 60% lysozyme-chitosan coatings, considered active packaging, showed promising attributes. They could be a viable alternative to existing techniques for maintaining the internal quality of fresh eggs during long-term storage. Chitosan coatings also improved shell strength. This study also confirms that measurements of albumen quality (pH, dry matter, viscosity and RWC) are excellent indicators of egg freshness.

The effectiveness of various coatings (whey protein isolate [WPI], whey protein concentrate [WPC], zein, and shellac) on functional properties, interior quality, and eggshell breaking strength of fresh eggs were evaluated during storage at 24 °: C for 6 weeks. Coatings and storage time had significant effects on Haugh unit, yolk index, albumen pH, dry matter (DMA), relative whipping capacity (RWC), and albumen viscosity. Uncoated eggs had higher albumen pH (9.56) and weight loss, and lower albumen viscosity (5.73), Haugh unit (HU), and yolk index (YI) during storage. Among the coated eggs, the shellac and zein coated eggs had the highest value of albumen viscosity (27.26 to 26.90), HU (74.10 to 73.61), and YI (44.84 to 44.63) after storage. Shellac (1.44%) was more effective in preventing weight loss than WPC (4.59%), WPI (4.60%), and zein (2.13%) coatings. Uncoated eggs had the higest value (6.71%) of weight lost. All coatings increased shell strength (5.18 to 5.73 for top and 3.58 to 4.71 for bottom) significantly (P < 0.05) compared to the uncoated eggs (4.70 for top and 3.15 for bottom). The functional properties such as albumen DMA (14.50 to 16.66 and 18.97 for uncoated) and albumen RWC (841 to 891 and 475 for uncoated) of fresh eggs can be preserved during storage when they are coated. The shellac and zein coatings were more effective for maintaining the internal quality of fresh eggs during storage. Fourier transform near infrared (FT-NIR) in the 800 to 2500 nm reflection spectra were used to quantify the contents of the fresh eggs at the end of storage. Eggs coated with shellac or zein displayed a higher absorbance at 970 and 1,197 nm respectively (OH vibration of water) compared with those coated with WPI or WPC and the uncoated group at the end of storage. The coatings improved functional properties and also shell strength and could be a viable alternative technology for maintaining the internal quality of eggs during long-term storage. This study highlights the promising use of various coatings to both enhance the functional properties and to reduce the breakage of eggs.

Power levels of 300 W and 450 W of ultrasound treatments had improved internal quality of fresh eggs during storage, but negative effect on shell strength. The study showed that ultrasound treatment could be an alternative and effective technique for maintaining the internal qualities of fresh eggs during long-term storage while Fourier transform near infrared spectroscopy could be used as a new tool for the assessment of freshness.

SummaryThe objective of this research was to investigate and compare the effect of different treatments including gaseous ozone (6‐ppm/4‐min), ultrasound (450 W/4 min) and coating of shellac, lysozyme–chitosan (L‐C) on fresh eggs internal quality during storage for six weeks at ambient temperature. The internal quality attributes such as weight loss (WL), albumen viscosity, Haugh unit (HU), yolk index, total soluble solids, albumen and yolk's pH were monitored. Control groups had the worst HU (50.04), WL (8.35%), albumen pH (9.27) and viscosity (7.72 mPa·s) values after storage. The best interior qualities were obtained by shellac coating [HU (72.37), WL (1.37) and viscosity (30.10 mPa·s)] and sonication (albumen pH: 8.22). Thus, the shellac‐coated eggs maintained all the internal quality parameters at the highest values, while the ozone and ultrasound only helped to keep the internal quality and enhance the shelf life of eggs.

Ozone treatments helped to maintain egg quality for a longer time. Ozone concentrations at 2 and 4 ppm showed promising results in maintaining internal quality and functional properties of fresh eggs during storage. Ozone at high concentration (6 ppm) caused a detrimental effect on eggshell quality. As a result, this study demonstrated that ozone treatments of 2, and especially 4 and 6 ppm concentration maintained eggshell quality during the storage. © 2015 Society of Chemical Industry.

Summary This research aims to investigate and compare the effect of different treatments, including gaseous ozone (6‐ppm/4‐min), ultrasound (450 W/4‐min), and coatings of shellac and lysozyme–chitosan (L–C), on fresh eggs during the storage for six weeks at ambient temperature. The internal quality analysis was performed in Part I. In Part II, the bacterial qualities, Fourier transform near‐infrared (FT‐NIR) spectral image and eggshell breaking strength were monitored. Ozone and ultrasound helped to maintain bacterial quality, but had an adverse effect on shell strength. Coated eggs had the highest value of strength (shellac: 3.63 ± 0.54 kgf; L–C: 3.56 ± 0.54 kgf) and ultrasound‐treated eggs had the lowest strength (3.13 ± 0.78 kgf) in egg top. FT‐NIR measurement showed that all treatments resulted in a decrease in absorption bands throughout storage. Overall, among the treatments investigated, the coatings were the best for enhancing shelf life with higher strength in eggshell breakage, while the ozone and ultrasound only helped to keep the microbial quality and enhance the shelf life.

The objective of this research was to evaluate the efficiency of phospholipase A2 (PLA) enzyme treatments (0.1%, 0.2%, and 0.3% by ‐v/v) on liquid egg white (LEW). The rheological behaviors and physico‐functional characteristics such as foam capacity (FC), foam stability, turbidity, color parameters, and pH‐values were evaluated during the 27 days at 4°C. The correlation coefficient (R2) were best fitted for the Herschel–Bulkley model in all LEW samples. The PLA increased FC compared to nontreated LEW. The use of PLAs were also significantly (p < .05) decreased turbidity, control, 0.1%, 0.2%, and 0.3% of PLA with 0.76 ± 0.07, 0.64 ± 0.06, 0.57 ± 0.04, and 0.62 ± 0.04, respectively. Significant changes in L* (lightness) was observed, while 0.1% treated LEW showed lower L* and higher a* (redness and greenness) values than the control (p < .05). The b* (yellowness and blueness) color of the treated samples remained stable except for the untreated samples (12.65 ± 0.14 to 5.71 ± 1.01). A considerable (p < .05) increase was observed in b* values, while lowest turbidity (0.57 ± 0.04) was obtained 0.2% treatment, while the best treatment was the 0.3% PLA with higher FC and lower foam stability. The effect of enzyme treatment concentrations was statistically nonsignificant (p > .05) on the pH values before and after the treatment. Practical applications The modification of the phospholipids presents in egg white during the egg breaking or in storage is critical in the egg processing. The fats and phospholipids from the yolk lead to migrate to egg white. The PLA enzymes could be used to improve the functionality or recover the adverse effects of the fresh eggs during aging. Understanding the effect of enzymes of LEW has great importance for the value‐added new product development in the egg processing industry and to enhance the functionality in final product such as baking products.

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