Abstract
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.
Highlights
Chicken eggs are one of the most common foods all over the world
Since we previously demonstrated that edible whey protein/pectin films obtained in the presence of the enzyme transglutaminase (EC 2.3.2.13) possess good water vapor and gases barrier properties [17,21,22,23,24,25,26,27,28], we decided to study their effectiveness as a coating to preserve the quality parameters of fresh eggs
Weight loss of eggs during storage is mainly caused by evaporation of water and loss of carbon dioxide from the albumen through the porous shells or micro-breakages of eggshell [17]
Summary
Chicken eggs are one of the most common foods all over the world. In 2016, Mexico ranked the fourth place on egg production worldwide, there was an approximate production of 2,653,000 tons of fresh eggs, and the main production was in the region of Jalisco (50%) [1,2]. The main activities involved in egg marketing include collecting, packaging, transporting, storing, and selling. During these operations, Coatings 2018, 8, 438; doi:10.3390/coatings8120438 www.mdpi.com/journal/coatings. Once the chicken egg is laid, the deterioration process starts due to a reduction in moisture content and a loss of carbon dioxide (CO2 ). These parameters are involved in the quality of the albumen and yolk [4,5,6,7] and can favor the penetration of microorganisms from the shell causing a microbial deterioration of the egg [7,8]
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