Egg high quality is multi-faceted, with bodily, purposeful, and microbial facets contributing to egg high quality. Analysis has proven that many components impression egg high quality together with flock age and administration, genetics, hen weight-reduction plan, housing design and administration, in addition to egg dealing with and storage. As laying egg manufacturing around the globe shifts to extra intensive housing methods, the impression of those housing methods on egg high quality is unclear. Moreover, the dealing with and storage of eggs have been proven to tremendously have an effect on egg high quality. Understanding the components influencing egg high quality permits for increased high quality eggs reaching customers.
D.R. Jones and R.Okay. Gast – United States Division of Agriculture, Agricultural Analysis Service, Egg Security and High quality Analysis Unit, Athens, Georgia, USA
Introduction
Eggs are an inexpensive uncooked agricultural commodity with a excessive nutrient density. Eggs serve a key function in diets around the globe. Sustaining the standard of eggs is a worldwide concern. Usually, there are three sorts of egg high quality: 1) bodily, 2) purposeful, and three) microbial. Throughout this presentation, all three sorts of egg high quality will probably be mentioned and components which affect egg high quality traits will probably be defined. Understanding the sorts of egg high quality, in addition to components impacting them, is integral to the final word aim of protected, prime quality eggs reaching customers.
Bodily egg high quality is outlined by the seen traits of the egg. Exterior options such egg form, shell texture, shell color, cleanliness, and soundness are the primary impression for customers when choosing eggs for buy. Inside bodily egg high quality components embody albumen peak and readability, in addition to yolk color, form, measurement, and construction.
Useful egg high quality describes the style which complete egg, albumen, and yolk carry out in a wide range of meals matrices. Eggs carry out quite a few purposeful properties in meals. Frequent purposeful attributes assessed for egg high quality embody foaming, coagulation, and emulsification.
Microbial high quality of eggs considers each meals security and spoilage organisms. Eggs are a uncooked agricultural commodity with a shelf life depending on preliminary flora current, dealing with, and storage situations. Salmonella spp. are the historic foodborne pathogens related to the consumption of eggs. Different spoilage organisms, together with yeasts and molds, can impression the shelf-life of eggs.
Bodily egg high quality
The form, texture, coloration, and soundness of the shell are the primary egg high quality components customers encounter. Shell high quality supplies aesthetics to the egg. It additionally serves as the primary line of protection for microorganisms coming into the eggs by way of horizontal transmission. A cracked egg is just not solely a possible lack of income resulting from lack of sale or retailer return, it’s also a meals security danger since organisms can simply transfer by means of the crack to the shell membranes. Damaged eggs with ruptured shell membranes (leakers) present microorganisms direct contact with the egg contents and shouldn’t be consumed. Within the US, leakers are thought-about a loss egg. The soundness of the egg additionally impacts the power for intact eggs to succeed in finish customers. Moreover, customers have expectations as to the brightness of white shell eggs, in addition to shade and consistency of color for brown or colored shells.
As soon as the egg is damaged, the form, readability, and look of the albumen and yolk outline the bodily high quality of the egg. The Haugh unit is utilised around the globe as a quantitative measure for egg grade requirements. Within the US, Grade AA is outlined as a Haugh unit rating > 72; Grade A is a rating > 60, however lower than 72; and Grade B is a rating lower than 60. The Haugh unit is calculated primarily based on egg weight and thick albumen peak. The rating has been questioned as a result of calculation being weighted for a big measurement egg (56 g). In such circumstances, thick albumen peak alone is utilised for reporting albumen and egg high quality.
Yolk high quality is monitored by figuring out yolk index and vitelline membrane mechanical traits. Yolk index is a calculation of yolk peak divided by yolk diameter and is an indicator of yolk form. As an egg ages, water migrates from the albumen into the upper solute yolk. This results in a flattening of the yolk leading to a decrease yolk index worth. Vitelline membrane power and elasticity are bodily properties of the membrane surrounding the yolk. The power of the vitelline membrane is necessary not solely to make sure the yolk stays intact throughout cracking and separation of the yolk and albumen fractions for cooking or the manufacturing of egg merchandise, the membrane can also be a barrier for microorganisms current within the albumen coming into the nutrient wealthy yolk. The elasticity of the vitelline membrane signifies how a lot the membrane can deform earlier than rupturing.
Useful egg high quality
Eggs are extremely purposeful elements in a wide range of meals matrices together with, however not restricted to, baked items, sauces, candies and confections, desserts, snacks, meal alternative bars, and drinks. Useful traits may be offered by albumen, yolk, and complete egg. Whereas there are a lot of recognized functionalities related the eggs, three of the overarching classes are: foaming, coagulation, and emulsification.
Primarily, albumen and complete eggs can present foaming capability to a meals matrix. The proteins within the albumen are significantly appropriate for unfolding and interacting throughout whipping to entrap air, forming foams. Throughout heating, the air and any moisture current will increase and supply leavening and lightness to the meals product.
Complete egg, yolk, and albumen all help with coagulation. Coagulation, typically resulting from warmth publicity, is the binding or setting of meals parts. Coagulation is chargeable for the feel created in the course of the scrambling of eggs. Moreover, coagulation permits for elements particles in quiches to be suspended with the dish. Coagulation can also be chargeable for the thickening achieved throughout heating of egg-containing puddings or sauces. Coagulation additionally accounts for the warmth setting of foams reminiscent of meringues and sponge desserts.
Yolk, complete egg, and to a lesser extent albumen, are emulsifiers bridging the hydrophobic and lipophobic parts of a meals matrix to assist within the creation of a secure emulsion. Eggs play a key function within the emulsification of mayonnaise and salad dressings, in addition to ice cream bases, Hollandaise, and bearnaise, to call just a few functions. Eggs additionally help with browning and color formation throughout cooking, adhering meals coatings, and enhancing mouth- really feel. The purposeful functions of eggs are countless, whereas additionally offering nutrient density and clear labels to the meals.
Microbial egg high quality
Foodborne pathogens and spoilage organisms contribute to the microbial high quality of eggs. Eggs can turn into contaminated by way of vertical transmission, in addition to horizontal contamination. Salmonella Enteritidis is deposited contained in the edible inside of eggs resulting from contaminated reproductive organs, though excessive frequencies of reproductive organ invasion by Salmonella don’t at all times lead to correspondingly excessive frequencies of egg contamination. Each the ovary and oviduct of laying hens may be invaded by S. Enteritidis, resulting in bacterial deposition in both edible egg fraction. The ample vitamins in egg yolk can help fast microbial development at heat temperatures, whereas albumen of contemporary eggs incorporates antimicrobial compounds that restrict iron availability and disrupt bacterial membranes. S. Enteritidis is usually deposited inside contaminated eggs within the albumen or on the vitelline (yolk) membrane. Eggs contaminated by S. Heidelberg, a standard serovar in laying housing environments, have been implicated in occasional studies of human illness within the US. In Australia, sporadic egg-associated sicknesses have been attributed to S. Typhimurium contamination of eggshells. Within the US, there have been Salmonella Enteritidis egg-associated outbreaks in 2010 and 2018, Salmonella Oranienburg in 2016, Salmonella Braenderup in 2018, and Listeria monocytogenes in hard-cooked eggs in 2019. Different salmonellae, together with S. Kentucky within the US, are prevalent in business laying flock housing environments however haven’t been proven to trigger egg contamination.
Pathogens apart from Salmonella are additionally necessary for eggs and the egg manufacturing surroundings. Campylobacter spp. and Listeria spp. have often been detected in environmental swabs from a wide range of hen housing methods. Extra research have decided the flora current on the shells of nest run eggs is numerous.
Spoilage organisms should even be thought-about when discussing the microbial high quality of eggs. Being a uncooked agricultural commodity, eggs are vulnerable to rotting, particularly if the eggs have been mishandled. Organisms which have been related to the rotting of eggs embody Pseudomonas, Acinetobacter, Proteus, Aeromonas, and Serratia. Fungi are additionally capable of develop on the shell floor and between the shell and shell membranes.
Egg dealing with and storage
All over the world, eggs are dealt with and saved in numerous manners. The managed washing of shell eggs for human consumption has been some extent of debate for over 50 years. Within the US, USDA Agricultural Advertising and marketing Service requirements for the voluntary grading of shell eggs function the idea for the washing of shell eggs. Below these requirements, eggs have to be spray washed in heat water (32 °C or 11 °C hotter than the warmest egg), uncovered to a sanitising rinse of 100-200 ppm chlorine or its equal, and be blown dry with excessive velocity, filtered air. Usually, caustic detergents are utilized within the wash water.
The washing of eggs has been a priority as a result of potential of disturbing the cuticle of the egg. The cuticle serves as the primary line of protection for the motion of water, air, and exterior microorganisms into and out of an intact egg. With the adjustments in flock administration, hen genetics, in addition to hen housing, trendy analysis has produced conflicting outcomes as to the impression of washing on cuticle integrity. Washing of shell eggs removes adhering matter, reminiscent of mud, feed, and fecal matter – all of which might harbour each pathogenic and spoilage microorganisms. Washing of shopper eggs enhances egg high quality.
Immediate refrigeration of eggs has been proven to be a key consider controlling the expansion of Salmonella Enteritidis, different Salmonella spp., and lots of different human pathogens. Because of this, within the US, shell eggs are required to be below refrigeration (7.2 °C) inside 36h of lay by means of distribution and retail. Refrigeration can also be key in retaining product bodily and purposeful high quality traits. In a comparability of widespread egg dealing with and storage practices utilised around the globe, it was decided that refrigeration had the best impression on retaining bodily egg high quality no matter washing standing.
Hen housing methods
Customers draw conclusions about housing methods partly primarily based on the standard of the eggs from housing methods obtainable in retail. In depth housing methods typically have increased manufacturing prices, leading to costlier eggs. A shopper has an expectation of enhanced high quality with the worth premium. A number of assessment articles have been printed on the impacts of hen housing on egg high quality. In lots of situations, research battle on the outcomes of egg high quality resulting from housing. Karcher et al. (2015) illustrate the complexity of evaluating hen manufacturing and egg high quality amongst housing methods and the components which might considerably affect outcomes.
Bodily and purposeful egg high quality affect market share and utilization, for each customers and meals producers. Many retailers, meals service, and meals producers within the US and around the globe have made pledges to transform to cage-free eggs, however little is called to the impacts of in depth housing methods on egg high quality – particularly egg performance.
Outcomes of egg high quality assessments carried out worldwide concerning hen housing have been inconsistent. Principal part evaluation of egg high quality and egg manufacturing when it comes to hen weight-reduction plan composition and environmental temperature throughout business typical cage, enriched colony cage, and cage-free aviary decided that many components affect numerous egg high quality parameters and the affect is usually depending on housing system. The efficient assortment of eggs from intensive methods impacts egg high quality. Immediate refrigeration has long-lasting constructive affect on all inside egg high quality components. Eggs laid exterior of the meant egg assortment space (mislaid eggs) might not be successfully collected and could possibly be older when packaged. A comparability of hen genetic strains in cage-free aviaries discovered strains produced eggs of various high quality and high quality declined at totally different charges throughout long-term chilly storage. Egg grade requirements are primarily based on typical cage eggs. Jones et al. (2014) decided that US federal egg grade requirements are equitable for business typical cage, enriched colony cage, and cage-free aviary produced eggs throughout long-term refrigerated storage.
Analysis has documented the adjustments in egg performance in the course of the prolonged chilly storage of eggs. As egg manufacturing shifts to cage-free and meals producers are making cage-free commitments, there’s restricted data on the impact of hen housing on egg performance. A single examine of retail eggs in Italy offered perception and retail egg research restrict the management of egg age and dealing with, which might impression egg high quality. A wide range of intensive methods have been developed together with enriched colony cages (offering decrease stocking densities for bigger hen teams plus environmental enhancements reminiscent of perches, nesting areas, and scratching pads), cage-free aviaries (permitting birds to maneuver freely amongst a number of open ranges of enriched cage and flooring areas inside homes), cage-free barn, and free-range housing (providing better alternatives for freedom of motion by way of various levels of entry to outside forage or pasture areas). The quite a few facility design options and administration practices related to every of those methods affect the environmental and flock persistence and transmission of pathogens reminiscent of Salmonella. A substantial physique of analysis has assessed the results of laying hen housing methods on necessary meals security parameters, however this work has generated no general consensus to counsel that anybody system is superior to others. Problem research have been carried out evaluating typical and enriched colony cages, however there was restricted skill to evaluate the impression of cage-free housing on an infection and transmissibility, in addition to egg contamination.
A excessive prevalence of Campylobacter spp. has been detected in each intensive and intensive hen housing methods. Jones et al. (2015, 2016) in contrast Campylobacter detection in typical cage, enriched colony cage, and multi-tier cage-free aviary housing and located scratch pads, system wires, and flooring substrate to be environmental reservoirs. Listeria monocytogenes is a vital foodborne pathogen, identified to proliferate in refrigerated situations. Listeria has been detected within the shell egg and egg merchandise processing surroundings however info as to on-farm incidence or impression of housing methods on Listeria prevalence is restricted. When hens have outside entry (reminiscent of natural or free vary), the environmental and egg flora are impacted. Mislaid eggs are outlined as these which can’t be successfully, effectively, or hygienically collected. These are sometimes called flooring eggs, however could not at all times happen on the ground of an in depth housing system. Analysis has discovered that mislaid eggs have a better probability of microbial contamination. Analysis has additionally discovered that cage-free methods, particularly cage-free aviaries, lead to excessive ranges of mud from hens foraging and dirt bathing within the substrate. The rise in mud impacts egg security and employee well being.
Conclusions
Sustaining and enhancing shell egg high quality requires a holistic strategy to egg manufacturing, dealing with, transportation, and distribution. A lot is understood about conserving egg high quality related to typical cage manufacturing methods. As world egg manufacturing shifts to a wide range of intensive housing methods for laying hens, in addition to adjustments in dietary formulations and laying hen genetic shares, controlling egg high quality may be difficult. It may be formidable to course of the knowledge or lack of understanding to make knowledgeable selections. Producers do not need to face these challenges alone. Attain out to the multitude of assets obtainable and in right now’s digital surroundings, it’s even simpler to obtain help from wherever on the planet.
References can be found on request
From the Proceedings of the APSS 2022
