Egg high quality is multi-faceted, with bodily, practical, and microbial features contributing to egg high quality. Analysis has proven that many components influence egg high quality together with flock age and administration, genetics, hen weight loss program, housing design and administration, in addition to egg dealing with and storage. As laying egg manufacturing all over the world shifts to extra intensive housing techniques, the influence of those housing techniques on egg high quality is unclear. Moreover, the dealing with and storage of eggs have been proven to significantly have an effect on egg high quality. Understanding the components influencing egg high quality permits for greater high quality eggs reaching customers.
D.R. Jones and R.Ok. 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 position in diets all over the world. Sustaining the standard of eggs is a worldwide concern. Typically, there are three forms of egg high quality: 1) bodily, 2) practical, and three) microbial. Throughout this presentation, all three forms of egg high quality might be mentioned and components which affect egg high quality traits might be defined. Understanding the forms of egg high quality, in addition to components impacting them, is integral to the last word objective of secure, 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 deciding on eggs for buy. Inside bodily egg high quality components embody albumen peak and readability, in addition to yolk color, form, dimension, and construction.
Practical 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 practical properties in meals. Frequent practical 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 influence the shelf-life of eggs.
Bodily egg high quality
The form, texture, colour, and soundness of the shell are the primary egg high quality components customers encounter. Shell high quality gives aesthetics to the egg. It additionally serves as the primary line of protection for microorganisms coming into the eggs through horizontal transmission. A cracked egg is just not solely a possible lack of income because of lack of sale or retailer return, it’s also a meals security threat since organisms can simply transfer via 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 of a loss egg. The soundness of the egg additionally impacts the flexibility 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 all over the world 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 dimension 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 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.
Practical egg high quality
Eggs are extremely practical components 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. Practical traits may be supplied by albumen, yolk, and complete egg. Whereas there are numerous 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 notably appropriate for unfolding and interacting throughout whipping to entrap air, forming foams. Throughout heating, the air and any moisture current will broaden and supply leavening and lightness to the meals product.
Entire egg, yolk, and albumen all help with coagulation. Coagulation, usually because of warmth publicity, is the binding or setting of meals parts. Coagulation is liable for the feel created in the course of the scrambling of eggs. Moreover, coagulation permits for components particles in quiches to be suspended with the dish. Coagulation can be liable for the thickening achieved throughout heating of egg-containing puddings or sauces. Coagulation additionally accounts for the warmth setting of foams corresponding to meringues and sponge muffins.
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 steady emulsion. Eggs play a key position within the emulsification of mayonnaise and salad dressings, in addition to ice cream bases, Hollandaise, and bearnaise, to call a couple of functions. Eggs additionally help with browning and color formation throughout cooking, adhering meals coatings, and enhancing mouth- really feel. The practical 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 grow to be contaminated through vertical transmission, in addition to horizontal contamination. Salmonella Enteritidis is deposited contained in the edible inside of eggs because of 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 plentiful vitamins in egg yolk can help speedy microbial development at heat temperatures, whereas albumen of recent eggs accommodates 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 typical serovar in laying housing environments, have been implicated in occasional experiences 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 industrial 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 steadily been detected in environmental swabs from a wide range of hen housing techniques. Extra research have decided the flora current on the shells of nest run eggs is numerous.
Spoilage organisms should even be thought of 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 in a position to 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 Service requirements for the voluntary grading of shell eggs function the premise for the washing of shell eggs. Beneath these requirements, eggs should 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. Typically, 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 modifications in flock administration, hen genetics, in addition to hen housing, trendy analysis has produced conflicting outcomes as to the influence of washing on cuticle integrity. Washing of shell eggs removes adhering matter, corresponding to 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 think about controlling the expansion of Salmonella Enteritidis, different Salmonella spp., and lots of different human pathogens. For that reason, within the US, shell eggs are required to be underneath refrigeration (7.2 °C) inside 36h of lay via distribution and retail. Refrigeration can be key in retaining product bodily and practical high quality traits. In a comparability of frequent egg dealing with and storage practices utilised all over the world, it was decided that refrigeration had the best influence on retaining bodily egg high quality no matter washing standing.
Hen housing techniques
Customers draw conclusions about housing techniques partly primarily based on the standard of the eggs from housing techniques accessible in retail. In depth housing techniques usually have greater manufacturing prices, leading to costlier eggs. A shopper has an expectation of enhanced high quality with the value premium. A number of evaluation articles have been printed on the impacts of hen housing on egg high quality. In lots of cases, research battle on the outcomes of egg high quality because of housing. Karcher et al. (2015) illustrate the complexity of evaluating hen manufacturing and egg high quality amongst housing techniques and the components which might considerably affect outcomes.
Bodily and practical 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 all over the world have made pledges to transform to cage-free eggs, however little is named to the impacts of in depth housing techniques on egg high quality – specifically 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 loss program composition and environmental temperature throughout industrial standard cage, enriched colony cage, and cage-free aviary decided that many components affect varied egg high quality parameters and the affect is usually depending on housing system. The efficient assortment of eggs from intensive techniques impacts egg high quality. Immediate refrigeration has long-lasting constructive affect on all inside egg high quality components. Eggs laid outdoors of the supposed 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 completely different charges throughout long-term chilly storage. Egg grade requirements are primarily based on standard cage eggs. Jones et al. (2014) decided that US federal egg grade requirements are equitable for industrial standard cage, enriched colony cage, and cage-free aviary produced eggs throughout long-term refrigerated storage.
Analysis has documented the modifications 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 may be restricted information on the impact of hen housing on egg performance. A single research of retail eggs in Italy supplied perception and retail egg research restrict the management of egg age and dealing with, which might influence egg high quality. A wide range of intensive techniques have been developed together with enriched colony cages (offering decrease stocking densities for bigger hen teams plus environmental enhancements corresponding to 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 larger alternatives for freedom of motion through 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 techniques affect the environmental and flock persistence and transmission of pathogens corresponding to Salmonella. A substantial physique of analysis has assessed the consequences of laying hen housing techniques on necessary meals security parameters, however this work has generated no general consensus to recommend that anybody system is superior to others. Problem research have been carried out evaluating standard and enriched colony cages, however there was restricted potential to evaluate the influence 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 techniques. Jones et al. (2015, 2016) in contrast Campylobacter detection in standard 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 influence of housing techniques on Listeria prevalence is restricted. When hens have outside entry (corresponding to 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 also known as flooring eggs, however could not at all times happen on the ground of an intensive housing system. Analysis has discovered that mislaid eggs have a better probability of microbial contamination. Analysis has additionally discovered that cage-free techniques, specifically 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 standard cage manufacturing techniques. As world egg manufacturing shifts to a wide range of intensive housing techniques for laying hens, in addition to modifications in dietary formulations and laying hen genetic shares, controlling egg high quality may be difficult. It may be formidable to course of the data or lack of awareness to make knowledgeable choices. Producers shouldn’t have to face these challenges alone. Attain out to the multitude of assets accessible and in at this time’s digital surroundings, it’s even simpler to obtain help from anyplace on this planet.
References can be found on request
From the Proceedings of the APSS 2022
