One of the most persistent debates in the food industry revolves around the color of eggshells and their relationship to nutritional value. Scientific evidence and the experience of culinary experts agree that external coloration is a purely genetic phenomenon that does not alter the egg’s internal chemical composition. Pigmentation is the result of a complex biological process that occurs during the final stages of egg formation inside the hen’s oviduct, specifically in the shell gland or uterus.

Different breeds of hens have specific genetic codes that dictate pigment synthesis. Brown eggs, which are often mistakenly perceived as more “natural” or “healthy,” owe their color to protoporphyrin IX. This pigment is derived from hemoglobin blood and is deposited by cells of the calcareous gland onto the surface of the calcium carbonate shell just before laying. A key technical detail is that protoporphyrin is deposited only in the outer cuticular layer; for this reason, when a brown egg is cracked open, the inside of the shell is seen to be white.

In contrast, there are less conventional but equally fascinating shades. Breeds such as the Araucana and the Ameraucana possess a dominant gene that enables the production of oocyanin, a pigment derived from bile (biliverdin) that becomes incorporated into all layers of the shell during the calcification process. This results in blue or turquoise eggs that keep their coloration even on the inner surface of the shell. When a hen has genes for both blue and brown production, the result is an olive-green egg, where the brown outer layer covers the blue base.

The intensity of the brown color can vary significantly throughout a hen’s life cycle. As the bird ages, eggs tend to increase in size; however, the amount of pigment the gland can produce stays constant. As a result, the same volume of pigment must cover a larger surface area, resulting in lighter-colored shells in older hens. This factor, combined with environmental stress that can release adrenaline and disrupt cuticle formation, proves that shell appearance is a volatile biological variable and not an indicator of nutritional quality.

Poultry nutrition and egg yolk as a dietary indicator

Unlike the shell, the color of the yolk provides a direct sign of the hen’s diet. The pigmentation of the yolk results from the transfer of carotenoids from the bird’s diet to the ovarian follicle. Carotenoids are natural fat-soluble pigments found in various plant ingredients and microorganisms. Since birds cannot synthesize these compounds endogenously, their presence in the yolk depends exclusively on dietary intake.

A diet rich in xanthophylls, such as those found in yellow corn, alfalfa, marigold extract, or achiote, produces yolks with hues ranging from deep yellow to vibrant orange. The use of natural supplements such as paprika or turmeric not only intensifies the color—which is highly valued by consumers due to its visual association with freshness and flavor—but also provides antioxidants that improve the egg’s oxidative stability. In production systems where wheat or barley predominate as the energy source, the yolk tends to be pale unless specific colorants are used.

Technical analysis of the egg yolk reveals a correlation between the rearing system and the lipid profile. Hens with access to pasture consume insects and fresh vegetation that diversify the spectrum of ingested carotenoids, which often results in yolks with higher viscosity and a higher yolk index. Nutrition also influences albumen quality; adequate levels of crude protein and essential amino acids such as methionine are crucial for keeping the height of the dense albumen, measured in Haugh Units, which is the gold standard for deciding the internal quality of the egg.

The Imperative of Freshness: Physicochemical Processes

Jordi Cruz argues that freshness is the supreme attribute that should take precedence over any aesthetic factor. A freshly laid egg is a biological system in dynamic equilibrium. However, from the moment it is laid, natural degradation processes begin. The egg has thousands of microscopic pores in its shell that allow for gas exchange. Over time, carbon dioxide ($CO_2$) diffuses outward, causing the internal pH of the albumen to rise from neutral to basic levels (close to 9.2).

This chemical change weakens the ovomucin fibers, the protein responsible for the viscous structure of the egg white. As a result, the white becomes waterier and loses its ability to hold the yolk in place. At the same time, the evaporation of water through the pores creates a vacuum that is filled with air at the blunt end of the egg, increasing the size of the air cell. The “water trick” described by Cruz is a direct application of Archimedes’ principle: a fresh egg, with a small, high-density air chamber, will sink; an old egg, whose air chamber has grown significantly, will float.

To mitigate these processes, controlling temperature and humidity during storage is vital. It is recommended to keep a relative humidity of between 50% and 65% to prevent excessive dehydration. It is at this point that packaging ceases to be merely a container and becomes a tool for preservation engineering.

Packaging Engineering at Molpack Corporation: Molded Pulp

Molpack Corporation has solidified its leadership in the packaging market by specializing in molded pulp, a material that offers unique competitive advantages for the poultry industry. Molded pulp is manufactured from a mixture of water and recycled plant fibers, primarily paper and cardboard. Through the process of vacuum molding and oven drying, rigid yet flexible structures are created with exceptional impact absorption capabilities.

Physical and mechanical properties of the packaging

Molpack’s cases and trays are designed to protect the structural integrity of the eggshell, which is vulnerable to microcracks during transport. The material’s sturdiness allows for safe stacking throughout the supply chain, improving planning space without compromising product safety.

A critical technical factor is breathability. Unlike plastic or expanded polystyrene (Styrofoam), molded pulp is a porous material that allows for controlled natural ventilation. This helps the gas exchange necessary to prevent the buildup of condensed moisture on the shell, which could allow bacteria to enter through the pores.

Molpack’s versatility is reflected in its extensive product portfolio, which ranges from windowed cartons for shelf display to high-capacity industrial trays. Models such as the 2×6 carton or the 30-unit trays are designed to accommodate egg sizes ranging from 45g to 73g, ensuring that each egg is optimally suspended and protected.

The Biopack label: At the forefront of safety and sustainability

Innovation at Molpack has led to the creation of the Biopack seal, a certification that distinguishes the most advanced products in terms of quality, food safety, and sustainability. The Biopack label guarantees that the packaging has been specifically manufactured for food contact, adhering to strict processes that ensure surfaces are resistant to grease and moisture.

This advancement is particularly significant in the poultry and food service sectors, where exposure to fluctuating humidity levels can compromise the structural integrity of traditional paper packaging. Biopack products keep their structural integrity in demanding environments, offering an eco-friendly alternative to plastic that does not compromise functionality. Furthermore, Molpack’s commitment to health is reflected in its use of materials free of harmful chemicals such as PFAS, in line with the strictest international regulations.

The sustainability of Biopack products is reinforced by Forest Stewardship Council (FSC®) certification. This certification guarantees that the plant fibers used come from responsibly managed forests, promoting biodiversity conservation and respect for local communities. By integrating the Biopack label into their value chain, poultry producers not only protect their eggs but also communicate a tangible ethical commitment to consumers who prioritize environmental responsibility in their purchasing decisions.

Sustainability and the circular economy: Molpack’s management model

Sustainability is not a peripheral concept for Molpack Corporation; it is at the core of its operational identity. The company runs under a circular economy model in which paper and cardboard waste is transformed into high-value-added products. Each year, Molpack processes more than 97,000 tons of recycled raw materials, resulting in the production of approximately 92,000 tons of eco-friendly packaging.

This environmental impact is complemented by a strategy focused on the efficient use of critical resources such as water and energy. The company implements advanced technologies to improve energy efficiency at its seven manufacturing plants across the Americas. In addition, Molpack’s products are more than 95% eco-friendly, as they are biodegradable, recyclable, and compostable.

The vision of “Building a clean planet, one package at a time” extends to the social pillar, where Molpack promotes the well-being of its more than 1,000 direct employees through professional development and comprehensive health programs. This ethical consistency strengthens the brand and positions it as a strategic partner for companies looking to meet their own corporate social responsibility goals.

The Role of Packaging in Communicating with Consumers

At the point of sale, packaging is the primary means of communication between the producer and the consumer. Current trends show that shoppers value transparency and ease of use. Molpack meets these demands by offering advanced customization options that allow brands to highlight their unique selling points, such as the origin of the eggs (cage-free, organic) or guaranteed freshness.

The visual design, which allows for up to four colors on the top and two on the sides, is combined with functional elements such as windowed lids, which meet consumers’ need to inspect the product before purchase without compromising hygiene. This combination of aesthetics and functionality is essential in a competitive market where packaging must grab attention in a matter of seconds.

Conclusions: A synergy between gastronomy, science, and packaging

Egg quality is a multifaceted attribute that begins with the hen’s genetics and culminates in the consumer’s experience at the table. Jordi Cruz’s insights underscore the importance of stripping the product of superficial myths to focus on what really matters: freshness and nutrition. This freshness, however, is fragile and depends on a technical support ecosystem that Molpack Corporation provides expertly.

It is concluded that the use of molded pulp is the superior choice for egg packaging due to its unmatched ability to balance mechanical protection with thermal and gas regulation. The transition to biocompostable materials and the Biopack label is not only a response to the climate crisis but also a smart business strategy that aligns poultry producers with 21st-century values. The integration of the circular economy, forest certification, and manufacturing excellence positions Molpack not only as a supplier of boxes, but as a guardian of food integrity and a driver of change toward a greener and more responsible future. Ultimately, protecting an egg is protecting a vital nutritional resource, and doing so with environmental awareness is an ethical imperative that defines success in the modern poultry industry.

SOURCES:

Diario La Vanguardia (Barcelona, España)

Departamento de Bioseguridad de Molpack Corporation

Avinews (www.avinews.com)