The research team, led by Ayşe Gül Filik and corresponding author Gökhan Filik of the university’s Agricultural Biotechnology Department, together with Olgay Kaan Tekin, set out to answer a question that has become increasingly urgent in modern animal science: can native plant resources rich in bioactive compounds serve as effective, natural alternatives to synthetic feed additives? Consumer pressure for so-called clean label animal products, combined with rising feed costs and concerns over chemical residues, has pushed researchers worldwide to screen local flora for phytogenic additives — plant-derived compounds that might improve animal health and product quality without pharmaceutical inputs. Viburnum opulus, which grows wild across Europe, North Africa, northern Asia, and particularly in the Turkish provinces of Kayseri, Sivas, Tokat, Kırşehir, and Ankara, presented an attractive candidate because of its unusually dense phytochemical profile.

That profile is what makes the fruit scientifically compelling. Analyses of Viburnum opulus berries have revealed high concentrations of polyphenols, flavonoids, tannins, carotenoids, and vitamin C. The dominant phenolic compound is chlorogenic acid, which can account for between 54 and 96 percent of the fruit’s total phenolic content and is regarded as a powerful antioxidant and antimicrobial agent. The fruit is also rich in organic acids, particularly malic and quinic acids, and contains notable concentrations of free amino acids such as aspartic and glutamic acid. Previous laboratory and pharmacological studies have linked Viburnum opulus extracts to lipid metabolism regulation, reductions in free fatty acids, cholesterol homeostasis effects, and even anticancer and antidiabetic activity, but almost none of this work had examined the plant as a direct dietary supplement in poultry. The Turkish team’s experiment was designed to fill that gap with a dose-response approach.

The trial involved 176 laying Japanese quails aged 30 weeks, a species favored in poultry nutrition research for its short generation interval and high egg production capacity. The birds — 132 females and 44 males — were randomly allocated into four dietary treatment groups, each with 11 replicate cages containing three females and one male. The cage, not the individual bird, served as the experimental unit for all performance and production measurements, a design choice that guards against pseudo-replication in statistical analysis. The control group received a standard basal diet formulated to meet quail nutritional requirements with 177 grams per kilogram of crude protein and 2800 kilocalories per kilogram of metabolizable energy. The three treatment groups received the same basal diet supplemented with Viburnum opulus fruit powder, abbreviated VOFP, at inclusion levels of 5, 10, and 15 grams per kilogram of feed. The fruit itself was harvested at full maturity from the university’s research fields, air-dried for a week, finished in a ventilated oven at 65 degrees Celsius for 48 hours, and ground through a one-millimeter sieve in an ultra-centrifuge mill to ensure homogeneous mixing. The feeding experiment ran for eight weeks under a 16:8 light-dark photoperiod with feed and water available ad libitum.

Over the 56-day trial, the researchers tracked body weight, body weight gain, feed intake, and feed conversion ratio weekly, collected eggs twice daily, and subjected eggs gathered on the third day of each week to a battery of quality analyses. External parameters included egg weight, dimensions measured with digital calipers, shape index, shell thickness at three points along the shell, and breaking resistance determined with a texture analyzer. Internal quality was assessed through albumen and yolk heights, albumen and yolk indices, and the Haugh unit, the internationally recognized standard for egg interior quality. Yolk color was quantified spectrophotometrically using CIELAB parameters. Critically, the team also monitored cholesterol metabolism by analyzing yolk cholesterol concentrations at the start of the trial and during weeks two, four, six, and eight, using a spectrophotometric extraction method adapted from earlier phytogenic additive research. Data were analyzed with general linear models, and orthogonal polynomial contrasts were applied to detect dose-response relationships across the supplementation levels.

The headline finding on performance was reassuring: dietary VOFP supplementation produced no statistically significant adverse effects on body weight, body weight gain, or feed conversion ratio, indicating that the birds tolerated even the highest inclusion level well. There were, however, subtle shifts in feeding behavior. Total feed intake was highest in the 5 gram per kilogram group at 7888.0 grams, while the 15 gram per kilogram group consumed the least at 7115.6 grams, a statistically significant difference. The authors suggest this reduction at the highest dose may reflect the fruit’s acidic profile — its abundant malic and quinic acids may slightly inhibit palatability — though the free amino acids in the fruit could simultaneously support protein metabolism. Egg production itself was statistically unchanged across groups, but the 5 gram per kilogram group achieved the highest total egg weight at 1828.60 grams and produced notably more afternoon-laid eggs than the control and highest-dose groups.

The most striking results emerged in egg internal quality. Supplementation at 5 grams per kilogram significantly increased egg yolk height, which reached 13.55 millimeters, and elevated the yolk index compared with controls, both indicators of a richer, more standing yolk. Albumen weight and albumen index were also highest at this dose. Among yolk color parameters, the b* value, which reflects yellowness, peaked at 19.74 in the 10 gram per kilogram group — an attribute with real market value, since consumers associate deeper yolk color with superior eggs. Shell characteristics told a more nuanced story: shell weight decreased with supplementation, reaching its lowest value of 1.22 grams in the 5 gram per kilogram group, yet shell thickness and breaking resistance were unaffected, suggesting that mineral metabolism and structural integrity were preserved even as shell mass shifted. The Haugh unit remained statistically unchanged across all treatments.

The cholesterol results are the most tantalizing and the most cautiously framed. Across the trial, average yolk cholesterol concentrations declined numerically in all supplemented groups, but statistical significance appeared only once: in the sixth week, when cholesterol in the 15 gram per kilogram group fell to 41.04 milligrams per gram of yolk, down from 52.31 milligrams per gram in the control group. The authors interpret this as a potential time-dependent effect of the fruit powder on cholesterol metabolism, plausibly connected to the phenolic compounds that earlier cell studies have linked to lipid accumulation and fatty acid metabolism pathways. Yet they are careful to note that the specific phytochemical composition of the powder used in this trial was not characterized, so the mechanism remains hypothetical rather than confirmed. The transient nature of the effect — significant in week six but not sustained across the full eight weeks — underscores how much remains unknown about how plant bioactives interact with avian physiology over time.

What the study ultimately delivers is preliminary but valuable evidence that Viburnum opulus fruit powder is a viable, well-tolerated phytogenic feed additive for laying quails, with the low dose improving selected internal egg quality traits and the high dose showing a potential, if inconsistent, cholesterol-modulating effect. The researchers call for follow-up work incorporating phytochemical characterization, hepatic cholesterol metabolism markers, antioxidant status measurements, and gut microbiota analyses to pin down the mechanisms at play. They also point to food science findings showing that encapsulation can stabilize the fruit’s bioactive compounds, hinting at strategies to enhance and prolong its effects in feed. For a fruit long celebrated in Anatolian folk tradition and now attracting attention in pharmacology laboratories worldwide, the journey from village juice press to scientific feed supplement is still at its beginning — but these quail eggs offer an early, measurable sign that the berry’s bioactive promise may extend from human health into the food chain itself.

Subject of Research: Effects of dietary Viburnum opulus fruit powder supplementation on performance, egg quality, and yolk cholesterol in laying Japanese quails

Article Title: The effects of Viburnum opulus L. fruit powder on the performance, egg traits, and egg cholesterol of laying Japanese quails

Article References: Filik, A. G., Filik, G., & Tekin, O. K. (2026). The effects of Viburnum opulus L. fruit powder on the performance, egg traits, and egg cholesterol of laying Japanese quails. Archives Animal Breeding, 69(3), 507-515. https://doi.org/10.5194/aab-69-507-2026

Image Credits: AI Generated

DOI: 10.5194/aab-69-507-2026

Keywords: Viburnum opulus, Japanese quail, phytogenic feed additive, egg quality, egg yolk cholesterol, poultry nutrition, chlorogenic acid, clean label, feed conversion ratio, Haugh unit, Anatolia, animal science

Researchers at the University of Jiroft in Kerman Province, Iran, set out to test whether aloe vera gel, used as an edible coating and enriched with fennel or lime peel essential oils, could extend the shelf life and microbial safety of table eggs stored under refrigeration. The team, led by Zahra Ranjbarinasab and Fatemeh Shahdadi, noted that although aloe vera gel and various essential oils have each been explored for egg preservation before, no previous study had investigated this particular combination for maintaining both the physicochemical quality and microbial stability of refrigerated eggs. Their findings point toward a natural, additive-free approach that could reduce food waste and economic losses in one of the world’s most consumed animal products.

The experimental design was straightforward but rigorous. The researchers obtained 300 fresh white-shelled chicken eggs from a local retail center, with an average weight of 62.39 grams, and excluded any showing cracks, shell defects, or surface contamination. The eggs were randomly divided into six groups: an uncoated control, eggs coated in pure 100 percent aloe vera gel, and four groups coated with aloe vera gel containing either 500 or 1000 parts per million of fennel essential oil or the same concentrations of lime peel essential oil. The essential oils were extracted by steam distillation using a Clevenger-type apparatus for three hours, following European Pharmacopeia guidelines, from dried Mexican lime peel and ground fennel seed. Each egg was dipped in its assigned coating for one minute, dried, dipped again, and dried once more before all samples were stored at 5 degrees Celsius for 30 days, with quality assessments performed on days 1, 15, and 30.

The choice of coating ingredients was far from arbitrary. Aloe vera gel is a transparent, viscous substance rich in carbohydrates, proteins, fibers, soluble sugars, vitamins, minerals, amino acids, organic acids, and phenolic compounds, and it has established antioxidant and antimicrobial credentials in food applications. Fennel essential oil, dominated by trans-anethole at roughly 65 to 78 percent of its composition, has demonstrated bacteriostatic effects against Escherichia coli, Bacillus subtilis, and Staphylococcus aureus. Lime peel essential oil is an even more complex mixture of more than 100 compounds, including limonene, citral, and linalool, and is prized for its potent antioxidant and antibacterial properties. By embedding these oils within the aloe vera matrix, the researchers aimed to create a coating that was simultaneously a physical barrier and an active antimicrobial delivery system.

The results on weight loss were striking. After 30 days of refrigerated storage, uncoated control eggs had lost 4.81 percent of their initial weight, while every coated group lost only about 3.35 percent, a roughly 30 percent reduction. The researchers attribute this to the formation of a semipermeable barrier on the shell surface that limits the diffusion of water vapor and carbon dioxide through the shell’s pores. Interestingly, adding essential oils provided no additional weight-loss benefit beyond the aloe vera gel alone, suggesting that the moisture barrier was supplied entirely by the gel matrix and that the oils’ contribution lay elsewhere, primarily in antimicrobial activity.

Internal quality told a similar story. The Haugh unit, the standard industry measure of albumen quality based on the height of the thick egg white, declined in all groups over the month, but coated eggs fared markedly better. Uncoated eggs fell from a Haugh unit of 76.21 on day one to just 54.17 by day 30, while eggs coated with aloe vera gel containing 1000 ppm of fennel essential oil retained a value of 65.74, and those with 1000 ppm lime peel oil reached 65.40. The mechanism is rooted in egg chemistry: as carbon dioxide escapes through the shell during storage, the albumen becomes more alkaline, protein structures break down, and the thick white thins into a watery state. By slowing carbon dioxide loss, the coatings delayed this alkalization and preserved the ovomucin network responsible for albumen viscosity.

The pH measurements reinforced this picture. Fresh albumen contains about 0.5 percent dissolved carbon dioxide, and its loss during storage can push albumen pH from around 7.2 toward 8.5 or higher. In this study, uncoated eggs climbed to an albumen pH of 8.26 after 30 days, whereas eggs coated with aloe vera gel plus 1000 ppm fennel oil reached only 7.60, and those with 1000 ppm lime peel oil reached 7.64. Yolk pH followed the same pattern, rising to 6.91 in controls but only to 6.54 and 6.57 in the highest-concentration fennel and lime peel treatments, respectively. Because yolk and albumen pH are both recognized freshness indicators, these numbers translate directly into longer commercial shelf life.

Functional properties also benefited. Albumen foaming capacity, which matters for baking and culinary performance, declined with storage in all groups, but coated eggs retained significantly more foaming ability than controls, with coated samples reaching about 7.5 milliliters of foam per gram of albumen at day 30 compared with 6.28 for uncoated eggs. The researchers explain that ovomucin stabilizes foam by forming insoluble films around air bubbles, and that coatings preserve this functionality by limiting the water and carbon dioxide losses that drive pH-driven protein degradation. Shell thickness, by contrast, was unaffected by either coating or storage time, indicating that the coatings act as surface barriers rather than altering the mineralized structure of the shell itself.

Perhaps the most compelling results came from the microbiological analysis. Total microbial counts rose in all groups over the storage period, but coated eggs consistently carried lower loads than controls. By day 30, uncoated eggs had reached 5.40 log CFU per gram, while eggs coated with aloe vera gel alone reached 4.67. The essential oil treatments pushed the counts down further still: 4.16 log CFU per gram for 1000 ppm fennel oil and 4.17 for 1000 ppm lime peel oil. The authors attribute this to a dual mechanism, in which the coating acts as a physical barrier against microbial penetration while simultaneously serving as a carrier for natural antimicrobial compounds. Aloe vera’s activity stems from anthraquinones, saponins, phenolics, and organic acids, while limonene and gamma-terpinene in lime oil disrupt bacterial cell membranes, and trans-anethole, fenchone, and methyl chavicol in fennel oil inhibit a wide range of pathogens and even biofilm formation.

The study does have limitations that the authors themselves acknowledge. Only two concentrations of each essential oil were tested, storage was confined to a single refrigerated condition for 30 days, and sensory properties and consumer acceptance of the coated eggs were not evaluated. Industrial scalability, long-term performance, and economic feasibility remain open questions. Nevertheless, the overall conclusion is clear: aloe vera gel enriched with 1000 ppm of either fennel or lime peel essential oil represents a promising natural coating for extending egg shelf life and maintaining quality during refrigerated storage. As food scientists worldwide search for alternatives to synthetic preservatives, this simple dip-and-dry treatment, built from ingredients with long histories of safe human use, offers an elegant demonstration that sometimes the best packaging material may already be growing in a garden.

Subject of Research: Edible aloe vera gel coatings enriched with fennel and lime peel essential oils for extending the shelf life and microbial safety of refrigerated eggs

Article Title: Enhancing the Shelf Life and Microbial Safety of Refrigerated Eggs Using Edible Coatings of Aloe Vera Gel Combined With Fennel and Lime Peel Essential Oils

Article References: Ranjbarinasab, Z., Shahdadi, F., Yousefi, M., Seyedimarghaki, Z., & Omidi, S. (2026). Enhancing the Shelf Life and Microbial Safety of Refrigerated Eggs Using Edible Coatings of Aloe Vera Gel Combined With Fennel and Lime Peel Essential Oils. Food Science & Nutrition, 14(10), Article e72389. https://doi.org/10.1002/fsn3.72389

Image Credits: AI Generated

DOI: 10.1002/fsn3.72389

Keywords: edible coatings, aloe vera gel, essential oils, fennel, lime peel, egg preservation, shelf life, microbial safety, Haugh unit, food science, natural preservatives, refrigerated storage