# Citrus-peel films tested for quality protection in frozen chicken burgers

> A 147-day study compares grapefruit, orange and lemon extracts, with the strongest chemical preservation results at the highest tested concentration.

URL: https://foodradar.org/citrus-peel-gelatin-film-frozen-chicken-burgers
Language: en
Author: FoodRadar Editorial
Published: 2026-10-07T11:06:18.836Z
Updated: 2026-10-07T11:06:18.836Z
Source publication date: 2026-09-28
Category: Packaging
Türkçe: https://foodradar.org/tr/citrus-peel-gelatin-film-frozen-chicken-burgers

## A frozen-storage trial using citrus by-products

Citrus peel extracts may give gelatin packaging an additional role in limiting quality deterioration during frozen storage. A study published in September tested grapefruit, orange and lemon peel extracts in films wrapped around chicken burgers. The 4% grapefruit formulation produced the strongest overall preservation results among the treatments, particularly on measurements associated with oxidation and protein deterioration.

The experiment followed the burgers for 147 days at −18 °C. That setting is central to the finding: this was a frozen-product trial, not evidence that the same films can safely keep fresh chicken at room temperature or extend a chilled product’s use-by date. It also compared specified laboratory formulations rather than commercially manufactured packaging systems.

## Eleven groups separated the effects of film and extract

The researchers obtained citrus fruit in Niğde, Türkiye, dried the peels and extracted them with 70% ethanol assisted by ultrasound. The ethanol was removed using a rotary evaporator. Grapefruit, orange and lemon extracts were then incorporated into gelatin films at 1%, 2% and 4%. Gelatin provided the film structure, with glycerol and sorbitol used in its preparation.

Eleven groups allowed comparison with both untreated burgers and burgers covered by gelatin without an extract. The remaining nine combined the three citrus types and three concentrations. Each 100-gram patty was placed between two films. Analyses at intervals during frozen storage followed pH, peroxide value, thiobarbituric-acid-related oxidation, total volatile basic nitrogen and several microbial counts.

## The highest concentration led the chemical comparison

At day 147, the 4% grapefruit treatment had a peroxide value of 4.50 milliequivalents of oxygen per kilogram and a thiobarbituric-acid value of 0.74 milligrams MDA per kilogram. Total volatile basic nitrogen was 11.20 milligrams of nitrogen per 100 grams, and pH was 6.77. The authors report these values as significantly lower than in the unwrapped control.

Grapefruit extract also led the separate extract-level antioxidant and phenolic measurements. The paper reports lower counts for several microbial groups in extract-treated burgers, but the response was not uniform: its detailed results found no significant treatment difference for lactic acid bacteria. The evidence should therefore not be compressed into a claim that the film eliminated microbes or improved every microbiological measure. Recoverable counts during frozen storage are also distinct from proving active growth at the storage temperature.

## What remains before a packaging application

The authors acknowledge that they measured antioxidant activity in the extracts, not directly in the completed composite films. They also did not measure the pH of the extracts or films. Release of active compounds, detailed chemical composition and performance under refrigerated conditions remain topics for further investigation, limiting how confidently a mechanism or a broader storage claim can be assigned.

Mechanical properties, manufacturing scale and consumer sensory acceptance still need assessment. The study identifies a candidate formulation and documents quality-related differences under prolonged freezing; it does not establish a validated commercial shelf-life extension in days. For frozen-food developers, its useful starting point is the controlled comparison of peel type and concentration, followed by testing in the actual product, packaging process and distribution conditions.

## Sources and rights

- [Citrus peel extract-enriched gelatin edible films as natural preservatives to enhance the shelf life and quality of chicken burgers.](https://europepmc.org/articles/PMC13619995?utm_source=foodradar.org&utm_medium=referral&utm_campaign=editorial&utm_content=citrus-peel-gelatin-film-frozen-chicken-burgers-en). Springer. Khalily F, Uçak İ, Sajid QUA, Asghar MU. Citrus peel extract-enriched gelatin edible films as natural preservatives to enhance the shelf life and quality of chicken burgers. Food science of animal resources. 2026. DOI: 10.1007/s44463-026-00110-8. © The Author(s) 2026 [CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/?utm_source=foodradar.org&utm_medium=referral&utm_campaign=editorial&utm_content=citrus-peel-gelatin-film-frozen-chicken-burgers-en-license).

Adapted by FoodRadar.

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