Food authenticity is a global issue and has caused growing concerns in recent decades. Immunochromatography-based methods are more favored over conventional sophisticated techniques for species identification and meat fraud detection. There is a growing need for an on-spot, minimally pre- processing detection tool for identifying donkey meat in beef within the routine meat inspection procedures by the food safety and quality inspectors during daily consumer meat purchases. The newly developed kit has a limit of detection as low as 10% donkey meat in beef meat and detects 1% (w/w%) of donkey meat with reduced visualization intensity, demonstrating the assay’s stability under different adulteration conditions. The kit was validated using 26 meat samples from different butcher shops in the Greater Cairo Area of Egypt, and compared with PCR analysis. Both methods confirmed that 4 samples (15.4%) were adulterated with donkey meat. The sensitivity of the developed lateral flow kit test reached 100%. This study introduces a powerful, rapid tool for detecting donkey meat adulteration in beef within 2 min, offering promising potential for real-world applications.

Over the past few decades, concerns over food authenticity have grown. Food fraud, defined as the intentional or inadvertent misrepresentation or adulteration of food products, can negatively affect customers’ health, leading to malnutrition, food allergies, poisoning, and even fatalities. In addition, food fraud damages public trust in governmental institutions and the food industry, costing the global food sector $10 to $15 billion annually. One of the most significant food fraud scandals occurred in Europe in 2013, involving the discovery of horse meat, sometimes present in beef products at levels of 60–100%. Donkey meat could also be used as an adulterant in similar situations. 

To slaughter horses or donkeys for food is not only illegal and culturally unacceptable in many English-speaking nations, but it is also forbidden to eat horse and donkey meats in Kosher and domestic donkey meats in Islamic traditions. Contrarily, donkey meat is considered a delicacy in a few nations such as Italy and China, and donkey skins are in high demand in the Asian market for making traditional Chinese supplements (such as Colla Corii Asini). As a result, manufacturers, retailers, and end users must verify the integrity and authenticity of these products. Some African countries need technical procedures to identify donkey components to restrict illegal exportation and the high occurrence of donkey-related meat adulteration due to
the exceptionally high demand described above. As a result, highly precise analytical techniques
are required to identify the donkey species in fresh meat and derived products.

In Egypt, meat adulteration is a critical issue, particularly regarding the substitution of low-cost or even banned meats, like donkey and dog, for higher-priced beef. Many producers adulterate minced beef meat with cheap meat. The growing cases of meat adulteration are mostly driven by the absence of effective analytical methods for identifying the meat species of raw, cooked, or processed meats. Products such as meatballs, kebabs, luncheon meats, and corned loaves – labeled as 100% beef – often contain undeclared species like chicken, rabbit, dog, cat, donkey, or pig. Adulterating premium-quality meat by inferior types is a common practice all over the world. Therefore, routine evaluation of meat species in minced meat is essential. 

Several techniques have been developed for food authentication, including spectroscopic, chromatographic, DNA-based, and immune-analytical methods. Each method has advantages and disadvantages depending on the specific analytical target (e.g., geographical origins and substitution) and food commodities (e.g., dairy, juice). Promising analytical techniques are typically based on the detection of distinct conservative protein/peptide biomarkers for species identification.

Lateral flow immunochromatographic assays have emerged as a promising rapid diagnostic tool in various fields. Lateral flow assays (LFAs) have been used for meat adulteration detection in the past 5 years. Several trials have been applied and evaluated in more than one meat adulteration detection model. However, previous LFA methods often require complex, time-consuming sample pre-processing, which complicates the simplicity of developing, production, and application that LFAs are known for. This study aimed to develop and validate a LFA for the rapid detection of donkey meat in beef, with the simplest and cost-effective development and application procedures.

The lateral flow immunochromatographic assay developed in this study offers a powerful tool for detecting donkey meat adulteration in beef. Due to its excellent specificity and satisfactory detection sensitivity in a variety of raw and cooked meats, it will be a very promising affordable,
accurate, and competitive technique, either to be used at the household level or to be adopted in government laboratories for routine examination in national abattoirs and regular inspection campaigns at local meat retails. Prospective investigations must focus on pinpointing and creating the best ultralow-cost materials with exceptional qualities for these kits. Finding low-cost, environmentally friendly, non-toxic, and biodegradable substances is crucial for the creation of inexpensive point-of-care (POC) devices. The future of this kind of development will be heavily reliant on the criteria that national and international regulatory agencies have established as benchmarks for quality clearance and standards for these POC kits.