# Post-Slaughter Age Classification and Sex Determination in Deboned Beef Using Lipofuscin Autofluorescence and Amelogenin Gene Analysis

## TL;DR

This study introduces reliable methods to determine the age and sex of deboned beef using natural pigments and genetic testing, improving meat labeling and consumer trust.

## Contribution

The study combines lipofuscin autofluorescence for age classification and amelogenin gene analysis for sex determination in processed beef.

## Key findings

- Lipofuscin autofluorescence reliably distinguished meat from young (1.5–2.2 years) and older (3–13 years) animals.
- Amelogenin gene analysis accurately identified the sex of beef samples, with 55.2% of older animals being female.
- The methods worked effectively on both fresh and market-obtained deboned beef samples.

## Abstract

Consumers often expect clear information about the quality of the meat they buy, including the age and sex of the animal it comes from. However, once meat is processed and sold without bones, it becomes difficult to tell whether it came from a young or old animal, or from a male or female. These factors affect meat tenderness, taste, and value. In this study, we tested two scientific methods that can help solve this problem. First, we looked at a natural pigment called lipofuscin, which builds up in animal muscles over time and glows under special light. By examining its pattern in muscle samples, we were able to group meat as coming from either young or older animals. Second, we used a simple genetic test to determine whether the meat came from a male or female. Both methods worked reliably, even on meat purchased from the market. This combined approach could help improve transparency in meat labeling, ensure fair pricing, and protect consumers from misleading information. It may also support regulations in countries where the age or sex of animals matters for religious, cultural, or economic reasons.

Beef meat quality and value are influenced by the breed, sex, and age of slaughtered animals. This study aimed to evaluate lipofuscin pigment autofluorescence as a method for age classification in beef meat samples and to determine the sex of market-obtained meat using PCR-based amelogenin gene amplification. Deboned beef meat samples from M. longissimus dorsi and M. biceps femoris were collected from 67 slaughtered cows with known age and sex. Additionally, 48 market samples were tested for sex identification and age classification using the same methods. Lipofuscin deposition was first observed at 1.5 years, and autofluorescence analysis effectively distinguished between meat from younger animals (1.5–2.2 years) and older ones (3–13 years), with a statistically significant difference (p < 0.001). Lipofuscin levels and excitation intensity increased with age, and no differences were found between the two muscles analyzed. The sex determination results were fully consistent with the records, and 55.2% of animals aged 3 years and older were identified as female. These findings demonstrate the reliability of lipofuscin autofluorescence for binary age determination in beef and support the potential of combining age and sex classification to identify meat derived from older dairy cows in the marketplace.