Touch DNA Recovery from Edible Surfaces: Forensic Implications for Crime Scene Evidence Collection

Author: Hafiz M. Salleh1, Salem K. Alketbi2,3,4*
Affiliation: 1. 1. Department of Biological Sciences, National University of Singapore, Singapore.
2. The Biology and DNA Section, General Department of Forensic Science and Criminology, Dubai Police General Head Quarters, Dubai, United Arab Emirates.
3. International Center for Forensic Sciences, Dubai Police General Head Quarters, Dubai, United Arab Emirates.
4. School of Law and Policing, University of Lancashire, Preston.
Date: 13-01-2026    DOI: 10.64475/jfas.vol.2.issue1.1
Keywords: Forensic Genetics, Forensic science, DNA Profiling, STR profiling, Touch DNA, Trace DNA, Forensic Trace Analysis, Edible Evidence, DNA degradation
Touch DNA analysis has become an essential tool in forensic science, enabling the recovery of trace genetic material from handled objects. However, the viability of edible items such as fruits as substrates for Touch DNA recovery remains underexplored, despite their frequent presence at crime scenes. This study investigates the recovery and persistence of Touch DNA from six commonly encountered fruits—apples, grapes, strawberries, raspberries, oranges, and lemons—selected to represent a spectrum of surface textures and biochemical compositions. Three individuals with varying DNA shedding profiles handled each fruit type, and DNA was collected at five post-deposition time intervals (0 hours to 7 days). DNA was extracted and quantified using standard forensic protocols, followed by STR profiling. Statistical analysis (ANOVA) was used to assess the effects of fruit type, surface texture, and time on DNA yield and profile completeness. Smooth-surfaced fruits (apples and grapes) yielded the highest DNA concentrations and retained the most alleles over time, with apples maintaining near-complete profiles after 7 days. In contrast, rough or porous fruits (strawberries and raspberries) exhibited significantly lower recovery rates and substantial allelic dropout. Moisture-rich, acidic fruits (oranges and lemons) showed moderate DNA persistence, with degradation accelerating after 3 days. Statistically significant differences were observed in both DNA concentration (p = 0.024) and allele counts (p = 1.09 × 10⁻⁵) across fruit types. Surface morphology, internal composition, and time since deposition critically influence Touch DNA recovery from fruits. These findings highlight the potential forensic value of edible evidence and support its inclusion in trace DNA protocols. As fruits and other food items are frequently encountered at crime scenes, expanding forensic attention to such substrates may enhance investigative outcomes. Further research under variable environmental conditions is recommended to validate these findings in practical casework settings.
Touch DNA Recovery from Edible Surfaces: Forensic Implications for Crime Scene Evidence Collection