Standard methods for chemical food safety testing in official laboratories rely largely on liquid or gas chromatography coupled with mass spectrometry. Although these methods are considered the gold standard for quantitative confirmatory analysis, they require sampling, transferring the samples to a central laboratory to be tested by highly trained personnel, and the use of expensive equipment. Therefore, there is an increasing demand for portable and handheld devices to provide rapid, efficient, and on-site screening of food contaminants. Recent technological advancements in the field include smartphone-based, microfluidic chip-based, and paper-based devices integrated with electrochemical and optical biosensing platforms. Furthermore, the potential application of portable mass spectrometers in food testing might bring the confirmatory analysis from the laboratory to the field in the future. Although such systems open new promising possibilities for portable food testing, few of these devices are commercially available. To understand why barriers remain, portable food analyzers reported in the literature over the last ten years were reviewed. To this end, the analytical performance of these devices and the extent they match the World Health Organization benchmark for diagnostic tests, i.e., the Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free, and Deliverable to end-users (ASSURED) criteria, was evaluated critically. A five-star scoring system was used to assess their potential to be implemented as food safety testing systems. The main findings highlight the need for concentrated efforts towards combining the best features of different technologies, to bridge technological gaps and meet commercialization requirements.

Considering the complexities and speed of modern food chains, there is an increasing demand for point-of-need detection of food contaminants, particularly highly regulated chemicals and carcinogens such as aflatoxin B1. We report a user-friendly smartphone-based magneto-immunosensor on carbon black modified electrodes for point-of-need detection of aflatoxin B1 in cereals. For buffered analyte solutions and a corn extract sample, the assay demonstrated a low limit of detection of 13 and 24 pg/mL, respectively. The assay was also highly reproducible, exhibiting mean relative standard deviations of 3.7% and 4.0% for the buffered analyte and corn extract samples. The applicability of the assay was validated on the basis of EU guidelines and the detection capability was lower than or equal to 2 μg/kg, which is the EU maximum residue limit for aflatoxin B1 in cereals. False-positive and false-negative rates were less than 5%. Additionally, an open-source android application, AflaESense, was designed to provide a simple interface that displays the result in a traffic-light-type format, thus minimizing user training and time for data analysis. AflaESense was used for smartphone-based screening of spiked corn samples containing aflatoxin B1 (0.1, 2, and 10 ng/mL), and naturally contaminated corn containing 0.15 ng aflatoxin B1/mL. The measured values were in close agreement with spiked concentrations (r² = 0.99), with recovery values ranging between 80 and 120%. Finally, contaminated samples correctly triggered a red alert while the non-contaminated samples led to the display of a green color of AflaESense. To the best of our knowledge, this is the first smartphone-based electrochemical system effective for screening samples for contamination with aflatoxin B1.