Robert Bradshaw

Rationale: In forensic investigations, questioned document examination (QDE) provides critical information for document authentication and the detection of forgeries. Conventional QDE approaches often require separate analyses of inks and of any potential fingerprints. This study compares two mass spectrometry imaging (MSI) techniques for QDE, enabling the simultaneous analysis of inks and fingerprints deposited onto paper, providing chemical and biometric information from a single sample. Methods: Two mock forgery samples containing two ballpoint pen inks, printed ink and latent fingerprints were each analysed using either desorption electrospray ionisation mass spectrometry imaging (DESI MSI) or matrix‐assisted laser desorption/ionisation mass spectrometry imaging (MALDI MSI) and the results were compared. Analyses were conducted using state‐of‐the‐art multi reflection time‐of‐flight (MRT) mass spectrometry instrumentation, providing high resolving power and sub‐ppm mass accuracy. Results: Both techniques successfully differentiated between two blue ballpoint pen inks by detecting ink components present in one pen but absent from the other (despite them being optically indistinguishable). Chemical information associated with the deposited fingerprints was also successfully detected and mapped using both DESI MSI and MALDI MSI. However, MALDI MSI outperformed DESI MSI in terms of the clarity of biometric information obtained. Conclusions: Overall, the strengths and limitations of DESI MSI and MALDI MSI for QDE were evaluated, demonstrating the potential of each technique for QDE. This assessment helps identify the most suitable approach for the analysis of this type of forensic casework by showing the benefits and reliability of each technique.

Since its inception in 2004, Desorption Electrospray Ionization Mass Spectrometry (DESI MS) has seen a significant increase in its application to the pharmaceutical and clinical setting, supported by a steady improvement of the sensitivity, mass accuracy, mass resolution, spatial resolution and usability, as well as by the advantages offered by its ambient nature. However, in comparison to the rapid growth for tissue imaging, the uptake of DESI-MSI in fingerprint imaging has not grown a substantial body of knowledge, compared to MALDI-MSI. In this work, we set off to dissect the application of DESI-MSI to fingerprint imaging to explore both the advantages and the potential challenges that might have slowed the uptake, taking stock from our previous work and that of others in this area. During this endeavor we have highlighted advantages but also discovered that, under a range of optimized operating conditions, fingerprint imaging by DESI-MSI is affected by a delocalization phenomenon which we termed "the bleeding effect". This phenomenon has been shown to be specific to fingerprints, as sample type, as opposed to biological tissues, and may be one of the contributing factors to a seemingly slower uptake of this technique in molecular fingerprinting. Therefore, a description of the observed effect, how to minimize it, and its implications in operational work are discussed.

As the global demand for sustainable protein sources grows, valorizing side streams in plant protein processing has become crucial. This study revisits the conventional alkaline–isoelectric extraction of faba bean protein isolates, introducing an enhanced mass balance-driven approach to recover underutilized protein fractions from typically discarded side streams. Through strategic pH manipulation and centrifugation, four distinct protein fractions were recovered with purities ranging from 34.6% to 89.6%, collectively recapturing a significant portion of the 16% protein loss in standard processing. SDS-PAGE and FTIR analyses confirmed the structural diversity among the recovered fractions, with albumin-rich and globulin-rich profiles exhibiting unique spectral and electrophoretic signatures. Functionally, fractions B and D exhibited superior water- and oil-holding capacities, indicating their potential utility in food formulations requiring enhanced moisture and lipid retention. In contrast, fraction C, characterized by low water-holding capacity and high solubility, may be better suited to applications prioritizing emulsification performance, such as in dairy or meat analogs. This study not only highlights the feasibility of reclaiming high-quality protein from industrial byproducts but also underscores the potential of these recovered proteins in diverse food and non-food sectors, including pharmaceuticals and cosmetics. These findings contribute to circular economy strategies by transforming waste into value-added ingredients with functional and commercial significance.

A multimodal imaging workflow (DESI MSI followed by MALDI MSI) for the analysis of ballpoint pen inks and substrates.

Demand for alternative sources of protein ingredients due to increasing population growth, environmental sustainability, and consumer demand is on the rise. However, processes used to generate these new food ingredients must be maximized to ensure a circular economy and a sustainable production system. In this study, the structural and functional properties of faba bean protein isolate and recovered fractions were investigated. Three different protein fractions were recovered with varying protein purities (35–89 %) using different pH conditions of protein fractions. Electrophoresis revealed major differences in protein distribution for protein isolate and recovered protein fractions. Additional FTIR analysis confirmed qualitative screening and differentiation of the different protein fractions based on protein amide regions and fingerprint regions. Faba bean protein isolates and the recovered fraction showed different functional properties with poor water-holding capacity for the albumin fraction. The application of discarded albumin fractions in food applications could improve resource efficiency.

The food industry, academia, food technologists, and consumers have become more interested in using faba bean seeds in the formulation of new products because of their nutritional content, accessibility, low costs, environmental advantages, and beneficial impacts on health. In this review, a systematic and up-to-date report on faba bean seeds’ antinutrients and bioactive and processing techniques is comprehensively presented. The chemical composition, including the oil composition and carbohydrate constituents, is discussed. Factors influencing the reduction of antinutrients and improvement of bioactive compounds, including processing techniques, are discussed. Thermal treatments (cooking, autoclaving, extrusion, microwaving, high-pressure processing, irradiation) and non-thermal treatments (soaking, germination, extraction, fermentation, and enzymatic treatment) are identified as methods to reduce the levels of antinutrients in faba bean seeds. Appropriate processing methods can reduce the antinutritional factors and enrich the bioactive components, which is useful for the seeds’ efficient utilization in developing functional foods. As a result, this evaluation focuses on the technologies that are employed to reduce the amounts of toxins in faba bean seeds. Additionally, a comparison of these methods is performed in terms of their advantages, disadvantages, viability, pharmacological activity, and potential for improvement using emerging technologies. Future research is expected in this area to fill the knowledge gap in exploiting the nutritional and health benefits of faba bean seeds and increase the utilization of faba bean seeds for different applications.

There are many different methodologies in the literature for the preparation of plant material for subsequent MALDI MSI analysis. This chapter overviews preparation of cucumbers (Cucumis sativus L.), with emphasis on sample freezing, cryosectioning, and matrix deposition. This should act as a representative example of sample preparation for plant tissue, and due to wide sample variation (e.g., leaves, seeds, and fruit) and analytes of interest, method optimization will be required for different samples. Key words MALDI MS Mass spectrometry imaging Matrix Plant tissue Cucumber

Questioned document examination aims to assess if a document of interest has been forged. Spectroscopy-based methods are the gold standard for this type of evaluation. In the past 15 years, Matrix-Assisted Laser Desorption Ionisation–Mass Spectrometry Imaging (MALDI-MSI) has emerged as a powerful analytical tool for the examination of finger marks, blood, and hair. Therefore, this study intended to explore the possibility of expanding the forensic versatility of this technique through its application to questioned documents. Specifically, a combination of MALDI-MSI and chemometric approaches was investigated for the differentiation of seven gel pens, through their ink composition, over 44 days to assess: (i) the ability of MALDI MSI to detect and image ink chemical composition and (ii) the robustness of the combined approach for the classification of different pens over time. The training data were modelled using elastic net logistic regression to obtain probabilities for each pen class and assess the time effect on the ink. This strategy led the classification model to yield predictions matching the ground truth. This model was validated using signatures generated by different pens (blind to the analyst), yielding a 100% accuracy in machine learning cross-validation. These data indicate that the coupling of MALDI-MSI with machine learning was robust for ink discrimination within the dataset and conditions investigated, which justifies further studies, including that of confounders such as paper brands and environmental factors.