The rising population and the ongoing climate crisis call for improved means to monitor and optimise agriculture. A promising approach to tackle current challenges in food production is the early diagnosis of plant diseases through non-invasive methods, such as the detection of volatiles. However, current devices for detection of multiple volatiles are based on electronic noses, which are expensive, require complex circuit assembly, may involve metal oxides with heating elements, and cannot easily be adapted for some applications that require miniaturisation or limit front-end use of electronic components. To address these challenges, a low-cost optoelectronic nose using chemo-responsive colorimetric dyes drop-casted onto filter paper has been developed in the current work. The final sensors could be used for the quantitative detection of up to six plant volatiles through changes in colour intensities with a sub-ppm level limit of detection, one of the lowest limits of detection reported so far using colorimetric gas sensors. Sensor colouration could be analysed using a low-cost spectrometer and the results could be processed using a microcontroller. The measured volatiles could be used for the early detection of plant abiotic stress as early as two days after exposure to two different stresses: high salinity and starvation. This approach allowed a lowering of costs to GBP 1 per diagnostic sensing paper. Furthermore, the small size of the paper sensors allows for their use in confined settings, such as Petri dishes. This detection of abiotic stress could be easily achieved by exposing the devices to living plants for 1 h. This technology has the potential to be used for monitoring of plant development in field applications, early recognition of stress, implementation of preventative measures, and mitigation of harvest losses.

Adopting plant-based diets high in fiber may reduce global warming and obesity prevalence. Physiological and psychological determinants of plant-based food decision-making remain unclear, particularly in real-life settings. As fiber has been linked with improved gut-brain signaling, we hypothesized that a single plant-based compared to an animal-based meal, would induce higher satiety, higher mood and less stress. In three smartphone-based studies adults (nall = 16,379) ranked satiety and mood on 5/10-point Likert scales before and after meal intake. Statistical analyses comprised linear mixed models, extended by nutrient composition, taste ratings, gender, social interaction, type of decision and dietary adherence to consider potential confounding. Overall, meal intake induced satiety and higher mood. Against our hypotheses, plant-based meal choice did not explain differences in hunger after the meal. Considering mood, individuals choosing a plant-based meal reported slightly higher mood before the meal and smaller mood increases after the meal compared to those choosing animal-based meals (post-meal*plant-based: b = -0.06 , t = -3.6, model comparison p < .001). Protein content marginally mediated post-meal satiety, while gender and taste ratings had a strong effect on satiety and mood in general. In this series of large-scale online studies, we could not detect profound effects of plant-based vs. animal-based meals on satiety and mood. Instead of meal category, satiety and mood depended on taste and protein content of the meal, as well as dietary habits and gender. Our findings might help to develop strategies to increase acceptability of healthy and sustainable plant-based food choices.

Adopting plant-based diets high in fiber may reduce global warming and obesity prevalence. Physiological and psychological determinants of plant-based food intake remain unclear. As fiber has been linked with improved gut-brain signaling, we hypothesized that a single plant-based (vegetarian and vegan) compared to an animal-based (animal flesh) meal, would induce higher satiety, higher mood and less stress. In three large-scale smartphone-based studies, adults (nall = 16,379) ranked satiety and mood before and after meal intake. Meal intake induced satiety and higher mood. Plant-based meal choices did not explain differences in post-meal hunger. Individuals choosing a plant-based meal reported slightly higher mood before and smaller mood increases after the meal compared to those choosing animal-based meals. Protein content marginally mediated post-meal satiety, while gender and taste ratings had a strong effect on satiety and mood in general. We could not detect the profound effects of plant-based vs. animal-based meals on satiety and mood.