## 3 Results and Discussion
### Point-of-Care Testing with Standard Operating Procedure and Evaluation of REASSURED Criteria  
Up to this point, the obtained results confirm that both assays enable user-friendly food controlling of plant- and animal-based food. Due to the lyophilization of the reaction mixture, the assays do not need to be prepared in-field and do not require refrigeration. To verify whether the tests described here are suitable for actual POC testing, a proof-of-concept field test was conducted and a local farmers market was visited for sample acquisition. Both assays were performed at the POC according to a proposed standard operating procedure (SOP, see Figure S4 for detailed step description). Figure 4 shows that the exemplarily tested food items showed the expected results. When using the _P. platessa_-specific assay for purchased fresh plaice, pla from the sampled item was detected, as evidenced by an exponential increase in fluorescence after 10 min. The faster amplification performance of the assay may be attributed to the fresh and not frozen sample material. Hence, simplified DNA extraction could be performed more efficiently. When the _C. tinctorius_-specific assay was used for a purchased tea sample, the assay detected DNA from _C. tinctorius_ in the sampled item. For a non-target purchased saffron spice, the POC test showed no amplification. Figure 3: Real-time fluorescence curves obtained with the Doctor Vida Pocket device for the plaice-specific assay (**A**) and the safflower-specific assay (**B**) after one and eight weeks of storage of the reaction mix. The results were verified by agarose gel electrophoresis. Thus, both assays were successfully conducted at the POC and the proposed SOP could build a good baseline for future in-field food-control testing to meet the REASSURED criteria (see Table 3). Combining a lyophilized LAMP reaction mix with the Doctor Vida Pocket test can ensure real-time monitoring of the quality of the ongoing test, both in the laboratory and on-site, with just a smartphone and a power bank. The strength of both proposed assays is obvious: Due to simplified sample collection and DNA extraction, our proposed SOP allows user-friendly and rapid preparation prior to the specific assay in 10 min. The previously published LAMP assays were sensitive and specific in laboratory settings [31; 32]. The results of the proof-of-concept field test revealed no difference in target specificity although the reaction mix was lyophilized and stored at ambient temperature for one week. Preliminary experiments suggest that the reaction mixture will still work with minimal loss of polymerase activity after 24 weeks. Further tests are needed to confirm the robustness of the performance in actual, non-controlled environments. Since the results are available in under 30 min, the tested assays can be performed rapidly. These characteristics of the proposed assays may enable close monitoring of the integrity of the value chain and may combat food fraud and ensure food safety for global markets. However, in order to deliver the test system to the relevant user, the commercialization of a complete test kit is necessary and remains a pending task. Following the example of the test systems marketed by Eiken Chemical Co., the inclusion of positive and negative controls in the kit should be considered. Developing combination devices like the PEBBLE to measure multiple samples at once would also be an advantageous development [25]. A possible limitation of the proposed SOP is the risk of contamination, due to the requirement to pipette the crude DNA isolate at the POC. All-in-one devices which facilitate the entire process including DNA extraction and amplification could help to reduce the risk of false positive results and improve user-friendliness by a pipette-free approach [41]. Figure 4: Real-time fluorescence curves obtained with the Doctor Vida Pocket device for the plaice-specific assay (**left**) and the safflower-specific assay (**middle** and **right**) in realistic settings at the POC.