## 3 Results and Discussion
### Detection of the Presence/Absence of Gluten in Commercial Hydrated Cassava Starch
In Italy, a study revealed that 16% of naturally gluten-free products were contaminated with gluten [58]. Although the contamination rates reported in these studies exceed those found in the present study, it is worth noting that the sample sizes in those investigations were larger. Globally, regulatory agencies adopt different thresholds for allowable gluten content in food products. These range from the widely accepted limit of 20 ppm, as established by the FDA in the United States (21 CFR $ 101.91--Food Labeling; Gluten-Free Labeling of Foods) and by Regulation (EU) N\({}^{\circ}\) 828/2014 in the European Union [59], to more restrictive standards such as the prohibition of any detectable gluten in products labeled \"gluten-free\" (B.24.018). Although there are no official numerical limits for gluten content in Japanese regulations, wheat must be declared an allergen on product labels. Additionally, organizations such as the Japan Celiac Association recommend a maximum gluten level of 1 ppm for products labeled \"zero gluten\". In general, even in the absence of national legislation, many countries adopt the regulatory criteria of their main export markets. Cross-contamination with gluten is recognized as a global issue [57], and it can occur at various processing stages [60; 61]. Therefore, industries must implement stringent preventive measures to ensure food safety for consumers. These measures include establishingdedicated production lines for gluten-free products, thorough cleaning and sanitization protocols for shared equipment, strict raw material sourcing from certified gluten-free suppliers, regular employee training on cross-contamination risks, and routine testing of final products to verify the absence of gluten contamination [24, 26]. The presence of gluten in foods labeled as gluten-free poses a significant health risk to consumers with dietary restrictions to this component. For individuals with gluten-related disorders, such as celiac disease, the only effective treatment is strict adherence to a gluten-free diet. The unintentional consumption of gluten not only delays recovery but can also lead to serious adverse health effects. This underscores the critical importance of rigorous quality control and accurate labeling to protect vulnerable populations [25, 57]. In addition to what has been previously mentioned, it is the responsibility of the regulatory agencies in each country to establish clear guidelines and ensure that products naturally free of gluten or labeled \"gluten-free\" truly possess this characteristic, thereby safeguarding consumer trust and food safety. It is important to highlight that the test used in this study is qualitative, providing only the presence or absence of gluten. While rapid qualitative methods are valuable for initial screening, more precise quantitative analyses are essential to accurately determine gluten levels. Considering that these products are consumed by a specific and sensitive population, it is crucial to employ a combination of detection methods, including both rapid tests and more sensitive quantitative assays, to ensure the reliable identification and measurement of gluten presence. Our research group intends, in future studies, to perform detailed quantitative analyses to better assess the extent of gluten contamination in products marketed as \"gluten-free\" and thus more accurately define the scope of the issue.