###### Abstract  
Conventional conservation techniques such as drying, salting or freezing do not allow for preserving the original characteristics of seaweeds. The present work aims to study the impact of minimal processing, in particular \"Modified Atmosphere Packaging\" (MAP), on the physicochemical characteristics and food safety of two seaweed species, \"layer\" (_Perolphra umbilicalis_) and \"sea-lettuce\" (_Ulva lactuca_), stored at 6 \({}^{\circ}\)C for 15 days. Different parameters were evaluated using analytical methods, namely the composition of headspace gases, color, texture, microorganisms, and volatile organic compounds (VOCs). The main findings of this study were that the MAP treatment was able to inhibit the respiration rate of minimally processed seaweeds, also preserving their color and texture. There was a remarkable reduction in the microbial load for _P. umbilicalis_ treated under modified and vacuum atmospheres, and _U. lactuca_ exhibited relatively steady values with no notable differences between the treatments and the control. Therefore, during the 15-day study period, both seaweeds met the requirements for food safety. GC-TOF-MS allowed to conclude that both MAP and vacuum treatments were more efficient in maintaining the odor characteristics of _U. lactuca_ compared to _P. umbilicalis_ with no significant differences throughout the storage days. Metabolic responses to diverse sources of abiotic stress seemed to account for most of the changes observed. seaweeds; modified atmosphere packaging (MAP); food conservation; physicochemical characterization; microbiology; food safety 2023122736202312273620231227362023122736202312273620231227362023122736202312273620231227362023122736202312273620231227362023122736202312273620231227362023122736202312273620231222736202312273620231227362023122736202312203122031220312203122031203120312031203120312031203 that edible seaweeds can promote in food formulations, rather than valuing them as an ingredient with gastronomic potential [5]. Marine macroalgae are rich in protein and dietary fiber, an excellent source of vitamins, trace elements and minerals, and are low in sugars and lipids, with a predominance of polyunsaturated fatty acids--\(\omega\)-3 (EPA and DHA) and \(\omega\)-6 (AA) types--in a balanced ratio. These nutritional characteristics make seaweeds wholesome ingredients and low in calories [2]. There is also a wide variation in the chemical composition of marine macroalgae of the same genus, resulting in different contents of the main nutrients (macro- and micronutrients), depending on seasonal, climatic and geographic conditions [6]. Despite seaweed's numerous nutritional benefits, its role in the diet of the Western world remains insignificant. An increasing interest in its use as food can be explained by a growing awareness of the Western public about its possible health benefits [7; 8]. Nevertheless, developing novel products and recipes in partnership with talented chefs or adapted to local cuisines could boost even more seaweed consumption in these countries [9]. The United Nations estimates that the population should approach 9.7 billion in 2050. In an increasingly populated planet, there is an emerging concern about the sustainability of the existing means of production and food resources [10]. In light of this, seaweeds with the potential for use in food have emerged as a viable strategy to meet the increase in demand for food, in particular due to their high protein content and low or negative carbon footprint [11]. Conservation techniques have the function of preserving the quality of food, from the moment of production to its consumption. They prevent microbial growth and physicochemical changes, thus allowing for the maintenance of organoleptic qualities and increasing shelf-life [12]. Processing methods can also be used for other purposes, such as transforming the flavor through salting, curing or smoking, or even making foods more nutritious and digestible through fermentation or cooking [13].