## 1 Introduction  
The population of the world is expected to reach 9.7 billion by 2050, and the global demand for food is estimated to nearly double by that time [1]. Scientists agree that supplying food to this growing population will be a major challenge of the next decade. They highlight the concern of excessive livestock production, which is considered unsustainable for several reasons. This sector is estimated to be responsible for 26% of total ice-free land surface use, 15% of total groundwater use, and 12% of water pollution [2]. Livestock production accounts for approximately 13% of global greenhouse gas (GHG) emissions; consequently, it presumably contributes significantly to climate change [3]. The transformation of natural lands into pastures and croplands leads to a significant decline in biodiversity and to the disruption of ecosystems. Animal farming is considered to be a major contributor to deforestation, which results in an increased level of carbon dioxide in the atmosphere and, hence, in the exacerbation of climate change [4]. Another adverse environmental impact of livestock production is the emergence of antibiotic resistance, which poses a serious threat not only to farm animals but also to surrounding ecosystems and human health due to the overuse of antibiotics [5]. In addition, animal welfare and ethical concerns about intensive animal farming practices are also important issues of agriculture, politics, and economics [6]. In developed countries, plant-based diets have gained increased popularity due to their perceived nutritional and environmental benefits, as well as ethical considerations. In European countries, the estimated percentage of vegetarians ranges between 1% and 10%. The prevalence of these diets is expected to increase in the future [7]; thus, assessing the quality and safety of alternative food sources is a pivotal field of science. Among the three primary macronutrients, the growing demand for proteins has raised concerns about whether traditional sources, such as livestock, can meet this need [1]. As a result, a variety of alternative protein sources have been introduced to consumers, including pulses, algae, insects, plant-based alternative proteins, and cultured meat [8]. The percentage of Google search results for the keyword \"alternative protein\" shows a slight but constant increase since 2004, while the term \"plant-based protein\" has gained increasing attention only in the last decade [9]. A systematic review including the results of 91 studies on the consumer acceptance of alternative proteins revealed that pulses and plant-based proteins are much more accepted by consumers than insects and cultured meat [8]. The so-called \"blue foods\", derived from aquatic sources, can significantly contribute to sustainable food supply. These include fish and other marine animals, as well as alternative food sources like aquatic vegetables, seaweeds, and microalgae, whether from natural or from artificially cultivated aquatic sources. Proteins from algae, especially species of _Chlorella_ and _Spirulina_, are in the focus of scientific attention due to their exceptionally high protein content, rich variety of essential amino acids, high biological utilisation rates, and low allergenicity [10]. Despite their potential, consumers' acceptance of microalgae is limited. Based on recent consumer surveys, Danish researchers concluded that microalgae are recommended to be used in small quantities when incorporated into foods, mainly due to their vivid green colour. Moreover, consumers tend to prefer the taste of freshwater algae over marine species due to the strong fishy flavour of the latter [11]. The study of [PERSON] and co-workers (2021) suggests that plant proteins are favoured over microalgae by consumers; hence, plant-based aquatic protein sources may be more suitable as food ingredients [8]. Duckweeds (Lemnoideae) are sustainable sources of nutrients found in still freshwater or wetlands worldwide.