# Current Status and Economic Prospects of Alternative Protein Sources for the Food Industry
## 2 Alternative Protein Sources  
### Plant-Based  
Plant-based (PB) proteins are derived from vegetable sources, commonly legumes, grains, nuts, and seeds ([PERSON] & [PERSON], 2023) [19]. Among these, soybeans, peas, chickpeas, beans, rice, lentils and almonds are the most widely used ([PERSON] & [PERSON], 2022) [21]. In addition, oilseeds are also regarded as potential sources since protein-rich meals (press cakes from oil extraction) are low-cost by-products from oil production (sunflower, rapeseed and sesame, for example), which can potentially be upcycled for  
Figure 1: Projection of alternative protein market growth. Adapted from EY Parthenon Analysis (2021) [14]. protein production ([PERSON], 2022) [22]. PB proteins have rapidly become popular as the most readily available and easily accessible alternative to animal-based protein. Although animal-sources are usually perceived as the most common protein source, plant proteins account for an average of 60% of the global protein supply, with a significant geographic dependence, ranging from as low as 35% in Northern America, to as high as 84% in Western Africa ([PERSON] et al., 2023) [23]. Protein profile and content are highly dependent not only on the PB source, but also on factors associated with plant growth conditions. Protein content in plant sources vary widely from as low as 2.9 g/100 g fresh weight (FW), for spinach and other green leaves, to 13.0-23 g/100 g FW, for common pulse sources such as peas and chickpeas ([PERSON] et al., 2023) [16]. Although proteins are a key part of human diet, the amount of protein ingested is not the only determinant influencing biological functions. Protein profile and digestibility also play a major role in the nutritional effects derived from protein intake. While animal-based protein sources, such as meat and eggs, have a complete profile of essential amino acids (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine), PB proteins usually lack select essential amino acids, which compromises their biological utilization ([PERSON] et al., 2016; [PERSON] & [PERSON], 2019; [PERSON] et al., 2014) [24; 25; 26]. Meat and eggs rank between 95-98% for digestibility, with a protein digestibility corrected amino acid score (PDCAAS) around 96-100%, while the digestibility of PB proteins is 97%, 89% and 64% for soybean, chickpea and kidney beans, with PDCAAS of 100%, 78% and 68%, respectively ([PERSON] et al., 2021; [PERSON] et al., 2022) [12; 27]. On the other hand, plant-based proteins have been associated with reduced allergenity (when compared to dairy and eggs), and with biologically active peptides linked to enhancement of gastrointestinal health, and anti-hypertensive and anti-microbial activities ([PERSON] et al., 2023) [16]. For instance, buckwheat, beans and peas have bioactive peptides with in vitro anti-hypertensive activity, while potent antioxidant activity (both metal chelating and radical scavenging) has been attributed to cocoa, walnuts, rye and maize ([PERSON] et al., 2014; [PERSON] & [PERSON], 2012; [PERSON] et al., 2014) [26; 28; 29]. The combination of different sources of plant proteins and the use of PB products (flours, concentrates and isolates) is an efficient strategy to meet the recommended daily allowance (RDA) of protein and essential amino acid intake in animal-free diets. Functionality and sensory performance of plant-based proteins are decisive factors for the use of AP for product development. Indeed, technological attributes such as emulsification, foaming and gelation capacities are essential aspects for processing and product development, although flavor and texture are still the biggest drivers for consumer acceptance of novel PB products ([PERSON] et al., 2022) [30]. Functional attributes are related to physical and chemical properties that affect their interaction with other food components during product development, processing and storage ([PERSON] et al., 2021; Grossmann & Weiss, 2021; [PERSON] et al., 2021) [11; 27; 31].