## 1 Introduction  
Beetroot (_Beta vulgaris_) is botanically classified as an herbaceous biennial from the _Chenopodiacene_ family and has several varieties with bulb colors ranging from yellow to red. Deep, red-colored beetroots are the most popular for human consumption; cooked, raw (in salad), or juiced. There is growing interest in using natural food colors because synthetic dyes are being increasingly critically assessed by the consumer [1, 2]. Beetroot contents such as carotenoids, nitrates, flavonoids, vitamins, minerals, and water-soluble pigments betalains such as betacyanins (red-violet color) and betaxanthins (yellow-orange color) are found to have many nutritional and health benefits [3]. Furthermore, studies have reported that beetroot is an important source of health-promoting phytochemicals [4]. Concretely, betalains and phenolic compounds that exist in red beetroot have been reported to increase the resistance of low-density lipoproteins (LDL) to oxidation and to prevent cancer and cardiovascular diseases by reducing the oxidative effect of free radicals on lipids [5, 6, 7]. Therefore, utilization of beetroot as an ingredient in different food productsimparts beneficial effects on human health and provides an opportunity for development of different functional foods.  
Bioactive compounds are sensitive to oxygen, light, heat, and water [8]. One effective method to preserve bioactive compounds is microencapsulation [9]. Microencapsulation is a technology for packing solids, liquids, or gaseous materials in miniature, sealed capsules to release their contents at controlled rates under specific conditions. Microencapsulation protects the core from adverse environmental conditions, improves shelf life of a product, and promotes controlled release [10].  
Spray drying (SD) is one technique employed for microencapsulation. The process of SD transforms a product from a fluid to solid powdered state, through the dispersion of the product droplets inside a chamber where it contacts hot air [11].  
Plant proteins could be an alternative to replace animal proteins and are extensively used in food, pharmaceutical, and cosmetic products. Particularly, seed storage proteins are used for emulsifying, film-forming, and gelling properties [12; 13; 14; 15; 16; 17]. The plant protein most extensively studied for its functional properties is from soy [18]. However, using storage proteins of pea (_Pisum sativum_ L.) seeds in the food industry for the formulation of new food products are interesting because of their nonallergenic characteristic and good functional properties [19].  
Pea protein isolate (P) made from _Pisum sativum_ L. is an important, readily available protein frequently incorporated into foods and supplements. Pea proteins have functional properties suitable for encapsulation, such as solubility, the ability to absorb water and oil, emulsion stabilization, gelation, foaming agents, and an ability to form the quality film and good organoleptic properties [20]. For example, pea protein has been used by [PERSON] et al. to stabilize hempseed oil nanoemulsion satisfactorily [21].  
Beetroot juice has been encapsulated by carrier agent such as Arabic gum or maltodextrin as a potential source of betalian using spray drying [22]. Soy protein has been used as carrier for encapsulation of betroot pomace extract by freeze drying [23]. However, this study aimed to evaluate the effect of adding pea protein to betroot juice as an encapsulating agent, and the processing spray-dried temperature on the physicochemical, structural, and functional properties of the powder, since pea protein could offer aptitude to encapsulate and protect the bioactive compounds present in betroot. In addition, spray-drying temperature is of vital importance to both powder yield and productivity and degradation of bioactive compounds.