# Development and Evaluation of a Fermented Pistachio-Based Beverage Obtained by Colloidal Mill
## 1 Introduction  
In the last fifteen years, there was an increasing prevalence of individuals consuming a vegetarian or vegan diet in high-income countries, both in adults and young people (12-20 years) [1]. The growing popularity of this lifestyle has led to an increase in the development of many non-dairy plant-based beverages [2]. The market for these nutrient-rich beverages, high in phenols and dietary fiber [3], will reach USD 38 billion by 2024, becoming the largest plant-based food segment [4]. The best-known plant-based beverages are those made from soy, rice, almonds, and hazelnuts [5], but a wide variety of plant-based products such as nuts, coconuts, cereals, legumes, seeds, and fruits can be used in their preparation [6]. In this regard, to offer a wide range of plant-based beverages to those seeking alternatives to milk, new raw materials such as chickpea [7], amaranth [8], quinoa [9], millet [10], pine nut [11], pistachio [12], pea [13], lupine, and faba bean have recently been investigated [14]. Pistachio nuts are widely appreciated for their sensorial properties and are included as an ingredient in numerous food formulations such as ice cream, pesto, sauces, salads, and desserts or as salty snacks [15]. Bronte pistachios have a significantly higher content of phenolic compounds in the skins than in the kernel and, in addition, some compounds,such as epicatechin, quercetin, naringenin, luteolin, kaempfer, cyanidin-3-O-galactoside, and cyanidin-3-O-glucoside, are only contained in pistachio skins, giving it an excellent antioxidant activity [16]. [PERSON] et al. (2016) [17] also suggested that the beneficial effects of pistachios could be greatly enhanced by the consumption of unpeeled kernels, as some bioactive compounds have a higher concentration in the pistachio skin than in the kernel itself. Recent studies [3; 18] have highlighted that several beverages derived from cereals and legumes present technological problems related to their processing and storage stability, such as sedimentation of larger particles, higher viscosity of the beverage, solubility, etc. Furthermore, poor sensory and flavor qualities have often been reported [18]. A common strategy used to solve many of these issues is fermentation by lactic acid bacteria and/or yeasts. This process is an ancient preservation technique that not only improves the availability of micronutrients but also has considerable advantages in improving the taste and quality of food while ensuring health properties and storage stability. Other studies have used probiotic bacteria for the development of plant-based beverages [19] showing that by-products of the cereal industry can also be successfully used for this purpose [20; 21]. Several studies on plant-based fermented beverages have highlighted the ability of lactic acid bacteria to grow and improve the stability and qualitative characteristics of the final products [12; 22; 23; 24; 25]. A recent study showed that pistachios are good substrates for the development of fermented beverages due to their fermentability by lactic acid bacteria [12]. Therefore, the aim of our research was to develop an innovative pistachio-based beverage fermented with selected lactic acid bacteria belonging to the species _Leuconostoc pseudomesenteroides_, _Companilactobacillus alimentarius_, _Lactiplantiobacillus plantarum_, _Lattiplantihacillus plantarum_, _Companilactobacillus kimchi_. A colloidal mill was considered for the preparation of the beverage as it was seen to have good application for different types of fruit, nuts, and legumes. [PERSON] et al. (2016) [26] pointed out that the colloid mill processing of mulberry generated small particle size and a disaggregated microstructure, contributing to a high content of phenolic compounds, as well as high antioxidative and \(\alpha\)-glucosidase inhibition activities in the juice. Also, [PERSON] et al.