## 1 Introduction  
Lactic acid fermentation has been recognized for centuries as a safe technique of food preservation which requires minimum of resources. The fermentation, with lactic acid bacteria (LAB) application, leads to a decrease in pH at the end of the process. Processing vegetables, such as by fermentation or heating, increases the bioavailability of nutrients and pigments, most likely by disrupting the plant tissues cell walls. The strains of _Levilactobacillus brevis_, _Limosilactobacillus fermentatum_, and _Laciplantibacillus plantarum_ are most often used in the fermentation of vegetables [1; 2; 3]. Pickled foods, because of low pH ensuring the long shelf-life of products, can be preserved for many months. However, it depends mainly on having good storage conditions, such as a low temperature and the lack of UV radiation [4; 5; 6]. Fermented products have unique taste properties. The taste of silage depends on both the type of raw material and the method and the parameters of the ensilage process [7]. The desired changes in taste, consistency, and color take place over time, ultimately creating products with a completely different taste impression from the initial ingredients. This is mainly due to microorganisms such as lactic acid bacteria, yeast, and filamentous fungi, which contribute to the unique taste of the silage and ensure the safety and required quality of the resulting product. Many pickled foods have been shown to be a valuable source of protein, carbohydrates, minerals, vitamins, and fiber [8]. As a result of lactic acid bacteria presence, fermented foods are classified as foods that have health-promoting properties. However, to be permanently classified as this type of food, it must have a high (over 1 \(\times\) 10\({}^{7}\) log CFU/g) number of lactic acid bacteria [9]. In addition, vegetables, due to their composition and the increasingly popular trend of a healthy life-style, have become a valuable processed raw material [8]. The combination of the health-promoting properties of vegetables and lactic acid bacteria in fermented products is an excellent replacement for dairy products containing LAB. Natural pigments include betalains, carotenoids, chlorophylls, and anthocyanins. The natural pigments found in vegetables and fruits are now progressively being used as a source for coloring food. They are increasingly replacing the use of artificial pigments, which nowadays are mentioned as \"not-safe\" and causing undesirable health effects [6]. The disadvantage of using natural pigments is their sensitivity to the influence of the environment through the action of UV rays, oxygen, temperature, pH or the presence of metal ions, enzymes, or sugars [4; 5; 10; 11]. In Western Europe the most popular fermented vegetables are cucumbers, cabbage, beetroot, carrots, and red bell peppers. Of these, the highest amount of pigments are in beetroot, carrots and red bell peppers [12; 13; 14]. Moreover, beetroot is rich in carbohydrates, a protein with unsaturated fatty acids [15]. The betalains isolated from the beetroot were vulgaxanthin I, vulgaxanthin II, indicaxanthin, betanin, neobetanin, prebetanin, and isobetanin [3; 16]. Betalains are soluble in water N-acylated pigments divided into yellow-orange-colored betaxanthus and red-violet-colored betacyanins. They are stable in a low pH range (3-7), their stability increases with decreasing oxygen concentration, and they are resistant to fermentation temperatures [11; 17]. However, the thermal stability of betacyanin and betaxanthins is still unclear, as mentioned in the beetroot pigments analysis made by [PERSON] et al. [4] Despite the process conditions, yellow or red beetroot pigments could be stable. Red bell peppers are rich in carotenoids and are botanically included in fruits, whereas a carrot is a root vegetable. Carrots have been recognized as an excellent source of flavonoids, quercetin, vitamin C, and carotenoids [18].