# The Role of Fermented Vegetables as a Sustainable and Health-Promoting Nutritional Resource
## 3. Femented Vegetables
### Probiotic Starter Cultures in Plant-Based Fermented Foods  
Spontaneous fermentation is prone to contamination by undesirable microorganisms, often resulting in inconsistent and subpar products, which presents a challenge for the industrial production of fermented vegetables [203]. To ensure product quality and safety, the strategic use of starter cultures can be paramount. In that sense, probiotic starters, generally recognized as safe (GRAS), have emerged as indispensable drivers of vegetable fermentation, not only referring to the process itself but also offering a plethora of benefits. Among these probiotic microorganisms, LAB are typically dominant in the microbiota of fermented vegetables. By introducing specific LAB, producers can effectively control the fermentation process and prevent spoilage and foodborne transmission, while enhancing the nutritional value of the final product [204,205]. These carefully selected microbial strains not only accelerate fermentation but also contribute to the singular flavors and health-promoting properties of fermented vegetables [203]. Probiotics actively promote diverse metabolic pathways and demonstrate a remarkable ability to metabolize various carbohydrates and organic acids [206]. Notably, the phenolic derivatives produced by probiotic metabolism significantly influence the sensory and health-promoting properties of fermented vegetables. Lactobacillus and _Pediococcus_ spp., renowned LAB, exhibit exceptional metabolic potential for the bioconversion of volatile compounds in vegetables during the fermentation process (especially phenols, terpen, alcohols, and aldehydes) [207,208]. Additionally, probiotics actively reinforce the biosynthesis of vitamins, antioxidants, and bacteriocins [209, 210, 211, 212, 213, 214]. Fermented vegetables are rich in vitamins, which are essential for a variety of energy-yielding metabolism pathways and support fundamental cellular functions, including DNA synthesis, oxygen transport, and neuronal functions [215]. The fermentation process plays a crucial role in preserving the vitamin content of raw materials [216]. Specifically, the co-fermentation of the _Pediococcus_ _pentosaceous_ strain AL and the _Cyberlidnera rhodamensis_ strain J52 substantially enhances the concentration of vitamin C in fermented capsicum [217]. Moreover, certain LAB possess the capability to synthesize vitamins. For instance, the _Limosilactobacillus reuteri_ strain F2 has demonstrated a remarkable capacity for the extracellular production of vitamin B12 [218]. Consequently, fermenting vegetables with probiotic strains can be an effective strategy for augmenting their health benefits. Manitol, a 6-carbon alcohol found naturally in certain microorganisms and plants, is absorbed slowly in the intestinal tract and does not elevate blood sugar levels [189,219]. Species of the genus _Leuconstoc_, including the _L. mesenteroides_ strain SKP88 and the _L. citereum_ strain SKP92, which were isolated from pa (green onion)-kimchi, have the ability to convert fructose into mannitol [219]. Ornithine, a non-proteinogenic amino acid derived from arginine, serves multiple functions, including anti-obesity and anti-fatigue effects, promotion of muscle growth, and treatment for cirrhosis [189]. The _Weissella korensis_ strain DB1 is capable of producing high amounts of ornithine, although it did not pose a health risk, making it suitable for incorporation into fermented foods [220]. Moreover, probiotics possess a remarkable capacity for producing gamma-aminobutyric acid (GABA), a key inhibitory neurotransmitter within the CNS, potentially leading to the reduction of anxiety [189,221]. Certain strains isolated from fermented vegetables, such as the _L. curvatus_ strain K285 isolated from gat-kimchi, the _Lactiplantitibacillus pentosus_ strain 9D3 isolated from Thai pickled weed, the _L.