Some lactic acid bacteria (LAB) are capable of producing exopolysaccharides (EPS), which can be used in the dairy industry to reduce syneresis and improve the viscosity and texture of fermented products. The aim of the present study was to screen the EPS-producing capacity of 123 LAB strains isolated from fermented foods to search for those able to produce EPS with the optimal technological aptitude to be applied in non-fat set yogurt manufacture. They were grown on MRS-sucrose and assigned to ropy or mucoid phenotype depending on the appearance of the colonies. Twenty-five of them were selected and assayed for production of both cell-bound EPS (EPS-b) and EPS released to the medium (EPS-r). Those resulting in the most EPS producers (Levilactobacillus brevis UCLM-Lb47, Leuconostoc mesenteroides subsp. mesenteroides 6F6-12 and Leuconostoc mesenteroides subsp. mesenteroides 2F6-9) were used to manufacture non-fat set yogurts. These yogurts were analyzed for microbiological and physicochemical properties (pH, titratable acidity, total solids), water-holding capacity, apparent viscosity, and sensory characteristics during a 28-day cold storage period. The yogurts made with the selected strains showed higher values of water-holding capacity, EPS concentration, and viscosity in the mouth than the control yogurt, which presented a more fluid texture. The results obtained suggest that the three selected strains could be used to replace hydrocolloids in non-fat set yogurt formulation, obtaining a clean-label product that would improve consumer acceptance. Graphical Abstract

Plant-based yogurts are increasingly recognized as sustainable and health-conscious alternatives to dairy-based products, driven by environmental, ethical, and nutritional motivations. Pistachio milk, derived from an efficient and resilient crop, emerges as a promising raw material for yogurt production, offering unique sensory qualities and a dense nutritional profile. Rich in unsaturated fatty acids, bioactive compounds, and essential nutrients, pistachios are ideal for fermentation with lactic acid bacteria (LAB). In this study, a novel pistachio-based yogurt analog (PBYA) was developed using lactic acid fermentation, with a yogurt commercial starter, of pistachio milk. The production process was optimized to create an additive-free, clean-label formulation without the use of stabilizers or thickeners. The physicochemical, microbiological, and sensory properties of the PBYA were evaluated over refrigerated storage. The final product exhibited high levels of protein (5.6%), fat (5.4–6.8%), and total solids (20.5–21.4%), along with desirable texture and flavor characteristics. Notably, PBYA presented significantly higher concentrations of total free amino acids (754 mg/L) compared to commercial soy (557 mg/L) and cow’s milk yogurts (390 mg/L), particularly in essential amino acids such as lysine, methionine, and tryptophan. This enhanced free amino acid profile contributes to the product’s functional and nutritional value. Sensory analysis revealed good acceptance of the product, with improvements in viscosity and firmness over time, likely due to microbial exopolysaccharide production. Overall, the findings highlight the feasibility and commercial potential of PBYA as a clean-label, plant-based fermented product that meets current consumer demands for sustainability, nutrition, and sensory quality.

Brain leptin signalling plays a central role in the regulation of energy balance and glucose homeostasis, yet its contribution to early metabolic dysfunction preceding overt obesity remains uncertain. In the present study, we examined the metabolic consequences of sustained attenuation of central leptin receptor signalling in lean rats. Adult animals received chronic i.c.v. infusion of a rat‐specific leptin receptor antagonist (SLA) or vehicle for 21 days. SLA administration increased food intake with modest gains in body weight and visceral adiposity at the same time as maintaining normoleptinemia, and induced hepatic and pancreatic lipid accumulation, hyperinsulinemia, impaired glucose tolerance and hyperglucagonemia. These alterations were accompanied by hepatic glucagon resistance, as indicated by attenuated gluconeogenic gene induction and reduced CREB phosphorylation following in vivo glucagon stimulation. SLA‐infused rats also exhibited elevated circulating total and branched‐chain amino acids, reduced hepatic branched‐chain α‐ketoacid dehydrogenase activity and increased fibroblast growth factor 21 levels, consistent with disrupted glucagon–amino acid signalling. Together, these findings indicate that impaired central leptin signalling induces co‐ordinated endocrine and metabolic disturbances in the absence of obesity, supporting a role for altered central neuroendocrine regulation in the early development of metabolic dysfunction. image Key points: Chronic attenuation of brain leptin signalling is associated with early metabolic dysfunction in lean rats. Central leptin disruption leads to hyperglucagonemia, hepatic glucagon resistance and altered amino acid metabolism. Elevated fibroblast growth factor 21 levels and impaired branched‐chain amino acid catabolism reflect early liver–α‐cell axis dysregulation. This model provides insight into neuroendocrine drivers of non‐obese prediabetes.