Evaluation of the phytochemical, biological, and sensory properties of Stevia rebaudiana in functional food formulations

Abstract

The increasing prevalence of obesity, diabetes, and other metabolic disorders associated with excessive sugar consumption has encouraged the search for natural low-calorie sweeteners with additional functional properties. In this context, the present study aimed to investigate the phytochemical composition, biological activities, and sensory applicability of Stevia rebaudiana in functional food formulations. Hydroethanolic extraction (70% ethanol) was selected due to its efficiency in extracting polar bioactive compounds, yielding an extraction recovery of 24.2%. The obtained extracts revealed a low total sugar content (0.23 ± 0.02 mg GE/g extract), along with the presence of phenolic compounds (2.91±0.11 mg GAE/g), flavonoids ( 0.87±0.003 mg QE/g), and tannins ( 1.088±0.042 mg CE/g). Antioxidant activity evaluation showed a moderate reducing power (A0.5 = 1.49 ± 0.23 mg/mL) and free radical scavenging activity with an IC₅₀ value of 4.84± 0.22 mg/mL for the DPPH assay. Biological evaluation also demonstrated promising antidiabetic and anti-inflammatory activities through α-amylase inhibition (IC₅₀ =4.69 ± 0.05 mg/mL) and inhibition of protein denaturation (IC₅₀ = 17.1 ± 0.37mg/mL), respectively. The functional applicability of stevia was further investigated in orange juice and madeleine cake formulations based on partial or total sucrose replacement, including formulations enriched with marine collagen. Sensory evaluation was performed to assess sweetness, bitterness, aroma, aftertaste, taste, texture, and overall acceptability in order to evaluate the feasibility of using stevia in different food matrices. The results showed that partial substitution of sucrose with stevia maintained relatively acceptable sensory properties, whereas complete replacement negatively affected bitterness, aftertaste, aroma, and overall acceptability. Marine collagen contributed additional nutritional and textural value, although its sensory masking effect remained limited. Overall, the study highlights the promising potential of Stevia rebaudiana as a natural low-calorie sweetener with functional and bioactive properties. However, further formulation optimization remains necessary to improve sensory quality and consumer acceptance of stevia-based functional foods.