Chemical, Physical, Microbial, and Sensory Properties of Innovative Sesame Milk Kefir, Focusing on the Ultrastructure of Kefir Grains

Abstract

The demand for innovative plant-based probiotic beverages is growing rapidly. This study aimed to develop and evaluate a novel kefir beverage using two types of sesame milk: permeate-based sesame milk (PSM) and water-based sesame milk (WSM). Chemical, physical, microbial, and sensory properties of kefir were assessed. The total solids content (protein, fat, carbohydrates, and ash) in fresh kefir was 12.68, 13.31, and 16.38% for cow milk kefir (CMK), WSM kefir (WSMK), and PSM kefir (PSMK), respectively, and increased slightly after 14 days of storage, reaching 13.18, 13.53, and 16.56%. The fresh PSMK exhibited notable mineral content, containing (mg/100 g) 258.23 Ca, 137.14 P, 70.24 K, and smaller amounts of Na, Mg, Cu, Fe, Zn, and Mn, along with 5.18 μg/100 g of Se. In terms of volatile compounds, PSMK had the highest acetaldehyde concentration (7.48 mg/L), followed by CMK (4.91 mg/L) and WSMK (4.44 mg/L). Ethanol levels were the highest in fresh WSMK (0.129%). The viscosity and color attributes of PSMK were closely aligned with those of CMK, with the viscosity increasing over time to 1.53, 1.40, and 1.57 cP for PSMK, WSMK, and CMK, respectively. All kefir types supported viable probiotic populations, with PSMK demonstrating superior Lactobacillus and Lactococcus growth compared to WSMK. Sensory evaluations revealed high consumer acceptability for PSMK, comparable to CMK, with a purchase recommendation rate exceeding 76% for both PSMK and WSMK. Scanning electron microscopy revealed that the microstructure of PSMK grains was well-balanced and similar to that of CMK grains. This study highlights PSM as a promising dairy alternative for producing high-quality probiotic kefir, offering consumers an appealing, nutritious option within the growing plant-based beverage market.

Figure 1

Volatile compounds in WSMK, PSMK, and CMK during the storage period. Values represent mean ± SD bare (n = 3). One-way ANOVA was applied. Tukey’s HSD posthoc test was used for pairwise comparisons (α ≤ 0.05). *Significant differences, MSD; minimum significant differences.

Figure 2

Sensory evaluation of WSMK, and PSMK compared to CMK during cold storage. Homogeneous and clear appearance, color, and slightly sour smell scored from 0 to 10, while consistency, slightly yeasty taste, refreshing taste, pleasant, fermented taste, and purchase recommendation scored from 0 to 5. Values are the mean of n = 20. One-way ANOVA was applied. Tukey’s HSD posthoc test was used for pairwise comparisons (α ≤ 0.05). *Significant differences, nanoseconds; nonsignificant differences, MSD; minimum significant difference.

Figure 3

SEM image of kefir grain, developed in cow milk medium, showcasing the interconnected network of microbial cells within the kefiran matrix at a magnification of 4500× (a) and 10,000 (b).

Figure 4

SEM image of kefir grain, developed in WSM medium, showcasing the interconnected network of microbial cells within the kefiran matrix at a magnification of 5000x (a) and 10000 (b).

Figure 5

SEM image of kefir grain, developed in PSM medium, showcasing the interconnected network of microbial cells within the kefiran matrix at a magnification of 8000× (a), and 10,000 (b).