Probiotic Potential and Technological Properties of Bacteriocinogenic Lactococcus lactis Subsp. Lactis UTNGt28 from a Native Amazonian Fruit as a Yogurt Starter Culture

Abstract

A native Lactococcus lactis subsp. lactis UTNGt28 (GenBank accession no: MG675576.1) isolated from Amazonian fruit of the tropical Caimitillo (Chrysophyllum oliviforme) tree and the commercial strain Lactococcus lactis subsp lactis ATCC11454 (LacAT) were targeted ex vitro in whole milk in combination with Streptococcus thermophilus ATCC19258 to obtain a fermented probiotic beverage. Concomitant with cell viability determination during storage (28 days), the pH, titratable acidity, syneresis, protein and fat were evaluated. The results indicated that neither UTNGt28 nor LacAT displayed a high capacity to ferment whole milk and survive during storage; a statistically significant difference (p < 0.05) in cell viability was registered for UTNGt28 compared with LacAT when inoculated alone or in combination with S. thermophilus. A principal component analysis showed a clear difference between the yogurt formulations at day 1 and 28 of storage. The PC 1 explained 46.8% of the total variance (day 28), was loaded in the negative (-) direction with titratable acidity (% lactic acid), while the PC 2 explained 22.5% (day 1) with pH. PC 1 was loaded in the positive (+) direction with pH, cell viability, syneresis, fat and protein. Overall results indicated that UTNGt28 has the technological properties for further development of a new probiotic product.

Keywords: Lactococcus lactis; Streptococcus thermophilus; probiotic; protein; starter culture.

Figure 1

Variation of pH and acidity of the yogurt formulations at day 28 of storage. Legend: T1: UTNGt28 + S. thermophilus ATCC19258:1:1 (g/g); T2: UTNGt28 + S. thermophilus ATCC19258:1:3 (g/g); T3: UTNGt28 + S. thermophilus ATCC19258:3:1 (g/g); T4: UTNGt28; T5: LacAT+ S. thermophilus ATCC19258:1:1 (g/g); T6: LacAT+ S. thermophilus ATCC19258:1:3 (g/g); T7: LacAT+ S. thermophilus ATCC19258:3:1 (g/g); T8: LacAT; T9: S. thermophilus ATCC19258. Bars represent the pH and the solid line is % of lactic acid.

Figure 2

Comparison between cell counts of yogurt formulations at Day 28 of storage with refrigeration. The experimental values (means and standard deviations for n = 3) that have no common superscript are significantly different (p < 0.05); where a is the highest viability and e the lowest viability. Legend: T1: UTNGt28 + S. thermophilus ATCC19258:1:1 (g/g); T2: UTNGt28 + S. thermophilus ATCC19258:1:3 (g/g); T3: UTNGt28 + S. thermophilus ATCC19258:3:1 (g/g); T4: UTNGt28; T5: LacAT+ S. thermophilus ATCC19258:1:1 (g/g); T6: LacAT+ S. thermophilus ATCC19258:1:3 (g/g); T7: LacAT+ S. thermophilus ATCC19258:3:1 (g/g); T8: LacAT; T9: S. thermophilus ATCC19258.

Figure 3

Cell viability (CFU/g) during storage: A) UTNGt28-based formulations; B) LacAT-based formulations. Legend: T1: UTNGt28 + S. thermophilus ATCC19258:1:1 (g/g); T2: UTNGt28 + S. thermophilus ATCC19258:1:3 (g/g); T3: UTNGt28 + S. thermophilus ATCC19258:3:1 (g/g); T4: UTNGt28; T5: LacAT+ S. thermophilus ATCC19258:1:1 (g/g); T6: LacAT+ S. thermophilus ATCC19258:1:3 (g/g); T7: LacAT+ S. thermophilus ATCC19258:3:1 (g/g); T8: LacAT; T9: S. thermophilus ATCC19258. The values represent the means and standard deviations for n = 3.

Figure 4

Principal component analysis of yogurt data at day 1 (red circle) and 28 of storage (blue circle). Legend: T1: UTNGt28 + S. thermophilus ATCC19258:1:1 (g/g); T2: UTNGt28 + S. thermophilus ATCC19258:1:3 (g/g); T3: UTNGt28 + S. thermophilus ATCC19258:3:1 (g/g); T4: UTNGt28; T5: LacAT+ S. thermophilus ATCC19258:1:1 (g/g); T6: LacAT+ S. thermophilus ATCC19258:1:3 (g/g); T7: LacAT+ S. thermophilus ATCC19258:3:1 (g/g); T8: LacAT; T9: S. thermophilus ATCC19258. The UTNGt28-based formulations are indicated with red font and the LacAT-based formulations with blue font; the commercial starter S. thermophilus ATCC19258 is indicated with green font, for better visualization.