Effect ofLactobacillus plantarumLS5 on oxidative stability and lipid modifications of Doogh

Rosmarinus officinalis L. Essential Oils Impact on the Microbiological and Oxidative Stability of Sarshir (Kaymak)

This study investigated the effect of Rosmarinus officinalis L. essential oil, REO (one, two and three percent) on the microbiological and oxidative stability of Sarshir during 20 days of refrigerated storage (4 °C). Initially, the chemical composition (gas chromatography/mass spectrometry, GC/MS), antimicrobial (paper disc diffusion) and antioxidant (DPPH) properties of REO were evaluated. Then, the microbial safety, oxidative stability (peroxide and anisidine values) and overall acceptability of the product after addition of REO to Sarshir and the subsequent storage period were determined. According to GC/MS analysis, the major components of REO were α-pinene (24.6%), 1,8-cineole (14.1%), camphor (13.5%), camphene (8.1%) and limonene (6.1%), respectively. Moreover, it was also found that Limosilactobacillus fermentum (inhibition zone (IZ) of 23.5 mm) and Salmonella Typhi (IZ of 16.4 mm) were the most sensitive and resistant spoilage and pathogenic bacteria against REO, respectively. In addition, the half-maximal inhibitory concentration (IC50) of the REO was measured at 24.8 mg/mL, while the IC50 value of butylated hydroxytoluene (BHT) was 16.6 mg/mL. The highest and lowest bacterial populations were detected in the control and the sample containing 3% REO, respectively. The control had the highest extent of lipid oxidation, while the lowest peroxide and anisidine values were measured in Sarshir containing 3% REO.

Fermentation of sarshir (kaymak) by lactic acid bacteria: antibacterial activity, antioxidant properties, lipid and protein oxidation and fatty acid profile

BACKGROUND

The antioxidant and antibacterial activities of fermented sarshir (traditional dairy food), with three probiotic Lactobacillus plantarum strains (LP3, AF1, and LU5), were investigated. The oxidative stability and the lipid profile of non-fermented and fermented sarshir were compared, in addition to radical scavenging activity, as well as peroxide, anisidine and carbonyl values (PV, AnV and CV, respectively).

RESULTS

The strong antibacterial activity of fermented sarshir against common pathogenic bacteria, including Gram-negative Escherichia coli O157: H7 ATCC 35150 and Pseudomonas aeruginosa ATCC 27853, as well as Gram-positive Bacillus cereus ATCC 10876 and Staphylococcus aureus ATCC 25923, was established. Among the strains examined, L. plantarum LP3 exhibited the highest radical scavenging activity (53.1 ± 1.8%) and lowest PV (3.0 meq kg^-1 ), AnV (1.31 ± 0.06) and CV (1.4 ± 0.08). The pH of sarshir decreased from 6.2 ± 0 to 3.5 ± 0.1 during 14 h of fermentation. Incorporated bacterial cells exhibited notable viability during 10 days of cold storage (4 °C).

CONCLUSION

The fermentation of sarshir by L. plantarum strains, especially LP3, resulted in beneficial changes in radical scavenging activity, as well as PV, AnV and carbonyl values, in addition to a broad spectrum of inhibitory activity against strains of P. aeruginosa, E. coli O157:H7, B. cereus and S. aureus. © 2017 Society of Chemical Industry.