Short communication: Influence of an aqueous myrrh suspension on yogurt culture bacteria over yogurt shelf life

Abstract

Myrrh is an essential oil and natural flavoring approved by the US Food and Drug Administration, and it has antibacterial and antifungal activity against pathogens. Our objective was to determine the effect of an aqueous myrrh suspension on Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus counts in peptone solution and yogurt, as well as pH and titratable acidity of yogurt during 5 wk of storage at 1 to 4°C. The myrrh suspension (10% wt/vol) was prepared and incorporated into a pure culture dilution in peptone and into yogurt mix at a 1% (vol/vol) level. A control with no myrrh was also prepared, and 3 replications were conducted. Streptococcus thermophilus were enumerated using Streptococcus thermophilus agar with aerobic incubation at 37°C for 24 h, and Lactobacillus delbrueckii ssp. bulgaricus were enumerated using de Man, Rogosa, and Sharpe agar adjusted to pH 5.2, with anaerobic incubation at 43°C for 72 h. During the 8-h period after inoculation, S. thermophilus and L. delbrueckii ssp. bulgaricus counts in peptone solution at 37°C and 43°C, respectively, were not significantly different in the presence or absence of the aqueous myrrh suspension. Counts of S. thermophilus in yogurt containing myrrh (mean ± SD; 4.96 ± 0.58 log cfu/mL) were not significantly different from those in the control yogurt (4.87 ± 0.39 log cfu/mL). The log counts for L. delbrueckii ssp. bulgaricus in yogurt containing myrrh (5.04 ± 1.44 log cfu/mL) and those of the control (5.52 ± 1.81 log cfu/mL) did not differ, and the counts remained within 1 log of each other throughout 5 wk of storage. The pH of the yogurts containing the aqueous myrrh suspension was not significantly different from that of the control yogurts, and their pH values were within 0.1 pH unit of each other in any given week. Titratable acidity values remained steady around 1.1 to 1.2% lactic acid for both yogurt types throughout the storage period, with no significant differences between them. Yogurt culture bacteria can survive in the presence of a myrrh suspension in yogurt with no significant change in pH or titratable acidity. Therefore, it may be beneficial to add an aqueous myrrh suspension to yogurt.

Nanoemulsion with Coconut Oil and Soy Lecithin as a Stable Delivery System for Lycopene and Its Incorporation into Yogurt to Enhance Antioxidant Properties and Maintain Quality

“…bulgaricus count compared to Y (P < 0.05). A similar observation was made by Alhejaili 46 in their attempt to find the influence of an aqueous myrrh (essential oil) suspension on yogurt culture bacteria.…”

“…THe DPPH assay was performed to measure the antioxidant activity of different yogurt samples. As per the results (Figure b), LNEY exhibited a higher antioxidant activity of 30% on the first day that eventually increased to a maximum of 40% in the second week of storage due to the interaction of lycopene with biologically active peptides released from milk as a result of the metabolic and proteolytic activities in yogurt upon storage. − Such a high level of radical scavenging activity in LNEY signifies the power of the nanoemulsion as an effective carrier for a sensitive antioxidant pigment like lycopene. − In the case of LY, the maximum scavenging activity exhibited was during the first week (25%), and later, it was decreased to 20% during the fourth week of storage. The study of Erica and Vassilios indicated that the enhanced stability of the lycopene improved the antioxidant property of the lycopene-incorporated beverage emulsion.…”

Physicochemical, microbiological, and sensory characteristics of probiotic yogurt enhanced with Anethum graveolens essential oil

“…Various levels of herb EOs can affect the activity of bifidobacteria and lactic acid bacteria (LAB) in dairy products and this has been evaluated by researchers (Mahmoudi, Zare, Hassanzadeh, & Nosratpour, ). The relationship between the concentration of DEO and antimicrobial effects remains uncertain, although some works have attributed the EO S antimicrobial characteristics to the presence of oxygenated monoterpenes in the EO, such as linalool, limonene, and α‐phellanoidrene (Alhejaili et al, ). Compared to other gram‐positive bacteria, LAB are usually considered as the most stable bacteria against essential oils of plants (Mahmoudi et al, ).…”

“…In another study by Tseng and Zhao (2013) using of dietary fiber with thyme, garlic, and mint showed increase in probiotic bacteria population in yogurt during storage time. Various levels of herb EOs can affect the activity of bifidobacteria and lactic acid bacteria (LAB) in dairy products and this has been evaluated by researchers (Mahmoudi, Zare, Hassanzadeh, & Nosratpour, 2014 (Alhejaili et al, 2019). Compared to other gram-positive bacteria, LAB are usually considered as the most stable bacteria against essential oils of plants (Mahmoudi et al, 2014).…”

Quality characteristics of yogurts fermented with short-chain fatty acid-producing probiotics and their effects on mucin production and probiotic adhesion onto human colon epithelial cells

“…Titratable acidity was measured by titrating 10 g of the yogurt blended with 10 mL of distilled water using 0.1 N NaOH solution until pH 8.3. Titratable acidity was calculated as percent lactate (Alhejaili et al, 2019). Titratable acidity was calculated as below: Titratable acidity (%) = used NaOH (mL) × 0.009/weight of yogurt (g) × 100, where 0.009 is the conversion factor for lactic acid.…”