Inhibitory effect of essential oils against Lactobacillus rhamnosus and starter culture in fermented milk during its shelf-life period

Abstract

The use of essential oils in foods has attracted great interest, due to their antagonistic action against pathogenic microorganisms. However, this action is undesirable for probiotic foods, as products containing Lactobacillus rhamnosus. The aim of the present study was to measure the sensitivity profile of L. rhamnosus and a yogurt starter culture in fermented milk, upon addition of increasing concentrations of cinnamon, clove and mint essential oils. Essential oils were prepared by steam distillation, and chemically characterised by gas chromatography-mass spectrometry (GC-MS) and determination of density. Survival curves were obtained from counts of L. rhamnosus and the starter culture (alone and in combination), upon addition of 0.04% essential oils. In parallel, titratable acidity was monitored over 28 experimental days. Minimum inhibitory concentration values, obtained using the microdilution method in Brain Heart Infusion medium, were 0.025, 0.2 and 0.4% for cinnamon, clove and mint essential oils, respectively. Cinnamon essential oil had the highest antimicrobial activity, especially against the starter culture, interfering with lactic acid production. Although viable cell counts of L. rhamnosus were lower following treatment with all 3 essential oils, relative to controls, these results were not statistically significant; in addition, cell counts remained greater than the minimum count of 10(8)CFU/mL required for a product to be considered a probiotic. Thus, although use of cinnamon essential oil in yogurt makes starter culture fermentation unfeasible, it does not prevent the application of L. rhamnosus to probiotic fermented milk. Furthermore, clove and mint essential oil caused sublethal stress to L. rhamnosus

Effects of using combined essential oils on quality parameters of bio-yogurt

“…Marafon et al () found the number of viable probiotics to be higher when spices cardamom and cinnamon were used, but not with nutmeg. Moritz, Rall, Saeki, and Júnior () reported the count of isolated L. rhamnosus treated with cinnamon EO to be reduced by 1 log, and cell counts were above the minimum count of 10 6 cfu/mL. Previously, De Lacey, Pérez‐Santín, López‐Caballero, and Montero () found green tea extracts to affect positively the survival of L. paracasei LAFTI‐L26, L. acidophilus LAFTI‐L10 and B. animalis ssp.…”

“…C1 containing probiotic culture and C samples were preferred more than the others in the present study. Moritz et al (2012) found in their study no statistical difference between the concentrations from 5% (lowest concentration) to 0.04% cinnamon EO and a mean acceptability score to be 6.28 for 0.04% cinnamon EO. Jimborean et al (2016) reported orange EOs fortified yogurt to get high acceptability score (7.50).…”

“…oil, titratable acidity (TA) increased during the storage period. Moritz et al () reported significantly higher titratable acidity for the samples containing only the yogurt starter culture and those with clove and mint EOs. Such results are in agreement with those found in the present study.…”

Effect of nisin and perilla oil combination against Listeria monocytogenes and Staphylococcus aureus in milk

“…PO is one of the naturally-flavored oils and obtained usually from roasted seeds to give good characteristic flavor. Yang et al (2012) reported the consumer acceptability of perilla oil porridges, Moritz et al (2012) have demonstrated that the consumer acceptability of essential oils used in fermented milk. In this research, nisin and PO synergistically and significantly inhibited the growth of S. aureus and L. monoctogenes in milk samples.…”

Lactobacilli and Clove Essential Oil Against Menace of E.COLI: A Possible Solution for Antibiotic Resistance

“…Only a sublethal effect of clove essential oil was observed against probiotic bacterial species L. rhamnosus, indicating the resistance of these microorganisms to clove essential oil. [50] This hints towards the possibility of harnessing their and E.coli, the optimum conditions for best activities of both-clove essential oil and lactobacilli, are a few criteria required to be considered to gain an overall increase in their combined anti-microbial actions.…”