Abstract
This study evaluated the influence of three inactivated yeast derivatives (IYDs) used in wine production, namely OptiRed®, OptiWhite® and Noblesse®, on the viability of the probiotic strain Lactobacillus rhamnosus HN001 in an acidic environment. Addition of the IYDs at 3 g/L significantly enhanced the survival of the probiotic bacteria by 2.75–4.05 log cycles after 10-h exposure in a pH 3.0 buffer. Acid stress assay with IYD components obtained after centrifugation and filtration revealed that water-soluble compounds were responsible for improving the acid tolerance of L. rhamnosus HN001 for all three preparations. Differences in protective effect amongst the IYDs on L. rhamnosus HN001 were observed when permeates and retentates of the water-soluble extracts, obtained through ultrafiltration with a 2 kDa membrane, were assayed against the lactic acid bacterium. Chemical analysis of the water-soluble components suggests that low molecular weight polysaccharides, specific free amino acids and/or antioxidants in the 2 kDa permeates could have contributed to the enhanced survival of L. rhamnosus HN001 during acid stress. The contrast amongst the 2 kDa retentates’ viability enhancing property may have been attributed to the differences in size and structure of the higher molecular weight carbohydrates and proteins, as the survival of the probiotic did not relate to the concentration of these compounds. These results suggests that oenological IYDs could potentially be applied to probiotic foods for enhancing the acid tolerance of the beneficial microorganisms, and consequently prolonging the shelf life of these products.
Highlights
Enhancing the survival of probiotic bacteria in acidic environments such as fermented food carriers and gastric juice is crucial for ensuring their optimal function as health promoting agents
For the negative control assay that was devoid of inactivated yeast derivatives (IYD) and live yeast, the viability of L. rhamnosus HN001 declined sharply after 6 h, leading to a 4.21 log cycle reduction in surviving probiotic bacteria at the end of the 10-h exposure period
Protective effects of water‐soluble and insoluble components of inactivated yeast derivatives Considering the partial solubility of the three IYDs in the buffer used for the acid stress assay, the autoclaved IYD extracts were centrifuged to obtain the water-soluble and insoluble fractions for preliminary investigation of the components responsible for enhancing the survival of L. rhamnosus HN001 in the acidic buffer
Summary
Enhancing the survival of probiotic bacteria in acidic environments such as fermented food carriers and gastric juice is crucial for ensuring their optimal function as health promoting agents. Kefir and cheese are the most popular vehicles for delivering probiotics to consumers. These food products are manufactured by fermentation with bacterial and/or yeast starter cultures, together with the probiotic bacteria, for improving the organoleptic properties of the milk and to allow propagation of the beneficial microorganisms to sufficient numbers required to exert their health effects (Heller 2001). Lactic acid is produced in the cytoplasm of starter and probiotic lactic acid bacteria (LAB) as an end-product of glycolysis.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
