Application of surface enhanced Raman spectroscopy (SERS) for the rapid detection and enumeration of probiotics in yogurt

Abstract

Probiotics are a critical component in fermented dairy products such as yogurt. An efficient method to enumerate probiotics in commercially produced yogurt is important, but traditional methods are time-consuming, sometimes taking up to 72 hours. The objective of this study was to develop a rapid method using surface-enhanced Raman spectroscopy (SERS) to identify and enumerate probiotic bacterial cells in yogurt. The identification and enumeration of three different probiotic bacterial strains, Lactobacillus acidophilus, Lactobacillus bulgaricus, and Streptococcus thermophilus were successfully conducted using a developed SERS protocol. L. bulgaricus and S. thermophilus were also identified from a yogurt matrix using a simple extraction procedure utilizing a Percoll gradient. Statistical spectral analysis including principal component analysis and partial least squares regression analysis allowed for the differentiation, characterization and quantification of probiotic strains. The limits of detection were 105 CFU mL−1 for L. acidophilus, 104 CFU mL−1 for L. bulgaricus, and 106 CFU mL−1 for S. thermophilus. Quantification capability was tested up to 108 cfu mL−1 and showed strong correlation coefficients (0.94, 0.98 and 0.95 respectively) between predicted and actual concentrations. The presence of probiotic mixtures were clearly detectable from a yogurt food matrix starting at 105 CFU mL−1. Sample analysis took less than three hours per sample set. Our results demonstrate the capability of SERS to detect and enumerate probiotics from a yogurt matrix rapidly.

Graphical abstract: Application of surface enhanced Raman spectroscopy (SERS) for the rapid detection and enumeration of probiotics in yogurt

Supplementary files

Article information

Article type
Paper
Submitted
05 Jun 2025
Accepted
15 Sep 2025
First published
01 Oct 2025
This article is Open Access
Creative Commons BY-NC license

Anal. Methods, 2025, Advance Article

Application of surface enhanced Raman spectroscopy (SERS) for the rapid detection and enumeration of probiotics in yogurt

K. Allen, G. Ahlborn, J. Wangsgard and S. Pang, Anal. Methods, 2025, Advance Article , DOI: 10.1039/D5AY00931F

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements