DOI: 10.5061/dryad.47d7wm3pk
title: Data from: Fermentation of the sugar kelp (Saccharina latissima) – exploring the potential of the kelp’s native microbiota as starter culture and the microbiological food safety of fermented products

description: This study investigated the use of native microbiota from the sugar kelp
 Saccharina latissima, in the form of fermented kelp fluid (FKF) from a
 spontaneous anaerobic fermentation process, as a starter culture (SC) for
 the fermentation of freshly harvested biomass of the same species. Rapid
 (&lt; 48 h) acidification (pH &lt; 4.3) was achieved for S.
 latissima inoculated with FKF, at a fermentation temperature of 21 °C.
 Kelp inoculated with a commercial strain of Lactiplantibacillus plantarum
 (Lp, positive control) reached a similar pH level after 5 days, while kelp
 with no SC (negative control) did not reach a pH level below 4.3 within
 nine days. The microbiota of the FKF-SC as well as the FKF-inoculated S.
 latissima samples was dominated by lactic acid bacteria (LAB) identified
 as L. plantarum. The SC in these samples successfully converted mannitol
 into lactic acid as the main fermentation product. In contrast, a higher
 production of acetic acid and ethanol was measured in the negative control
 samples compared to other groups reflecting a different microbial profile
 including marine bacteria which could not be identified by MALDI-TOF
 biotyping. Challenge trials of S. latissima samples from experimental and
 commercial fermentation processes with Bacillus cereus did not result in
 the growth of this food pathogen, even at pH levels within viable range
 for this species (pH &gt; 4.3). These preliminary results provide a
 foundation for further isolation of suitable SCs for kelp fermentation in
 commercial production and for assessing the food safety of fermented kelp.
description: The collected data results from monitoring the fermentation
 process, and quality and safety of fermented sugar kelp
 <em>(Saccharina latissima)</em> under 5 different conditions
 using laboratory methods. The variables analyzed include pH, dry weight,
 drip loss, concentrations of soluble sugars and organic acids (HPLC
 method), and microbial characterization of kelp samples using plating
 techniques and MALDI-TOF biotyping. 
description: # Data from: Fermentation of the sugar kelp (Saccharina latissima) –
 exploring the potential of the kelp’s native microbiota as starter culture
 and the microbiological food safety of fermented products
 [https://doi.org/10.5061/dryad.47d7wm3pk](https://doi.org/10.5061/dryad.47d7wm3pk) Stévant et al. 2024 Frontiers in Food Science and technology --- ## Description of the Data and file structure This dataset contains five files: i) from monitoring the fermentation process, and quality and safety of fermented sugar kelp (Saccharina latissima) under 5 different conditions using laboratory methods, ii) from a challenge test of commercially fermented S. latissima with the spore-forming food pathogen Bacillus cereus. Please note that all files are delimited with a semicolon and that decimal is a comma. #### File: raw\_ferm.csv **Description:** Raw data for pH, drip loss, dry weight (DW), water-soluble carbohydrates (glucose, fucose, and mannitol), organic acids (lactic and acetic acids), and ethanol. Empty cells indicate that the samples were not analysed for the given variable. ##### Variables * Sample * NO-SC-21: kelp did not receive any starter culture (SC), stored at 21 degrees * FKF-21: kelp inoculated with fermented kelp fluid (FKF), stored at 21 degrees * FKF-10: kelp inoculated with fermented kelp fluid (FKF), stored at 10 degrees * FKF+Lp-21: kelp inoculated with both FKF and *Lactiplantibacillus plantarum* (Lp), stored at 21 degrees * Lp-21: kelp inoculated with Lp, stored at 21 degrees * Fresh-SL: unfermented fresh kelp before the experiment * Replicate: sample replicates (categorical variable) * Time: sampling time (categorical variable) * Days: sampling time (numerical variable). Days after inoculation with SC * pH: expressed in pH units * Drip: drip loss during fermentation. Expressed in % of initial weight * DW: dry weight. Expressed in % wet weight * Glucose, Mannitol, Fucose, Lactic acid, Acetic acid, Ethanol: concentrations measured in fermented kelp samples by HPLC. Expressed in g/100g DW. #### File: bact\_count.csv **Description:** Raw data from bacterial counts on kelp samples during experimental fermentation. Empty cells indicate aberrant results which were discarded. ##### Variables * Sample * NO-SC-21: kelp did not receive any starter culture (SC), stored at 21 degrees * FKF-21: kelp inoculated with fermented kelp fluid (FKF), stored at 21 degrees * FKF-10: kelp inoculated with fermented kelp fluid (FKF), stored at 10 degrees * FKF+Lp-21: kelp inoculated with both FKF and Lactiplantibacillus plantarum (Lp), stored at 21 degrees * Lp-21: kelp inoculated with Lp, stored at 21 degrees * Replicate:sample replicates (categorical variable) * Time: sampling time (categorical variable) * Days: sampling time (numerical variable). Days after inoculation with SC * TAC: total aerobic counts, expressed in log(CFU/g) * YM: yeasts and moulds, expressed in log(CFU/g) * LAB: lactic acid bacteria, expressed in log(CFU/g) * SFae: aerobe spore-formers, expressed in log(CFU/g) * SFan: anaerobe spore-formers, expressed in log(CFU/g) #### File: maldi\_tof.csv **Description:** Summary of isolated and identified bacterial colonies grown on different substrates analyzed using MALDI-TOF biotyping. ##### Variables * Sample * NO-SC-21: kelp did not receive any starter culture (SC), stored at 21 degrees * FKF-21: kelp inoculated with fermented kelp fluid (FKF), stored at 21 degrees * FKF-10: kelp inoculated with fermented kelp fluid (FKF), stored at 10 degrees * FKF+Lp-21: kelp inoculated with both FKF and Lactiplantibacillus plantarum (Lp), stored at 21 degrees * Lp-21: kelp inoculated with Lp, stored at 21 degrees * Fresh-SL: unfermented fresh kelp before the experiment * FKF-SC: FKF used as SC to inoculate fresh kelp * Days: sampling time (numerical variable). Days after inoculation with SC * Colonies: categorize isolated colonies from plating and identified colonies from biotyping * Medium: growth medium * Marine: marine agar * YPD: yeast extract peptone dextrose * LB: Luria-Bertani agar * MRS: de Man, Rogosa and Sharpe agar * Counts (n) #### File: challenge\_2023.csv **Description:** Raw data from a challenge test of commercially fermented *S. latissima* with *Bacillus cereus*.  Missing values indicate that counts were below the limit of quantification of 2 log(CFU/g). ##### Variables * Sample * Control: kelp inoculated with *Latilactobacillus sakei* and autoclaved water, stored at 10 degrees * BC-10: kelp inoculated with L. sakei and B. cereus, stored at 10 degrees * BC-15: kelp inoculated with L. sakei and B. cereus, stored at 15 degrees * Time: sampling time (categorical variable) * Replicate: sample replicates (categorical variable) * Days: sampling time (numerical variable). Days after inoculation with SC * Var: categorize the analyzed variables * pH * Aer: Total aerobic plate counts * Bacillus: bacterial load of B. cereus * LAB: bacterial load of lactic acid bacteria * Value: result for each sample and variable. pH is expressed in pH units while Aer, Bacillus and LAB are expressed in log(CFU/g). #### File: Fermentation\_sugar\_kelp.R **Description:** R script that executes main data analyses. Uses the .csv files listed above as input files. ## Code/software The R script uses the .csv files as input files for further data analysis i.e. descriptive statistics, plots and repeated measures analysis of variance (RM ANOVA). The script uses the following packages: ggplot2, reshape, multcomp, lawstat, car, cowplot, lme4, dplyr, lsmeans, ARTool, lmerTest. ## Access information Other publicly accessible locations of the data: * These datasets are not publicly accessible in other locations Data was derived from the following sources: * These datasets were not derived from another source