Optimization of Bacterial Strains and Development of Fermented Seaweed

Abstract

This study aimed to understand the exploitation of bacterial strains used in various combinations to assist in the fermentation of seaweeds. The topic stems from the need to consider the valorization of seaweeds due to their abundance in natural habitats as well as their use as an innovative and sustainable food.
Fermentation is a traditional method that has been utilized for food preservation. It offers beneficial properties in addition to constituting a sustainable solution. Seaweed is an aquatic flora that is divided into three categories; brown, red, and green. In this study, the brown seaweed Alaria esculenta was considered. The starter cultures contained utilizing commercially procured lactic acid bacteria in their freeze-dried forms. The main species selected for this study were Lactobacillus strains; mainly involving L. plantarum, L. casei, L. paracasei, and L. rhamnosus.
Given that glucose and mannitol form some of the main saccharides readily available in brown seaweeds, they were evaluated as substrates to be utilized for the growth of the combined lactobacilli strains. Subsequently, it was seen that all the combinations of
the bacterial strains were able to use mannitol and glucose as substrates, by bringing about a pH drop in an industrially relevant timeframe. Analyzing the substrate consumption, it was found that mannitol consumption was over 50% in most of the
combinatorial co-cultures. Estimating the short-chain fatty acids in mannitol samples, it was observed that lactic, propionic and butyric acid were the only significant acids detected. Consequently, the bacterial combinations were applied for the fermentation
of seaweeds.
Upon analysis of the results, the optimal combination of bacterial strains was not identified due to equal amounts of positive results involving the samples. The seaweed fermentation experiments lasted 6 days although the pH decreased to 4.5 after 1 day. The optical density was closely correlated to the growth of the bacterial strains, which was also increased after 1 day in all of the co-cultures. As a long-term goal, the fermentation process is aimed to be designed to not only help improve the seaweed’s nutritional and storage properties but also to create a commercial product empowered
with a consumer-friendly taste and smell.

Popular Abstract

Exploring synergies – Fermentation and Seaweed!

What if seaweed could become more nutritious and be available in the market for everyone that wants to try innovative food? Seaweed is an aquatic plant that grows in any marine environment. Farmed seaweeds have skyrocketed as many of their applications have been developed a lot in the last years; industrial applications, food sources, fertilizers, and chemical extractions. However, seaweed has been used for many years all around the world, mostly in Asian countries, as its health benefits have been known. It provides high nutritional value; it contains a high amino acid profile and it is rich in protein, vitamins, and minerals. It also contains sugars like glucose and mannitol that can be fermented.
Fermentation is a globally used method that utilizes raw materials, with lactic acid bacteria (LAB) contribution, in order to develop food products that can be preserved longer and offer probiotic health benefits. Although fermentation is a process that has
been used in many other food products, like yogurt and sauerkraut, seaweed is a novel product its fermentation conditions are still under research. In this study, four different types of commercial freeze-dried bacterial strains and brown seaweed were mainly used.
A detailed experiment was designed to study how the fermentation process can work for seaweed. Firstly, an experiment was done to evaluate different lactic acid bacterial strains and to acknowledge if the strains could work synergistically when they are combined. Glucose and mannitol were the main carbon sources that combined cultures utilized. It was found that all of the co-cultures are able to ferment, as the bacteria
consumed the available carbohydrates. Moreover, at the end of the fermentation process, lactic acid was mainly produced from lactic acid bacteria. Finally, it was found that the seaweed can be fermented in a short time and reach a pH of 4.5 after 2 days.

• author: Milopoulou, Eleni
• supervisor: Ed van Niel
• organization: Applied Microbiology; Biotechnology
• course: KMBM01 20221
• year: 2022
• type: H2 - Master's Degree (Two Years)
• subject: Agriculture and Food Sciences
• keywords: fermentation, lactic acid bacteria, seaweed, cultivation, bacterial growth, applied microbiology
• language: English
• id: 9091598
• date added to LUP: 2022-06-21 10:51:12
• date last changed: 2022-12-01 03:41:03