Abstract
Nourishment of the growing human population requires new and alternative food sources, preferable produced without occupying new land areas. Cultivation of seaweed presents an opportunity, however, a major obstacle is sustainable preservation. Fermentation has been used for centuries to preserve vegetables, e.g., to produce kimchi based on cabbage. This study investigated changes in the microbiota, characteristics (pH, organic acids and water soluble carbohydrates) and food safety of raw shredded Alaria esculenta and Saccharina latissima during fermentation by the natural microbiota with or without addition of a Lactiplantibacillus plantarum starter culture. The Lb. plantarum fermented products retained a high Shannon diversity index, indicating a partially unsuccessful fermentation. Lb. plantarum performed better in A. esculenta causing pH to drop to below 4.6, a critical limit for control of growth of Clostridium botulinum, within 2 days compared to 7 days for S. latissima. Natural fermentation by the endogenous microbiota resulted in unsafe products with high final pH values (4.8–5.2), presence of unwanted organic acids, such as butyric acid, and in the case of A. esculenta sustenance of inoculated Listeria monocytogenes. Fermentation of A. esculenta and S. latissima by Lb. plantarum is a promising preservation method. However, future work is needed to optimise the process, by investigation of the use of different starter cultures, seaweed pre-treatments (blanching, freezing, etc.) and adjuvants (i.e., addition of sugars, minerals and similar) to promote growth of the starter culture and ensure the fermented products are safe to eat.
Highlights
The growing human population constitutes a significant challenge for global food production and security
This study investigated changes in the microbiota, characteristics and food safety of raw shredded Alaria esculenta and Saccharina latissima during fermentation by the natural microbiota with or without addition of a Lactiplantibacillus plantarum starter culture
The buffering capacity of A. esculenta used in this study is unknown and the mannitol content is at a lower level compared to S. latissima, 10.4 ± 3.9 and 18.0 ± 8.5% of dry matter (DM), respectively, which are comparable to levels previously reported (Schiener, Black, Stanley, & Green, 2015)
Summary
The growing human population constitutes a significant challenge for global food production and security. The arable area available for food production has not increased since 1992 (FAO, 2020). From 2005 to 2015, the annual global seaweed production increased from 13.5 to 30.4 million tons per year, making it one of the fastest-growing food sectors with a projected global seaweed production in 2050 of 500 million tons (FAO, 2018; World Bank Group, 2016). Today the seaweeds are utilised for human consumption (Mahadevan, 2015), food additives (Bixler & Porse, 2011), animal feed (Rajauria, 2015) and biofuels (Marquez et al, 2015)
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