Effect of coconut powder as a drying carrier medium on long-term preservation of Lactobacillus plantarum and Streptococcus thermophilus for development of starter cultures with potential application in traditionally fermented foods
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Date
Authors
Zulu, Nontobeko Xolisiwe
Kunadu, Angela Parry-Hanson
Kayitesi, Eugenie
Dlamini, Bhekisisa
Journal Title
Journal ISSN
Volume Title
Publisher
Wiley
Abstract
Fermentation is of great importance to the food industry as it extends the shelf life of food while imparting desirable nutritional
and sensory properties. However, the unpredictable fermentation period, inconsistency of the final product quality, and
contamination with spoilage microorganisms of spontaneously fermented food remain a challenge. The aim of this study was
to explore the storage stability of Lactobacillus plantarum and Streptococcus thermophilus prepared by freeze-drying using
coconut powder (CCN) (25%) as a carrier medium in comparison to skim milk powder (SMP). Freeze-dried lactic acid
bacteria (LAB) were evaluated for cell viability, vitality, moisture content, water activity (aw), acidification kinetics, cell
morphology, and glass transition temperature (Tg). In general, LAB stored at 4°C showed better survival after 112 days than
LAB stored at room temperature (RT). With cell viability, the reduction in S. thermophilus and L. plantarum counts was not
significantly (p < 0 05) affected by the type of carrier media (CCN or SMP) after 112 days at 4°C. SMP supported better cell
vitality (approx. 2.0) at 4°C than CCN after 112 days for L. plantarum. The moisture content and aw were within acceptable
levels throughout storage on all samples. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM)
depicted a normal cell structure at 4°C for S. thermophilus and L. plantarum in SMP and CCN, while negative changes were
observed at RT. The Tg on all samples was above 75°C, and this suggested long-term stability of the LAB strains. Overall, our
findings show that CCN shows similar protection of L. plantarum and S. thermophilus strains to that of SMP during storage at
4°C. Further work is needed to confirm the fermentation performance of CCN-preserved strains.
Description
DATA AVAILABILITY STATEMENT : The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.
Keywords
Coconut powder, Freeze-drying, Lactobacillus plantarum, Storage stability, Streptococcus thermophilus, SDG-02: Zero hunger, SDG-12: Responsible consumption and production, Skim milk powder (SMP), Lactic acid bacteria (LAB), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM)
Sustainable Development Goals
SDG-02:Zero Hunger
SDG-12:Responsible consumption and production
SDG-12:Responsible consumption and production
Citation
Zulu, N.X., Kunadu, A.P.-H., Kayitesi, E. et al. 2024, 'Effect of coconut powder as a drying carrier medium on long-term preservation of lactobacillus plantarum and streptococcus thermophilus for development of starter cultures with potential application in traditionally fermented foods', Journal of Food Processing and Preservation, vol. 2024, art. 7030605, pp. 1-13. https://DOI.org/10.1155/jfpp/7030605.