Yeasts preservation: alternatives for lyophilisation.

Area of Science:

• Microbiology
• Food Science
• Biotechnology

Background:

• Starter cultures are crucial for fermentation processes.
• Traditional preservation methods are often low-cost and accessible.
• Lyophilisation is a standard but resource-intensive preservation technique.

Purpose of the Study:

• To compare the efficacy of two low-cost, low-technology drying methods against standard lyophilisation for preserving yeast starter cultures.
• To evaluate the viability of yeast cells after storage using different preservation techniques.

Main Methods:

• Yeast starter cultures were preserved using lyophilisation, dry rice cakes, and dry plant fibre strands.
• Viable cell counts were assessed over 6 months of storage at 4°C and 25°C.
• Specific yeast strains, including Saccharomyces cerevisiae and Issatchenkia orientalis, were examined.

Main Results:

• No significant loss in viable yeast cell counts was observed after 6 months at 4°C for lyophilised cultures and those preserved in dry rice cakes.
• At 25°C, lyophilised cultures and those on dry rice cakes showed minimal viable cell loss up to 4 months.
• Yeast cultures preserved in dry plant fibre strands exhibited the highest loss of viable cells during storage at 25°C.

Conclusions:

• Preservation of yeast starter cultures in dry rice cakes demonstrated superior or comparable survival rates to lyophilisation, particularly at 4°C.
• Traditional, low-technology drying methods are effective for starter culture preservation in resource-limited, small-scale settings.
• Dry rice cake preservation presents a viable, cost-effective alternative to lyophilisation for specific applications.