Methods for Preserving Your Live Cultures
Starter cultures, a collection of microorganisms including bacteria, yeast, and mould, play a crucial role in fermentation processes. To ensure their longevity and viability, various storage methods are recommended.
Freezer Storage
Freezing is a common method for storing starter cultures, particularly those containing bacterial cultures. This includes yogurt cultures like vegan, matsoni, viili, Caldwell's Starter Culture, L. Reuteri Superfood Starter, and natto culture. Additionally, tempeh culture and Koji culture (miso, shoyu, amazake) benefit from freezer storage. Freezing slows down microbial and enzymatic activity, extending the shelf life of these starter cultures.
Refrigerator Storage
While freezing is the preferred method for bacterial cultures, some starter cultures are best stored in the refrigerator. Enzymes, used in the fermentation of food, are mainly stored in the fridge.
Specific Culture Storage Methods
Kombucha SCOBY
Kombucha SCOBY is typically stored hydrated in some sweet tea at room temperature for short periods. For longer storage, it can be refrigerated with some starter liquid. Long-term storage often involves drying or freezing methods, but specifics vary.
Milk Kefir Grains
Milk kefir grains are best stored in fresh sugar milk at room temperature with some sugar. They can be refrigerated but only for up to two weeks. To maintain their strength, they will need a few refreshment ferments after being refrigerated. Avoid rinsing grains to preserve protective bacteria. For longer storage, drying and freezing is recommended, although drying is the preferred method before freezing to maintain viability.
Water Kefir Grains
Water kefir grains are similar to milk kefir, best kept hydrated at room temperature in sugar water for ongoing use. Refrigeration is discouraged except for short-term storage (up to two weeks), after which grains may weaken. Drying and freezing grains is considered the best long-term preservation, ensuring viability after storage.
Mesophilic Cheese Starter Cultures
Mesophilic cheese starter cultures, such as Lactococcus lactis, are supplied as freeze-dried powders. These should be stored in the freezer to maintain viability until use. They can be kept frozen for extended periods, months to years, depending on packaging and conditions.
Spray-dried Lactobacillus
Spray-dried Lactobacillus cultures are also stored as freeze-dried powders. These should be stored at 4°C or -20°C. Lower temperatures significantly improve the survival and stability of these cultures, with 4°C preferred for cost-effective storage.
Long-term Storage
For long-term storage, drying (freeze-drying or spray-drying) combined with freezing is the gold standard. Hydrated cultures generally have shorter shelf lives and require periodic refreshment to maintain health.
Summary
In all cases, lower temperature storage improves culture viability, and drying (freeze-drying or spray-drying) combined with freezing is the gold standard for long-term preservation. It is always recommended to follow the manufacturer's recommendations for starter culture storage.
This guidance is consistent across scientific studies and practical fermentation resources.
Storage and Duration Table
| Starter Culture | Storage Method | Optimal Temp | Storage Duration | Notes | |--------------------------|------------------------------------------------|--------------|--------------------------------|----------------------------------------------------------------------------------------| | Kombucha SCOBY | Hydrated in sweet tea, refrigerated or dried | RT to fridge | Days to weeks (rehydrate if dried) | Drying/freezing possible for longer storage, specifics vary | | Milk Kefir Grains | Fresh milk with sugar or dried + frozen | RT or fridge | RT: ongoing; Fridge: ≤2 weeks | Drying + freezing best for long-term; avoid rinsing grains | | Water Kefir Grains | Sugar water at RT or dried + frozen | RT or fridge | RT: ongoing; Fridge: ≤2 weeks | Drying + freezing best for long-term storage | | Mesophilic Cheese Starters| Freeze-dried powder, store frozen | Freezer | Months to years | Freeze immediately on receipt for prolonged shelf life | | Spray-dried Lactobacillus| Freeze-dried powders stored at 4°C or −20°C | 4°C or −20°C | At least 2 months | Higher survival at lower temps; 4°C preferred for cost effective storage[1] |
[1]: Source for scientific study on probiotic and bacterial culture storage [2]: Source for practical fermentation resources on starter culture storage
- In the realm of health-and-wellness, several starter cultures used in food-and-drink production, such as yogurt cultures, tempeh culture, and Koji culture, are preserved in the refrigerator or freezer to maintain their viability.
- When considering long-term lifestyle changes, it's worth noting that the storage techniques for starter cultures in cooking, like Kombucha SCOBY and milk kefir grains, can involve drying, freezing, or a combination of the two, depending on the specific culture and desired storage duration.
