Refrigeration should be in a range 32- 39F (0-4C). 

Without proper refrigeration the phytoplankton will quickly lose its nutritional value, even though it stays alive.  

The following graph is based on research published in the 2002 Marine Fish and Reef Annual by Fancy Publications. 

Refrigerated DT’s performed equally well for up to 4 months. At 6 months there was a slight but significant decrease in larval growth rates. Our “best if used by” date is based on a 5 month shelf life from the date of harvest. Larvae cultured on DT’s that was left at room temperature for just a few days, had a rapid decline in health and died within 8 days.

2. Shaking it up at least weekly:

Phytoplankton settles out of suspension and will die if left packed down on the bottom for too long. Shaking it up vigorously with the bottle inverted is necessary to wash the cells off the bottom. Shake at least once a week to prevent the phytoplankton from packing down. Immediate settling is normal and it does not need to be shaken up every day. Keeping up this maintenance is extremely important for the storage of this product.

3. Odor: There are several causes of odor in DT’s Live Marine Phytoplankton;

A. Sulfides produced by living phytoplankton: A small amount of sulfides are produced by some phytoplankton that are always in the product. Sulfides are very volatile and they come out of solution even at low temperatures. If the phytoplankton is kept at a temperature in the 40’s instead of the 30’s it will have more odor. If it warms up for even a short time, say during shipping, it will have more odor. Dimethylsulfide is produced by some phytoplankton and is associated with cryoprotection in algae. The levels found were very low ranging from 17 to 21 ppb (ppb = parts per billion). People are very sensitive to sulfides, which are detected at the very low levels of 0.5 ppm.

B. Decomposition of cellular detritus: It is impossible to separate every bit of the cellular detritus from the phytoplankton cells when it is harvested. Although we have several steps to remove as much of the cellular detritus as possible, some small amount is always present.

C. Natural phytoplankton odor: Some species such as the Chlorella simply smell stronger.

D. Mortality: While in storage a small percentage of the cells will die. In recent testing of DT’s Live Marine Phytoplankton, more then 90 % of the cells were still alive and intact after 13 weeks of storage. It is reasonable to assume that by the “best if used by date”, based on a 5 month shelf life, less than 15 % of the cells may die.

Any odor from the phytoplankton is most noticeable in the air that is trapped in the bottle, and it builds up over time. That is why a half empty bottle smells more than a full bottle, and a large bottle smells more than a small bottle. To remove the old air, squeeze the bottle until the phytoplankton is at the surface. While odor intensity is almost impossible to describe; it is normal for some odor of sulfides to be detected, particularly in DT’s that has been in storage for a while.

If a significant amount of the phytoplankton is dead, the intensity of the odor will be so strong that it is unlikely that anyone could stand smelling it. 

Comparisons of various phytoplankton in refrigerated storage:

As part of a study, one species of Isochrysis, Pavlova and Tetraselmis, were grown in the lab, refrigerated and observed along with the DT’s phytoplankton product to determine their survivability in refrigerated storage.  The results are as follows:

DT’s Live Marine Phytoplankton was refrigerated for 3 weeks before the beginning of the experiment (a) and at 4 (b), 7 (c) and 10 (d) weeks after the start of the trial. This product contains Chlorella sp. (6-8µm) and two Nannochloropsis sp., N. oculata (3-4µm) and N. salina (1-3 µm).

After 13 weeks of refrigerated storage, over 90% of the cells presented intact wall and
chloroplasts and only very few empty cells (ghosts) or cell debris are noticed.

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