Chlorella Shipping Experiment

Introduction

We ship Chlorella via USPS Priority Mail to all continental U.S. addresses. For a single bag, we package the Chlorella in a small flat-rate box. During the summer, we usually include an ice pack to help prevent overheating in transit, although Chlorella is generally heat-tolerant and issues are not expected.

In this experiment, we aim to understand the temperatures the package encounters during transit and the condition of the Chlorella during extended shipping times.

Material and Methods

Figure 1:The package content that reflects our typical Chlorella shipment in the summer (with an additional temperature sensor).

We packaged 8 oz of Chlorella in a small flat-rate box, along with a single ice pack. A temperature sensor was included to log the temperature throughout the entire transit, with readings recorded at 1-minute intervals. The data was retrieved at the end of the experiment.

The package was shipped from San Diego to Orlando, a relatively hot destination during the summer, and then back to San Diego using the same service. The timeline summary is provided in the table below. It’s important to note that the drop-off location in San Diego was an outdoor USPS drop-off box, while in Orlando, the drop-off was in an indoor mailroom.

Table 1: Summary of the timeline of the shipment.

Results and Discussion

Transit Temperature

Overall, the package’s temperature closely mirrored the day-night cycle, suggesting that it was likely not stored in temperature-controlled environments during transit (Figs 2 and 3). The only time the temperature remained stable was when the package was at the USPS distribution centers in both San Diego and Orlando.

The temperature peaked at around 29°C on the first day, likely due to the outdoor mailbox being heated by the sun. There was no exposure to extreme heat throughout the transit.

Figure 2: Temperature during transit from San Diego to Orlando

Figure 3: Temperature during transit from Orlando to San Diego

Chlorella Conditions

Surprisingly, after 12 days in transit — including about a week of idle time at room temperature in Orlando — the Chlorella arrived back in San Diego in relatively good condition. The Chlorella bag remained green with no unpleasant odor (Fig. 4), indicating that the culture was still viable and suitable for feeding.

Microscopic observation revealed that the Chlorella cells were less healthy than when freshly harvested (Fig. 6). The bag contained a mix of both healthy and unhealthy cells, with the unhealthy ones showing signs of chloroplast reduction (Fig. 5). Despite this, the overall condition of the Chlorella was still sufficient for both feeding and culturing.

Figure 4: The 8oz Chlorella bag after 12 days (no refrigeration).

Figure 5: Chlorella cells after 12 days under microscope showing unhealthy cells with healthy cells.

Figure 6: Chlorella cells immediately after harvest showing all healthy cells.

Conclusion

This experiment gives an example of a data collected during a Chlorella shipment across the country. Even though it is not an exhaustive experiment, it does demonstrate that the temperature during transit is not harmful to Chlorella, even during peak summer conditions. It also highlights Chlorella’s resilience in withstanding prolonged transit times without refrigeration. Chlorella shows surprisingly long shelf-life and heat-tolerance that makes it a good candidate for many aquaculture application. These results give us confidence in shipping Chlorella to customers across the continental U.S. during the summer.