Eleanor Ott and Dr. Randy Lewis, Chemical Engineering Department

Introduction

Food preservation is an issue in third-world countries around the world where electricity and monetary means are not present to maintain a modern refrigerator. The short shelf life of unrefrigerated food items creates waste, requires time and energy with frequent trips to buy food, and lowers quality of life. Multiple solutions for this problem have been devised which are principally applicable in Asia and Africa. Implementation of these solutions has increased shelf-life of perishable foods and eliminated the need for daily trips to the market for food. A natural consequence has been increased profits, more educational opportunities for women, and a greater variety in diet. However, while solutions have been devised and implemented successfully in other parts of the world, simple cooling systems remain relatively unexplored in South America. The goal is to find a solution that will work well in South American conditions and cultural practices, although the primary focus is to find a specific solution to preserve food on the Uros Islands located on Lake Titicaca, Peru. The Uros Islands are a group of approximately 80 man made reed islands. The amenities on the islands are very basic and limited, including electricity that is inconsistent and weak. The main contact in Peru is Dora Coila Lujana. She lives on one of these islands with her family and runs a restaurant that feeds tourists and other visitors that come to the islands several days each week. Running a restaurant is time-consuming and strenuous. Every other day Dora travels into Puno, a trip that requires at least four hours round trip and additional money for transportation within Puno. There she buys approximately 30 kg (over 70 lb) of fruits and vegetables and 4 chickens to supply the kitchen for that day and the next. Unfortunately, the meat goes bad within a day and many of the fruits and vegetables only last for two or three days. This means that Dora is required to throw away spoiled food if she was unable to use it in the restaurant, and has no other option than to make frequent trips to Puno. Additionally, she pays a premium of 25-40% by buying food during the week instead of on the weekends. Currently Dora does not have an effective means of food preservation. This project will allow Dora to save money by throwing out food less frequently, purchasing food when it is the least expensive, and making less frequent trips to Puno where she pays for transportation. The solution will also save Dora four hours every week. It will be sustainable as the cooling system will be low-cost and made from parts that can be purchased in Puno. The purpose of this project is to create a simple, low-cost non-electric refrigeration system using an innovative cooling system to extend useful shelf life of fish and chicken by 50% by May 2017. Currently the direct application of this project is for a restaurant located in Uros Islands, Peru.

Methodology

After much research and trial and error of multiple different systems, the system created to solve this problem uses ice to keep food cold and uses insulation to keep the ice from melting for as long as possible. It is a simple system with two main parts, an outside bucket and an inside bucket. Ice is placed between the two buckets and food is stored in the inner bucket. This system is then buried in the island and the reeds around the outside of the system provide insulation, which will help keep the ice and food cold. When full, the system holds 40 lbs of ice. If not refilled, the system can keep meat below 0 °C for up to 5 days. If refilled with 20 lbs of ice every 3-4 days, the system can remain at 0 °C indefinitely. Part 1 in Figure 1 is the outer bucket, this is a plastic, 100 L bucket and contains all the other pieces in the system: the inner bucket (part 2), the lid (part 3), and the small blocks that hold up the inner bucket (part5). The system is lowered into a hole in the island up to the handles. Wooden rods (Part 4 in Figure 1) are tied onto the handles to support the system and prevent it from sinking farther into the island. The cheapest way to get the wooden rods was to buy a broom with a wooden handle, take off the brush, and cut the handle in half. The outer container has small holes in the bottom that allow for the melted ice to exit the system.

Results

When full, the system holds 40 lbs of ice. If not refilled, the system can keep meat below 0 °C for up to 5 days. If refilled with 20 lbs of ice every 3-4 days, the system can remain at 0 °C indefinitely (See figure 2). The line labeled “food storage” shows what temperature the inside container was through the time period. Each decrease in temperature by 5°C doubles the shelf life of meat and fish. This means that this system will more that triple the shelf life of Dora’s food. Unfortunately, we were not able to monitor the system in place on the Uros Islands because of travel constraints. The tests run at BYU in Provo should prove to work the same if not even better because of the increase in insulation of the reeds on the island. Every year a Global Engineering Outreach group goes to the Uros Islands to work on projects and next year’s group will be able to check the sustainability of the cooling system.

Discussion

Some minor changes were made upon arrival in Peru due to the fact that the different materials were available. Most of changes had to do with a change in size of buckets and were very small differences. These parts were more difficult to find due to the lack language knowledge and the type of stores available. It would be beneficial to go to the shopping market with Dora or another native. It is hard to gauge how this system will affect Dora’s family. The system needs to be filled about everyday with ice to keep the system cold enough to be effective. When we spoke to Dora about this, she told us that this would not be a problem. We also had to be careful to not do anything that would take away from the culture of the Uros Islands. Culture is easy to destroy with the implementation of new inventions. I feel confident that this system will not take away from the culture, but instead increase the time they can spend on cultural activities.

Conclusion

The purpose of this project is to create a simple, low-cost non-electric refrigeration system using an innovative cooling system to extend useful shelf life of fish and chicken by 50% by May 2017. If Dora and her family use the system, then this project purpose was achieved. Dora will not need to boat into the closest town as often and she will be able to spend more time with her family.