Maintaining Freshness
Maintaining the long-term freshness of stored fruits and vegetables has challenged people throughout human history. Technological advancements have been developed by nearly all participants in the supply chain including growers, traders and consumers. Once harvested, the freshness and quality of the fruit and vegetable starts to diminish. Placing the produce into the proper conditions maintains its freshness over time. Results indicate that with proper climate control and monitoring, fruits and vegetables can last 3-4 times longer than under non-controlled conditions. These conditions can be monitored using E+E Elektronik CO2, humidity, and temperature sensors.
Traditional farming creates specific harvesting seasons such as the summer and autumn. However, demand for high-quality produce can remain steady throughout the year. In order to maintain a continuous supply, fruits and vegetables are stored under very specific and stable conditions. Potatoes, carrots, onions, apples, pears, and cherries all need different climates to maintain their freshness. Any change to the temperature, humidity, and CO2 levels of their storage environment can cause early ripening and aging. Controlling these conditions is critical to maintain freshness and reduce waste.
ULO/XLO Storage and Climate Control
One way to slow down the aging of fruits and vegetables is to store them in ultra or extremely low oxygen (ULO/XLO) environments. O2, C2H4, and CO2 concentrations impact the rate at which produce ripens and ages. Controlling exposure to these gases is essential but not the only factor. Temperature and relative humidity are also critical and must be controlled with a reliable air conditioning system. These systems rely on accurate sensors. Maintaining a proper climate has proven to keep fruits and vegetables fresh until the next harvest replaces the existing supply. By controlling these key variables, this method also reduces the need for harsher storage methods that use chemicals.
ULO and XLO technologies can achieve O2 concentrations from 0.7% to 1.0% at fruit-specific CO2 levels. Under these conditions, the fruit does not degrade.
Typical Storage Conditions
| Parameter | Value |
|---|---|
| O2 | < 2% |
| Temperature | 0.5 – 5.0 °C |
| CO2 | 0.0 – 5.0% |
| Humidity | Up to 98% rH |
Monitor Conditions with Highly Precise Sensors from E+E Elektronik
The above-described conditions turn storage into demanding applications. Precise, stable, and moisture-resistant CO2, temperature, and humidity sensors from E+E ensure accurate readings over long periods of time in these conditions.
EE211 Series Sensor
The EE211 series sensor features a heated humidity probe designed to deliver accurate measurements even under continuous high humidity conditions. The anti-corrosive E+E sensor coating is formulated for industrial use, making it useful for agricultural applications as well.
EE872 Sensor
The heated EE872 features a NDIR two-beam CO2 sensor that automatically compensates for the effects of age and pollution. The IP65 housing and replaceable sensor module also improve reliability.
EE210 Outdoor Sensor
Additionally, measuring temperature and humidity outdoors is important. The EE210 Outdoor is the right choice to do so. Not only does it read temperature and relative humidity, but it can also offer dew point, frost point, and specific enthalpy. Its electronics are sealed, and a special E+E coating on the sensor element ensures that the device will work in dusty outdoor conditions. Additional protection is provided with the HA010501 radiation shields. These protect the probe from solar radiation and precipitation while allowing natural ventilation. This natural ventilation also helps to maintain a short response time.
Challenges and Solutions
The Challenge
- Provide stability in high humidity over long periods of time
- Maintain accuracy even at low temperatures
- Ensure no interruption to the storage operation
- Easy device maintenance and calibration
The Solution
- EE872 for CO2 monitoring
- EE211 for humidity / temperature monitoring
- EE210 Outdoor for monitoring the outdoor climate
Product Benefits
- Heated probes provide long-term stability
- Excellent measurement accuracy
- Interchangeable sensor modules
- Reliable in rough and condensing conditions
- Easy to integrate to ensure safe storage
Overall Value
- Maintaining the freshness and firmness of the fruits and vegetables improves total yield
- Reduced cleaning costs
- Competitively priced
