Finding the perfect moisture for coffee beans
Getting the perfect cup of coffee has many steps before you can enjoy that rich aroma and taste. Controlling moisture content is essential to ensure the highest quality.
With its focus on bringing every coffee drinker the perfect cup, the coffee bean processing industry must ensure quality at every stage. One of the critical parameters that needs to be measured and controlled at many of these stages is the coffee beans’ moisture content.
Accurate, repeatable inline moisture measurement is essential to the coffee bean processing industry and the latest Digital Microwave Technology makes this possible, ensuring a plant-wide solution that can guarantee final product quality.
Controlling moisture from bean to pack
Controlling moisture can bring benefits at many stages of the process, but until now, the high purchase costs and the extensive maintenance required by existing solutions has restricted where this technique can be used.
Many stages of the process, from the green beans to final packaging of the finished product, demand moisture control to improve the yield and quality of the coffee.
Laboratory tests
Laboratory tests are standard procedures used in the process. In these, the moisture content of a collected sample is determined by heating it until all the water has evaporated and only the dry material remains. The difference in the weight of the sample before and after heating allows the moisture content to be calculated.
One drawback of this method is the extensive time required, making it impossible to provide valuable real-time feedback to control the process. Also, as only small quantities of the large volumes of product flow are tested, this type of test is often not representative because of the sampling errors it introduces.
Online moisture sensors
Online moisture sensors allow continuous, rapid measurements of the material flow, and several different types are available. However, the high degree of accuracy and stability required during the coffee production process means that not all measurement techniques are suitable.
Microwave moisture measurements
Techniques based on microwave moisture measurement techniques are recognised as giving a very high degree of precision and accuracy. Yet, one often overlooked factor in microwave technology is the linearity and stability of the measurement.
Older technology, as used in analogue microwave sensors, has a nonlinear measurement, meaning that the sensor reading, and the actual moisture content are not directly proportional. This makes these sensors very difficult to calibrate as they require numerous points to fit the curve. Their nonlinearity also implies that they offer low accuracy (see the red line in the figure).
Digital multi-frequency technique
Hydronix sensors use a digital multi-frequency measurement technique. The advantage here is that this provides a linear measurement, where the sensor value and water content are directly proportional to each other. The sensor is more accurate throughout the moisture range and can be calibrated more precisely (the blue line in the figure).
Because it removes the need for recalibrations after commissioning, this has lower lifetime costs and is the recommended method for all coffee producers.
Rugged sensors
Each Hydronix sensor is made up of a single, intelligent unit that contains all the necessary on-board functionality, including signal processing and averaging. The sensors are also built from high-quality materials, contributing to extreme reliability and high durability.
