ISO 6540 specifies two methods — a basic reference method for the determination of the moisture content of maize grains and ground whole maize, groats, grits, and maize flour; and a routine method for the evaluation of the moisture content of maize in whole grains. However, the routine method is not suitable for use for experts’ reports, or for calibration or checking of humidity meters, because of its significant bias to the reference method.
Meanwhile, the basic reference method and the routine reference method relating to cereals are only applicable to other cereals than maize and cereal products. Therefore, ISO 6540 has been developed to specify the two methods for maize, based on research works published in 1979.
ISO 6540 on the determination of moisture content in maize is particularly useful for the agricultural and food industry. The users include but are not limited to:
As maize has a very high moisture content (sometimes as much as 40% mass fraction) and as its size and texture make it hard to detect moisture, measurement of moisture in maize poses challenges in terms of grinding and pre-drying.
Consequently, to allow the pre-drying and grinding to be avoided, ISO 6540 also describes a routine method for whole grains, which is easier to use and allows working in series. Its response time is longer but the workload is lower, because of the absence of grinding.
As the moisture content determines the processibility, shelf-life, usability, and quality of the product, ISO 6540 provides procedures and methods that help ensure optimal quality of products and services throughout the supply chain in the food industry.
BS EN ISO 6540:2021 supersedes ISO 6540:1980. BS EN ISO 6540:2021 includes some technical changes with respect to ISO 6540:1980. This includes:
EN ISO 6540
ISO 6540