is a percentage measure of the ability of a batch of grain to germinate. (Germination, in nature, is the first step in the development of a new plant from seed. In the malt house, it is the step between steeping the cleaned grain for proper hydration and drying it in a kiln or drum. See germination.) A grain’s viability rate is essential in assessing malt quality, because it is during germination that enzymes in the kernel’s skin, the aleuron layer, become active and start breaking down large-molecular nutrients into smaller molecules and thus make them accessible either to the new plant as food or to the brewer as starches that will become wort compounds. Because kernels that fail to germinate do not become malt, depending on their number, they can drastically reduce the quality of a malt shipment. Excessive wetness or drought in the fields, infestations of plant diseases and pests, poor malting procedures, and, most important, improper storage conditions can severely reduce viability. However, a perfect batch of grain, in which all kernels manage to germinate, is a rare occurrence. The brew industry, therefore, uses specific viability values below 100% as reasonable benchmarks for quality. The minimum acceptable viability for brewing barley and wheat varies from one maltster to the next, ranging from 92% to 98% for top-quality specialty malt. For rye, it is usually 85% to 90%. Grains with viability ratings below these thresholds are usually not suitable for brewing and tend to end up as animal feed.
