Endosperm Modification is produced by the actions of enzymes that result in the development of brewer’s extract in the endosperms of cereal grains during malting. Milling and mashing of malted grains will turn potential extract into “brewer’s extract.” The potential extract of malted barley develops during the malting process. During malting the germinated embryo secretes natural plant hormones called gibberellins (e.g., gibberellic acid) into the adjoining aleurone layer.
Some of these factors are determined by varietal characteristics; some are related to malting practice such as applying enough steeping time to ensure that hydration of the grain is optimal and that husk-microbial levels are kept low. During malting, only about 10% of endosperm starch is broken down. However, protein breakdown, which is mainly from hordein, is about 40%, whereas cell wall breakdown, in terms of beta-glucans, is about 90% in well- modified malts. Degrees of endosperm modification can be described as under-modified, well-modified, or over-modified. In under-modified malt, extract development in the brewhouse may be suboptimal and extract may conceal insufficient breakdown of cell wall and protein materials, which could cause problems such as slow wort and/or beer filtration and haze development. In over-modified malts, milling may produce too much flour, slowing wort filtration and lowering extract yield. Protein breakdown may be excessive, which could lead to excessive color development, reduced foam potential, and excessive levels of amino acids. The injudicious blending of malts of different modifications can conceal potential brewing problems, although modification specifications may have been met analytically. All cereals can be malted. However, the principles of modification are unlikely to be identical to that of barley malt. Malted wheat has high foam potential but contains high levels of gluten. In contrast, malted sorghum is used to make gluten-free beer.