The relationship between gushing and antifungal peptides in barley and malt kernels was examined for five barley varieties produced in the Czech Republic with four conditions of infection and treatment. Proteome changes during pathogen-seed interaction were observed with SDS-PAGE and MALDI-TOF MS. These methods were applied as a fast screening for observing the relationship between gushing and peptides/proteins. It was found that the presence of basic peptides, presumably hordothionins and non-specific lipid transfer protein type 1, did not correlate with the degree of gushing for malt (|r|Ao0.07, 0.344), (|r|Ao0.01, 0.494), respectively, as detected by both methods.
IntroductionCereal grains are the major source of dietary nutrients all over the world. Barley (Hordeum vulgare L.) is an ancient cereal, which, upon domestication, has evolved from largely a food grain to a feed and malting grain. Barley food use today remains important in some cultures around the world, particularly Asia and northern Africa, and there is renewed interest throughout the world in barley food because of its nutritional value [1]. Barley serves as an important model plant specie for numerous studies in malting and brewing chemistry [2]. Hence, there is an effort to assess product quality by analysis of the primary raw material, barley.Beer quality can be defined in terms of physical and sensory attributes. Pathogen infection on barley is often associated with many aspects of beer quality, e.g. gushing [3]. The term gushing is the uncontrolled release of carbon dioxide occurring when a bottle is opened and beer/foam gushes out; it is related mainly not only to beer, but also to non-alcoholic beverages [4]. Two types of gushing are described in beer. The primary gushing relates to fungal metabolites, i.e. gushing factor, which are present in malt or in other cereal raw materials of beer. The secondary gushing so-called non-malt related can be induced by production factors as are rough bottle surface, carbon dioxide supersaturation, high concentration of heavy metals, high content of oxalates, etc.The primary gushing of beer is associated with the grain being attacked by microscopic fibrous fungi, which is commonly caused by the Fusarium species and other genera such as Aspergillus, Rhizopus, Penicillium and Nigrospora species [4][5][6]. Gushing factors produced by fungi have been studied for decades. Fungal polypeptides (16.5 kDa hydrophobic peptides with eight disulphide bonds) [6][7][8] are produced and secreted by fungi and are involved in the formation of infection structures among other things [6,9]. This may explain that interaction of the fungi with substrate (in this case barley) was required for gushing occurrence [10]. Axcell et al. [11] suggested that gushing may be induced by antimicrobial peptides produced by barley in response to microbial contamination. Hippeli and Elstner [12] suggested that the gushing factor can/could be the member of the non-specific lipid transfer protein (nsLTP) multigenic family of proteins. Barle...
