The Influence of Lactic Acid Bacteria on the Quality of Malt

Abstract

In this study three strains of lactic acid bacteria were applied during the malting process to evaluate the impact on malt and wort quality. The trials were performed in a micromalting plant simulating an industrial malting programme. The samples were compared to chemically acidified as well as non-acidified malt. Bacterial cultures were chosen with reference to their enzymatic (proteolytic /amylolytic) activity, or their good acidifying properties. The effects of lactic acid bacteria on wort characteristics were investigated and compared to wort produced from 100% unacidified malt. A chemical food grade lactic acid was also used to acidify the barley for comparison purposes. Characteristics such as pH, extract, colour, viscosity, total soluble nitrogen, free amino nitrogen, apparent fermentability, ␤-glucan and lautering performance of the resultant worts were determined. Results showed improved levels of ␤-glucanase in the malt although reduced malt friability was observed where LAB was employed. An improved lautering performance, lower wort viscosity and elevated TSN levels were also reported where LAB exhibiting protease activity were applied.

Characterisation of barley-associated bacteria and their impact on wort separation performance

“…All worts, however, showed similar levels of viscosity. These results are in line with observations made by other research groups, who also did not report any correlation between the content of β-glucan and the viscosity of wort (33,34). Barley cell wall β-glucans could not be identified as the components causing filtration difficulties.…”

125thAnniversary Review: Bacteria in brewing: The good, the bad and the ugly

“…The second most prevalent LAB, Pediococcus damnosus , has the ability to produce a variety of undesirable flavours and aromas, including diacetyl . Some LAB have been reported to lower the quality of malt ; however, select strains of LAB are used to improve a number of malt characteristics . They also have the ability to produce a variety of biogenic amines that pose a potential health threat .…”

The effect of acidic steeping on malt technological parameters.

“…The malts then exhibited a much lower level of contamination compared to common malts (Haikara and Laitila, 1995;Laitila et al ., 1997 (Szwajgier et al ., 2006;Tubaro et al ., 2007) . V práci Lowe a kolegů byl pak prokázán pozitivní vliv nízkého pH na aktivitu β-glukanasy a s tím spojený úbytek β-glukanů v hotovém sladu (Lowe et al ., 2005) . Kyselé máčení může také při-spívat ke snížení obsahu kyseliny fytové (Haraldsson et al ., 2004), mykotoxinů a snížení gushingového potenciálu sladu (Lowe a Arendt, 2004) .…”

“…Ve všech případech bylo nejlepších výsledků dosaženo při použití acidic water (pH ranged from 5-5 .5) (Szwajgier et al ., 2006;Tubaro et al ., 2007) . Lowe and colleagues demonstrated a positive effect of low pH on β-glucanase activity and the associated loss of β-glucans in the finished malt (Lowe et al ., 2005) . Acidic steeping may also contribute to the reduction of phytic acid content (Haraldsson et al ., 2004), mycotoxins and gushing potential of malt (Lowe and Arendt, 2004) .…”