Effects of Lysozyme on the Microbiological Stability and Organoleptic Properties of Unpasteurized Beer

Abstract

Lysozyme is an antimicrobial enzyme that could be applied to counteract those bacterial species which, due to their own metabolic activity, possess notable beer spoilage ability and lead to loss of beer quality. Experiments were carried out to assess lysozyme potential to prevent the growth of beer spoilage bacteria, and to verify the effect of lysozyme on the microbiological stability and sensory characteristics of unpasteurized beer. Eight replicates, all from the same lot of Italian beer, were treated with 0 and 100 ppm lysozyme. Microbiological analyses were conducted bimonthly to investigate the presence of spoilage bacteria. Sensory analyses were performed to determine whether there were any significant differences in sensory impressions between beers produced with and without lysozyme. Lysozyme exerted a strong inhibitory action on the lactic acid bacteria (LAB) present in the beer and was very stable throughout the shelf life. Sensory tests revealed no unfavourable influence on beer flavour when using lysozyme. Indeed, the shelf life of beer with added lysozyme proved to be extended. Even as late as 1 month after the expiry date it still met with the panellists' approval. Lysozyme may be regarded as an effective agent for preventing microbiological contamination and prolonging the stability of unpasteurized beer.

Aptamer-Based Electrochemical Sensing of Lysozyme

“…Residual levels of 0.06-327 mg/L were found in lysozyme-treated wines [22,23], while in commercial cheeses, concentrations of 30.8-386.2 mg/kg were found to be present [24]. Lysozyme has also been used as an antibacterial agent during beer production [25], to extend the shelf-life of meat [26] and shrimp [27], as an alternative to antibiotics [28,29] in veterinary medicine or as anti-inflammatory drug in the treatment of wounds and infections [4,30].…”

An aerogel obtained from chemo-enzymatically oxidized fenugreek galactomannans as a versatile delivery system

“…Activity of lysozyme was determined by a modified biochemical assay described by Silvetti et al (2010), as follows. Fifteen ml of a sterilized medium composed of 1% agar dissolved in 0.1 M citrate buffer (pH 6.2) were poured in a Petri dish (Ø 9 cm) and left to solidify at room temperature.…”

“…3.2.1.17), a natural antimicrobial enzyme present in several mammalian secretion fluids, which is industrially obtained from hen's egg white (HEW) (Brasca et al, 2013). This enzyme has the ability to hydrolyze the ␤-1,4-glycosidic bond between N-acetyl-muramic acid and N-acetyl-glucosamine in the cell wall peptidoglycans of gram-positive bacteria (Silvetti et al, 2010) and to inhibit the growth of Clostridium tyrobutyricum vegetative cells in cheese (Ávila, Gómez-Torres, Hernández, & Garde, 2014). It is also effective in controlling Listeria monocytogenes growth on raw minced tuna and salmon roe (Takahashi et al, 2011).…”

Inactivation of Lactobacillus brevis in Beer Utilizing a Combination of High-Pressure Homogenization and Lysozyme Treatment

“…A permanent L. brevis inhibition was however observed at 100 mg.L -1 of lysozyme concentration. Previous results evaluated the effect of lysozyme in controlling beer spoilage, showing that the antimicrobial action was not only capable of slowing 19 or inhibiting 22 the growth of beer contaminants, but was also able to inactivate microorganisms 22 , thus increasing the shelf life of non-pasteurized beer over one month with no sensory changes 22 . These data highlight the potential application of the use of lysozyme in beer.…”

“…Following this request, the application of antimicrobials seems to be effective in inactivating or delaying the growth of beer contaminants 21,22 , increasing the beer shelf-life up to a month with no negative sensory changes 22 . Lysozyme is an enzyme extracted from egg white and is able to lyse the peptidoglycan from the Gram positive bacterial cell wall at the β (1-4)-N-acetylmuramic and N-acetyl-glucosamine linkage, thus causing cellular death of such organisms 18 .…”