The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. http://http://dspace.unitus.it:80 2013-05-19T00:09:07Z 2013-05-19T00:09:07Z Benucci, Ilaria Liburdi, Katia Garzillo, Anna Maria Vittoria Esti, Marco http://hdl.handle.net/2067/1396 2011-06-29T11:31:27Z 2010-12-31T23:00:00Z

Title: Bromelain from pineapple stem in alcoholic- acidic buffers for Wine application Authors: Benucci, Ilaria; Liburdi, Katia; Garzillo, Anna Maria Vittoria; Esti, Marco Abstract: Bromelain from pineapple stem has been studied in unexplored model wine buffer (pH 3.2 tartaric acid and ethanol) in order to evaluate its applicability for white wine protein stabilisation. Bromelain proteolytic activity was studied against several synthetic peptide substrates in McIlvaine buffer covering a wide pH range. Among different synthetic substrates, Bz-Phe-Val-Arg-pNA turned out to be the most suitable one to test bromelain activity at the average minimum pH value of wine (3.2). The protease activity was significantly increased by the presence of 5 mM cysteine while no influence was exerted by EDTA. The inhibiting effect of ethanol was investigated in the range 0–25% (v/v), resulting in being rather limited at the average minimum concentration found in wine (10% v/v). The kinetic parameters were estimated in both McIlvaine (as reference) and model wine buffers. This study showed that stem bromelain worked well at the average minimum pH value of wine, and had a significantly higher activity in model wine buffer (Ka increased of 42%). These results are the basis for suggesting a future biotechnological application of this protease in winemaking. Description: L'articolo è disponibile sul sito dell'editore http://www.sciencedirect.com/

2010-12-31T23:00:00Z Esti, Marco Benucci, Ilaria Liburdi, Katia Garzillo, Anna Maria Vittoria http://hdl.handle.net/2067/1492 2011-09-29T23:05:05Z 2010-12-31T23:00:00Z

Title: Effect of wine inhibitors on free pineapple stem bromelain activity in a model wine system Authors: Esti, Marco; Benucci, Ilaria; Liburdi, Katia; Garzillo, Anna Maria Vittoria Abstract: The influence of potential inhibitors, naturally present in wine, on the activity of stem bromelain was investigated in order to evaluate the applicability of this enzyme for protein stabilization in white wine. Bromelain proteolytic activity was tested against a synthetic substrate (Bz-Phe-Val-Arg-pNA) in a model wine system after adding ethanol, sulphur dioxide (SO2), skin, seed, and gallic and ellagic tannins at the average range of their concentration in wine. All the inhibitors of stem bromelain activity tested turned out to be reversible. Ethanol was a competitive inhibitor with a rather limited effect. Gallic and ellagic tannins have no inhibitory effect on stem bromelain activity, while both seed and skin tannins were uncompetitive inhibitors. The strongest inhibition effect was revealed for sulphur dioxide which was a mixed-type inhibitor for the enzyme activity. This study provides useful information relative to a future biotechnological application of stem bromelain in winemaking. Description: L'articolo è disponibile sul sito dell'editore http://pubs.acs.org

2010-12-31T23:00:00Z