The growth dynamics of the natural microbial community responsible for the fermentation of Scamorza Altamurana, a stretched cheese from whole cow's milk typical of Southern Italy, was investigated in order to understand the role of bacterial populations from natural whey culture in fermentation and ripening of this cheese. The application of a RAPD-PCRprotocol made it possible to isolate 25 biotypes belonging to five species of Lactobacillus, three of Streptococcus, one of Weissella and one of Enterococcus. The physiological analyses of all lactic acid bacteria strains revealed that the isolates belonging to Streptococcus genus were the most acidifiing, whereas lactobacilli were most proteolytic. The analysis of different Lactobacillus cell envelope proteinase (CEP) genes (prtB, prtH, prtP), carried out extracting and amplifiing DNA directh from samples collected during processing and ripening of Scamorza, showed their presence also when their respective oroteolytic strains were not isolated by traditional techniques. Four proteolytic strains belonging to L. delbrueckii subsp. bulgaricus, L. helveticus, L. paracasei subsp. paracasei and L. gasseri, used as starters in laboratory, exhibited a total proteolytic activity until the sixth day of ripening of cheese. Urea-PAGE analyses ofpH 4.6 soluble and insoluble nitrogen fractions, carried out on cheeses obtained in laboratofy using, for each Scamorza, as starter and ripening microflora, one of the different proteolytic Lactobacillus, indicated that each CEP strain contributes, with its ownproteolytic activities, to provide peptide profiles present in typical cheese.
La crescita e la dinamica della microflora naturale responsabile della fermentazione della Scamorza Altamurana, un formaggio a pasta filata da latte bovino intero tipico dell'ltalia Meridionale, sono state studiate per comprendere il ruolo delle popolazioni batteriche, presenti nel siero innesto naturale, nella fermentazione e stagionatura di questo formaggio. L'applicazione di un protocollo RAPD-PCR ha portato all'isolamento di 25 biotipi appartenenti a cinque specie di Lactobacillus, tre di Streptococcus, una di Weissella ed una di Enterococcus. Le analisi fisiologiche di tutti i ceppi hanno mostrato che gli isolati appartenenti al genere Streptococcus erano i più acidificanti mentre alcuni ceppi di lattobacilli erano dotati di un'elevata attività proteolitica totale in latte. L'analisi dei diversi geni (prtB, prtH, prtP) delle proteinasi associate alla parete cellulare (CEP) dei lattobacilli, effettuata estraendo ed amplificando il DNA direttamente dai campioni prelevati durante la lavorazione e stagionatura della Scamorza Altamurana, ha rivelato la loro presenza anche quando i relativi ceppi proteolitici non sono stati isolati con tecniche tradizionali. In particolare, quattro ceppi proteolitici appartenenti alle specie L. delbrueckii subsp. bulgaricus, L. helveticus, L. paracasei subsp. paracasei e L. gasseri, utilizzati come starter in laboratorio, hanno mostrato attività proteolitica totale fino al sesto giomo di stagionatura del formaggio. L'analisi delle frazioni caseiniche solubili ed insolubili a pH 4,6, effettuata su scamorze prodotte in laboratorio inoculando il latte con un ceppo proteolitico alla volta, ha I indicato come ogni ceppo CEP concorre, con le proprie attività proteolitiche, nel determinare il profilo peptidico presente nel formaggio tipico.
Ruolo di lattobacilli proteolitici naturali nella fermentazione e stagionatura della scamorza altamurana.
Baruzzi F;De Angelis M;Morea M
2004
Abstract
The growth dynamics of the natural microbial community responsible for the fermentation of Scamorza Altamurana, a stretched cheese from whole cow's milk typical of Southern Italy, was investigated in order to understand the role of bacterial populations from natural whey culture in fermentation and ripening of this cheese. The application of a RAPD-PCRprotocol made it possible to isolate 25 biotypes belonging to five species of Lactobacillus, three of Streptococcus, one of Weissella and one of Enterococcus. The physiological analyses of all lactic acid bacteria strains revealed that the isolates belonging to Streptococcus genus were the most acidifiing, whereas lactobacilli were most proteolytic. The analysis of different Lactobacillus cell envelope proteinase (CEP) genes (prtB, prtH, prtP), carried out extracting and amplifiing DNA directh from samples collected during processing and ripening of Scamorza, showed their presence also when their respective oroteolytic strains were not isolated by traditional techniques. Four proteolytic strains belonging to L. delbrueckii subsp. bulgaricus, L. helveticus, L. paracasei subsp. paracasei and L. gasseri, used as starters in laboratory, exhibited a total proteolytic activity until the sixth day of ripening of cheese. Urea-PAGE analyses ofpH 4.6 soluble and insoluble nitrogen fractions, carried out on cheeses obtained in laboratofy using, for each Scamorza, as starter and ripening microflora, one of the different proteolytic Lactobacillus, indicated that each CEP strain contributes, with its ownproteolytic activities, to provide peptide profiles present in typical cheese.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
