Effect of lactic acid starter and probiotic bacteria association on acidification, texture and viability of fermented milk

O presente trabalho tem como objetivo estudar o perfil de acidificação e a inter-relação entre Streptococcus thermophilus TAO, Lactobacillus delbrueckii subsp. bulgaricus LB340, Lactobacillus acidophilus LAC, Lactobacillus rhamnosus LBA, Bifidobacterium lactis BL04 como culturas associadas em leite fermentado. Cinco leites fermentados foram preparados, sendo a composição das co-culturas a variável estudada. O perfil de acidificação foi monitorado e os parâmetros cinéticos, calculados. Os produtos foram submetidos às análises físico-químicas e microbiológicas durante o armazenamento a 4°C. As associações em cultura mista provocaram a redução do tempo de fermentação do leite. Durante os 21 dias de armazenamento o pH e a firmeza dos leites fermentados variaram. Streptococcus thermophilus TAO, Bifidobacterium lactis BL04 e Lactobacillus rhamnosus LBA forneceram contagens acima de 106 log UFC/mL, porém Lactobacillus acidophilus LAC e Lactobacillus bulgaricus LB340 foram inibidos em cultura mista, demonstrando dificuldades de crescimento quando associados às demais bactérias ácido-láticas.The present study aimed to evaluate the acidification kinectic and inter-relation between Streptococcus thermophilus TAO, Lactobacillus delbrueckii subsp. bulgaricus LB340, Lactobacillus acidophilus LAC, Lactobacillus rhamnosus LBA, Bifidobacterium lactis BL04 like association cultures in fermented milk. Five fermented milks were prepared and studied variable analyzed was the co-cultures composition. Acidification was monitored and the kinectic parameters were calculated. The products were submitted to physical chemistry and microbiological analyses during the storage at 4°C. The associations in mixed cultures promoted the reduction of fermentation time of the milks. During 21 days of storage, pH and firmness of fermented milks varied. Streptococcus thermophilus TAO, Bifidobacterium lactis BL04 and Lactobacillus rhamnosus LBA presented counts above 106 log cfu/mL. However, Lactobacillus acidophilus LAC and Lactobacillus bulgaricus LB340 were inhibited in mixed cultures demonstrating that these strains had difficulty to grow when in associated cultures with lactic acid bacteria