Survival and therapeutic potential of probiotic microorganisms in fermented milk

Abstract

The survival and therapeutic potential of probiotic microorganisms in fermented milk is estimated on the basis of the number present. The level of probiotic microorganisms which has a positive prophylactic effect and therefore therapeutic potential is > 106cfu/ml. After the fermentation process and during the storage period the number of probiotic microorganisms in fermented milk should remain 106cfu/ml. One mono and two mixed cultures of lactic acid bacteria were investigated. The mono culture consisted of Lactobacillus acidophilus. The first mixed culture contained L.acidophilus, Bifidobactehum spp. and Streptococcus salivarius subs, thermophilus. The second mixed culture, besides the above mentioned bacteria also contained Bifidobactehum longum BB 536. Milk fermentation was carried out in laboratory conditions using sterile 9% reconstituted skimmed milk, incubated at 37 °C till the optimal pH value for fermented milk was obtained. The number of lactic acid bacteria and change of pH value were determined after I, 4 and 8 days storage at 8±I°C. It was found that Lactobacillus acidophilus number in the milk fermented with the monoculture remained above the therapeutical minimum during 8 days storage. Moreover, the number of Lactobacillus acidophilus and Bifidobacterium spp. in the milk fermented with mixed culture I remained above the therapeutical minimum during the storage period of 8 days. The number of Bifidobacterium longum BB 536 in fermented milk obtained with mixed culture II also remained above the therapeutical minimum during the storage period of 8 days.

Preživljavanje i terapeutski potencijal probiotskih mikroorganizama se procenjuju na osnovu broja ovih mikroorganizama u fermentisanom mleku. Terapeutski potencijal je onaj nivo probiotskih mikroorganizama koji ima pozitivno profilakticko delovanje a ono se ostvaruje ako je njihov broj u fermentisanom mleku 106cfu/ml. Posle fermentacije i za vreme perioda čuvanja fermentisanog mleka broj probiotskih mikroorganizama treba da iznosi 106cfu/ml. Materijal u ovim ispitivanjima su predstavljale jedna mono kultura i dve mešovite kulture bakterija mlečne kiseline. Mono kultura se sastojala -od Lactobacillus acidophilus a prva mešovita kultura od tri vrste mikroorganizama: Lactobacillus acidophilus, Bifidobactehum spp. i Streptococcus salivarius subs. thermophilus. Druga mešovita kultura je pored bakterija koje ulaze u sastav prve mešovite kulture sadržavala i Bifidobactehum longum BB536. Fermentacija mleka je izvođena u laboratorijskim uslovima u sterilnom 9% obranom mleku a inkubacija je sprovedena pri 37 °C do postizanja optimalnog pH za pojedina fermentisana mleka. Broj bakterija mlečne kiseline određivan je na podlogama odgovarajućeg sastava i iskazan kao logiocfu/ml. Laktobacili su dokazivani na AC-agaru (Wiesby GmbH Application), bifidobakterije na CPA-0,5% agaru (Wiesby GmbH Application) a streptokoke na M17 agaru (Merck). Broj bakterija mlečne kiseline i promena pH određivani su posle 1., 4. i 8.-og dana čuvanja na 8±1°C. Na osnovu rezultata dobijenih u eksperimentu izvedeni su sledeći zaključci: 1. broj Lactobacillus acidophilus u fermentisanom mleku dobijenom sa mono kulturom tokom perioda čuvanja od 8 dana na 8 + 1°C održava se iznad terapeutskog minimuma. 2. broj Lactobacillus acidophilus i Bifidobacterium spp. u fermentisanom mleku dobijenom sa mešovitom kulturom I tokom perioda čuvanja od 8 dana na 8±1 °C održava se iznad terapeutskog minimuma. 3. broj Bifidobacterium longum BB 536 u fermentisanom mleku dobijenom sa mešovitom kulturom II tokom perioda čuvanja od 8 dana na 8±1 °C održava se iznad terapeutskog minimuma.