Effect Of Water Activity, Sodium Chloride (NACL) And Smoke Concentrations On The Growth Of Lactic Acid Bacteria:- Nwaka, Chiedozie M

ABSTRACT ix This work studied the isolation ofLactic Acid Bacteria (LAB) from fermented foods and the effect ofsmoke, water and salt on their growth. Five fermented foods were used including Ugba, Oguri, Akamu, Okpei and Iru. Results ofisolation show variation in the occurrence. Lactobacillus casei (60%), Leuconostoc (60%), Lactobacillus planetarium (100%), Streptococcus (40%) and Pedicoccus (60%). The effect ofsalt concentration shows suppression of growth with increasing concentration from 1% upwards in which there was reduction in population from 1.2xl08cfu/g to 8.6 xl07cfu/g (L. casei), 1.24 xl08cfu/g to 5.8 xl07cfu/g to 5.7 xl07cfu/g (Streptococcus). Similarly, smoking had suppressive effect which increased with smoking time from 5 minutes to 20 minutes. Smoking for 20 minutes caused population reduction of each test Lactic Acid Bacteria isolate to the tunes of 47.83%, 5.79%, 48.8%, 54.91% and 51.37% respectively for Lactobacillus casei, Lauconostoc spp, Lactobacillus planetarium, Streptococcus spp and Pedicoccus spp. In converse, Lactic Acid Bacteria growth was found to increase with increasing moisture content with loads of 5.0xl05 to 2.5107 (L. casei), 4.8xl05 to 1.76cl07cfu/g (Lenconostoc), 5.2xl05cfulg to 2.8xl07cfu/g to 2.8x107cfu/g (L. plantarium) 5.18xl05cfu/g to 1.65xl07cfu/g (Streptococcus) and from 4.9xl05to 1.8xl07cfu/g (Pedicoccus) after 24 hours’ incubation. It was noted that these test conditions could be used to control the growth ofLactic Acid Bacteria in cultures.