Incubation Conditions and Physico-Chemical Factors Affecting Aflatoxin B1Binding of Lactic Acid Bacteria

It has been shown (Barkworth & Irwin, 1938) that the distribution of coliform organisms in milk follows a Poisson series, and on this basis it should be possible to estimate the population from the results of replicate tests at several dilution levels by reference to tables. In later experiments with water (Barkworth & Irwin, 1941), it was found that the number of positive tubes did not always reach expectation, having regard to the known numbers of organisms inoculated. The peculiar physico-chemical constitution of milk naturally raises the question whether coliform organisms, though present, might fail to give a positive reaction in the presumptive test. It is well known that in favourable circumstances lactic acid bacteria will overgrow all other organisms in milk. In the presumptive test the greatest concentration of milk in routine technique is 1 ml. of milk in 5 ml. of medium. This dilution would not affect the ratio of coliform organisms to lactic acid bacteria. Even when the coliform contamination at the time of testing is ‘present in 0·001 ml.’ the agreement with the fermentation test is only about 50% (Barkworth, 1929). It will be argued that the gas tube would disclose the presence of gas in more cases than the fermentation test, nevertheless it is not perfect, for Chalmers (1928) recovered Bact. coli from plates of 1: 10 dilution of samples of milk which had given a negative presumptive test. There is therefore some reason to expect a small proportion of false negative coliform results to occur with milk samples, and the object of the present experiment was to see if inoculation with a known number of organisms would produce similar numbers of positive tubes in milk and in water.

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Typical Moroccan goat Lactic Acid Bacteria and their assay as starters

Nova Biotechnologica et Chimica ◽

10.36547/nbc.958 ◽

2021 ◽

Author(s):

Linda Zaaraoui ◽

Abdellah Bouksaim ◽

Maha Elhamdani ◽

Aouatif Benali ◽

Mohammed Oukassou ◽

...

Keyword(s):

Lactic Acid ◽

Lactic Acid Bacteria ◽

Research Study ◽

Goat Milk ◽

Lactobacillus Brevis ◽

Raw Milk ◽

Isolation And Identification ◽

Lactobacillus Pentosus ◽

Factors Affecting ◽

Main Factors

The knowledge of lactic acid bacteria of raw milk and the main factors affecting their variability are particularly important issues for the control of cheese processing and the bioconservation of farm raw milk food products. The present research study concerned the isolation and identification of twenty strains of the Lactobacillus genus from goat milk originating from the Oulmes region, using the API 50 CH system. All isolates found represented five species: Lactobacillus plantarum (43.75 %), Lactobacillus brevis (37.75 %), Lactobacillus pentosus (6.25 %), Lactobacillus salivarus (6.25 %), and Lactobacillus acidophilus (6.25 %). According to biochemical activities, the majority of the strains displayed weak acidification and autolysis activities in milk. In contrast, they showed high extracellular proteolytic activity. All isolates produced exopolysaccharides and most of them could metabolize citrate. The absence of hemolytic activity may suggest the use of these isolates as adjunct starters in the food fermentation process.

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Influence of Drying Type of Selected Fermented Vegetables Pomace on the Natural Colorants and Concentration of Lactic Acid Bacteria

Applied Sciences ◽

10.3390/app11177864 ◽

2021 ◽

Vol 11 (17) ◽

pp. 7864

Author(s):

Emilia Janiszewska-Turak ◽

Weronika Kołakowska ◽

Katarzyna Pobiega ◽

Anna Gramza-Michałowska

Keyword(s):

Lactic Acid ◽

Lactic Acid Bacteria ◽

Starter Culture ◽

Chemical Properties ◽

Starter Cultures ◽

Physico Chemical ◽

Natural Colorants ◽

Fermented Vegetables ◽

Physical And Chemical ◽

Selection Of

Nowadays, foods with probiotic bacteria are valuable and desired, because of their influence on human gut and health. Currently, in the era of zero waste, the food industry is interested in managing its waste. Therefore, the aim of the study was to determine the influence of drying process on the physicochemical properties of fermented vegetable pomace. The work included examining the influence of the lactic acid bacteria (Levilactobacillus brevis, Lactiplantibacillus plantarum, Limosilactobacillus fermentum and its mixture in the ratio 1:1:1) used for vegetable fermentation (beetroot, red pepper, carrot), obtaining pomace from fermented vegetables, and then selection of drying technique using the following methods: convection drying (CD) or freeze-drying (FD) on the physical and chemical properties of pomace. In the obtained pomace and its dried form, dry substance, water activity, color, and active substances such as betalains and carotenoids by spectrophotometric method and also bacteria concentration were evaluated. After fermentation of pomace from the same vegetable, a similar concentration of lactic acid bacteria was found as well as dry substances, color and colorants. Results of physico-chemical properties were related to the used vegetable type. After drying of pomace, it could be seen a high decrease in bacteria and colorant concentration (betalains, carotenoids) independently from drying and vegetable type as well as used starter cultures. The smallest change was observed for spontaneously fermented vegetables compared to those in which the starter culture was used.

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