Milk bioactives and early infant nutrition

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Mackey, Sinead Marie
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University College Cork
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The gastrointestinal microbiota is established following birth with bifidobacteria present at elevated levels in the gastrointestinal tract of breast fed infants when compared to formula fed infants. This thesis identified two fermented dairy ingredients that enhanced bifidobacterial growth. Additionally, the cultures utilised in the production of the fermented ingredients were further assessed for antimicrobials with one identified. In vitro studies were performed using the fermented ingredients to establish the true extent of the bifidobacterial enhancing capabilities. Further studies confirmed the ability of the ingredients to survive simulated gastrointestinal conditions, while a study using a mixed culture fermentation model confirmed the ability of the fermented ingredients to enhance levels of bifidobacteria in a mixed culture environment. The bacterial fermentates enhanced total bifidobacterial counts to levels that were comparable to those recorded for the control vessel containing Fructooligosaccharides (an ingredient readily utilised in infant milk formula). An animal study was completed and the microbial composition of the mice caecum was assessed for the four study groups following four weeks of feeding the fermented ingredients, FOS and the unfermented control. 454-sequencing technologies confirmed similar levels of lactobacilli and bifidobacteria were present in the caecum, relative to the FOS. Additionally, one of the fermented ingredients reduced levels of the genus Clostridium when compared to the unfermented control. In summary, this thesis describes the generation of two bacterial fermentates which potentially may contribute to gastrointestinal health based on their bifidobacterial enhancing capabilities. One culture was also confirmed to possess a helveticin J bacteriocin. All three are of particular interest as the fermenting starter cultures and the strain possessing the helveticin J are classified as GRAS (generally recognised as safe) and QPS (qualified presumption of safety). Furthermore, the research also describes possible vehicles in which the functional ingredients can be delivered to the gastrointestinal tract.
Milk , Bifidobacteria , Infant nutrition
Mackey, S. M. 2019. Milk bioactives and early infant nutrition. PhD Thesis, University College Cork.
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