Year of Publication
Doctor of Philosophy (PhD)
Agriculture, Food and Environment
Animal and Food Sciences
Dr. Melissa C. Newman
This study investigated the antimicrobial efficacy of bioactive plant compounds along with high pressure processing (HPP) against pathogens Bacillus cereus and Cronobacter sakazakii in infant formula and infant rice cereal. The influence of these applications on antimicrobial activity, shelf-life and sensory attributes of infant foods were examined.
Trans-cinnamaldehyde (TC), (-)-Epigallocatechin gallate (EGCG) and -Gingerol (GI) were incorporated (0.05%) in infant rice cereal reconstituted with infant formula. The cereal was inoculated with either B. cereus (ATCC 14579) or B. cereus spores (107-108 log CFU g-1). All the samples were stored at 7, 23 or 37°C for 0, 4, 8 and 24 h. TC showed the highest antimicrobial activity by inhibiting the B. cereus and its spores up to 2.72 and 3.8 log CFU g-1, respectively.
HPP (600 MPa for 5 m), and TC (0.05-0.1%) along with Chitosan (CH) (1%), were applied to reconstituted powder infant formula which was inoculated with either 3 strains of C. sakazakii (ATCC 29544, ATCC 12868, and ATCC BAA 894) or 5 strains of B. cereus spore (ATCC 14579, ATCC 33018, ATCC 12826, ATCC 4342, and Difco Spores) cocktail (107-108 log CFU ml-1). All the samples were stored at 7, 23 or 45°C for 5-8 weeks. HPP and TC (0.1%) combination exhibited the highest inhibition (P < 0.05) by reducing the B. cereus spores 2.97 log CFU ml-1 after 7 d. C. sakazakii was fully inactivated by HPP, TC (0.05%) and C (1%) combination following 8 weeks of storage at 7 and 23°C and 2 weeks storage at 45°C. The combination of HPP and bioactive compounds exhibited additive antimicrobial effect.
Gradual decrease (P < 0.05) in pH was observed in rice cereal and non-HPP formula samples due to the microbial growth and metabolic activity. Significant differences (P < 0.05) were found in color, aroma and general appearance of EGCG and GI applied cereal samples, while TC only did exhibit a cinnamon taste.
In summary, the antimicrobial findings suggest that TC, EGCG, GI and CH could be incorporated in infant foods along with HPP as natural and safe alternatives to synthetic preservatives and thermal applications.
Cetin-Karaca, Hayriye, "ANTIMICROBIAL EFFICACY OF NATURAL BIOACTIVE COMPOUNDS AND HIGH PRESSURE PROCESSING AGAINST POTENTIAL PATHOGENS IN INFANT FOODS" (2015). Theses and Dissertations--Animal and Food Sciences. 57.