89D-12 |
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Q. WEI1, C. Wolf-Hall2, and C. A. Hall, III1. (1) Cereal and Food Sciences, North Dakota State Univ., Fargo, ND 58102, (2) Dept. of Veterinary & Microbiological Sciences, North Dakota State Univ., 114- A Van ES Hall, Fargo, ND 58105 Shelf-life extension is one of the multi-functions of raisins. Raisins have been shown to have antimicrobial activities in beef jerky. We wanted to see if raisins possessed antimicrobial activities against Bacillus spp. that cause ropiness defect in bread. Our objective was to screen the antimicrobial effect of crude raisin extracts on ropy-bread-causing Bacillus spp. Raisin extracts were obtained using water and solvents with different ratios of ethanol to water. The crude extracts were freeze-dried and re-hydrated in distilled water. An agar well (5 mm in diameter) screening technique was used for screening antimicrobial activities of the hydrated extracts against 5 Bacillus spp. that were isolated from flour and ropy bread. The extracts in 3 different hydration ratios were prepared by sterile filtration, autoclave treatment, and non-sterilization. The solution from the 60% ethanol extraction had more activity than the water extract. The autoclaved extract had more activity than the filter sterilized and non-sterilized solutions. The ethanol extract had a significant inhibitory effect (5.43 ± 0.38 mm in diameter for filtered extract, 8.00 ± 0.00 mm for autoclaved, 6.50 ± 0.55 mm for non-sterilized) on the growth of Bacillus subtilis. The autoclaved water extract showed antimicrobial activities against Bacillus licheniformis(6.50 ± 0.55 mm) and pumilus (6.00 ± 0.00 mm). The results suggest that the raisin extracts have inhibitory effects on the growth of ropy-bread Bacillus spp. The ethanol extractions (60, 70, and 80% of ethanol to water) seemed to have more antimicrobial compounds from raisins than the water extraction. The autoclaving process may alter composition and/or concentration of the microbial inhibitory compounds of raisin extracts.
Session 89D, Food Microbiology: Antimicrobial effects on foodborne microorganisms
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |