Caffeic acid (CA) is widely distributed among higher fruits and vegetables. While CA has antimicrobial activity, little information exists on its utility as a food additive. As such, CA was tested for activity against Clostridium botulinum spores. At 0.78 and 3.25 mM, CA inhibited germination for 6 and 24 hr, respectively, with >lOO mM required to render spores nonviable. CA concentrations 5: 50mM reduced 80°C spore thermal resistance. Sporostatic activity was retained when tested in commercial meat broths, and 5.0 mM CA delayed toxigenesis. Caffeic acid has potential as a food additive to inhibit growth of C. botulinurn, and reduce thermal processing requirements of heat sensitive foods.

Aromatic and aliphatic aldehydes were tested for their effectiveness against Clostridium botulinum spores and cells. Six-tenths millimolar benzaldehyde, piperonal, phenylacetaldehyde, α-amylcinnamaldehyde, vanillin, or phenylglyoxal delayed germination in botulinal assay medium (BAM) broth after 6 h exposure at 32°C. Sporicidal activity was observed with 1.25 mM vanillin, 39 mM isobutyraldehyde, 156 mM pyruvaldehyde or valeraldehyde, 625 mM benzaldehyde, and 2,500 mM α-amylcinnamaldehyde. Twenty-five millimolars of cinnamaldehyde, phenylacetaldehyde, pyruvaldehyde, and vanillin were most active against vegetative cells at pH 7.0 in BAM broth, while 125 mM was required for benzaldehyde, acetaldehyde, piperonal, or phenylglyoxal. Three millimolars benzaldehyde, 5.0 mM phenylglyoxal, 150 mM cinnamaldehyde, 200 mM pyruvaldehyde and vanillin, and 300 mM piperonal inhibited 9 h dipicolinic acid release in BAM broth at 32°C. Spore resistance to a 20-min 80°C thermal treatment was reduced when challenged with prior exposure to 100 mM cinnamaldehyde, piperonal, pyruvaldehyde, vanillin, or phenylglyoxal. Inhibition by cinnamaldehyde, piperonal, and phenylglyoxal was retained in commercial canned chicken and in beef broths. Five millimolars of benzaldehyde, cinnamaldehyde, piperonal, pyruvaldehyde, or phenylglyoxal delayed neurotoxin production for 48 h at 32°C, while 25 mM was required for vanillin. These results indicate that certain aldehydes inhibit C. botulinum, and aromaticity improves efficacy.

In this study, diacetyl (DI), benzaldehyde (BE), pyruvic aldehyde (PY) and piperonal (PI) were tested for activity against Yersinia enterocolitica, Listeria monocytogenes, Salmonella typhimurium, Bacillus cereus, Shigella flexneri, Aeromonas hydrophila, Escherichia coli O157:H7, Staphylococcus aureus, and proteolytic Clostridium botulinum spores. The minimal inhibitory concentrations (MICs) required to inhibit pathogens ranged from 0.05 to 7.81 mM. The only exception was C. botulinum which was least sensitive, with DI or PY MIC of 25 mM; the MIC of BE or PI was 125 mM. A 30 min 56.8C heat treatment, of the organism/inhibitor mixture, reduced the MICs of BE and PI by 50–87%, and 77% less PY was required to inhibit E. coli O157:H7. BE or PI reduced C. botulinum spore 80C thermal‐ and radio‐resistance. To determine whether antibacterial plant components exist naturally at inhibitory concentrations, EtOH‐extracts of asparagus (As), carrots (Ca), radishes (Ra), shallots (Sh), and turnips (Tu) were tested for antibotulinal activity. As or Ca extracts were antigerminative at 0.07%. When combined equal quantities of As and Ca were tested, ± 0.03% delayed germination, however. Although no activity was observed when Ra and Sh were test singly, 0.13% AsCaRa, AsCaRaSh or AsCaRaShTu combinations were inhibitory. These data indicate that the naturally occurring food additives may be employed to control the foodborne pathogens assessed in this study.