Development of an antimicrobial sachet containing encapsulated allyl isothiocyanate to inactivate Escherichia coli O157:H7 on spinach leaves.
A sachet releasing allyl isothiocyanate (AIT) vapor was developed and its effectiveness as an antimicrobial packaging system for fresh spinach was evaluated. AIT was encapsulated in calcium alginate beads (AIT beads) and the release of AIT as affected by temperature and relative humidity (RH) was determined. The release rate of AIT from beads increased with increased temperature, but was not significantly affected by RH. A low-density polyethylene (LDPE) sachet containing AIT beads (AIT sachet) was prepared and the rate of release of AIT as affected by film thickness and temperature was studied. The release of AIT from sachets increased significantly with decreased LDPE thickness and increased temperature. Finally, antimicrobial effects of the AIT sachet against Escherichia coli O157:H7 and molds and yeasts (MY) on fresh spinach leaves were determined. E. coli O157:H7 and MY had similar sensitivities to AIT vapor. The number of E. coli O157:H7 on spinach leaves (5.6logCFU/leaf) decreased by 1.6-2.6logCFU/leaf at 4°C and 2.1-5.7logCFU/leaf at 25°C within 5days. The reduction of E. coli O157:H7 was significantly greater at 85% RH than at 43% RH. Reductions on control leaves (no AIT sachet) did not exceed 1.2logCFU/leaf under any of the test conditions. Results of the study will be useful when developing antimicrobial packaging systems to increase the microbiological safety and extend the shelf life of spinach and possibly other fresh produces.
Graduate School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-ku, Seoul 136-701, Republic of Korea.
Hyun-Sun
HS
Seo
Jihyun
J
Bang
Hoikyung
H
Kim
Larry R
LR
Beuchat
Seung Yong
SY
Cho
Jee-Hoon
JH
Ryu
D000464:Alginates; D000890:Anti-Infective Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004926:Escherichia coli; D019453:Escherichia coli O157 / Q000187:drug effects* / Q000254:growth & development; D005506:Food Contamination / Q000517:prevention & control; D005519:Food Preservation / Q000379:methods; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006813:Humidity; D017879:Isothiocyanates / Q000494:pharmacology*; D018515:Plant Leaves; D018724:Spinacia oleracea / Q000382:microbiology*; D013696:Temperature
D000464:Alginates; D000890:Anti-Infective Agents; D006603:Hexuronic Acids; D017879:Isothiocyanates; D020723:Glucuronic Acid; C004471:allyl isothiocyanate