Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2010
Publication Date: 9/27/2010
Citation: Guan, W., Huang, L., Fan, X. 2010. Acids in combination with sodium dodecyl sulfate caused quality deterioration of fresh-cut iceburg lettuce during storage in modified atmosphere package. Journal of Food Science. 75:S435-S440.
Interpretive Summary: Consumption of fresh-cut fruits and vegetables has been increasing in developed countries in recent years. However, this increase in consumption is accompanied by increased frequencies of foodborne illnesses caused by the presence of human pathogens on or even inside fresh produce. Washing fresh-cut produce after cutting and prior to packaging is an important step in reducing microbial populations. Chlorine has been widely used to sanitize washing water and to prevent cross-contamination, but its effectiveness in reducing microbial population of fresh produce is very limited. Recent studies suggest that acids may be effective in reducing microbial population on fresh produce. The present study was conducted to compare and identify the effects of three acids in comparison with chlorine on the inactivation of E. coli O157:H7 and the sensory quality of fresh-cut Iceberg lettuce during cold storage. Results showed that treatment with acids caused detrimental effect on the sensory quality of fresh-cut Iceberg lettuce. Among all sanitizer treatments, chorine achieved the best overall visual quality of fresh-cut Iceberg lettuce even though reduction of E. coli O157:H7 population was less than 99%. Our studies demonstrated that novel intervention technologies are needed to improve the microbial safety of fresh produce. The information may be useful to fresh produce industry to search for more effective means to enhance microbial safety of fresh produce.
Technical Abstract: Recent studies showed that levulinic acid (LA) and sodium acid sulfate (SAS) were effective in inactivating human pathogens on fresh produce. The present study investigated the effects of LA and SAS in comparison with citric acid and chlorine on the inactivation of E. coli O157:H7 and the sensory quality of fresh-cut Iceberg lettuce in modified atmosphere packages during cold storage. Results showed that LA and SAS with 0.05% SDS caused detrimental effects on the sensory quality of lettuce due to poor visual quality after 7 and 14 days storage at 4 C. Compared with other treatments, LA was found to be effective in retarding tissue browning of cut lettuce (P < 0.05). However, the treatment caused severe sogginess. SAS caused less sogginess than LA but did not consistently reduce tissue browning. It appears that the acid treatments caused an increase in the respiration rate of fresh-cut lettuce as indicated by higher CO2 and lower O2 in modified atmosphere packages. LA (0.5%), SAS (0.25%), and FIT (~0.25% citric acid) reduced population of E. coli OH157:H7 by only 0.41, 0.87, and 0.58 log CFU/g, respectively, and yet all acids (particularly LA and SAS) at these concentrations caused injury to cut lettuce. Chlorine achieved a reduction of E. coli O157:H7 populations by 0.94 log CFU/g without damage to the lettuce. Overall, chlorine is better than the acids in inactivating E. coli O157:H7 (though achieving less than 1 log CFU/g reduction) and maintaining visual quality of fresh-cut lettuce.