Effectiveness of non-chlorine sanitizers in improving the safety and quality of fresh betel leaf

Use of Acetic Acid to Partially Replace Lactic Acid for Decontamination against Escherichia coli O157:H7 in Fresh Produce and Mechanism of Action

Escherichia coli O157:H7 is frequently detected in ready-to-eat produce and causes serious food-borne diseases. The decontamination efficacy of lactic acid (LA) is clearly established. In this study, LA was mixed with acetic acid (AA) to reduce costs while achieving consistent or better inhibitory effects. Time-kill curves and inoculation experiments using fresh-cut spinach and arugula indicated that 0.8%LA+0.2%AA shows similar antibacterial effects to those of 1%LA. To determine whether 1%LA and 0.8%LA+0.2%AA exert antibacterial effects by similar mechanisms, proteomics analysis was used. The proteins related to macromolecule localization, cellular localization, and protein unfolding were uniquely altered after the treatment with 1%LA, and the proteins related to taxis, response to stress, catabolic process, and the regulation of molecular function were uniquely altered after the treatment with 0.8%LA+0.2%AA. Based on these findings, combined with the results of a network clustering analysis, we speculate that cell membrane damage is greater in response to LA than to 0.8%LA+0.2%AA. This prediction was supported by cell membrane permeability experiments (analyses of protein, nucleotide, ATP, and alkaline phosphatase leakage), which showed that LA causes greater membrane damage than 0.8%LA+0.2%AA. These results provide a theoretical basis for the application of an acid mixture to replace LA for produce decontamination.

A study on the prevalence of heavy metals, pesticides, and microbial contaminants and antibiotics resistance pathogens in raw salad vegetables sold in Dhaka, Bangladesh

The presence of undesirable heavy metals, pesticide residues, and microbial contaminants in fresh produces is a worldwide public health concern. This study was undertaken to evaluate the residual pesticides (Diazinon, Malathion, Cypermethrin, Dimethoate, Quinalphos, and Chloropyrofos), heavy metal contamination (Pb, Cd, and Cr), and microbiological quality and safety of 4 common raw salad vegetables (RSVs) samples from different local markets in Dhaka. Results showed the presence of heavy metals residues were within the acceptable limits of local and international standards. None of the above-mentioned pesticides were found in tomato and cucumber samples but presence of Dimethoate was noticed in 13 coriander samples (12.94–158.3 μg/kg) and 7 lettuce samples (9.6–74.8 μg/kg) exceeding the maximum permissible limit of EU guideline. The microbiological analysis showed irrespective of RSV types, total aerobic bacteria was present in higher number (4.0–7.0 log CFU/g), whereas 3.36–5.57 log CFU/g coliform count was recorded. In comparison with retail markets, lower level of total aerobic, and coliform bacterial presence was observed in the samples collected from sophisticated shops, but presence of E. coli and Salmonella spp. were evident in more than 60% samples in these shops. However, 50% and 33% samples from wholesale and retail markets respectively were noticed to be contaminated with Staphylococcus spp. Irrespective of RSV types, isolated E. coli were found resistance to 2–5 different antibiotics, where Salmonella spp. isolated from cucumber and coriander leaves showed resistance against 4–8 different antimicrobials. Therefore, the study results demonstrated that, the presence of residual pesticides, multidrug resistant E. coli and Salmonella spp. in the RSV samples posing concern when consumed raw. The regulatory bodies are expected to monitor and ensure the overall quality standards are in place and practiced by food producers and marketers responsible for handling and distribution of RSVs.