Ready-to-Use Vegetable Salads: Physicochemical and Microbiological Evaluation

Abstract

Ready-to-use vegetable salads are minimally processed products, rich in antioxidants, but are associated with a high microbiological risk and possibly, in some cases, with a high content of nitrites. The purpose of this study was to investigate the physicochemical and microbiological properties of different ready-to-use vegetable salad assortments on the Romanian market. Seventeen types of salad vegetables were evaluated for the determination of water activity, antioxidant activity and nitrite concentration and tested for the presence of microorganisms. The water activity of the samples varied from 0.873 to 0.933, and the IC50 values were between 1.31 ± 0.02 and 5.43 ± 0.04 µg/mL. Nitrites were present in all samples investigated (ranging from 290.6 to 3041.17 mg/kg). Staphylococci and Enterobacteriaceae were detected in 35.3% and 70.5% of the samples. Furthermore, 17.6% of the salads were contaminated with Escherichia coli, and Listeria was detected in 29.4% of the samples. Salmonella was detected in only one sample, and Faecal streptococci were not present in any of the samples. The results indicated high nitrite values and also revealed pathogens’ presence. Producers should make more efforts to lower microbial contamination, while maximum limits for nitrites in vegetables should be set based on the impact on human health.