High microbial loads found in minimally-processed sliced mushrooms from Italian market

Abstract

There is an increased consumer interest in minimally processed vegetables that has led to the development of products, such as pre-cut sliced mushrooms. Few data are available on the hygienic condition and the presence of foodborne pathogens in such products. Therefore, the current study aimed to evaluate the safety and hygienic characteristics of both ready-to-eat and ready-to-cook, pre-cut sliced mushrooms obtained from a local Italian market. For the evaluation of the hygienic condition, the aerobic mesophilic bacteria, aerobic psychrotrophic bacteria and Escherichia coli enumerations were performed. Salmonella spp., Listeria monocytogenes and Campylobacter spp. were considered in the assessment of the foodborne pathogens. High microbial loads were detected, including counts higher than 5 log CFU/g for E. coli and 6 log CFU/g for the other bacteria counts considered, but no pathogens were found. Ready-to-eat and ready-to-cook products differed only for aerobic mesophilic counts (7.87 and 8.26 log CFU/g, respectively, P=0.003). Strategies to enhance the hygienic level of the mushrooms, particularly the ready-to-eat products, are needed.

Microbial Safety of Black Summer Truffle Collected from Sicily and Umbria Regions, Italy

“…However, TPC values detected in the present work followed the general trend observed for wild and cultivated mushrooms. Gaglio et al (2019) showed TPC loads in range of 6.85-7.86 log CFU/g in wild mushrooms, comparable results were also showed by Jiang et al (2018) who found mean load of 7.80 log CFU/g in sliced cultivated mushrooms.…”

“…Rivera et al (2010) besides whole truffle, also investigated on the microbial loads of gleba and peridium; as expected, the highest mean loads (8.50 log CFU/g) of microorganisms were revealed on the external part of truffles (peridum), almost superimposable to the levels registered for samples TAR 2 and TAR 5. Other works analyzed microbiological parameters of several mushrooms and shown similar results of TMC in fresh wild or cultivated mushrooms (Venturini et al, 2011) and in minimally processed sliced mushrooms (Jiang et al, 2018;Kim et al, 2016).…”

Microbiological evaluation of whole, sliced, and freeze‐dried black truffles (Tuber melanosporum) under vacuum packaging and refrigerator storage

“…39,44 A recent study observed a high microbial population in the sliced mushrooms (Agaricus bisporus) as slicing provides more exposed surface area on which microbes can grow and the release of nutrients from the damaged tissues provide a complete nourishing environment for microbial growth. 45 In contrast, the presence of a cuticle on the surface of the uncut mushrooms could function as a natural protective barrier and limits the availability of nutrients and moisture for microbial proliferation. 45 The reason for the contradictory finding was not clear, but we speculate that it could be due to differences in the texture, chemical composition, water content, and microbial communities between truffles and mushrooms.…”

Microbiological Safety and Sensory Quality of Cultivated Mushrooms (Pleurotus eryngii, Pleurotus ostreatus and Lentinula edodes) at Retail Level and Post-Retail Storage

“…At retail, the shelf life of food products can be affected by extrinsic factors such as changes in the storage environment (e.g., refrigeration temperature exceeded, moisture level at retail, packing defects) and by intrinsic factors in the product itself (e.g., microbial contamination, especially spoilage bacteria, moisture, pH, redox potential). Mushrooms contain about 80% to 90% water, have an average pH of 6.9 (6.6 to 7.0) and a high CO 2 respiration rate and are highly perishable in nature [ 15 , 16 , 17 ]. After harvest, the bacterial load of mushrooms ranges from between 2.5 to 5.8 log cfu/g [ 18 , 19 ].…”