Power ultrasound decontamination of wastewater from fresh-cut lettuce washing for potential water recycling

The decontamination effect of pulsed and continuous power ultrasound, provided at either controlled or uncontrolled temperature regimes, was studiedwith reference to nativemicroflora and inoculated pathogenic bacteria in wastewater obtained by fresh-cut lamb's lettuce washing. Results showed that decontamination efficacy increased with increasing specific energy and was higher when ultrasound treatment was provided under uncontrolled temperature regime. Continuous ultrasound supplied without temperature control allowed to achieve 3.2 Log reductions of native microflora during 20 min treatment, while 5 Log reductions of inoculated Listeria monocytogenes, Escherichia coli and Salmonella enterica were attained within 5 min of ultrasonication. The heat generated during continuous ultrasound accounted for approximately 58% of the total decontamination effect against L. monocytogenes, while it contributed for 100% to E. coli and S. enterica inactivation. Industrial relevance: The application of power ultrasound combined with in situ generated heat could represent an effective tool for water decontamination and recycling in the fresh-cut industry. In addition, besides safety requirements, this technology would also meet cost-effectiveness criteria and existing standards

Pediococcus spp.: caratterizzazione fenotipica, tecnologica e genotipica

Lo scopo di questa sperimentazione \ue8 stato quello di esplorare alcuni aspetti specifici legati ai batteri appartenenti al genere Pediococcus, al fine di un potenziale utilizzo tecnologico. Il progetto ha previsto un\u2019indagine attraverso l\u2019impiego di metodi tradizionali e molecolari sulla presenza di la Pediococcus spp. isolati da differenti alimenti fermentati con lo scopo di identificarli e caratterizzarl

Evaluation of amino acid-decarboxylative microbiota throughout the ripening of an Italian PDO cheese produced using different manufacturing practices

Aim: To investigate the presence of biogenic amines (BAs) in Montasio cheese produced by using different cheese manufacturing practices. Methods and Results: Three batches of Montasio cheese were made in the following way: batch A using raw milk and natural milk culture, batch B with thermized milk and natural milk culture and batch C with thermized milk and natural milk culture added of a commercial starter culture. During 120 days of ripening analyses were performed for microbial counts and BA content; indeed, the potential to produce BAs was screened in lactic acid bacteria and Enterobacteriaceae isolates. At the end of ripening, the total BA contents of cheeses from batches A, B and C were 166\uc63, 207\uc63 and 29\uc68 mg kg)1, respectively. Amino acid decarboxylase activity was widespread among isolates. Conclusions: The BA content of Montasio cheese from the three batches was below the threshold proposed as potentially toxic. The highest BA content was found in cheese produced using thermized milk and natural milk culture; therefore, the thermal treatment of milk was not enough by itself to reduce the counts of decarboxylase-positive bacteria in cheese. The use of selected starters guaranteed a low BA content in Montasio cheese. Significance and Impact of the Study: The study of the effects of some technological processes on the incidence of decarboxylative microbiota in \u2018protected denomination of origin\u2019 cheeses could provide useful information on the hygienic risk related to their production

Microbial biofilm: Bio-forming ability in Staphylococcus aureus in the dairy industry

S. aureus is a major cause of contamination in milk and dairy products, representing a problem for the safety of the consumer. The ability to form biofilms, a pathogenic factor present in S. aureus, has been studied in a limited way in mastitic and food isolates. The purpose of this study was to investigate the ability to form biofilms and the peracetic acid resistance of dairy S. aureus isolates. The biofilm-forming ability was found to be widespread in S. aureus, and this trait may in part explain the presence and persistence of S. aureus in the dairy industry. The biofilm of S. aureus have been shown to be quite tolerant to peracetic acid, which highlights the need, in the development of a cleaning protocol, to keep in consideration the spread of microbial forms capable of forming biofilms in the dairy industry

Study on the applicability of high-pressure homogenization for the production of banana juices

The aim of this preliminary study was to evaluate the potential applicability of high-pressure homogenization (HPH) for the production of banana juices. To this purpose, a prototype equipment working up to 400 MPa and a lab-scale homogenizer working up to 150 MPa were used. Temperature, microbial load, pectate lyase activity, colour and viscosity of the samples homogenized at increasing pressure were evaluated. Pressures higher than 200 MPa were needed to obtain 4 log unit reduction of total mesophilic bacteria and pectate lyase inactivation. Following HPH, banana juice resulted brighter and less viscous than the untreated one. Data suggest that HPH treatments could be a reliable technological alternative to conventional heat treatments for the production of added-value fruit juices. However, the homogenization design could play a critical role in affecting the product quality attributes. In fact, homogenization performed at the same operative pressure by using different equipment leads to different effects on product qualit

Surface decontamination of fresh-cut apple by pulsed light: Effects on structure, colour and sensory properties

The effect of pulsed light at increasing fluence (17.5, 52.5, 105.0 and 157.5 kJ/m2) was studied with reference to germicidal efficiency and changes in fresh-like appearance of sliced apple. Independent of fluence, viable counts and inoculated bacteria were reduced by 1 and 3 logs respectively. Fluence significantly affected weight loss, colour and sensory attributes of apple slices during storage at 6 \u25e6C. Pulsed light at 17.5 kJ/m2 resulted in apple slices comparable to the untreated samples, with limited quality changes. By contrast, at higher fluence, apple slices underwent dehydration and browning due to loss of cell integrity. Exposure to high fluence treatments was also associated with negative changes in the flavour profile of sliced apple during storage

Comparison of culture-dependent and culture-independent methods for bacterial community monitoring during Montasio cheese manufacturing

The microbial community in milk is of great importance in the manufacture of traditional cheeses produced using raw milk and natural cultures. During milk curdling and cheese ripening, complex interactions occur in the microbial community, and accurate identification of the microorganisms involved provides essential information for understanding their role in these processes and in flavor production. Recent improvements in molecular biological methods have led to their application to food matrices, and thereby opened new perspectives for the study of microbial communities in fermented foods. In this study, a description of microbial community composition during the manufacture and ripening of Montasio cheese was provided. A combined approach using culture-dependent and -independent methods was applied. Culture-dependent identification was compared with 16S clone libraries sequencing data obtained from both DNA and reverse-transcribed RNA (cDNA) amplification and real-time quantitative PCR (qPCR) assays developed to detect and quantify specific bacterial species/genera (Streptococcus thermophilus, Lactobacillus casei, Pediococcus pentosaceus, Enterococcus spp., Pseudomonas spp.). S. thermophilus was the predominant LAB species throughout the entire ripening period of Montasio cheese. The culture-independent method demonstrates the relevant presence of Pseudomonas spp. and Lactococcus piscium at the beginning of ripening. The culture-dependent approach and the two culture-independent approaches produced complementary information, together generating a general view of cheese microbial ecology

Water saving in fresh-cut salad washing by pulsed light

The possibility to wash salad with recycled water submitted to pulsed light decontamination was studied. Wastewater deriving from lamb's lettuce washing was exposed to pulsed light at increasing fluence up to 17.5 kJ/m2. Pulsed light dose of 11.0 kJ/m2 allowed the inactivation of most of the native microflora and the achievement of more than 6-Log reductions in inoculated microorganisms (Salmonella enterica, Listeria monocytogenes and Escherichia coli). The increase in washing cycles up to 5 did not impair the efficacy of wastewater decontamination promoted by pulsed light (circa 4-Log reduction in native microflora) nor the hygienic level of the washed salad (circa 1-Log reduction in native microflora). Industrial relevance The application of pulsed light to decontaminate wastewater deriving from salad washing could decrease the water footprint of fresh-cut vegetables by minimising the overall requirement for water in industrial plants. In addition, it would decrease the risk for residuals of toxic chemicals in fresh-cut vegetables by avoiding the use of sanitizers, such as chlorine. \ua9 2015 Elsevier Ltd. All rights reserved

Bacterial biofilm as a possible source of contamination in the microbrewery environment

In this study, possible sources of bacterial contamination on surfaces were identified in an Italian microbrewery. A high degree of microbial diversity was detected, which suggests very little selective pressure on these environments from cleaning agents and disinfectants, or from the presence of beer. Lactobacillus brevis, Lactobacillus lindneri, and Pediococcus pentosaceus isolates that were able to grow in beer were detected on the surfaces, among other potential beer-spoiling species. Most of the isolates showed a strong ability to form biofilms on both polystyrene and on stainless steel, and the mature biofilms on stainless steel were insufficiently inactivated by peracetic acid-based sanitiser