Effect of negative air ionization technology on microbial reduction of food-related microorganisms

Negative air ions (NAI) have been shown to have bactericidal effects on various microbial species. Different concentrations of NAI and ozone (106-7x106 NAI cm-3 s−1, 2.20 mg h-1 of ozone or 8 × 106-2x107 NAI cm−3 s−1, 0.02 mg h−1 of ozone, respectively) were studied to determine whether the effect of these treatments on six food-related microorganisms was due to NAI or also to the ozone that forms. Bacillus subtilis, Escherichia coli, and Listeria monocytogenes showed a significantly microbial reduction after the treatments of NAI with a low concentration of ozone, while Pseudomonas fluorescens, Penicillium roqueforti, and Saccharomyces cerevisiae were affected mainly by NAI and higher ozone concentration. It should be noticed that the reduction of the pathogen L. monocytogenes has been 2.17 Log after 72 h treatment to NAI and low ozone concentration. The results proved that ions (NAI) contribute to microbial killing. However, the sensitivity of microbial species is different and depends on individual parameters of the different microorganisms. NAI technology with low ozone production can be rapid, green, and low-cost and it can represent an alternative to the use of chemicals for the sanitation of air and surfaces in the food sector in order to reduce microbial contamination

Inactivation of Foodborne Bacteria Biofilms by Aqueous and Gaseous Ozone

In this study, the efficacy of treatments with ozone in water and gaseous ozone against attached cells and microbial biofilms of three foodborne species, Pseudomonas fluorescens, Staphylococcus aureus, and Listeria monocytogenes, was investigated. Biofilms formed on AISI 304 stainless steel coupons from a mixture of three strains (one reference and two wild strains) of each microbial species were subjected to three types of treatment for increasing times: (i) ozonized water (0.5 ppm) by immersion in static condition, (ii) ozonized water under flow conditions, and (iii) gaseous ozone at different concentrations (0.1\u201320 ppm). The Excel add-in GinaFit tool allowed to estimate the survival curves of attached cells and microbial biofilms, highlighting that, regardless of the treatment, the antimicrobial effect occurred in the first minutes of treatment, while by increasing contact times probably the residual biofilm population acquired greater resistance to ozonation. Treatment with aqueous ozone under static conditions resulted in an estimated viability reduction of 1.61\u20132.14 Log CFU/cm2 after 20 min, while reduction values were higher (3.26\u20135.23 Log CFU/cm2 ) for biofilms treated in dynamic conditions. S. aureus was the most sensitive species to aqueous ozone under dynamic conditions. With regard to the use of gaseous ozone, at low concentrations (up to 0.2 ppm), estimated inactivations of 2.01\u20132.46 Log CFU/cm2 were obtained after 60 min, while at the highest concentrations a complete inactivation (<10 CFU/cm2 ) of the biofilms of L. monocytogenes and the reduction of 5.51 and 4.72 Log CFU/cm2 of P. fluorescens and S. aureus respectively after 60 and 20 min were achieved. Considering the results, ozone in water form might be used in daily sanitation protocols at the end of the day or during process downtime, while gaseous ozone might be used for the treatment of confined spaces for longer times (e.g., overnight) and in the absence of personnel, to allow an eco-friendly control of microbial biofilms and consequently reduce the risk of cross-contamination in the food industry

Application of pre-adaptation strategies to improve the growth of probiotic lactobacilli under food-relevant stressful conditions

While formulating a probiotic food, it is mandatory to make sure that the viability of probiotics is adequate at the point of consumption, which can be strongly compromised by stressful conditions due to low pH and high osmolarity. In this study, three probiotic lactobacilli were subjected to different pre-adaptation conditions, and the turbidimetric growth kinetics in challenging conditions (pH 4.0–6.5, NaCl 1–7%, sucrose 0.1–0.7 M) were evaluated. Different effects were observed for Lactobacillus acidophilus, Lacticaseibacillus casei, and Lactiplantibacillus plantarum. Indeed, pre-exposition to sub-optimal conditions in terms of pH and % NaCl significantly improved the ability of L. acidophilus and L. casei to overcome the osmotic stress due to salt or sucrose, and similar effects were observed for acidic stress. L. plantarum showed to be more tolerant to the challenging conditions applied in this study. Anyway, the pre-adaptation at conditions SUB_1 (pH 4.5 and NaCl 4%) and SUB_2 (pH 5 and NaCl 2%) speeded-up its growth kinetics by reducing the length of the lag phase under sucrose stress and enhancing the maximum growth rate at the highest pH tested. Moreover, an improvement in biomass amount was observed under sucrose stress. The whole data evidenced that the application of the appropriate pre-adaptation condition could contribute to making probiotics more robust towards challenging conditions due to food matrix, processing, and storage as well as gastrointestinal transit. Further studies will be necessary to gain insight into the proteomics and metabolomics responsible for increased tolerance to stressful conditions

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

Diversity within Italian Cheesemaking Brine-Associated Bacterial Communities Evidenced by Massive Parallel 16S rRNA Gene Tag Sequencing

This study explored the bacterial diversity of brines used for cheesemaking in Italy, as well as their physicochemical characteristics. In this context, 19 brines used to salt soft, semi-hard, and hard Italian cheeses were collected in 14 commercial cheese plants and analyzed using a culture-independent amplicon sequencing approach in order to describe their bacterial microbiota. Large NaCl concentration variations were observed among the selected brines, with hard cheese brines exhibiting the highest values. Acidity values showed a great variability too, probably in relation to the brine use prior to sampling. Despite their high salt content, brine microbial loads ranged from 2.11 to 6.51 log CFU/mL for the total mesophilic count. Microbial community profiling assessed by 16S rRNA gene sequencing showed that these ecosystems were dominated by Firmicutes and Proteobacteria, followed by Actinobacteria and Bacteroidetes. Cheese type and brine salinity seem to be the main parameters accountable for brine microbial diversity. On the contrary, brine pH, acidity and protein concentration, correlated to cheese brine age, did not have any selective effect on the microbiota composition. Nine major genera were present in all analyzed brines, indicating that they might compose the core microbiome of cheese brines. Staphylococcus aureus was occasionally detected in brines using selective culture media. Interestingly, bacterial genera associated with a functional and technological use were frequently detected. Indeed Bifidobacteriaceae, which might be valuable probiotic candidates, and specific microbial genera such as Tetragenococcus, Corynebacterium and non-pathogenic Staphylococcus, which can contribute to sensorial properties of ripened cheeses, were widespread within brines. \ua9 2017 Marino, Innocente, Maifreni, Mounier, Cobo-D\uedaz, Coton, Carraro and Cardazzo

Hyperbaric storage of egg white at room temperature: Effects on hygienic properties, protein structure and technological functionality

Fresh hen (Gallus gallus domesticus) egg white was submitted to hyperbaric storage at 200 MPa at room temperature for up to 28 days. Control samples were stored at 4 °C and 0.1 MPa. Storage conditions were compared for antimicrobial capacity towards inoculated (circa 4 log CFU g−1) Staphylococcus aureus and Salmonella enterica, and changes in physical, structural and functional properties. S. enterica was completely inactivated within 3 h of hyperbaric storage. Prolonged hyperbaric storage promoted slight egg white yellowing, probably due to non-enzymatic browning or riboflavin-protein decomplexation, and induced minor changes in egg white protein structure. Partial conversion of ovalbumin into S-ovalbumin led to slightly decreased gelling capacity. Pressurized egg white proteins also resulted slightly compressed and electrically stabilized, becoming more prone to solvent interactions. Based on these effects, viscosity of egg white increased almost 4-fold and foaming capacity increased by circa 35%. Our work demonstrated for the first time that hyperbaric storage guarantees safety and hygiene of egg white without detriment to its technological functionality

Impact of UV-C light on safety and quality of fresh-cut melon

The effectiveness of UV-C light exposure on safety and quality of fresh-cut fruit was investigated with reference to melon cubes. UV-C light was applied during cutting operations and before packaging. Melon cubes were then analysed for microbial counts, colour, firmness, juice leakage, sensory properties and preference during storage at 6 \ub0C for up to 14 days. Fruit exposure to UV-C light leaded to 2 log reductions for both total viable count and Enterobacteriaceae, whose counts remained 2 log units lower than that of the untreated sample during storage. No significant effect of UV-C light treatment on product colour and firmness was detected during storage. By contrast, the exposure to UV-C light decreased melon leakage, probably due to the formation of a thin dried film on the product surface. UV-C treated samples were also associated to a better flavour which made them significantly preferred to the untreated ones. UV-C light treatment was demonstrated to be a high potential novel technology for surface decontamination of ready-to-eat food surface. Industrial Relevance: UV-C light treatment represents a high potential novel technology allowing to achieve surface decontamination of ready-to-eat fruit products while improving their sensory properties

Potential application of monoglyceride structured emulsions as delivery systems of probiotic bacteria in reduced saturated fat ice cream

This study investigated the potentialities of saturated monoglyceride structured emulsions (MSEs) as delivery systems of probiotics in ice cream. MSEs containing a probiotic Lactobacillus rhamnosus strain were prepared using anhydrous milk fat (AMF-MSE) or sunflower oil (Oil-MSE) as lipid phase and were added to the ice cream mix in substitution to milk cream just before freezing. Results highlighted the good capacity of MSEs to protect probiotic bacteria cells against stresses suffered during processing and storage. The physical state of the lipid phase included in the emulsion did not affect the survival of microorganisms. At the same time, the use of MSEs as fat phase allowed to obtain ice cream with minor modifications in terms of quality characteristics in comparison to control sample. In particular, Oil-MSE demonstrated the ability to create a melt-resistant fat network structure in ice cream when milk fat was replaced with sunflower oil. It was concluded that the monoglyceride crystalline structures formed in the MSE played both probiotic protective and structuring role. This approach allowed obtaining a low-saturated fat ice cream functionalized with probiotic bacteria

Resistenza agli antimicrobici: metodi rapidi di analisi e soluzioni alternative per tutti i settori

Introduzione-Scopo Oggigiorno la resistenza agli antimicrobici (AMR) è una delle maggiori minacce per la salute umana e animale. Gli antibiotici svolgono un ruolo fondamentale nella cura delle malattie di origine batterica, ma spesso vengono utilizzati in modo improprio o irrazionale causando esiti invalidanti sulla qualità della vita e proliferazione di multi-resistenza (MDR) con un significativo impatto economico. L’AMR è comunemente ascritta al settore sanitario, ma molti altri possono essere considerati i focolai per la proliferazione. Nell’ambiente i batteri AMR trovano condizioni adatte per riprodursi, l’acqua raccoglie e trasporta microrganismi, antibiotici, liquami, fertilizzanti e materiale genetico; anche l’industria alimentare fornisce fattori favorevoli per la crescita di batteri resistenti dal campo alla tavola, dalle attrezzature agli operatori. Tramite l’approccio One Health, il quale considera strettamente legati esseri umani, animali e ambiente, questa review mette in risalto metodi con elevata specificità, tempi brevi e applicazioni pratiche per rilevare l’AMR e promuovere alternative agli antibiotici. Metodi di analisi I test di sensibilità agli antibiotici sono oggi i più utilizzati; tuttavia, sono dispendiosi in termini di tempo e denaro. Per ovviare al problema, il Biosensing e la Next Generation Sequencing (NGS) sono metodi usati per rilevare batteri AMR e tracciare geni antibiotico resistenti (ARGs) in tempi brevi e con costi contenuti, favorendo la valutazione del rischio, l’identificazione di punti critici e la correzione. Protocolli ottimizzati sono impiegati per l’analisi di differenti microrganismi, tra cui tecniche di spettroscopia di impedenza elettrochimica (EIS) e voltammetria differenziale a impulsi (DPV) hanno permesso di testare la sensibilità agli antibiotici di ceppi di Staphylococcus aureus, Escherichia coli e Klebsiella pneumoniae in meno di un’ora. La NGS è utilizzata per indagare vari ARGs contemporaneamente in molteplici settori. In particolare, la produzione alimentare è stata considerata una via di diffusione di ARGs: integroni isolati da frutta e verdura si sono rivelati responsabili di dispersione di geni dall’ambiente al microbioma umano, prodotti ittici hanno mostrato interazione tra fagi e batteri, lo stesso per gli allevamenti. Grazie al sequenziamento, inoltre, in suolo e acque è stata rilevata abbondanza di geni codificanti per la resistenza, evidenziando un altrettanto serio rischio di trasferimento. Trasmissione da batteri non-patogeni a patogeni Ceppi di batteri lattici (LABs) non-patogeni sono stati valutati per l’abilità di trasferire ARGs a forme patogene per via orizzontale (HGT). Un esempio esplicativo riguarda Enterococcus faecium, il quale trova largo impiego nell’industria alimentare: il rischio di trasportare plasmidi con determinanti di resistenza, se pur basso, è concreto, perciò è indispensabile la valutazione completa in tutti i processi produttivi per l’uso dei ceppi di E. faecium. Tale approccio è indispensabile nel noto latte fermentato danese Gaio®. Le stesse considerazioni sono state fatte anche su prodotti fermentati con colture starter e probiotici. Alternative agli antibiotici La rapida comparsa di agenti patogeni MDR ha stimolato la ricerca di antibatterici alternativi, tra cui peptidi antimicrobici (AMPs), come l’istatina 5 contro S. aureus e Acinetobacter baumannii, batteriofagi, ad esempio cocktails anti-Listeria e inibitori del quorum sensing (QSIs), tra cui la molecola ibrida 4-(Benzylamino)cyclohexyl 2-hydroxycinnamate in grado di ridurre il biofilm e la comunicazione batterica, con applicazioni in ambienti ospedalieri e alimentari. Conclusioni L’azione di veterinari, agricoltori, allevatori, tecnologi alimentari, oltre agli operatori sanitari, è fondamentale per ridurre il problema dell’AMR. Il Biosensing e la NGS sono essenziali per gestire l’AMR, potenziare repentinamente gli interventi correttivi e favorire il progresso tecnologico. Sostanze alternative agli antibiotici hanno un ruolo di alto potenziale per migliorare il benessere umano e garantire alimenti sicuri con riduzione delle pressioni e dei costi sanitari