Chemical Composition and Antimicrobial Activity of Artemisia herba-alba and Origanum majorana Essential Oils from Morocco.

Essential oils (EOs) are one of the most important groups of plant metabolites responsible for their biological activities. This study was carried out to study the chemical composition and the antimicrobial effects of Artemisia herba-alba and Origanum majorana essential oils against some Gram-positive and Gram-negative bacteria, and a fungal strain isolated from spoiled butter. The plants were collected in the region Azzemour of South West Morocco and the EOs, extracted by hydrodistillation, were analyzed by GC-MS. The antimicrobial activity was determined using the agar paper disc method. The main components of A. herba-alba EO were cis-thujone, trans-thujone and vanillyl alcohol; in O. majorana EO terpinen-4-ol, isopulegol and ß-phellandrene predominated. Both essential oils exhibited growth inhibiting activities in a concentration-dependent manner on several microorganism species. Our results demonstrated that O. majorana and A. herba-alba EOs could be effective natural antibacterial agents in foods.

Fate of Escherichia coli O157:H7 and Salmonella enterica in the manure-amended soil-plant ecosystem of fresh vegetable crops: a review.

Enterohemorrhagic Escherichia coli (EHEC) and Salmonella enterica have been implicated in several disease outbreaks linked to consumption of fresh vegetables. Both ruminant and non-ruminant animals carry EHEC and S. enterica in their gastrointestinal tracts and can shed the pathogens in the faecal matter both in symptomatic and asymptomatic states. Application of animal waste in soil fertility management and irrigation of crops with contaminated waste water has been recognised as an important route through which EHEC and S. enterica can contaminate fresh vegetables during primary production. The behavior of E. coli O157:H7 and S. enterica in the agricultural environment has been extensively studied in the last decades. Several microbiological detection methods have been applied. This review therefore puts together current knowledge on the behavior of E. coli O157:H7 and S. enterica in the manure-amended soil-plant ecosystem of fresh vegetable crops during cultivation under various environmental conditions. The review focuses on methodological issues involved in undertaking survival studies and makes comparative analysis of experimental results obtained from studies conducted under controlled environmental conditions integrating results obtained from field experiments. Finally, a theoretical discussion on the potential likely impact of climate change on pre-harvest safety of field-cultivated vegetables is highlighted.

Transcriptomic analysis reveals differential gene expression patterns of Lacticaseibacillus casei ATCC 393 in response to ultrasound stress.

In recent years, there has been a growing interest in modulating the performance of probiotic, mainly Lactic Acid Bacteria (LAB), in the field of probiotic food. Attenuation, induced by sub-lethal stresses, delays the probiotic metabolism, and induces a metabolic shift as survival strategy. In this paper, RNA sequencing was used to uncover the transcriptional regulation in Lacticaseibacillus casei ATCC 393 after ultrasound-induced attenuation. Six (T) and 8 (ST) min of sonication induced a significant differential expression of 742 and 409 genes, respectively. We identified 198 up-regulated and 321 down-regulated genes in T, and similarly 321 up-regulated and 249 down-regulated in ST. These results revealed a strong defensive response at 6 min, followed by adaptation at 8 min. Ultrasound attenuation modified the expression of genes related to a series of crucial biomolecular processes including membrane transport, carbohydrate and purine metabolism, phage-related genes, and translation. Specifically, genes encoding PTS transporters and genes involved in the glycolytic pathway and pyruvate metabolism were up-regulated, indicating an increased need for energy supply, as also suggested by an increase in the transcription of purine biosynthetic genes. Instead, protein translation, a high-energy process, was inhibited with the down-regulation of ribosomal protein biosynthetic genes. Moreover, phage-related genes were down-regulated suggesting a tight transcriptional control on DNA structure. The observed phenomena highlight the cell need of ATP to cope with the multiple ultrasound stresses and the activation of processes to stabilize and preserve the DNA structure. Our work demonstrates that ultrasound has remarkable effects on the tested strain and elucidates the involvement of different pathways in its defensive stress-response and in the modification of its phenotype.

Delivery of Probiotic-Loaded Microcapsules in the Gastrointestinal Tract: A Review.

Probiotics are live microorganisms that inhabit the gastrointestinal tract and confer health benefits to consumers. However, a sufficient number of viable probiotic cells must be delivered to the specific site of interest in the gastrointestinal tract to exert these benefits. Enhanced viability and tolerance to sublethal gastrointestinal stress can be achieved using appropriate coating materials and food matrices for orally consumed probiotics. The release mechanism and interaction of probiotic microcapsules with the gastrointestinal tract have been minimally explored in the literature to date. To the authors' knowledge, no review has been published to discuss the nature of release and the challenges in the targeted delivery of probiotics. This review addresses gastrointestinal-related complications in the formulation of targeted delivery and controlled release of probiotic strains. It investigates the impacts of environmental stresses during the transition stage and delivery to the target region in the gastrointestinal tract. The influence of factors such as pH levels, enzymatic degradation, and redox conditions on the release mechanisms of probiotics is presented. Finally, the available methods to evaluate the efficiency of a probiotic delivery system, including in vitro and in vivo, are reviewed and assessed. The paper concludes with a discussion highlighting the emerging technologies in the field and emphasising key areas in need of future study.

Limosilactobacillus reuteri DSM 17938 relieves inflammation, endoplasmic reticulum stress, and autophagy in hippocampus of western diet-fed rats by modulation of systemic inflammation.

The consumption of western diets, high in fats and sugars, is a crucial contributor to brain molecular alterations, cognitive dysfunction and neurodegenerative diseases. Therefore, a mandatory challenge is the individuation of strategies capable of preventing diet-induced impairment of brain physiology. A promising strategy might consist in the administration of probiotics that are known to influence brain function via the gut-brain axis. In this study, we explored whether Limosilactobacillus reuteri DSM 17938 (L. reuteri)-based approach can counteract diet-induced neuroinflammation, endoplasmic reticulum stress (ERS), and autophagy in hippocampus, an area involved in learning and memory, in rat fed a high fat and fructose diet. The western diet induced a microbiota reshaping, but L. reuteri neither modulated this change, nor the plasma levels of short-chain fatty acids. Interestingly, pro-inflammatory signaling pathway activation (increased NFkB phosphorylation, raised amounts of toll-like receptor-4, tumor necrosis factor-alpha, interleukin-6, GFAP, and Haptoglobin), as well as activation of ERS (increased PERK and eif2α phosphorylation, higher C/EBP-homologous protein amounts) and autophagy (increased beclin, P62-sequestosome-1, and LC3 II) was revealed in hippocampus of western diet fed rats. All these hippocampal alterations were prevented by L. reuteri administration, showing for the first time a neuroprotective role of this specific probiotic strain, mainly attributable to its ability to regulate western diet-induced metabolic endotoxemia and systemic inflammation, as decreased levels of lipopolysaccharide, plasma cytokines, and adipokines were also found. Therapeutic strategies based on the use of L. reuteri DSM17938 could be beneficial in reversing metabolic syndrome-mediated brain dysfunction and cognitive decline.

Ultrasound Attenuation Improves Some Surface Properties of the Probiotic Strain Lacticaseibacillus casei ATCC 393.

Ultrasound attenuation has been recently proposed as a tool to modulate probiotic metabolism. The study aimed to characterize the response of the probiotic Lacticaseibacillus casei ATCC 393 to sonication. Two ultrasound treatments were tested (57 W, duty cycle 50%, 6 or 8 min). Attenuation was assessed as a pH decrease in MRS broth after 6 and 24 h of incubation at 37 °C. Cultivability was evaluated by plate count immediately after sonication and by growth index on overnight cultures. Surface changes were determined by auto-aggregation, hydrophobicity, biofilm production tests, and by membrane damages. The 6 min treatment induced a temporary attenuation, while a prolongated exposure to sonic waves caused major attenuation effects (ΔpH 0.97 after 24 h). Both sonication treatments affected probiotic cultivability with a significant (p < 0.05) reduction of plate counts and an alteration of the growth index. Although auto-aggregation was negatively affected upon sonication, the hydrophobicity and biofilm production were improved with no significant differences (p > 0.05) between the sonicated samples. Moreover, sonicated L. casei ATCC 393 resulted in increased membrane permeability. These results suggest that ultrasound technology can be successfully used to modulate the L. casei ATCC 393 fermentative metabolism and to improve its surface properties.

Special Issue "Probiotics and Their Metabolism": Editorial.

As a general theory, the benefits of probiotics to human health and the prevention of disease are promoted by metabolites, which include antimicrobial compounds, short-chain fatty acids (SCFAs), organic acids, and bio-actives [...].

Microencapsulation and sonication: A multiple physical approach to attenuate the probiotic Lacticaseibacillus casei ATCC 393.

Modulation of probiotic performances represents a tool to avoid the probiotic off-flavor in probiotic food. Microencapsulation and sonication were evaluated in slowing down the Lacticaseibacillus casei ATCC 393 induced acidification. Firstly, the influence of alginate concentration and chitosan coating on acidification rate were tested. Microcapsule morphology and the entrapment efficacy were also evaluated. Then, two time of exposure to ultrasound, 6 and 8 min, were applied for L. casei attenuation. Finally, sonicated cells were encapsulated. ΔpH after 6 and 24 h of incubation at 37 °C revealed that chitosan-alginate microcapsules and the 8-min sonicated probiotic presented a significant delayed acidification. When all the systems were compared, the encapsulation of 8-min sonicated L. casei in chitosan-alginate microcapsules significantly improved the results obtained with the single technologies. These results suggest that by modulating the operating parameters and combining these two technologies an increasingly efficient attenuation system can be developed.

Anti-Quorum Sensing Activity of Probiotics: The Mechanism and Role in Food and Gut Health.

BACKGROUND: Quorum sensing (QS) is a cell-to-cell communication mechanism that occurs between inter- and intra-bacterial species and is regulated by signaling molecules called autoinducers (AIs). It has been suggested that probiotics can exert a QS inhibitory effect through their metabolites. PURPOSE: To provide an overview of (1) the anti-QS activity of probiotics and its mechanism against foodborne pathogenic and spoilage bacteria; (2) the potential role of the QS of probiotics in gut health; and (3) the impact of microencapsulation on QS. RESULTS: Lactobacillus species have been extensively studied for their anti-QS activity and have been found to effectively disrupt QS in vitro. However, their effectiveness in a food matrix is yet to be determined as they interfere with the AI receptor or its synthesis. QS plays an important role in both the biofilm formation of probiotics and pathogenic bacteria. Moreover, in vitro and animal studies have shown that QS molecules can modulate cytokine responses and gut dysbiosis and maintain intestinal barrier function. In this scenario, microencapsulation was found to enhance AI activity. However, its impact on the anti-QS activity of probiotics and its underlying mechanism remains unclear. CONCLUSIONS: Probiotics are potential candidates to block QS activity in foodborne pathogenic and food spoilage bacteria. Microencapsulation increases QS efficacy. However, more research is still needed for the identification of the QS inhibitory metabolites from probiotics and for the elucidation of the anti-QS mechanism of probiotics (microcapsules and free cells) in food and the human gut.

Evaluation of GABA Production by Alginate-Microencapsulated Fresh and Freeze-Dried Bacteria Enriched with Monosodium Glutamate during Storage in Chocolate Milk.

Two strains of γ-aminobutyric acid (GABA) producing bacteria, L. brevis Y1 and L. plantarum LM2, were microencapsulated in sodium alginate with two concentrations (1% and 2%) of monosodium glutamate (MSG) by using vibrating technology. The mix of both species was microencapsulated both in fresh and freeze-dried form. After 0, 1, 2, and 4 weeks of storage at 4 °C in quarter strength Ringer's solution, the microcapsules were subjected to cell viable counting and sub-cultured in MRS at 37° for 24 h. The MRS cultures were analyzed for the GABA content. The amount of GABA produced per CFU of MRS inoculum was then calculated. Only the 4-week-old microcapsules were used to inoculate a chocolate milk drink with the aim of obtaining a functionalized drink containing viable probiotic cells and GABA after a 1-week incubation at 4 °C. Therefore, the GABA production in chocolate milk per CFU of the probiotic culture after the incubation time was calculated. Results of the GABA analysis by liquid chromatography mass spectrometry of the MRS sub-cultures showed no significant difference (p > 0.05) in GABA yield between 1% and 2% MSG for the microcapsules containing fresh cells. On the contrary, a significant difference (p < 0.05) in productivity along the storage was registered. Microcapsules containing freeze-dried cells showed significant differences (p < 0.05) in GABA yield between 1% and 2% MSG only after 2 and 4 weeks of storage. A significant difference (p < 0.05) in GABA yield between the storage time was found only for the trials with 2% MSG for freeze-dried cells. The synthesis of GABA in chocolate milk significantly decreased (p < 0.05) only for fresh cells when comparing 2% with 1% MSG. In conclusion, a 1-month storage of microcapsules containing both culture forms, fresh and freeze-dried, did not affect GABA production.

Gut microbiome and blood glucose control in type 1 diabetes: a systematic review.

Objective: The risk of developing micro- and macrovascular complications is higher for individuals with type 1 diabetes (T1D). Numerous studies have indicated variations in gut microbial composition between healthy individuals and those with T1D. These changes in the gut ecosystem may lead to inflammation, modifications in intestinal permeability, and alterations in metabolites. Such effects can collectively impact the metabolic regulation system, thereby influencing blood glucose control. This review aims to explore the relationship between the gut microbiome, inflammation, and blood glucose parameters in patients with T1D. Methods: Google Scholar, PubMed, and Web of Science were systematically searched from 2003 to 2023 using the following keywords: "gut microbiota," "gut microbiome," "bacteria," "T1D," "type 1 diabetes," "autoimmune diabetes," "glycemic control," "glucose control," "HbA1c," "inflammation," "inflammatory," and "cytokine." The examination has shown 18,680 articles with relevant keywords. After the exclusion of irrelevant articles, seven observational papers showed a distinct gut microbial signature in T1D patients. Results: This review shows that, in T1D patients, HbA1c level was negatively correlated with abundance of Prevotella, Faecalibacterium, and Ruminococcaceae and positively correlated with abundance of Dorea formicigenerans, Bacteroidetes, Lactobacillales, and Bacteriodes. Instead, Bifidobacteria was negatively correlated with fasting blood glucose. In addition, there was a positive correlation between Clostridiaceae and time in range. Furthermore, a positive correlation between inflammatory parameters and gut dysbiosis was revealed in T1D patients. Conclusion: We draw the conclusion that the gut microbiome profiles of T1D patients and healthy controls differ. Patients with T1D may experience leaky gut, bacterial translocation, inflammation, and poor glucose management due to microbiome dysbiosis. Direct manipulation of the gut microbiome in humans and its effects on gut permeability and glycemic control, however, have not been thoroughly investigated. Future research should therefore thoroughly examine other potential pathophysiological mechanisms in larger studies.

Limosilactobacillus reuteri DSM 17938 reverses gut metabolic dysfunction induced by Western diet in adult rats.

Introduction: Microencapsulation of probiotic bacteria is an efficient and innovative new technique aimed at preserving bacterial survival in the hostile conditions of the gastrointestinal tract. However, understanding whether a microcapsule preserves the effectiveness of the bacterium contained within it is of fundamental importance. Methods: Male Wistar rats aged 90 days were fed a control diet or a Western diet for 8 weeks, with rats fed the Western diet divided into three groups: one receiving the diet only (W), the second group receiving the Western diet and free L. reuteri DSM 17938 (WR), and the third group receiving the Western diet and microencapsulated L. reuteri DSM 17938 (WRM). After 8 weeks of treatment, gut microbiota composition was evaluated, together with occludin, one of the tight junction proteins, in the ileum and the colon. Markers of inflammation were also quantified in the portal plasma, ileum, and colon, as well as markers for gut redox homeostasis. Results: The Western diet negatively influenced the intestinal microbiota, with no significant effect caused by supplementation with free and microencapsulated L. reuteri. However, L. reuteri, in both forms, effectively preserved the integrity of the intestinal barrier, thus protecting enterocytes from the development of inflammation and oxidative stress. Conclusion: From these whole data, it emerges that L. reuteri DSM 17938 can be an effective probiotic in preventing the unhealthy consequences of the Western diet, especially in the gut, and that microencapsulation preserves the probiotic effects, thus opening the formulation of new preparations to be able to improve gut function independent of dietary habits.

Development of Antimicrobial Cellulose Nanofiber-Based Films Activated with Nisin for Food Packaging Applications.

The cellulose nanofiber (CNF) is characterized by the nano-sized (fibers with a diameter between 5 and 20 nm and a length between 2 and 10 µm), flexible and cross-linked structure that confer enhanced mechanical and gas barrier properties to cellulosic fiber-based packaging materials. The purpose of this work was to develop an antimicrobial packaging film by direct mixing nisin with CNF, followed by coating it onto polyethylene (PE), polypropylene (PP), and polylactic acid (PLA) films. The antimicrobial effectiveness of CNF-Nis+PE, CNF-Nis+PP, and CNF-Nis+PLA was investigated both in vitro end in ex vivo tests. In the latter case, challenge test experiments were carried out to investigate the antimicrobial activity of the coupled films of CNF-Nisin+PLA to inhibit the growth of Listeria innocua 1770 during the storage of a meat product. The films were active against the indicator microorganisms Brochothrix thermosphacta and Listeria innocua in in vitro test. Moreover, a reduction in the Listeria population of about 1.3 log cycles was observed immediately after the contact (T0) of the active films with hamburgers. Moreover, when the hamburgers were stored in active films, a further reduction of the Listeria population of about 1.4 log cycles was registered after 2 days of storage. After this time, even though an increase in Listeria load was observed, the trend of the Listeria population in hamburgers packed with active films was maintained significantly lower than the meat samples packed with control films during the whole storage period.

Comparison between Quality Traits of Solar-Dried and Freeze-Dried Origanum syriacum L. (Za'atar).

There is growing interest in Origanum syriacum due to attractive culinary applications and functional properties. Solar drying is the most common conventional method for drying Origanum syriacum L. (Za'atar) in Mediterranean region. This study aimed to evaluate the quality traits of solar dried za'atar in comparison to freeze dried za'atar. Proximate composition (moisture, protein, fat, fiber, carbohydrates, and ash), color index (L*a*b*), macro and microstructure, sensory, and microbiological characteristics were evaluated. Solar dried za'atar exhibited significantly lower fat content (1.10 vs. 1.64%, p < 0.05) than freeze dried za'atar. Solar drying led to severe changes in color values compared to freeze drying. Solar drying exhibited loss in the structural integrity and leave hairs more than freeze drying. Moreover, freeze-dried za'atar exhibited significantly lower total aerobic count (4.92 vs. 5.23, p < 0.05) and yeasts and mold count (4.59 vs. 5.36, p < 0.05) than solar-dried za'atar. Panelists were able significantly to differentiate between solar- and freeze dried za'atar. Freeze-dried za'atar had significantly lower hedonic score of color, odor, taste, and overall acceptance than solar dried za'atar. In conclusion, using freeze drying achieved good improvements in some quality traits for za'atar while solar dried za'atar showed better sensory perception.

Layer-by-Layer Coating of Single-Cell Lacticaseibacillus rhamnosus to Increase Viability Under Simulated Gastrointestinal Conditions and Use in Film Formation.

Probiotics and prebiotics are widely used as functional food ingredients. Viability of probiotics in the food matrix and further in the digestive system is still a challenge for the food industry. Different approaches were used to enhance the viability of probiotics including microencapsulation and layer-by-layer cell coating. The of aim of this study was to evaluate the viability of coated Lacticaseibacillus rhamnosus using a layer-by-layer (LbL) technique with black seed protein (BSP) extracted from Nigella sativa defatted seeds cakes (NsDSC), as a coating material, with alginate, inulin, or glucomannan, separately, and the final number of coating layers was 3. The viable cell counts of the plain and coated L. rhamnosus were determined under sequential simulated gastric fluid (SGF) for 120 min and simulated intestinal fluid (SIF) for 180 min. Additionally, the viability after exposure to 37, 45, and 55°C for 30 min was also determined. Generally, the survivability of coated L. rhamnosus showed significant (p ≤ 0.05) improvement (<4, 3, and 1.5 logs reduction for glucomannan, alginate and inulin, respectively) compared with plain cells (∼6.7 log reduction) under sequential exposure to SGF and SIF. Moreover, the cells coated with BSP and inulin showed the best protection for L. rhamnosus under high temperatures. Edible films prepared with pectin with LbL-coated cells showed significantly higher values in their tensile strength (TS) of 50% and elongation at the break (EB) of 32.5% than pectin without LbL-coated cells. The LbL technique showed a significant protection of probiotic cells and potential use in food application.

Limosilactobacillus reuteri in Health and Disease.

Limosilactobacillus reuteri is a microorganism with valuable probiotic qualities that has been widely employed in humans to promote health. It is a well-studied probiotic bacterium that exerts beneficial health effects due to several metabolic mechanisms that enhance the production of anti-inflammatory cytochines and modulate the gut microbiota by the production of antimicrobial molecules, including reuterin. This review provides an overview of the data that support the role of probiotic properties, and the antimicrobial and immunomodulatory effects of some L. reuteri strains in relation to their metabolite production profile on the amelioration of many diseases and disorders. Although the results discussed in this paper are strain dependent, they show that L. reuteri, by different mechanisms and various metabolites, may control body weight and obesity, improve insulin sensitivity and glucose homeostasis, increase gut integrity and immunomodulation, and attenuate hepatic disorders. Gut microbiota modulation by ingesting probiotic L. reuteri strains could be a promising preventative and therapeutic approach against many diseases and disorders.

Microencapsulation of Probiotics for Food Functionalization: An Update on Literature Reviews.

Functional foods comprise the largest growing food category due to both consumer demands and health claims by manufacturers. Probiotics are considered one of the best choices for meeting these demands. Traditionally, the food vehicle for introducing probiotics to consumers was dairy products, and to expand the benefits of probiotics for a wider range of consumers, the need to use other food items was essential. To achieve this goal while maximising the benefits of probiotics, protection methods used during food processing were tackled. The microencapsulation of probiotics is a promising methodology for achieving this function. This review highlights the use of the microencapsulation of probiotics in order to functionalise food items that initially were not considered suitable for probiotication, such as baked products, or to increase their functionality such as dairy products. The co-microencapsulation of probiotics with other functional ingredients such polyphenol, prebiotics, or omega-3 is also highlighted.

Application of the Hurdle Technology Concept to the Fresh Za'atar (Origanum syriacum) Preservation.

Oregano (Origanum syriacum) is popularly called za'atar in the Middle East region. It is widely used in the Mediterranean diet as an aromatic herb. This study aimed to evaluate the preservation effect of natural additives, vacuum packaging, and refrigeration on the quality traits of fresh oregano. In total, 132 fresh oregano samples were formulated and split into 4 groups (n = 33) labeled group A (100% fresh oregano leaves, Control), group B (fresh oregano 63.2%, 15% fresh onion, 20% oil, 1.8% salt), group C (fresh oregano 61.91%, 15% fresh Allium cepa, 20% oil, 1.8% salt, 1.29% sumac), and group D (fresh oregano 59.2%, 15% fresh Allium cepa, 20% corn oil, 1.8% salt, 4% lactic acid, ultimate pH 4.4). Different quality traits such as color index (L*a*b*), microbiological analysis (total aerobic, anaerobic, and psychrotrophic bacteria and yeasts and molds), and sensory features (taste, flavor, appearance, saltiness, and overall acceptance) were assessed during the storage period (42 days) for all groups. Our study showed that the addition of lactic acid (group D) exhibited a strong preservation effect against aerobic and anaerobic bacteria. In this context, group D had significantly lower aerobic and anaerobic bacterial counts (5.12 vs. 6.7, 6, and 6.7 log (cfu/g); p < 0.05) and (4.75 vs. 6.6, 6.1, 6.77 (cfu/g); p < 0.05) than group A, B, and C; respectively. Group D exhibited significantly (p < 0.05) lower psychrotrophic bacterial count (3.6 log (cfu/g)) during the whole period of storage compared with control. Group B had a lower redness index (a*) (−3.3 vs. −1.8, −1.65, −1.23; p < 0.05) than groups A, C, and D; respectively. In conclusion, our study showed that there is a possibility of improving the preservation of oregano (Origanum syriacum) by using lactic acid and sumac combined with vacuum packaging under refrigeration conditions.

Application of ultrasound and microencapsulation on Limosilactobacillus reuteri DSM 17938 as a metabolic attenuation strategy for tomato juice probiotication.

Counteracting probiotic-induced physicochemical and sensory changes is a challenge in the development of probiotic beverages. The aim of the study is to apply ultrasound and microencapsulation for the attenuation of Limosilactobacillus reuteri DSM 17938 to avoid change in a probiotic tomato juice. Preliminarily, six ultrasound treatments were applied. Probiotic survival in acid environment (pH 2.5) and bile salts (1.5 g/l) after ultrasound treatment was also studied. The probiotic was inoculated in tomato juice in four forms: free cells (PRO-TJ), sonicated-free cells (US-TJ), untreated-microencapsulated (PRO-MC-TJ) and sonicated-microencapsulated cells (US-MC-TJ). Probiotic viability and pH were monitored during 28 days of storage at 4 and 20 °C. Sensory analysis was performed for PRO-TJ and US-MC-TJ sample (4 °C). Ultrasound (57 W for 6 min) did not affect cell survival and transitorily modulated probiotic acidifying capacity; it reduced probiotic survival in acidic environment but increased probiotic survival in bile salts solution. Ultrasound was effective in maintain pH value of tomato juice but only at 4 °C. Instead, microencapsulation with sodium-alginate leads to a more stable probiotic juice, particularly at 20 °C. Finally, probiotication slightly modified some sensory attributes of the juice. This study shows the potential of ultrasound and microencapsulation as attenuation strategies and highlights the need for process optimization to increase ultrasound efficacy.

Spoilage-related activity of Carnobacterium maltaromaticum strains in air-stored and vacuum-packed meat.

One hundred three isolates of Carnobacterium spp. from raw meat were analyzed by random amplification of polymorphic DNA (RAPD) and PCR and were identified by 16S rRNA gene sequencing. Forty-five strains of Carnobacterium maltaromaticum were characterized for their growth capabilities at different temperatures, NaCl concentrations, and pH values and for in vitro lipolytic and proteolytic activities. Moreover, their spoilage potential in meat was investigated by analyzing the release of volatile organic compounds (VOCs) in meat stored in air or vacuum packs. Almost all the strains were able to grow at 4, 10, and 20°C, at pH values of 6 to 9, and in the presence of 2.5% NaCl. The release of VOCs by each strain in beef stored at 4°C in air and vacuum packs was evaluated by headspace solid-phase microextraction (HS-SPME)-gas chromatography-mass spectrometry (GC-MS) analysis. All the meat samples inoculated and stored in air showed higher numbers of VOCs than the vacuum-packed meat samples. Acetoin, 1-octen-3-ol, and butanoic acid were the compounds most frequently found under both storage conditions. The contaminated meat samples were evaluated by a sensory panel; the results indicated that for all sensory odors, no effect of strain was significant (P > 0.05). The storage conditions significantly affected (P < 0.05) the perception of dairy, spoiled-meat, and mozzarella cheese odors, which were more intense in meat stored in air than in vacuum packs but were never very intense. In conclusion, different strains of C. maltaromaticum can grow efficiently in meat stored at low temperatures both in air and in vacuum packs, producing volatile molecules with low sensory impacts, with a negligible contribution to meat spoilage overall.