An Update on Prebiotics and on Their Health Effects.

Prebiotic compounds were originally defined as "a nondigestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon, and thus improves host health"; however, a significant modulation of the definition was carried out in the consensus panel of The International Scientific Association for Probiotics and Prebiotics (ISAPP), and the last definition states that "prebiotics are substrates that are selectively utilized by host microorganisms conferring a health benefit". Health effects of prebiotics compounds attracted the interest of researchers, food companies and Regulatory Agencies, as inferred by the number of articles on Scopus for the keywords "prebiotic" and "health effects", that is ca. 2000, for the period January 2021-January 2024. Therefore, the aim of this paper is to contribute to the debate on these topics by offering an overview of existing knowledge and advances in this field. A literature search was performed for the period 2012-2023 and after the selection of the most relevant items, the attention was focused on seven conditions for which at least 8-10 different studies were found, namely colorectal cancer, neurological or psychiatric conditions, intestinal diseases, obesity, diabetes, metabolic syndrome, and immune system disorders. In addition, the analysis of the most recent articles through the software VosViewer version 1.6.20 pointed out the existence of five clusters or macro-categories, namely: (i) pathologies; (ii) metabolic condvitions; (iii) structure and use in food; (iv) immunomodulation; (v) effect on gut microbiota.

A narrative review on the use of probiotics in several diseases. Evidence and perspectives.

Gut microbiota is a complex ecosystem, strictly linked to health and disease, as a balanced composition (referred as eubiosis) is necessary for several physiological functions, while an unbalanced composition (dysbiosis) is often associated to pathological conditions and/or diseases. An altered microbiota could be positively affected and partially restored through probiotic supplementation, among others. This review addresses the effects of probiotics in several conditions, used as case-studies (colorectal cancer, neuro-psychiatric diseases, intestinal diseases, obesity, diabetes, metabolic syndrome, immune system, and musculoskeletal system disorders) by pointing out the clinical outcomes, the mode of action, mainly related to the production of short chain fatty acids (SCFA), the impact of probiotic dose and mode of supplementation, as well as trying to highlight a hit of the most used genera.

Microbiological Risk Assessment in Foods: Background and Tools, with a Focus on Risk Ranger.

Risk assessment is an important phase of the food production path; it is strictly related to the processing chain as a necessary step for safe foods. This paper represents a contribution to understanding what is and how risk assessment could be conducted; it aims to provide some information on the structure of risk assessment, the tools for its identification and measurement and the importance of risk assessment for correct communication. In this context, after a focus on the background and on some commonly used tools (Risk Ranger, FDA-iRisk, decision tree, among others), the paper describes how to perform risk assessment through three case studies: lettuce (for Listeria monocytogenes), chicken salad (for Escherichia coli), and fresh egg pasta (for Staphylococcus aureus) in the first step, and then a comparison of risk for chicken salad contaminated by different pathogens (E. coli O157:H7, Campylobacter spp. and Salmonella sp.). As a final step, a critical evaluation of Risk Ranger was carried out, pointing out its pros and cons.

Ultrasound can increase biofilm formation by Lactiplantibacillus plantarum and Bifidobacterium spp.

The main goal of this research was to study the effect of an Ultrasound (US) treatment on biofilm formation of Lactiplantibacillus plantarum (strains c19 and DSM 1055), Bifidobacterium animalis subsp. lactis DSM 10140, Bifidobacterium longum subsp. longum DSM 20219, and Bifidobacterium longum subsp. infantis DSM 20088. From a methodological point of view, each microorganism was treated through six US treatments, different for the power (10, 30, or 50% of the net power, 130 W), the duration (2, 6, or 10 min) and the application of pulses (0 or 10 s). After the treatment, a biofilm of the strains was let to form on glass slides and the concentration of sessile cells was analyzed for 16 days. Biofilms formed by untreated microorganisms were used as controls. As a first result, it was found that US significantly increased the concentration of sessile cells of B. longum subsp. infantis, while for some other strains US treatment could not affect the formation of biofilm while improving its stability, as found for L. plantarum DSM1055 after 16 days. The variable mainly involved in this positive effect of US was the duration of the treatment, as biofilm formation and stability were improved only for 2 min-treatments; on the other hand, the effect of power and pulses were strain-dependent. In conclusion, the results suggest practical implication of a US pre-treatment for various fields (improvement of adhesion of microorganisms useful in food or in the gut, biomedical and environmental industries), although further investigations are required to elucidate the mode of action.

Psycho-Microbiology, a New Frontier for Probiotics: An Exploratory Overview.

Probiotics are gradually gaining importance in the field of psychiatry in the form of psychobiotics. Psychobiotics' studies examine the existing relationship between gut microbiota and mental phenomena; the intake of certain strains of probiotics, such as Bifidobacterium and Lactobacillus, for example, allow the gut microbial system to be modified in order to provide benefits at the psychic, immune, hormonal, and mental levels. Those who suffer from forms of depression, anxiety disorders, chronic stress, low mood, but also people who do not suffer from such disorders, can therefore benefit from the use of psychobiotics. Thanks to probiotics, neurochemicals can in fact be produced within the gut microbiota and interact with receptors of the enteric nervous system that innervate the entire gastrointestinal tract. Once they enter the portal circulation, these substances go on to influence components of the nervous system and ultimately the brain, through what is called the gut-brain axis. This article proposes an exploratory overview of the proven effects of probiotics on brain activity and psycho-related diseases, focusing on clinical studies and measurable outcomes. The search was conducted using two different online tools: ClinicalTrials.gov and PubMed.

How Diet and Physical Activity Modulate Gut Microbiota: Evidence, and Perspectives.

Gut microbiota plays a significant role in the maintenance of physiological homeostasis, contributing to human health. Nevertheless, some factors (sex, age, lifestyle, physical activity, drug-based therapies, diet, etc.) affect its composition and functionality, linked to pathologies and immunological diseases. Concerning diet, it interacts with microorganisms, leading to beneficial or detrimental outcomes for the health of host. On the other hand, physical activity is known to be useful for preventing and, sometimes, treating several diseases of cardiovascular, neuroendocrine, respiratory, and muscular systems. This paper focuses on diet and physical activity presenting the current knowledge about how different diets (Western, ketogenic, vegan, gluten free, Mediterranean) as well as different types of exercise (intensive, endurance, aerobic) could shape gut microbiota.

Use of Food Spoilage and Safety Predictor for an "A Priori" Modeling of the Growth of Lactic Acid Bacteria in Fermented Smoked Fish Products.

Fermentation is one of the oldest methods to assure the safety and quality of foods, and to prolong their shelf life. However, a successful fermentation relies on the correct kinetics depending on some factors (i.e., ingredients, preservatives, temperature, inoculum of starter cultures). Predictive microbiology is a precious tool in modern food safety and quality management; based on the product characteristics and the conditions occurring in food processing, the inactivation of or increase in microbial populations could be accurately predicted as a function of the relevant intrinsic or extrinsic variables. The main aim of this study was the optimization of the formula of a smoked fermented fish product using predictive modeling tools (tertiary and secondary models) in order to define the role of each factor involved in the formulation and assure a correct course of fermentation. Product optimization was conducted through the software Food Spoilage and Safety Predictor (FSSP), by modeling the growth of lactic acid bacteria (LAB) as a function of some key parameters such as temperature, pH, salt, liquid smoke, carbon dioxide, and nitrites. The variables were combined through a fractional design of experiments (DoE) (3k-p), and the outputs of the software, i.e., the maximal growth rate (µmax) and the time to attain the critical threshold (tcrit), were modeled through a multiple regression procedure. The simulation, through FSSP and DoE, showed that liquid smoke is the most critical factor affecting fermentation, followed by temperature and salt. Concerning temperature, fermentation at 20-25 °C is advisable, although a low fermentation temperature is also possible. Other parameters are not significant.

Fish Loss/Waste and Low-Value Fish Challenges: State of Art, Advances, and Perspectives.

The sustainability of fishery is a global challenge due to overfishing and reduced stocks all over the world; one of the leading factors of this threat is fish loss/waste. As a contribution to the global efforts towards a sustainable world, this review addresses the topic from different sides and proposes an overview of biorefinery approaches by discussing bioactive compounds that could be produced from fish loss (nitrogen compounds, lipids, minerals and pigments, and fish-based compounds such as chitosan). The second part of this review reports on the possibility of using loss or unwanted fish to design products for human consumption or for animal feeding, with a focus on economic criteria, consumers' segmentation, and some examples of products. The final focus is on Food and Agriculture Organization FAO guidelines as a roadmap for the future with respect to solving this threat by addressing the problem from different sides (technology, skills, market, policy, social and gender equity, and infrastructures).

Innovative Preservation Methods Improving the Quality and Safety of Fish Products: Beneficial Effects and Limits.

Fish products are highly perishable, requiring proper processing to maintain their quality and safety during the entire storage. Different from traditional methods used to extend the shelf-life of these products (smoking, salting, marinating, icing, chilling, freezing, drying, boiling, steaming, etc.), in recent years, some alternative methods have been proposed as innovative processing technologies able to guarantee the extension of their shelf-life while minimally affecting their organoleptic properties. The present review aims to describe the primary mechanisms of some of these innovative methods applied to preserve quality and safety of fish products; namely, non-thermal atmospheric plasma (NTAP), pulsed electric fields (PEF), pulsed light (PL), ultrasounds (US) and electrolyzed water (EW) are analysed, focusing on the main results of the studies published over the last 10 years. The limits and the benefits of each method are addressed in order to provide a global overview about these promising emerging technologies and to facilitate their greater use at industrial level. In general, all the innovative methods analysed in this review have shown a good effectiveness to control microbial growth in fish products maintaining their organoleptic, nutritional and sensory characteristics. Most of the technologies have also shown the great advantage to have a lower energy consumption and shorter production times. In contrast, not all the methods are in the same development stage; thus, we suggest further investigations to develop one (or more) hurdle-like non-thermal method able to meet both food production requirements and the modern consumers' demand.

Marinated Sea Bream Fillets Enriched with Lactiplantibacillus plantarum and Bifidobacterium animalis subsp. lactis: Brine Optimization and Product Design.

This study aimed to design marinated sea bream fillets, inoculated with either Lactiplantibacillus plantarum (strains 11, 68, 69) or Bifidobacterium animalis subsp. lactis DSM 10140. In the first step, the optimization of brine composition was performed through a centroid; the factors of the design were citric acid, vinegar, and salt. As a result of optimization, the optimal composition of brine was set to 0.75% citric acid, 55% vinegar, and 3% NaCl. In the second step, sea bream fillets were inoculated with L. plantarum strain 69 and B. animalis subsp. lactis, marinated and then packed in a conditioning solution (oil or diluted brine); the samples were stored at 4 °C for 21 days. The viability of the strains and sensory scores were assessed. The bacteria retained a high viability throughout storage (21 days); however, the sensory scores were at their highest level for 4 days. In particular, sensory assessment suggested a preference for a conditioning solution with oil, rather than with a diluted brine. In addition, a slightly higher preference was found for B. animalis subsp. lactis.

Use of Autochthonous Lactiplantibacillus plantarum Strains to Produce Fermented Fish Products.

The present research was aimed to the optimization of the production of a fish fermented salami-like product using autochthonous Lactiplantibacillus plantarum starters. The activity was performed through two phases: (1) Optimization of fermented fish product composition by using a 2k-p Fractional Factorial Design: the variables tested were nitrites (0-150 ppm), salt (2.5-7.5%), sucrose (0-4%), white pepper (0-0.10%), and fermentation temperature (10-30°C); (2) Product realization and evaluation of its microbiological profile [aerobic microbiota (APC), Pseudomonadaceae (PSE), Enterobacteriaceae (E), and lactic acid bacteria (LAB) populations], chemico-physical parameters (pH and aw), and sensorial quality (odor, texture, color, and overall acceptability) during its storage at 4°C for 21 days. In the first step, the fish pulp was mixed with the appropriate amounts of ingredients, according to the experimental design; each batch was individually inoculated with the studied starter (L. plantarum 11, L. plantarum 69, and L. plantarum DSM1055) at 107 cfu/g and incubated at 10, 20, or 30°C for 7 days. The lowest fermentation time (time to reach pH 4.4) was obtained with 4% sucrose, 100 ppm nitrite and a process temperature of 30°C. In the second step, salami-like were produced according to the individuated formulation and inoculated with the studied starters (107 cfu/g); the fish mixture was stuffed into a natural casing and left to ferment at 30°C for 7 days. The use of the selected strains not only assured a correct fermentation but reduced the process time at only 2 days; during refrigerated storage, a good microbiological, chemico-physical and sensorial quality of the final product was recorded for at least 21 days.

Microencapsulation of Saccharomyces cerevisiae into Alginate Beads: A Focus on Functional Properties of Released Cells.

Five yeast strains (four wild Saccharomyces cerevisiae strains and a collection strain-S. cerevisiae var. boulardii) were encapsulated in alginate beads. Encapsulation yield was at least 60% (100% for some strains) and yeasts survived in beads for 30 days at 4 °C, although the viability was strongly affected during storage at 25 °C (3 log reduction after 7 days). The kinetic of cell release was studied under static and dynamic conditions, but the results suggest that, after 48 h, beads contained a high number of yeasts. Thus, their use is advisable as re-usable carriers of starter cultures or as a vehicle of probiotics into the gut. Finally, some functional properties (biofilm formation, hydrophobicity, auto-aggregation, survival during the transit into the gut) were evaluated on yeasts released by beads to assess if microencapsulation could negatively affect these traits. The results showed that yeasts' entrapment in beads did not affect probiotic properties.

A low-power ultrasound attenuation improves the stability of biofilm and hydrophobicity of Propionibacterium freudenreichii subsp. freudenreichii DSM 20271 and Acidipropionibacterium jensenii DSM 20535.

The main topic of this paper was to study the effect of ultrasound-attenuation (US) on the surface properties of propionibacteria (Acidipropionibacterium jensenii DSM 20535 and Propionibacterium freudenreichii DSM 20271). A preliminary screening was done by using different power levels (40 and 60%) and treatment times (4, 6, and 8 min); immediately after sonication, acidification and viable count were tested. The best combinations to avoid post-acidification after 6 h were the following: A. jensenii DSM 20535: power, 40%; time, 8 min; P. freudenreichii subsp. freudenreichii DSM 20271: power, 60%; time, 4 min. Moreover, the effect of US on the growth patterns, surface properties (biofilm formation and hydrophobicity), resistance to some selected antibiotics, and release of intracellular components was evaluated; the experiments were done immediately after the treatment. US-treatment improved the stability of biofilm after 5-7 days, caused an increase of hydrophobicity (from 15 to 27%) immediately after sonication, and determined an increase of cell permeability, as suggested by the release of intracellular components within 24 h and by the increased sensitivity to some antibiotics. This paper is the first report on US-attenuation on propionibacteria and could the background for future researches to modulate the surface properties of these microorganisms.

Autochthonous lactic acid bacteria with probiotic aptitudes as starter cultures for fish-based products.

This study focused on the selection of lactic starters with probiotic properties for the production of fermented fish-products by the use of a multivariate approach (Cluster Analysis and Principal Component Analysis). Seventy-five isolates were recovered from fish intestinal microbiota and characterized by evaluating phenotypical, technological and probiotic traits; the most promising isolates were molecularly identified and then used into fish fermented sausage production. Namely, data from technological characterization were modelled through Growth Index and used as input to run a preliminary selection. Thus, 15 promising strains were selected and subjected to probiotic characterization; considering the results from probiotic tests, 3 promising strains were finally chosen (11, 68 and 69), identified as members of the genus Lactobacillus and used for the validation at laboratory level through the assessment of their performances for the production of fermented fish sausages. The results were promising as the use of the selected strains reduced the fermentation time (2 days) ensuring a good microbiological quality of the final product.

Ultrasound attenuation of lactobacilli and bifidobacteria: Effect on some technological and probiotic properties.

Attenuation can be regarded as a tool to modulate the metabolism of probiotic bacteria and, consequently, a strategy to reduce the acidification of the active drinks. Attenuation can be done through chemical and physical approaches and ultrasound (US) is a possibility, previously tested to modulate the metabolism of lactic acid bacteria inoculated in a rice drink, but no data are available on the effect of this treatment of the overall profile of probiotic bacteria. Therefore, the main topic of this paper was to study the effect of US-attenuation on some properties of Lactobacillus reuteri, Lactobacillus plantarum, Bifidobacterium longum, and Bifidobacterium infantis (survival at pH2, and 2.5, and with 0.3% of bile salt added, hydrophobicity, acidification, and growth at different temperatures, pH or in presence of 7% NaCl). A preliminary screening was done by using 3 power levels (40, 60, and 80%) and 3 different treatment times (2, 4, and 6min); immediately after sonication, acidification and viable count were tested. The best combination to avoid post-acidification was the following one: power, 60%; time, 6min; pulse, 2s. The effect of this combination on the overall profile of the test strains (functional and technological properties) was studied. This combination exerted a positive effect on the hydrophobicity and adhesion to Caco-2 cells of L. reuteri, although the growth at pH4 was negatively affected. In the other strains, there a was negative effect on acid and bile resistance.

Use of central composite design in food microbiology: a case study on the effects of secondary phenols on lactic acid bacteria from olives.

This paper focuses on the use of statistical Design of Experiments (DoE) to investigate the effects of two anti-lactic acid bacteria compounds on growth and metabolism of lactobacilli isolated from Italian table olives. p-Coumaric and vanillic acids (0.0-0.4%) were used as phenolic compounds, which were combined with salt (0.0-6.0%) and glucose (0.0-4.0%) through a Central Composite Design. Three strains of Lactobacillus plantarum (5 log cfu/ml) were used as test organisms, samples were stored at 37 °C, and cell counts and pH were evaluated periodically. The growth of lactobacilli was affected in a significant way by salt, p-coumaric and vanillic acids, being the salt the most significant factor after 24 h (short storage time), then replaced by p-coumaric acid. p-Coumaric acid also played a significant role on the acidifying ability, expressed as decrease of pH of the medium: microbial metabolism, in fact, appeared as completely inhibited at 0.2% of p-coumaric acid.

Selection of autochthonous strains as starter cultures for fermented fish products.

This paper was the 1st research focusing on the design of a halophilic lactic starter for the production of fermented fish products using a quantitative approach, based on the evaluation of the growth index and acidification score, as well as on the use of a multivariate approach to select the most promising strains. Fifty-nine strains were randomly selected from salted fish and phenotypically characterized through Gram staining, catalase activity, glucose metabolism, H2 S and indole production, nitrate reduction, citrate utilization, and hydrolysis of arginine, esculin, casein, gelatin, starch, Tween 80, and urea. Then the Gram positive isolates (44 out of 59) were studied for their growth at different temperatures (10, 25, 40, and 55 °C), salt (0%, 20%, and 30%), pHs (4.5 and 9.5), and acidification score in lab medium. Data were modelled through growth index and used as input to run a preliminary cluster analysis and a principal component analysis. Three promising strains were selected, identified as members of the genus Pediococcus and used for the validation at laboratory level through the assessment of their performances in the production of a fermented fish sauce. The results were really promising as their use not only reduced the fermentation time (2 d) but also improved the microbiological quality of the final product. This paper represents a 1st report on the use of a simple step-by-step methodology to select promising halophilic strains for the optimization of a starter for fish-fermented products.