Using regression and Multifactorial Analysis of Variance to assess the effect of ascorbic, citric, and malic acids on spores and activated spores of Alicyclobacillusacidoterrestris.

The type strain of the species Alicyclobacillus acidoterrestris (DSM 3922) and the strain CB1 (accession number: KP144333) were studied in this research to assess the effects of three weak acids (malic, citric, and ascorbic acids), pH (3 or 4), and spore status (spores, and activated spores). Acids were used to prepare 7 different blends, and the blends used to reduce the pH of Malt Extract broth to 3 and 4; then, media were inoculated with spores or activated spores, stored at 45 °C (optimal temperature for A. acidoterrestris growth), and analyzed immediately and after 2 and 7 days. Data were preliminary standardized as increase/reduction of microbial population, compared to the initial concentration, and modelled through two different statistical approaches (multifactorial ANOVA, and multiple regression). Finally, a binary code (0-no growth or reduction of viable count; 1-growth) was used to perform a multiple regression analysis on the growth probability of A. acidoterrestris. Generally, ascorbic acid was the most effective compound, but other acids (e.g., malic acid) could contribute to increase the inactivation ratio; concerning spore status, the highest sensitivity of activated spores suggests that acids probably act during the outgrowing phase. Finally, the two strains showed different trends at pH 3.0, being the type strain the most resistant one.

Biofilm formation by potentially probiotic Saccharomyces cerevisiae strains.

Four wild strains of Saccharomyces cerevisiae and the collection strain S. cerevisiae var. boulardii ATCC MYA-796 were used as test organisms to study the effect of some environmental conditions on the formation of biofilm by potentially probiotic yeasts. In a first step, the formation of biofilm was studied in four different media (YPD-Yeast Peptone Glucose; diluted YPD; 2% BP, a medium containing only bacteriological peptone; 2% GLC, a medium containing only glucose). Then, the dilution of YPD was combined with pH and temperature through a mixture design to assess the weight of the interaction of the variables; the experiments were done on S. boulardii and on S. cerevisiae strain 4. The dilution of nutrients generally determined an increased biofilm formation, whereas the effect of pH relied upon the strain. For S. cerevisiae strain 4, the highest level of sessile cells was found at pH 4-5, while S. boulardii experienced an enhanced biofilm formation at pH 6.0. Concerning temperature, the highest biofilm formation was found at 25-30 °C for both strains. The importance of this work lies in its extension of our knowledge of the effect of different environmental conditions on biofilm formation by potentially probiotic S. cerevisiae strains, as a better understanding of this trait could be an important screening tool into the selection of new multifunctional yeasts.

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.

Functional cream cheese supplemented with Bifidobacterium animalis subsp. lactis DSM 10140 and Lactobacillus reuteri DSM 20016 and prebiotics.

The aim of this study was to develop a functional fresh cream cheese with Bifidobacterium animalis subsp. lactis DSM 10140 or Lactobacillus reuteri DSM 20016 and prebiotics (inulin, FOS and lactulose). The research was divided into two steps: in vitro evaluation of the effects of prebiotic compounds; validation at laboratory level with production of functional cream mini-cheeses. Prebiotics showed a protective effect: B. animalis subsp. lactis DSM 10140 cultivability on Petri dishes was positively influenced by lactulose, whereas fructooligosaccharides (FOS) were the prebiotic compounds able to prolong Lb. reuteri DSM 20016 cultivability. At 30 °C, a prolongation of the death time (more than 300 days) was observed, while the controls showed death time values about 100 days. At 45 °C, death time values increased from 32.2 (control) to 33, 35, and 38 days in the samples added with FOS, inulin and lactulose, respectively. Lactulose and FOS were chosen to be added to cream mini-cheeses inoculated with B. animalis subsp. lactis DSM 10140 and Lb. reuteri DSM 20016, respectively; the proposed functional cream cheese resulted in a product with favourable conditions for the viability of both probiotics which maintained cultivable cells above the recommended level during 28 days of storage at 4 °C with good sensory characteristics.

Nonthermal Technologies for Fruit and Vegetable Juices and Beverages: Overview and Advances.

In recent years, there has been a growing interest in the design of novel nonthermal processing systems that minimally modify sensory, nutritional, and functional properties of fruit and vegetable juices and beverages. The benefits of nonthermal treatments are strongly dependent on the food matrix. Thus, an understanding of the effects that these technologies exert on the properties of juices and beverages is important to design and optimize technological parameters to produce value-added products. This review covers research on nonthermal electrical treatments, high pressure processing, ultrasound, radiation processing, inert gas treatments, cold plasma, and membrane processing. Advances towards optimization of processing conditions, and combined technologies approaches have been also extensively reviewed. This information could be useful to: (1) manage processing systems and optimize resources; (2) preserve nutritional value and organoleptic properties, and (3) provide processing conditions for validation of these technologies at the industrial scale.

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.

A possible approach to assess acidification of meat starter cultures: a case study from some wild strains of Lactobacillus plantarum.

BACKGROUND: The performances of four autochthonous isolates of Lactobacillus plantarum were assessed to study the most important variables acting on acidification and to propose a possible step-by-step approach for the validation at laboratory scale. This main topic was addressed through three intermediate steps: (1) evaluation of acidification in liquid and solid media, as a function of salt, nitrites, nitrates, lactose, pepper and temperature; (2) assessing acidification in a pork-meat preparation; and (3) designing a protocol to improve the performances at sub-optimal temperatures. The concentration of the ingredients and the temperature were combined through a 3k-p Fractional Factorial Design. Acidification and viable count were assessed and modelled through a multi-factorial ANOVA. RESULTS: In model systems acidification was affected by lactose and was maximum (ΔpH of ca. 2.8-3.0) in the combinations containing 0.4% lactose, 250 mg kg-1 nitrates or 150 mg kg-1 nitrites, 5% salt, and at 30 °C. Solid media caused a higher acidification. In the pork meat preparation, the effect of salt and nitrites was significant. At 10 °C the strains could not reduce pH, but this ability could be induced using an adaptation step. CONCLUSION: Acidification was affected by lactose in the model system, whereas in meat preparation the other variables were significant. In addition, a protocol to improve acidification at 10 °C was optimised. © 2016 Society of Chemical Industry.

Thermal Treatments for Fruit and Vegetable Juices and Beverages: A Literature Overview.

Fruit and vegetable juices and beverages are generally preserved by thermal processing, currently being the most cost-effective means ensuring microbial safety and enzyme deactivation. However, thermal treatments may induce several chemical and physical changes that impair the organoleptic properties and may reduce the content or bioavailability of some nutrients; in most cases, these effects are strongly dependent on the food matrix. Moreover, the efficacy of treatments can also be affected by the complexity of the product and microorganisms. This review covers researches on this topic, with a particular emphasis on products derived from different botanical sources. Technologies presented include conventional and alternative thermal treatments. Advances toward hurdle-based technology approaches have been also reviewed.

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 promising starter cultures for Fior di Latte, a traditional cheese of southern Italy.

BACKGROUND: This paper describes the selection of promising strains intended as starter cultures from the autochthonous lactic acid bacteria of Fior di Latte cheese (Apulia region, southern Italy). RESULTS: Ninety-five isolates were randomly selected from whey and Fior di Latte. After preliminary characterization based upon Gram staining, deamination of arginine, hydrolysis of esculine and production of CO2 from glucose and citrate, the isolates were studied for their growth at different temperatures (10, 15 and 45 °C), with salt addition (20, 40 and 65 g L(-1) ) and at pH 4.4 and their acidification score in MRS broth after 6 and 24 h. Data were modeled through the growth index and used as input to run a preliminary cluster analysis and a principal component analysis. In this way, nine promising strains were selected and used for validation at laboratory level, to study the acidification score in milk and propose some possible microbial mixtures. CONCLUSION: This paper reports the first research focusing on the design of a lactic starter for the production of Fior di Latte cheese, using a quantitative approach based on the evaluation of growth index and acidification score as well as on the use of a multivariate approach to select the most promising nine strains.

Decontamination of ochratoxin A by yeasts: possible approaches and factors leading to toxin removal in wine.

Biological decontamination of mycotoxins using microorganisms is one of the well-known strategies for the management of mycotoxins in foods and feeds. Yeasts are an efficient biosorbant, used in winemaking to reduce the concentration of harmful substances from the must which affect alcoholic fermentation (medium-chain fatty acids) or which affect wine quality in a negative way (ethyl phenols and sulphur products). In recent years, several studies have demonstrated the ability of yeasts to remove ochratoxin A (OTA) by live cells, cell walls and cell wall extracts, yeast lees. In spite of the physical and chemical methods applied to remove the toxin, the biological removal is considered a promising solution, since it is possible to attain the decontamination without using harmful chemicals and without losses in nutrient value or palatability of decontaminated food. In addition, adsorption is recognized as economically viable, technically feasible and socially acceptable. This paper intends to review the current achievements of OTA removal mediated by yeasts, the recent updates in the selection of strains acting at the same time as starters and as biological tools to remove OTA and the factors affecting the removal process.

Selection of promising lactic acid bacteria as starter cultures for sourdough: using a step-by-step approach through quantitative analyses and statistics.

BACKGROUND: The main goal of this research was to show how to use a qualitative assessment of some technological properties of lactic acid bacteria (LAB), combined with the evaluation of the growth index (GI), to select promising starter cultures for sourdough. RESULTS: Fifty-four strains of LAB were isolated from a single factory, identified by molecular tools and studied for their growth as a function of NaCl (20, 40 and 65 g L(-1)), temperature (45, 15 and 10 °C), pH 9.2 and acidification in MRS broth. The growth was evaluated through absorbance and data were modelled as GI. GIs were used to build frequency histograms and to run a principal component analysis (PCA). In this way, six strains, identified as Lactobacillus plantarum and able to grow in a wide range of conditions (temperature, pH and salt) and/or able to decrease the pH by 1.77-2.0 units, were selected and tested in a model system (flour and water) to study the acidification after 24 h and their viability after 14 days. CONCLUSION: The main result of this paper was to show how a simple step-by-step approach could be a useful tool to select promising starter cultures for sourdough. The method was based on (1) strain identification, (2) assessment of some traits through the GI, combined with simple statistical approaches (frequency histograms and PCA), and (3) preliminary validation in model systems.

Valorization of fish from the Adriatic Sea: nutritional properties and shelf life prolongation of Aphia minuta through essential oils.

This study aimed to exploit the nutritional and microbiological qualities of Aphia minuta, which are still largely unknown; they are collected from Golfo di Manfredonia (Adriatic Sea). Chemical composition, fatty acids, and amino acid profiles were evaluated during winter, spring, and summer (two samples each season). The protein content was highest in spring, while no significant differences were found for fat and ash contents across all sampling periods. Fatty acid profile analyses revealed that monounsaturated and polyunsaturated fatty acids were affected by the sampling season. Notably, the value of n-3 polyunsaturated fatty acids increased in spring and summer compared to the winter season. The highest content of essential amino acids was measured during the spring and summer seasons (P < 0.01), with leucine and lysine being the most dominant. Regardless of the fishing season, from a nutritional point of view, this species is an excellent source of bioactive compounds. This study also focused on the microbiological quality and shelf life of Aphia minuta. Initially, the bioactivity of three different essential oils (thymol, lemon, and citrus extract) was tested on Pseudomonas fluorescens, Staphylococcus aureus, and Escherichia coli. These essential oils were then combined with various packaging materials (conventional, maize starch, and polylactate) and packaging atmosphere (air, vacuum, and a modified atmosphere with reduced oxygen content). The results indicated that combining citrus extract with vacuum packaging significantly reduced the psychrotrophic viable count to undetectable levels after 7 days. This study suggests some important considerations for exploiting and expanding the market of the Aphia minuta.

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.

Effect of ultrasound-attenuation on technological and functional properties of two strains of Lactiplantibacillus plantarum isolated from table olives.

While probiotics have a wide range of beneficial properties, they can also negatively affect the taste or aroma of foods products by resulting in the phenomenon of post-acidification. Ultrasound (US) is a tool to modulate the metabolism of probiotic bacteria, counteracting post-acidification and improving the performance and functional properties of microorganisms without affecting their viability. The purpose of this paper was to evaluate the effect of 10 different combinations of power (20 and 40 %) and duration (2, 4, 6, 8 and 10 min) of US treatment on two functional strains of Lactiplantibacillus plantarum (c16 and c19) isolated from table olives, with the aim of understanding how, some of the main functional and technological traits (viability, acidification, growth profile under different conditions, antibiotic resistance, viability at pH 2.0 and 0.3 % bile salts), were affected. It was found that the effects were strain dependent, and the best results were obtained for strain c19 in the combinations at 20 % for 8 and 10 min and 40 % for 2 min, where an improvement in functional characteristics was found, with some effects on biofilm stability, inhibition of acidification, without adverse results on some technological properties.

Gut-Microbiota, and Multiple Sclerosis: Background, Evidence, and Perspectives.

Many scientific studies reveal a significant connection between human intestinal microbiota, eating habits, and the development of chronic-degenerative diseases; therefore, alterations in the composition and function of the microbiota may be accompanied by different chronic inflammatory mechanisms. Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS), in which autoreactive immune cells attack the myelin sheaths of the neurons. The purpose of this paper was to describe the main changes that occur in the gut microbiota of MS patients, with a focus on both microbiota and its implications for health and disease, as well as the variables that influence it. Another point stressed by this paper is the role of microbiota as a triggering factor to modulate the responses of the innate and adaptive immune systems, both in the intestine and in the brain. In addition, a comprehensive overview of the taxa modified by the disease is presented, with some points on microbiota modulation as a therapeutic approach for MS. Finally, the significance of gastro-intestinal pains (indirectly related to dysbiosis) was assessed using a case study (questionnaire for MS patients), as was the willingness of MS patients to modulate gut microbiota with probiotics.

Minimal Inhibitory Concentrations of Thymol and Carvacrol: Toward a Unified Statistical Approach to Find Common Trends.

Thymol and carvacrol are some of the most important and used components of Essential oils (EOs); they are widely studied, and there are much data available in the literature. Their Minimal Inhibitory Concentration (MIC) values found in the literature from 2005 to present were used to assess the bioactivity toward yeasts, molds, Gram-positive bacteria, and Gram-negative bacteria, as well as on some bacterial species/serotypes (Salmonella sp., Escherichia coli, E. coli O157:H7, lactic acid bacteria, Listeria monocytogenes, Staphylococcus aureus, S. epidermidis, etc.) to find possible common trends or differences between the two compounds and among the tested species. The results were quite interesting and pointed out that there is a common range for the MIC of thymol and carvacrol for some bacterial species (150-400 mg/L), with some exceptions to this generalized statement. In addition, the statistics pointed out that bacteria could experience homogeneous (S. epidermidis, E. coli O157:H7) or heterogeneous trends (for example, Salmonella sp.) depending on the existence of possible sub-species or different experimental set-ups. Moreover, this paper suggests that there are some drawbacks and issues that should be solved for the effective use of EOs, which are the strong variability among the microorganisms and the lack of standard protocols and reference strains.

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.