Showing papers by "Milena Sinigaglia published in 2017"

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

Abstract: 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.

The role of Plant Growth Promoting Bacteria in improving nitrogen use efficiency for sustainable crop production: a focus on wheat

Abstract: Due to the increase in both human population growth and environmental pressure, it is necessary to raise agricultural productivity without enhancing environmental footprint. Within this context, soil inoculation with PGPB (Plant Growth Promoting Bacteria) may be considered a promising tool of integrated management systems. In particular, PGPB may improve plant growth either directly, by facilitating resource use or modulating plant hormone levels, or indirectly by decreasing the inhibitory effects of various pathogenic agents. PGPB comprise different functional and taxonomic groups of bacteria like Pseudomonas, Bacillus, Rhizobium and others. Their ability to either mobilize mineral or organic bound nutrients from the pedosphere or to fix atmospheric N2 and make it available to the plants, is a crucial feature in their application. In literature some data are available on the use of commercial PGPB, while less efforts have been made on the study of the effect of autochthonous PGPB isolated from soils on sustainability of cropping systems; thus a literature survey on these aspects was carried out with special focus on wheat, a staple food for a large part of world population. In particular, the main topic of this review is the potential of PGPB to enhance use efficiency of agro-environmental resources focusing on the interaction PGPB-wheat for improving nitrogen use efficiency.

Microbial Resources and Enological Significance: Opportunities and Benefits

Abstract: Among the innovative trends in the wine sector, the continuous exploration of enological properties associated with wine microbial resources represents a cornerstone driver of quality improvement. Since the advent of starter cultures technology, the attention has been focused on intraspecific biodiversity within the primary species responsible for alcoholic fermentation (Saccharomyces cerevisiae) and, subsequently, for the so-called ‘malolactic fermentation’ (Oenococcus oeni). However, in the last decade, a relevant number of studies proposed the enological exploitation of an increasing number of species (e.g. non-Saccharomyces yeasts) associated with spontaneous fermentation in wine. These new species/strains may provide technological solutions to specific problems and/or improve sensory characteristics, such as complexity, mouth-feel and flavours. This review offers an overview of the available information on the enological/protechnological significance of microbial resources associated with winemaking, summarizing the opportunities and the benefits associated with the enological exploitation of this microbial potential. We discuss proposed solutions to improve quality and safety of wines (e.g alternative starter cultures, multistrains starter cultures) and future perspectives.

Microbial Spoilage of Foods: Fundamentals

Abstract: Despite modern technological advances, spoilage of foods continues to occur. Excessive economic losses are due to microbial spoilage, resulting in final products with an inadequate shape or appearance. Understanding how different properties of a food, its environment and “history,” can influence the microbiota that develops in products, is a pivotal step to control quality and safety. The present chapter discusses the characteristics of microbial spoilage of foods with a focus on the major spoilage microorganisms and how they can be detected and controlled.

Biotechnological application of yeasts in food science: Starter cultures, probiotics and enzyme production

Abstract: This review is an account of experiences of two research teams (from Italy to Spain); the leading idea is the following: yeasts represent valuable sources in food science and microbiology and are a kind of food factories, because of the potentiality of whole cells or for their produced compounds. This review covers three major areas: the first section addresses the role of yeasts as starter cultures with a special focus on wine. The second section is an update on probiotic yeasts. Finally, the focus of the last section is on enzymes produced by yeasts, with a short description of the removal of mycotoxin.

Encapsulation of Active Compounds in Fruit and Vegetable Juice Processing: Current State and Perspectives

Abstract: The production of value-added and/or functional juices has increased significantly in recent years, following an increased consumer demand to promote health and/or prevent disease through diet and nutrition. Micro and nano-encapsulation are promising technologies to protect and deliver sensitive compounds, allowing a controlled release in the target sites. This paper offers an overview of current applications, limits and challenges of encapsulation technologies in the production of fruit and vegetable juices, with a particular emphasis on products derived from different botanical sources.

Fungal bioremediation of olive mill wastewater: Using a multi‐step approach to model inhibition or stimulation

Abstract: Olive mill wastewaters (OMWWs) possess a strong environmental impact; the use of fungi as tools for bioremediation could be a promising method.; Results: Twenty-nine fungi were grown on minimal media supplemented with five different kinds of OMWWs (5-15%). Radial growth was assessed for 21 days and the data were modelled through the Dantigny-logistic like function to estimate τ, i.e. the time to attain half of the maximum diameter. Growth on potato dextrose agar and water agar (WA, minimal medium without supplementation) was used as reference. The differences in τ between PDA/WA and minimal media with OMWWs were modelled through a multi-factorial ANOVA, using the concentration of OMWW, the kind of wastes and fungi as categorical predictors. Finally, a principal component analysis was run to group and divide resistant and sensitive fungi. Some fungi experienced a positive Δτ, thus suggesting an inhibition by OMWW, whereas other isolates were enhanced.; Conclusions: Some isolates (for example Aspergillus ochraceus) showed a promising trend and could be possible candidates for a validation on a real scale. © 2016 Society of Chemical Industry.; © 2016 Society of Chemical Industry.

Selection of wild lactic acid bacteria for sausages: Design of a selection protocol combining statistic tools, technological and functional properties

Abstract: The main topic of this paper was the combination of statistic tools, technological, and functional properties to select starter cultures for fermented sausages. One-hundred sixty-four isolates were recovered from pork meat, and studied for their enzymatic patterns, growth as a function of temperature, pH, NaCl, nitrites and nitrates, and acidification. The growth was assessed through a spectrophotometric approach to evaluate the Growth Index; then, the data were used as input variables to run Cluster and Principal Component Analyses. Fifty-three promising isolates were selected for their Growth Index in presence of salt, nitrites, at low temperatures, or acidification. These isolates were studied for some functional properties (survival at pH 2.0/2.5, and in presence of bile salts, hydrophobicity, auto-aggregation, antibiotic resistance, antimicrobial activity towards some foodborne pathogens). The results of these experiments were used to select 4 best candidates, using the statistical distribution of each trait (median and quartiles). As a final step, the isolates were identified as Lactobacillus plantarum and studied for their ability to inhibit foodborne pathogens, a mould (Mucor spp.) or for the lacking of negative interactions with an adjunct starter of fermented sausages (Staphylococcus xylosus).

An In Vitro Fermentation Study on the Effects of Gluten FriendlyTM Bread on Microbiota and Short Chain Fatty Acids of Fecal Samples from Healthy and Celiac Subjects.

Abstract: Recently, an innovative gluten detoxification method called Gluten FriendlyTM (GF) has been developed. It induces structural modifications, which abolish the antigenic capacity of gluten and reduce the in vitro immunogenicity of the most common epitopes involved in coeliac disease, without compromising the nutritional and technological properties. This study investigated the in vitro effects of GF bread (GFB) on the faecal microbiota from healthy and coeliac individuals by a three-stage continuous fermentative system, which simulates the colon (vessel 1, proximal colon; vessel 2, transverse colon; vessel 3, distal colon), as well as on the production of short chain fatty acids (SCFA, acetate, propionate, butyrate). The system was fed with GFB and the changes in microbiota through fluorescence in situ hybridization (FISH) and in SCFA content were assessed. GFB exerted beneficial modulations such as bifidogenic effects in each compartment of the model both with healthy and coeliac derived samples, as well as growth in Clostridium clusters XIVa+b in coeliac derived samples. Furthermore, increased levels of acetic acid were found in vessel 1 inoculated with the faecal microbiota of healthy individuals, as well as acetic and propionic in vessel 1 and 2 with coeliac derived samples. In addition, the use of multivariate approaches showed that the supplementation of GFB could result in a different modulation of the faecal microbiota and SCFA, as a function of initial equilibrium.

Chapter 10 – Wine Spoiling Phenomena

Abstract: For consumption, foods should be safe, healthy, and uncontaminated; nevertheless, foods are subjected to a deterioration of the microbial, physical, and sensory properties, which causes the reduction of the food quality and the loss of ca. 10% of the total product. Yeasts, molds, and bacteria are the main factors responsible for microbial contaminations: they grow in food, producing substances that alter texture, color, odor and appearance, and making the products unacceptable. As microorganisms are ubiquitous, they can be easily transferred to the food through the hands of the operator as well as through contact with surfaces or equipment. In this chapter we investigate the main microorganisms responsible for spoilage focusing on wine, an alcoholic beverage, to highlight the most common species found in this product, their modes of action, and the diseases and alteration processes which they cause.

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

Abstract: 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.; © 2016 Society of Chemical Industry.

Approaches to Removal and Killing of Salmonella Spp. Biofilms

Abstract: This study aims to assess the effectiveness of three sanitizers (an alkaline solution, an acid solution and a quaternary ammonium salt) to remove biofilm formed by Salmonella spp. on stainless steel surfaces. To evaluate the individual or combined effects of sanitizer concentration, time (5.0–25 min) and temperature (25–65C) on survival of Salmonella spp. biofilms three different Central Composite Designs (CCD) were developed. Results highlighted that treatments containing NaOH were able to eliminate more than 82–83% of sessile population, whereas the total removal of biofilm was obtained using a solution at least 800 ppm for 15 min at 45C. Peracetic acid seemed to be more effective than NaOH assuring the total removal of biofilm at low temperature. Even the quaternary ammonium salt was able to remove completely Salmonella spp. biofilms at 60C using a solution at 12 ppm, or at higher temperature (65C), using a less concentrated solution (6 ppm). Practical Applications Due to the wide range of contributing factors (surface type, availability of nutrients and oxygen, microbial species, etc.) biofilms are quite diverse; in essence it can be said that each biofilm is different. Even if numerous attempts have been made to find standardized systems to prevent, remove and kill biofilm cells, until now there is no unique system that is able to remove all biofilms. Thus, a study on the factors affecting the resistance of Salmonella spp. biofilms against sanitizers may be useful into the development of new sanitation strategies in food industries.

Lactic acid bacteria as starter cultures

Abstract: Starter cultures have a basic role: to drive the fermentation process. Concomitantly, they contribute to all the characteristics of products, as well as to their sensorial and safety characteristics. Therefore, the introduction of starter cultures has undoubtedly improved the quality of products and the standardization of the industrial process. A very important aspect is to have a good knowledge of the metabolic properties required to improve a specific product and to select useful microbial strains. Nevertheless, the limited number of already selected and studied strains that are also able to possess highly technological properties, as well as the con­ stant risk of bacteriophage attacks, are stimulating research into new starter strains, in order to obtain higher quality and product diversification, in response to more and more aware consumers.

Evaluation of Fungal Growth on Olive-Mill Wastewaters Treated at High Temperature and by High-Pressure Homogenization.

Abstract: Reuse of olive mill wastewaters (OMWWs) in agriculture represents a significant challenge for health and safety of our planet. Phytotoxic compounds in OMWW generally prohibit use of untreated OMWWs for agricultural irrigation or direct discharge into surface waters. However, pretreated OMWW can have positive effects on chemical and microbiological soil characteristics, to fight against fungal soil-borne pathogens. Low amounts of OMWW following thermal (TT-OMWW) and high-pressure homogenization (HPH-OMWW) pretreatments counteracted growth of some of 12 soil-borne and/or pathogenic fungi examined. With fungal growth measured as standardized change in time to half maximum colony diameter, Δτ, overall, HPH-OMWW showed increased bioactivity, as increased mean Δτ from 3.0 to 4.8 days. Principal component analysis highlighted two fungal groups: Colletotrichum gloeosporioides , Alternaria alternata, Sclerotium rolfsii, and Rosellinia necatrix, with growth strongly inhibited by the treated OMWWs; and Aspergillus ochraceus and Phaeoacremonium parasiticum, with stimulated growth by the treated OMWWs. As a non-thermal treatment, HPH-OMWW generally shows improved positive effects, which potentially arise from preservation of the phenols.

Chapter 5 – Yeasts

Abstract: Yeasts are eukaryotic organisms that are included in a group of organisms called “fungi,” which also includes molds and mushrooms. Yeasts can have both positive and negative effects on fermented products consumed by humans and animals. Yeasts are used as starter cultures in cheeses and bread, as well as wine, beer, and other alcoholic fermentation products, but they can also initiate spoilage in foods, such as yoghurt, fruit juice, salads, and mayonnaise. A group of authors have published a list of yeasts that are frequently associated with the spoilage of foods and beverages: to these lists of “dangerous” spoiling yeasts four other yeast species have also been added, which were the members of the “second-division spoiling yeasts.” The ability of some yeasts to survive in harsh conditions makes them potent food spoilage organisms responsible for large economic losses of some food products.