Use of Essential Oils to Inhibit Alicyclobacillus Acidoterrestris: A Short Overview of the Literature

Essential oils (EOs) are promising and friendly antimicrobials for the prolongation of the shelf life of many foods. They have been extensively used to inhibit spoiling and pathogenic microorganisms of many kinds of products like fruit juices and acidic drinks. Therefore, they could be used successfully to control the germination of spores of Alicyclobacillus acidoterrestris, that finds in these products an optimal environment for growth. This paper reports a brief overview of the literature available, focusing on the effects of EOs toward alicyclobacilli

Selection of Yeasts as Starter Cultures for Table Olives: A Step-by-Step Procedure

The selection of yeasts intended as starters for table olives is a complex process, including a characterization step at laboratory level and a validation at lab level and factory-scale. The characterization at lab level deals with the assessment of some technological traits (growth under different temperatures and at alkaline pHs, effect of salt, and for probiotic strains the resistance to preservatives), enzymatic activities, and some new functional properties (probiotic traits, production of vitamin B-complex, biological debittering). The paper reports on these traits, focusing both on their theoretical implications and lab protocols; moreover, there are some details on predictive microbiology for yeasts of table olives and on the use of multivariate approaches to select suitable starters

Selection of Promising Bacterial Strains as Potential Tools for the Bioremediation of Olive Mill Wastewater

The main objective of this paper was the selection of promising bacterial strains to be used as potential tools to remove phenols in olive mill wastewater (OMW) or in other food wastes. Therefore, 12 OMW samples were analyzed and 119 isolates were collected. After a preliminary screening on a medium containing vanillic and cinnamic acids, three isolates were selected to evaluate their viability in presence of different compounds (cinnamic, vanillic and caffeic acids, rutin, tyrosol and oleuropein) and a possible bioremediation effect. The isolates generally survived with phenols added and exerted a significant bioremediation activity in some samples (reduction of phenols by 20%). The last step was focused on the evaluation of the combined effects of pH, cinnamic and vanillic acids on the viability of a selected isolate (13M); the combination of the acids exerted a strong effect on the target, but alkaline pH played a protective role

Microbial Characterization of Table Olives Processed According to Spanish and Natural Styles

A study on the microflora of table olives »Bella di Cerignola«, produced according to Spanish style and natural processing, is presented. The samples (olives and brines) were taken at different fermentation phases; olives, before treatments, were analyzed too. pH was monitored and microbial populations were assessed by standard plate count. Determination of the following microbial groups was carried out: mesophilic bacteria, lactic acid bacteria, Enterobacteriaceae, Pseudomonadaceae, staphylococci, Micrococcaceae and yeasts. In the second phase, the identification of mesophilic bacteria, lactic acid bacteria and yeasts was performed. The amount of lactic acid bacteria and yeasts increased during the storage in all the samples, but no significant differences were observed between the two styles. At the end of fermentation an increase of Pseudomonadaceae cell load was observed, which was absent in the first phase of fermentation. The samples analyzed were extremely unsteady, therefore the addition of starter lactic acid bacteria could standardize olive processing. Lactobacillus plantarum, Bacillus spp. (mainly B. subtilis) and Candida spp. were the predominant species at the end of the processing

Two Nonthermal Technologies for Food Safety and Quality-Ultrasound and High Pressure Homogenization: Effects on Microorganisms, Advances, and Possibilities: A Review.

Some nonthermal technologies have gained special interest as alternative approaches to thermal treatments. High pressure homogenization (HPH) and ultrasound (US) are two of the most promising approaches. They rely upon two different modes of action, although they share some mechanisms or ways of actions (mechanic burden against cells, cavitation and micronization, primary targets being the cell wall and the membrane, temperature and pressure playing important roles for their antimicrobial potential, and their effect on cells can be either positive or negative). HPH is generally used in milk and dairy products to break lipid micelles, whereas US is used for mixing and/or to obtain active compounds of food. HPH and US have been tested on pathogens and spoilers with different effects; thus, the main goal of this article is to describe how US and HPH act on biological systems, with a focus on antimicrobial activity, mode of action, positive effects, and equipment. The article is composed of three main parts: (i) an overview of US and HPH, with a focus on some results covered by other reviews (mode of action toward microorganisms and effect on enzymes) and some new data (positive effect and modulation of metabolism); (ii) a tentative approach for a comparative resistance of microorganisms; and (iii) future perspectives

Combined effects of temperature, water activity, and pH on Alicyclobacillus acidoterrestris spores.

A response surface model was developed to describe the effects of temperature (35 to 55 degrees C), pH (3.5 to 5.5), and water activity (a(w), 0.960 to 0.992) on germination of Alicyclobacillus acidoterrestris spores. Germination and growth or viability loss depended, to varying extents, on the interactions among the independent variables and the complexity of the medium. In particular, maximum growth was achieved at temperatures between 35 and 42 degrees C and at pH values from 3.5 to 4.5. The model was validated against data not used in its development. Bias factors of 0.999 and 0.817 for 2- and 7-day models, respectively, were obtained, indicating that the models were "fail safe." Results indicated that the model provided reliable predictions of growth of A. acidoterrestris spores

Vocalização da onça-parda (Puma concolor) e mudança de frequência como resposta ao playback

Recordings of cougar (Puma concolor) vocalizations are rare in the wild. We made two night recordings from the same individual. The first recording was spontaneous whereas the second was made after a playback emission (using a third party recording) allowing for comparisons. We measured the calls before and after playback stimuli using Raven software and noted that only the minimum fundamental frequency presented differences between calls. As fundamental frequency is closely related to body size, a frequency reduction may indicate territoriality engagement. Our recording seems to be the first held in the Brazilian wild. Little is known about cougar natural history and behavior, and our data suggest that acoustic communication may have an important role on the species intraspecific interactions.Registros de vocalizações de onça-parda (Puma concolor) são raros na natureza. Fizemos uma gravação espontânea da espécie à noite, em seguida tocamos o playback com uma gravação prévia disponível em bibliografia, o que fez com que a onça-parda se aproximasse e vocalizasse, permitindo que pudéssemos gravar novamente e assim comparar. Comparamos os chamados antes e depois do estímulo do playback, usando o programa Raven, e constatamos que somente a frequência fundamental mínima apresentou diferenças entre os chamados. Como a frequência fundamental está diretamente relacionada com o tamanho corporal, uma redução neste parâmetro pode significar defesa territorial. Nossas gravações aparentemente são as primeiras realizadas na natureza no Brasil. Pouco se sabe sobre história natural e comportamento da onça parda no Brasil, e nossos dados sugerem que a comunicação acústica tem um papel importante nas interações intraespecíficas desta espécie.13313

Genotypic and phenotypic heterogeneity in Alicyclobacillus acidoterrestris: a contribution to species characterization

Alicyclobacillus acidoterrestris is the main cause of most spoilage problems in fruit juices and acidic products. Since soil borne species often contaminate fruit juices and do not need strict extreme requirements for survival, it is a great concern to investigate whether and how soil species could evolve from their ecological niches in microbial community to new environments as fruit juices. In this study, 23 isolates of thermo-acidophilic, spore-forming bacteria from soil were characterized by cultural and molecular methods. In addition, 2 strains isolated from a spoilage incident in pear juice were typed. Strains phenotyping showed that they could be grouped into 3 different clusters, and some isolates showed identical or quite similar patterns. Analyzing pH and temperature ranges for growth, the majority of strains were able to grow at values described for many species of Alicyclobacillus. Qualitative utilization of lysine, arginine and indole production from tryptophan revealed, for the first time, deamination of lysine and decarboxylation of arginine. Resistance to 5% NaCl as well as the ability to hydrolyze starch and gelatin, nitrate reduction, catalase and oxidase activities confirmed literature evidences. Examining of 16S rRNA, showed that isolates were divided into three blocks represented by effectively soil species and strains that are moving from soil to other possible growing source characterized by parameters that could strongly influence bacterial survival. RAPD PCR technique evidenced a great variability in banding patterns and, although it was not possible to obtain genotypically well-distinguished groups, it was feasible to appreciate genetic similarity between some strains. In conclusion, the investigation of a microbial community entails a combination of metagenomic and classic culture-dependent approaches to expand our knowledge about Alicyclobacillus and to look for new subspecies

Controlled release of antimicrobial compounds from highly swellable polymers.

The suitability of antimicrobial release films made from highly swellable polymers for use in food packaging was evaluated. The possibility of modulating the release kinetics of active compounds either by regulating the degree of cross-link of the polymer matrix or by using multilayer structures was addressed. The release kinetics of lysozyme, nisin, and sodium benzoate (active compounds with different molecular weights) were determined at ambient temperature (25 degrees C). The effectiveness of the proposed active films in inhibiting microbial growth was addressed by determining the antimicrobial efficiency of the released active compounds. Micrococcus lysodeikticus, Alicyclobacillus acidoterrestris, and Saccharomyces cerevisiae were used to test the antimicrobial efficiency of released lysozyme, nisin, and sodium benzoate, respectively. Results indicate that the release kinetics of both lysozyme and nisin can be modulated through the degree of cross-link of the polymer matrix, whereas multilayer structures need to be used to control the release kinetics of sodium benzoate. All the active compounds released from the investigated active films were effective in inhibiting microbial growth