Emulsified and Nanoemulsified Essential Oils in the Control of Clostridium botulinum and Clostridium sporogenes in Mortadella.

Clostridium botulinum is a foodborne pathogen responsible for severe neuroparalytic disease associated with the ingestion of pre-formed toxin in food, with processed meats and canned foods being the most affected. Control of this pathogen in meat products is carried out using the preservative sodium nitrite (NaNO2), which in food, under certain conditions, such as thermal processing and storage, can form carcinogenic compounds. Therefore, the objective was to use nanoemulsified essential oils (EOs) as natural antimicrobial agents, with the aim of reducing the dose of NaNO2 applied in mortadella. The antimicrobial activity of nanoemulsions prepared with mixtures of EOs of garlic, clove, pink pepper, and black pepper was evaluated on endospores and vegetative cells of C. botulinum and Clostridium sporogenes (surrogate model) inoculated in mortadella prepared with 50 parts per million NaNO2. The effects on the technological (pH, water activity, and color) and sensory characteristics of the product were also evaluated. The combinations of EOs and their nanoemulsions showed sporicidal effects on the endospores of both tested microorganisms, with no counts observed from the 10th day of analysis. Furthermore, bacteriostatic effects on the studied microorganisms were observed. Regarding the technological and sensorial characteristics of the product, the addition of the combined EOs had a negative impact on the color of the mortadella and on the flavor/aroma. Despite the strong commercial appeal of adding natural preservatives to foods, the effects on flavor and color must be considered. Given the importance of controlling C. botulinum in this type of product, as well as the reduction in the amount of NaNO2 used, this combination of EOs represents a promising antimicrobial alternative to this preservative, encouraging further research in this direction.

Combined effects of yacon flour and probiotic yogurt on the metabolic parameters and inflammatory and insulin signaling proteins in high-fat-diet-induced obese mice.

BACKGROUND: Prebiotics and probiotics may be effective dietary components that can alter the gut microbiota of the host and, consequently, overcome imbalances associated with obesity. This work aimed to evaluate the synergistic and isolated effects and mechanisms by which probiotic yogurt containing Bifidobacterium animalis and/or Lactobacillus acidophilus and yacon flour alter metabolic parameters and inflammatory and insulin signaling proteins in diet-induced obese mice. Swiss mice were fed a high-fat diet (n = 48) or a standard diet (control; n = 6) for 56 days. The 42 mice that gained the most weight were selected and divided into seven groups that received different combinations of probiotic yogurt and yacon flour. After 30 days, biochemical parameters (blood glucose, serum total cholesterol, and triacylglycerols), crude fat excretion in feces, and periepididymal fat were assessed and an immunoblotting analysis of insulin signaling proteins and interleukin-1ß was conducted. RESULTS: The combination of yacon flour and a yogurt with two strains of probiotics exerted positive effects on the parameters evaluated, such as decreased body weight (-6.5%; P < 0.05), fasting glucose (-23.1%; P < 0.05), and triacylglycerol levels (-21.4%; P < 0.05) and decreased periepididymal fat accumulation (-44.2%; P < 0.05). There was a decrease in inflammatory markers (P < 0.001) and an improvement in insulin signaling (P < 0.001). CONCLUSIONS: The combination of a prebiotic with two strains of probiotics in a food matrix may exert a protective effect against obesity-associated inflammation, improving insulin resistance, even in the short term. © 2022 Society of Chemical Industry.

Microbial trace based on PCR-DGGE to evaluate the ripening stage of minas artisanal cheeses from the Canastra microregion produced by different dairies.

The Minas artisanal cheese from the Serra da Canastra (MAC-CM) microregion is a traditional product due to its production and ripening process. Artisanal chesses manufactured with raw cow's milk and endogenous dairy starters ("also known as pingo") have distinctive flavors and other sensory characteristics because of the unknown microbiota. The aim of this study was to evaluate the microbiota during 30 days of ripening, the physicochemical changes, and their relation in MACs produced in two different microregions located in the Serra da Canastra microregion through culture-dependent and culture-independent methods. The MACs were collected in the cities of Bambuí (MAC-CMB) and Tapiraí (MAC-CMT) in the Canastra microregion (n = 21). Cheeses uniqueness was demonstrated with the multivariate analysis that joined the microbiota and physicochemical characteristics, mainly to the proteolysis process, in which the MAC-CMT showed deeper proteolysis (DI -T0:14.18; T30: 13.95), while the MAC-CMB reached only a primary level (EI -T0:24.23; T30: 31.10). Abiotic factors were responsible for the differences in microbial diversity between the cheese farms. Different microbial groups: the prokaryotes, like Corynebacterium variabile, Lactococcus lactis, and Staphylococcus saprophyticus; and the eukaryotes, like Kluyveromyces lactis and Diutina catenulata dominated ripening over time. The microbial community and proteolysis were responsible for the predominance of volatile groups, with alcohols predominating in MAC-CMB and free fatty acids/acids and esters in MAC-CMT.

Untargeted Metabolomics Approach of Cross-Adaptation in Salmonella Enterica Induced by Major Compounds of Essential Oils.

Cross-adaptation phenomena in bacterial populations, induced by sublethal doses of antibacterial solutions, are a major problem in the field of food safety. In this regard, essential oils and their major compounds appear as an effective alternative to common sanitizers in food industry environments. The present study aimed to evaluate the untargeted metabolomics perturbations of Salmonella enterica serovar Enteritidis that has been previously exposed to the sublethal doses of the major components of essential oils: cinnamaldehyde, citral, and linalool (CIN, CIT, and LIN, respectively). Cinnamaldehyde appeared to be the most efficient compound in the assays evaluating the inhibitory effects [0.06% (v/v) as MBC]. Also, preliminary tests exhibited a phenotype of adaptation in planktonic and sessile cells of S. Enteritidis when exposed to sublethal doses of linalool, resulting in tolerance to previously lethal concentrations of citral. A metabolomics approach on S. Enteritidis provided an important insight into the phenomenon of cross-adaptation induced by sublethal doses of major compounds of some essential oils. In addition, according to the results obtained, when single molecules were used, many pathways may be involved in bacterial tolerance, which could be different from the findings revealed in previous studies regarding the use of phytocomplex of essential oils. Orthogonal projection to latent structures (OPLS) proved to be an interesting predictive model to demonstrate the adaptation events in pathogenic bacteria because of the global engagement to prevent and control foodborne outbreaks.

Influence of lipid nanoparticle physical state on ß-carotene stability kinetics under different environmental conditions.

Carotenoids are lipophilic compounds that provide important health-related benefits for human body functions. However, they have low water solubility and chemical stability, hence their incorporation in aqueous-based foods requires the use of emulsion-based lipid carriers. This work aimed at elucidating whether their inclusion in emulsion-based Solid Lipid Nanoparticles (SLNs) can provide a protective effect against ß-carotene degradation under different environmental conditions in comparison to liquid lipid nanoemulsions. Glyceryl Stearate (GS) was mixed with Medium Chain Trygliceride (MCT) oil to formulate SLNs. SLNs presented a significantly enhanced ß-carotene retention and a slower ß-carotene degradation kinetics at increasing storage temperature, acidic conditions and light exposure. In fact, SLNs formulated with 5% GS in the lipid phase and stored at 4 °C and pH 7 retained almost 70% of the initially encapsulated ß-carotene after 55 days of storage, while it was completely degraded when it was encapsulated in liquid nanoemulsions. Moreover, it was observed that the solid lipid type affects the protective effect that SLNs may confer to the encapsulated lipophilic bioactives. Saturated long chain triglycerides, such as hydrogenated palm oil (HPO) presented slower and lower ß-carotene degradation kinetics in comparison to solid lipids composed of MCT, such as Coconut Oil (CNUT) or MCT + 5% of GS in the lipid phase. This work evidences that the incorporation of lipophilic bioactive compounds, such as ß-carotene, into SLNs slows down their degradation kinetics which might be attributed to a reduced diffusion of the oxidative species due to the lipid crystalline structure.

Morphological and metabolomics impact of sublethal doses of natural compounds and its nanoemulsions in Bacillus cereus.

Microbiological safety in food industry are always a concern regarding sublethal tolerance in bacteria for common and natural sanitizers. Natural bacteriocins, such as nisin (NIS), may negatively interfere in the efficiency of major compounds of essential oils against foodborne pathogenic bacteria. However, nanoemulsioned forms increase the bactericidal potential of natural compounds acting synergistically. In this study, cinnamaldehyde (CIN), citral (CIT), and linalool (LIN) were evaluated independently, associated with NIS, and in nanoemulsions (NEs) against Bacillus cereus using untargeted-metabolomics. Results revealed morphological changes in the structure of B. cereus treated with NEs of CIN and CIT, both NIS-associated. In addition, sensibility tests and UHPLC-QTOF-MS analyses indicated that NIS might react together with CIT reducing the bactericidal efficiency, while the nanoemulsion of CIT effect was enhanced by NIS in nanoemulsioned forms. This study highlights the importance of prudent administration of natural compounds as antimicrobial agents to prevent sublethal tolerance in pathogenic bacteria.

The lipid type affects the in vitro digestibility and ß-carotene bioaccessibility of liquid or solid lipid nanoparticles.

Solid lipid nanoparticles (SLNs) are emulsion-based carriers of lipophilic bioactive compounds. However, their digestibility may be affected by the solid lipid phase composition. Hence, the aim of this work was to study the in vitro lipolysis kinetics as well as the relationship between the lipid digestion, micelle fraction composition and ß-carotene bioaccessibility of SLNs with different solid lipids, being blends of medium chain triglyceride (MCT) oil, glyceryl stearate (GS) or hydrogenated palm oil (HPO) as compared to liquid lipid nanoparticles (LLNs) with pure MCT. SLNs formulated with GS were fully digested, similarly to LLNs. However, HPO-containing SLNs presented slower lipolysis kinetics during the intestinal phase at increasing HPO concentration. Despite this, HPO-SLNs showed higher ß-carotene bioaccessibility, which was related to the higher amount of monounstaturated free fatty acids in the micelle fraction. Thus, this work provides valuable insight for designing delivery systems of bioactive compounds with optimal functionality.

Phenolic profiling and in vitro bioactivity of Moringa oleifera leaves as affected by different extraction solvents.

In this work the (poly)-phenolic profile of Moringa oleifera leaves was comprehensively investigated through untargeted metabolomics, following a homogenizer-assisted extraction (HAE) using three solvent systems, i.e. methanol (HAE-1), methanol-water 50:50 v/v (HAE-2) and ethyl acetate (HAE-3). This approach allowed to putatively annotate 291 compounds, recording mainly flavonoids and phenolic acids. Thereafter, antioxidant capacity, antimicrobial activity and enzyme inhibition were assayed in the different extracts. HAE-1 extract showed the highest total phenolic content (31.84 mg/g), followed by HAE-2 (26.95 mg/g) and HAE-3 (14.71 mg/g). In addition, HAE-1 and HAE-2 extracts exhibited an expressive activity against Bacillus cereus and Listeria innocua. The HAE-2 leaf extract was characterized by the highest DPPH and ABTS values (being 49.55 and 45.26 mgTE/g), while ferric reducing antioxidant power was found to be higher in HAE-1 (58.26 mgTE/g). Finally, the enzyme inhibitory effects of M. oleifera leaf extracts were investigated against five enzymes, namely acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, α-amylase and α-glucosidase. All of the tested extracts exhibited inhibitory effects on AChE and BChE with a higher activity for HAE-3 and HAE-1, whilst HAE-1 showed the higher impact on tyrosinase, glucosidase and amylase activities. Taken together, these findings suggest that M. oleifera leaf extracts are a good source of bioactive polyphenols with a potential use in food and pharma industries.

Essential oils of thyme and Rosemary in the control of Listeria monocytogenes in raw beef

This study was developed in order to evaluate two alternatives for the control of Listeria monocytogenes in raw bovine meat pieces, both based on the use of Thymus vulgaris and Rosmarinus officinalis essential oils (EOs). The antilisterial activity of different concentrations of the EOs was tested in vitro using agar dilution and disk volatilization techniques. In addition, L. monocytogenes was inoculated in meat pieces, which were submerged in edible gelatin coatings containing 2% (v/v) EOs or submitted to the vapor of EOs (0.74 L.cm-3). L. monocytogenes was quantified after one, 48 and 96 hours of storage (7 °C). In the in vitro tests, the EO of T. vulgaris presented higher activity. The two options used (edible gelatin coating and vapor activity), in spite of exercising effects with differentiated behaviors, presented antibacterial activity against L. monocytogenes inoculated in raw bovine meat (p 0.05). Greatest antibacterial activity were obtained in the experiment that used edible coatings containing EOs, at 48 hours of storage reductions in bacterial counts between 1.09 and 1.25 Log CFU.g-1 were obtained. In the vapor effect experiment, the EO of T. vulgaris caused the highest reduction in the population of bacteria inoculated in raw bovine meat (p 0.05), 0.40 Log CFU.g-1 at 96 hours of storage. This study supplied important information regarding new and promising natural alternatives, based on the concept of active packaging, for the control of L. monocytogenes in the meat industry.

Effects of yeast cell wall extract in dry diet on microbiology, short-chain fatty acids and fecal odor reduction of adult cats / Efeitos do extrato de parede de levedura em dieta seca sobre a microbiologia, ácidos graxos de cadeia curta e redução do odor das fezes de gatos adultos

The aim of this study was to evaluate the effects of yeast cell wall extract (YCW) in dry diet on the fecal microbiota, concentration of short-chain fatty acids (SCFA) and on the odor reduction of cats feces. We used 20 animals of both sexes, randomly assigned to four treatments and five repetitions totaling 20 experimental units: 1) dry commercial diet (control); 2) control + 0.2%, 3) control + 0.4%, and 4) control + 0.6% of YCW in dry matter. Enterobacteriaceae and lactic acid bacteria, fecal concentration of acetic, propionic and butyric acids, ammonia nitrogen and sensory panel were performed. There were no significant differences (p> 0.05) for bacterial counts and the concentration of SCFA and ammonia, but in sensory panel a reduction in the odor of feces could be noted with the use of 0.2% of YCW. We concluded that the addition of up to 0.6% YCW had no effect on the microbiology and the concentration of fatty acids, but there is potential for its use as an additive because of the improvement in the odor of feces. However, further studies are needed to understand the mechanisms of action and the effects of prebiotics for domestic cats. KEYWORDS: ammoniacal nitrogen; butyric acid; feline; lactic bacteria; mannanoligosacharide.

Objetivou-se avaliar os efeitos do extrato de parede de levedura (EPL) em dieta seca sobre a microbiota fecal, concentração de ácidos graxos de cadeia curta (AGCC) e redução do odor das fezes de gatos adultos. Foram utilizados 20 animais, dez de cada sexo, distribuídos ao acaso em quatro tratamentos e cinco repetições, totalizando 20 unidades experimentais: 1) dieta comercial seca (controle); 2) controle + 0,2%; 3) controle + 0,4%; e 4) controle + 0,6% de EPL na matéria seca da dieta. Foram realizados contagem de enterobactérias, E.coli e bactérias láticas, concentração fecal dos ácidos acético, propiônico, butírico e nitrogênio amoniacal, além de painel sensorial. Não foram observadas diferenças significativas (p>0,05) para as contagens bacterianas e a concentração de AGCC e nitrogênio amoniacal; no entanto, por meio do painel sensorial pôde ser notada redução no odor das fezes com o uso de 0,2% de EPL na dieta. Concluiu-se que a adição de até 0,6% de EPL não teve efeito sobre a microbiologia e a concentração de ácidos graxos, mas há potencial uso como aditivo devido à melhora no odor das fezes. Outros estudos são necessários para compreender os mecanismos de ação, efeitos e níveis de inclusão desse prebiótico para gatos domésticos.PALAVRAS-CHAVE: ácido butírico; bactérias láticas; felinos; mananoligossacarídeo; nitrogênio amoniacal.

Qualidade de pequis fatiados e inteiros submetidos ao congelamento

This research was carried out aiming to evaluate the quality of pequi fruit (whole and sliced) after forced-air freezing storage during 12 months. The fruits were submitted to treatments as follows: selecting, washing, sanitizing, peeling, blanching, cooling, and slicing or not. After that, the fruits were storage using low density polyethylene bags and submitted to forced-air freezing (-18°C) for 6 hours and stored in freezer at the same temperature (±2°C) for 12 months. Each three months were measured: pH, titratable acidity, soluble solids, firmness, color (L*, a*, b*, h° and C* values), total carotenoids, -carotene, vitamin C, peroxide value, coliforms at 35°C and 45°C and Salmonella sp. Frozen whole pequi fruits is more effective in preserving the soluble solids and vitamin C contents and L* and b* values as compared to the sliced pequi fruits. The freezing-storage time reduce a*, b* and C* values, firmness values, soluble solids, total carotenoids, -carotene and vitamin C contents of the pequi fruit, whole or sliced. Pequi fruit frozen is not affected by rancidity oxidative process, and also does not alter the pH, titratable acidity, and color (h°). Pequi fruit frozen and stored during 12 months are considered microbiologically safe, not offering health risks to consumers, since that the good practices of manufacture are realized and the freezing and stored process are performed correctly.

O trabalho foi realizado com o objetivo de avaliar a qualidade de pequis inteiros e fatiados submetidos ao congelamento por ar forçado durante 12 meses de armazenamento. Os frutos foram selecionados, lavados, sanitizados, descascados, branqueados, resfriados, fatiados e mantidos inteiros, acondicionados em saco de polietileno de baixa densidade, congelados em túnel de congelamento com ar forçado por 6 horas (-18°C) e armazenados em congelador doméstico a -18°C (±2°C), por 12 meses. A cada três meses, foram realizadas as seguintes análises: pH, acidez titulável, sólidos solúveis, firmeza, valores L*, a*, b*, h° e C*, carotenoides totais, -caroteno, vitamina C, índice de peróxidos, coliformes a 35°C e a 45°C e pesquisa de Salmonella sp. O congelamento do pequi inteiro é mais efetivo em preservar os teores de sólidos solúveis e vitamina C e os valores L* e b* quando comparado com o do pequi fatiado. O tempo de armazenamento de 12 meses determina redução nos valores a*, b*, C* e de firmeza e nos teores de sólidos solúveis, carotenoides totais, -caroteno e vitamina C em pequi congelado, independentemente do corte usado. O pequi congelado não sofre o processo de rancificação oxidativa nem alterações no pH, nos teores de acidez titulável e na tonalidade de cor (h°). Pequis congelados, na forma inteira e fatiada, são considerados seguros microbiologicamente durante 12 meses de armazenamento, não oferecendo riscos à saúde dos consumidores, desde que obedecidas à cadeia de frio e às boas práticas de fabricação.

Qualidade de pequis fatiados e inteiros submetidos ao congelamento

This research was carried out aiming to evaluate the quality of pequi fruit (whole and sliced) after forced-air freezing storage during 12 months. The fruits were submitted to treatments as follows: selecting, washing, sanitizing, peeling, blanching, cooling, and slicing or not. After that, the fruits were storage using low density polyethylene bags and submitted to forced-air freezing (-18°C) for 6 hours and stored in freezer at the same temperature (±2°C) for 12 months. Each three months were measured: pH, titratable acidity, soluble solids, firmness, color (L*, a*, b*, h° and C* values), total carotenoids, -carotene, vitamin C, peroxide value, coliforms at 35°C and 45°C and Salmonella sp. Frozen whole pequi fruits is more effective in preserving the soluble solids and vitamin C contents and L* and b* values as compared to the sliced pequi fruits. The freezing-storage time reduce a*, b* and C* values, firmness values, soluble solids, total carotenoids, -carotene and vitamin C contents of the pequi fruit, whole or sliced. Pequi fruit frozen is not affected by rancidity oxidative process, and also does not alter the pH, titratable acidity, and color (h°). Pequi fruit frozen and stored during 12 months are considered microbiologically safe, not offering health risks to consumers, since that the good practices of manufacture are realized and the freezing and stored process are performed correctly.

O trabalho foi realizado com o objetivo de avaliar a qualidade de pequis inteiros e fatiados submetidos ao congelamento por ar forçado durante 12 meses de armazenamento. Os frutos foram selecionados, lavados, sanitizados, descascados, branqueados, resfriados, fatiados e mantidos inteiros, acondicionados em saco de polietileno de baixa densidade, congelados em túnel de congelamento com ar forçado por 6 horas (-18°C) e armazenados em congelador doméstico a -18°C (±2°C), por 12 meses. A cada três meses, foram realizadas as seguintes análises: pH, acidez titulável, sólidos solúveis, firmeza, valores L*, a*, b*, h° e C*, carotenoides totais, -caroteno, vitamina C, índice de peróxidos, coliformes a 35°C e a 45°C e pesquisa de Salmonella sp. O congelamento do pequi inteiro é mais efetivo em preservar os teores de sólidos solúveis e vitamina C e os valores L* e b* quando comparado com o do pequi fatiado. O tempo de armazenamento de 12 meses determina redução nos valores a*, b*, C* e de firmeza e nos teores de sólidos solúveis, carotenoides totais, -caroteno e vitamina C em pequi congelado, independentemente do corte usado. O pequi congelado não sofre o processo de rancificação oxidativa nem alterações no pH, nos teores de acidez titulável e na tonalidade de cor (h°). Pequis congelados, na forma inteira e fatiada, são considerados seguros microbiologicamente durante 12 meses de armazenamento, não oferecendo riscos à saúde dos consumidores, desde que obedecidas à cadeia de frio e às boas práticas de fabricação.

Qualidade de pequis fatiados e inteiros submetidos ao congelamento

This research was carried out aiming to evaluate the quality of pequi fruit (whole and sliced) after forced-air freezing storage during 12 months. The fruits were submitted to treatments as follows: selecting, washing, sanitizing, peeling, blanching, cooling, and slicing or not. After that, the fruits were storage using low density polyethylene bags and submitted to forced-air freezing (-18°C) for 6 hours and stored in freezer at the same temperature (±2°C) for 12 months. Each three months were measured: pH, titratable acidity, soluble solids, firmness, color (L*, a*, b*, h° and C* values), total carotenoids, -carotene, vitamin C, peroxide value, coliforms at 35°C and 45°C and Salmonella sp. Frozen whole pequi fruits is more effective in preserving the soluble solids and vitamin C contents and L* and b* values as compared to the sliced pequi fruits. The freezing-storage time reduce a*, b* and C* values, firmness values, soluble solids, total carotenoids, -carotene and vitamin C contents of the pequi fruit, whole or sliced. Pequi fruit frozen is not affected by rancidity oxidative process, and also does not alter the pH, titratable acidity, and color (h°). Pequi fruit frozen and stored during 12 months are considered microbiologically safe, not offering health risks to consumers, since that the good practices of manufacture are realized and the freezing and stored process are performed correctly.

O trabalho foi realizado com o objetivo de avaliar a qualidade de pequis inteiros e fatiados submetidos ao congelamento por ar forçado durante 12 meses de armazenamento. Os frutos foram selecionados, lavados, sanitizados, descascados, branqueados, resfriados, fatiados e mantidos inteiros, acondicionados em saco de polietileno de baixa densidade, congelados em túnel de congelamento com ar forçado por 6 horas (-18°C) e armazenados em congelador doméstico a -18°C (±2°C), por 12 meses. A cada três meses, foram realizadas as seguintes análises: pH, acidez titulável, sólidos solúveis, firmeza, valores L*, a*, b*, h° e C*, carotenoides totais, -caroteno, vitamina C, índice de peróxidos, coliformes a 35°C e a 45°C e pesquisa de Salmonella sp. O congelamento do pequi inteiro é mais efetivo em preservar os teores de sólidos solúveis e vitamina C e os valores L* e b* quando comparado com o do pequi fatiado. O tempo de armazenamento de 12 meses determina redução nos valores a*, b*, C* e de firmeza e nos teores de sólidos solúveis, carotenoides totais, -caroteno e vitamina C em pequi congelado, independentemente do corte usado. O pequi congelado não sofre o processo de rancificação oxidativa nem alterações no pH, nos teores de acidez titulável e na tonalidade de cor (h°). Pequis congelados, na forma inteira e fatiada, são considerados seguros microbiologicamente durante 12 meses de armazenamento, não oferecendo riscos à saúde dos consumidores, desde que obedecidas à cadeia de frio e às boas práticas de fabricação.

Biofilm formation by Listeria monocytogenes on stainless steel surface and biotransfer potential

An experimental model was proposed to study biofilm formation by Listeria monocytogenes ATCC 19117 on AISI 304 (/4) stainless steel surface and biotransfer potential during this process. In this model, biofilm formation was conducted on the surface of stainless steel coupons, set on a stainless steel base with 4 divisions, each one supporting 21 coupons. Trypic Soy Broth was used as bacterial growth substrate, with incubation at 37 ºC and stirring of 50 rpm. The number of adhered cells was determined after 3, 48, 96, 144, 192 and 240 hours of biofilm formation and biotransfer potential from 96 hours. Stainless steel coupons were submitted to Scanning Electron Microscopy (SEM) after 3, 144 and 240 hours. Based on the number of adhered cells and SEM, it was observed that L. monocytogenes adhered rapidly to the stainless steel surface, with mature biofilm being formed after 240 hours. The biotransfer potential of bacterium to substrate occurred at all the stages analyzed. The rapid capacity of adhesion to surface, combined with biotransfer potential throughout the biofilm formation stages, make L. monocytogenes a potential risk to the food industry. Both the experimental model developed and the methodology used were efficient in the study of biofilm formation by L. monocytogenes on stainless steel surface and biotransfer potential.

Formation of biofilms by Staphylococcus aureus on stainless steel and glass surfaces and its resistance to some selected chemical sanitizers

The objectives of this work were to verify the capability of Staphylococcus aureus of forming bio-film on stainless steel and glass surfaces; to evaluate the efficiency of sodium dichloroisocyanurate, hydrogen peroxide and peracetic acid in inactivating Staphylococcus aureus cells adhered onto these surfaces; and to visualize biofilm development by scanning electron microscopy before and after sanitizer treatment. The surfaces studied consisted of 10x20mm chips immersed in Petri dishes containing BHI broth inoculated with S. aureus ATCC 25923. Biofilm formation was observed after 15-day incubation, when the cells were removed using the swab technique, followed by Baird Parker agar plating. Also, the efficiency of the chemical sanitizers on the chip surfaces was tested and the non-removed cells were counted on the Baird-Parker agar. After biofilm formation and use of sanitizers, the chips were respectively observed by scanning electronic microscopy following a pre-existing protocol. The obtained results showed biofilm formation on both surfaces, with bacterial count in the order of 10(7) CFU/cm² on and 10(8) CFU/cm² on stainless steel and glass surfaces, respectively. Peracetic acid was the most efficient in removing adhered cells, presenting 5.26 and 4.5 decimal reduction for adhered cells on stainless steel and glass surfaces, respectively.

Os objetivos deste trabalho foram verificar a capacidade de Staphylococcus aureus formar biofilme nas superfícies de aço inoxidável e vidro, avaliar a eficiência do dicloroisocianurato de sódio, peróxido de hidrogênio e ácido peracético na inativação de células de S. aureus aderidas e visualização por microscopia eletrônica de varredura, o desenvolvimento antes e depois do tratamento das superfícies com os sanificantes. As superfícies foram cupons 10x200mm imersos em placas de Petri contendo caldo BHI inoculado com cultura de Staphylococcus aureus ATCC 25923. A formação de biofilme foi observada após 15 dias de incubação, quando as células foram removidas pela técnica do suabe, seguiram-se diluições seriadas e plaqueamento em ágar Baird Parker. Testou-se a eficiência dos sanificantes nas superfícies dos cupons e as células não removidas foram enumeradas no ágar Baird Parker. Os cupons após formação do biofilme e cupons sanificados foram observados pela microscopia eletrônica de varredura seguindo um protocolo. Os resultados obtidos indicaram a formação de biofilme em ambas superfícies, com contagens bacterianas na ordem de 10(7) UFC/cm² e 10(8) UFC/cm² nas superfícies de aço inoxidável e vidro, respectivamente. Dentre os sanificantes estudados o ácido peracético apresentou uma eficiência maior na remoção das células aderidas, apresentado redução decimal de 5,26 e 4,5 para as células aderidas na superfície de vidro e aço inoxidável.

Microbial biofilms in the food industry: a review / Biofilmes microbianos na indústria de alimentos: uma revisão

Bacterial biofilms are defined as microbial communities surrounded by an extracellular matrix of polymersand adhered to surfaces. In food industry, the microorganisms can adhere to organic and inorganic wasteoccurring on the equipment and utensils surfaces, if the cleaning and sanitization procedures are doneincorrectly. The presence of sessile cells in the biofilm reduces the efficiency and durability of equipmentsthrough the phenomenon called microbiologically induced corrosion. Additionally, they show muchgreater resistance to the sanitization process; the cells can be loosen and contaminate foods that passthrough the place, causing economic losses and risk of occurrence of foodborne diseases. Understandingthe concept, the structure and composition inherent aspects, and also the producing process of microbialbiofilms, are fundamental for establishing effective control strategies and being assured on the risks thatthey represent to the food industry. This article reviews the crucial aspects concerned with microbialbiofilms in the food industry i) definition, structure and composition; ii) steps involved in the formation;iii) mechanisms of resistance to antimicrobials; iv) risks; v) involved microorganisms; and vi) importanceof hygienization as a control strategy.

Biofilmes podem ser definidos como comunidades microbianas envoltas por uma matriz de polímerosextracelulares e aderidas a superfícies. Na indústria de alimentos, os microrganismos podem se aderir aresíduos orgânicos e inorgânicos presentes na superfície de equipamentos e utensílios, caso o processode higienização seja aplicado incorretamente. Células sésseis, presentes no biofilme, além de reduzir aeficiência e vida útil de equipamentos, em função do fenômeno denominado corrosão microbiologicamenteinduzida, são mais resistentes ao processo de desinfecção. As células podem se desprender e contaminar osalimentos que passam pelo local, que causam prejuízos econômicos e risco de ocorrência de toxinfecçõesalimentares. A compreensão do conceito de biofilmes microbianos e de aspectos inerentes a sua estruturae composição, bem como de seu processo de formação, são fundamentais para efetuar o desenvolvimentode estratégias de controle efetivas e entendimento do risco que estes representam para as indústrias dealimentos. Na presente revisão bibliográfica, estão descritos os principais aspectos de biofilmes microbianosde importância na indústria de alimentos: i) definição, estrutura e composição; ii) etapas envolvidas naformação; iii) mecanismos de resistência a antimicrobianos; iv) riscos; v) microrganismos envolvidos; vi)importância da higienização como ferramenta de controle.

EFFECTS OF YEAST CELL WALL EXTRACT IN DRY DIET ON MICROBIOLOGY, SHORT-CHAIN FATTY ACIDS AND FECAL ODOR REDUCTION OF ADULT CATS / EFEITOS DO EXTRATO DE PAREDE DE LEVEDURA EM DIETA SECA SOBRE A MICROBIOLOGIA, ÁCIDOS GRAXOS DE CADEIA CURTA E REDUÇÃO DO ODOR DAS FEZES DE GATOS ADULTOS

The aim of this study was to evaluate the effects of yeast cell wall extract (YCW) in dry diet on the fecal microbiota, concentration of short-chain fatty acids (SCFA) and on the odor reduction of cats feces. We used 20 animals of both sexes, randomly assigned to four treatments and five repetitions totaling 20 experimental units: 1) dry commercial diet (control); 2) control + 0.2%, 3) control + 0.4%, and 4) control + 0.6% of YCW in dry matter. Enterobacteriaceae and lactic acid bacteria, fecal concentration of acetic, propionic and butyric acids, ammonia nitrogen and sensory panel were performed. There were no significant differences (p> 0.05) for bacterial counts and the concentration of SCFA and ammonia, but in sensory panel a reduction in the odor of feces could be noted with the use of 0.2% of YCW. We concluded that the addition of up to 0.6% YCW had no effect on the microbiology and the concentration of fatty acids, but there is potential for its use as an additive because of the improvement in the odor of feces. However, further studies are needed to understand the mechanisms of action and the effects of prebiotics for domestic cats. KEYWORDS: ammoniacal nitrogen; butyric acid; feline; lactic bacteria; mannanoligosacharide.

Objetivou-se avaliar os efeitos do extrato de parede de levedura (EPL) em dieta seca sobre a microbiota fecal, concentração de ácidos graxos de cadeia curta (AGCC) e redução do odor das fezes de gatos adultos. Foram utilizados 20 animais, dez de cada sexo, distribuídos ao acaso em quatro tratamentos e cinco repetições, totalizando 20 unidades experimentais: 1) dieta comercial seca (controle); 2) controle + 0,2%; 3) controle + 0,4%; e 4) controle + 0,6% de EPL na matéria seca da dieta. Foram realizados contagem de enterobactérias, E.coli e bactérias láticas, concentração fecal dos ácidos acético, propiônico, butírico e nitrogênio amoniacal, além de painel sensorial. Não foram observadas diferenças significativas (p>0,05) para as contagens bacterianas e a concentração de AGCC e nitrogênio amoniacal; no entanto, por meio do painel sensorial pôde ser notada redução no odor das fezes com o uso de 0,2% de EPL na dieta. Concluiu-se que a adição de até 0,6% de EPL não teve efeito sobre a microbiologia e a concentração de ácidos graxos, mas há potencial uso como aditivo devido à melhora no odor das fezes. Outros estudos são necessários para compreender os mecanismos de ação, efeitos e níveis de inclusão desse prebiótico para gatos domésticos.PALAVRAS-CHAVE: ácido butírico; bactérias láticas; felinos; mananoligossacarídeo; nitrogênio amoniacal.