A study on the effect of Zataria multiflora Bioss essential oil and Nisin on the growth of Lactococcus garvieae in the rainbow trout fillet (Oncorhynchus mykiss)

The ever-increasing population of the world and the growing need for animal protein has doubled the modern man’s demand for food. Additionally, the improvement in the general public health, and the worsening of environmental/ecological pollution have prompted today’s world to look for ways to procure healthy food. And one such attempt is the use of natural preservatives to decrease the bacterial load in foodstuffs, in other words, to increase their durability. This study evaluates the effects of different concentrations of Zataria multiflora Bioss (EO 0, 0.005, 0.015, 0.045, 0.135, 0.405%) and Nisin (0, 0.25, 0.5, 0.75 μg/ml) and storage time (9 days) on the growth of Lactococcus garvieae Ir-170A(856bp) alone, and their combination in a food model system (fillets of the rainbow trout (Oncorhynchus mykiss). Additionally, the growth of a sample of this bacteria in laboratory conditions was studied. The results of this study showed that different concentrations of Nisin had a significant impact (p<0.05) on Lactococcus garvieae. With the value of t in 0.75 μg/ml, the effectiveness rose to 65.77%; the biggest effect on Lactococcus garvieae. And the effect at 4 0C exceeded 80C. The study has also demonstrated that all concentrations of Zataria multiflora Bioss were effective against Lactococcus garvieae. However, with the value of t at 0.405%, the effectiveness was 71.91%. This value had the biggest effect on Lactococcus garvieae. At 4 0C, the effect surpassed the one at 80C. The synergistic effects of the EO and Nisin showed that with the value of t at 0.405% EO and 0.75 μg/ml Nisin was 14.62% had the greatest effect on Lactococcus garvieae. In this study, multi-factorial effects for different concentrations of Zataria multiflora Bioss (EO 0, 0.005, 0.015, 0.0025%), three different concentrations of 122 Nisin (0, 0.25,0.75 μg/ml) and two different levels of PH (5.5 , 7) at two incubation temperatures (15,37) on logp% of Lactococcus garvieae during 43 days in BHI broth were evaluated. Most of the effects on Lactococcus garvieae occurred in PH 5.5 and at a temperature of 150C.

Efeito do ácido lático sobre as características microbiológicas, físico-químicas e sensoriais na carne do sol

The dried beef is a food traditionally eaten by Northeastern and has an extensive trade in the city of Natal-RN. It is usually produced in an empirical manner, without any standardization in production. Characterized as partially dehydrated meat product, so that the activity of water present is not sufficient to prevent microbial growth, degradation or the production of microbial toxins. The guarantee that the market dried beef is to provide a quality product hygienic, microbiological, physicochemical and sensory stable and adequate for the safety and consumer satisfaction, which has been increasingly attracted to food with natural preservatives. Thus, the meat industries are replacing the current seasonings and natural preservatives for similar, with it without affecting the shelf life of products. Lactic acid has been used to meet these requirements. In this sense, this study aimed to evaluate the effect of lactic acid on the physico-chemical, microbiological and sensory, besides knowing the consumer profile of dried meat of the City of Natal / RN. The results demonstrated that the use of lactic acid in concentrations of 1% and 2% during the processing of dried meat, had statistically significant effect (p < 0.05) on the physico-chemical (pH and water activity) and consequently reduced the microbial count does not alter the taste of the new product developed. Regarding the results on the consumer profile, it was found that the majority of respondents (71.75%) did not observe the presence of the stamp of the Federal Inspection Service (SIF) to buy this meat food that 81.55% of consumers check the hygiene conditions of the site and handlers, however, a large proportion of respondents not concerned with the guarantee of origin of typical regional products featuring a hazard to food safety for consumers of the city of Natal-RN

Lactic Acid Bacteria Antimicrobial Compounds: Characteristics and Applications

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Antibacterial activity of oregano essential oil against foodborne pathogens

Purpose: This paper aims to evaluate in vitro antibacterial activity of oregano essential oil against foodborne pathogens as a starting point for the use of spice as a natural preservative in food. Design/methodology/approach: Disc and well-diffusion assays were performed to investigate antibacterial activity of oregano essential oil against six bacteria strains: Bacillus cereus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Salmonella Typhimurium. Three concentrations of oregano essential oil were employed: 1.0 percent, 2.0 percent and 5.0 percent. Bacterial growth inhibition was determinate as the diameter of the inhibition zones. Findings: Oregano essential oil showed antibacterial activity against spoilage microorganisms, at different concentrations, except for P. aeruginosa. There was a significant difference between methodologies only for the microorganism S. aureus. The results provided evidence of the existence of significant differences among the concentrations of oregano essential oil for each microorganism evaluated. Research limitations/implications: Although the research for this paper involved only oregano essential oil, it provided a starting-point for further investigations concerning spices as natural preservatives for food systems. Practical implications: Disc and well-assays were found to be simple and reproducible practical methods. Other spices, their essential oil and extracts might be researched against other micro-organisms. Furthermore, in situ studies need to be performed to evaluate possible interactions between essential oils and compounds naturally present in food against microbial strains. Social implications: The imminent adoption of measures to reduce the use of additives in foods and the reduction on using such compounds. Originality/value: This study provides insights that suggest a promising exploratory development of food natural preservative against spoilage microorganisms in food systems by the use of oregano essential oil. © Emerald Group Publishing Limited.

Assessment of antimicrobial activity of cinnamon (Cinnamomum zeylanicum) essential oil combined with EDTA and polyethylene glycol in yogurt

Essential oils (EOs) are technological options that may be employed in natural foods due to their antimicrobial activities. However, restrictions exist when high EOs concentrations are required which, in their turn, affect sensory qualities. Technological alternatives, such as combination of EOs with chelating and dispersing agents, have been proposed in the literature. Current research determined the antimicrobial activity of cinnamon EO against microbial spoilage in yogurt when added at the highest acceptable sensory EO concentration, alone or associated with ethylenediaminetetraacetic acid (EDTA) and/or polyethylene glycol. Cinnamon EO's chemical analysis was performed by gas chromatography-mass spectrometry (GC-MS). Sensory analysis was conducted to define the highest acceptable sensory concentration of cinnamon EO in yogurt, stipulated at 0.04% cinnamon EO. Antimicrobial activity in yogurt was then evaluated for aerobic mesophiles, psychrotrophilic microorganisms, yeasts and molds counts. Treatments comprised (1) control, (2) 0.04% EO, (3) 0.04% EO + 0.01% EDTA, (4) 0.04% EO + 0.02% polyethylene glycol; (5) 0.04% EO + 0.01% EDTA + 0.2% polyethylene glycol, in triplicates. Concentration 0.04% of cinnamon EO, alone or associated with EDTA and/or polyethylene glycol, failed to show any antimicrobial activity against aerobic mesophiles, yeasts and molds.

Atividade antibacteriana de óleo essencial de orégano (Origanum vulgare): ações in vitro e in situ para preservação de alimento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

“Green preservatives” – combating fungi in the food industry by applying antifungal lactic acid bacteria

Fungal spoilage is the most common type of microbial spoilage in food leading to significant economical and health problems throughout the world. Fermentation by lactic acid bacteria (LAB) is one of the oldest and most economical methods of producing and preserving food. Thus, LAB can be seen as an interesting tool in the development of novel bio-preservatives for food industry. The overall objective of this study was to demonstrate, that LAB can be used as a natural way to improve the shelf-life and safety of a wide range of food products. In the first part of the thesis, 116 LAB isolates were screened for their antifungal activity against four Aspergillus and Penicillium spp. commonly found in food. Approximately 83% of them showed antifungal activity, but only 1% showed a broad range antifungal activity against all tested fungi. The second approach was to apply LAB antifungal strains in production of food products with extended shelf-life. L. reuteri R29 strain was identified as having strong antifungal activity in vitro, as well as in sourdough bread against Aspergillus niger, Fusarium culmorum and Penicillium expansum. The ability of the strain to produce bread of good quality was also determined using standard baking tests. Another strain, L. amylovorus DSM19280, was also identified as having strong antifungal activity in vitro and in vivo. The strain was used as an adjunct culture in a Cheddar cheese model system and demonstrated the inhibition of P. expansum. Significantly, its presence had no detectable negative impact on cheese quality as determined by analysis of moisture, salt, pH, and primary and secondary proteolysis. L. brevis PS1 a further strain identified during the screening as very antifungal, showed activity in vitro against common Fusarium spp. and was used in the production of a novel functional wortbased alcohol-free beverage. Challenge tests performed with F. culmorum confirmed the effectiveness of the antifungal strain in vivo. The shelf-life of the beverage was extended significantly when compared to not inoculated wort sample. A range of antifungal compounds were identified for the 4 LAB strains, namely L. reuteri ee1p, L. reuteri R29, L. brevis PS1 and L. amylovorous DSM20531. The identification of the compounds was based on liquid chromatography interfaced to the mass spectrometer and PDA detector

Use of Natural Products for Post-Harvest Preservation of 'Vega' Cut Roses

Use of natural products as floral preservatives has helped to reduce the indiscriminate use of chemical products in flower preservation. In this study, we tested the ability of certain natural products to maintain the quality and to increase the commercial durability of 'Vega' cut roses. We employed a randomized factorial design with six post-harvest treatments and four evaluation dates. The following treatments were tested: 1) distilled water; 2) methyl jasmonate (350 mu M) applied in a four-hour pulse; 3) methyl jasmonate (500 mu M) spraying; 4) mint oil (100 ppm); 5) ginger oil (100 ppm); and 6) propolis (0.05%) as a maintenance solution. Flowers were kept at 20+/-2 degrees C and 67+/-3% RH. Physiological and qualitative evaluations were conducted. Natural products had a beneficial effect on the shelf life of the flowers. However, for all evaluated parameters, the methyl jasmonate spray was the most efficient treatment to maintain floral quality, resulting in less fresh-mass loss and a lower flower respiratory rate. Methyl jasmonate spray also improved the maintenance of coloration, relative water content and concentration of reducing sugars, thus extending the shelf life of roses.

Efeito da resistência natural e tratamentos químicos no lenho juvenil e adulto de Hevea brasiliensis Mull.Arg. ao fungo manchador Botryodiplodia theobromae e cupim Cryptotermes brevis

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Biocompatibility studies of natural rubber latex from different tree clones and collection methods

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)