Study of the Oxidative and Microbiological Stability of Nitrite-Reduced, Vacuum-Packed, Refrigerated Lamb Sausages Supplemented with Red Propolis Extract.

Vacuum-packed lamb sausages with or without red propolis extract and a reduced sodium nitrite content were evaluated for oxidative and microbiological stability during storage for 21 days at 2 °C. The following treatments were evaluated: EN150 (control, base formulation (BF) + 500 mg/kg sodium erythorbate and 150 mg/kg sodium nitrite); EN75 (BF + 500 mg/kg sodium erythorbate and 75 mg/kg sodium nitrite); P1N75 (without the addition of erythorbate, BF + 1800 mg/kg propolis extract and 75 mg/kg sodium nitrite); and P2N75 (without the addition of erythorbate, BF + 3600 mg/kg propolis extract and 75 mg/kg sodium nitrite). Analyses were conducted to characterize the samples on day 0 with respect to the proximate composition (moisture, protein, fat, and ash) and sensory acceptance. Stability during refrigerated storage was evaluated on days 0, 7, 14 and 21 for the parameters pH, color profile (L*, a*, and b*), TBARs index (oxidative stability) and microbiological count of aerobic psychrotrophic microorganisms. Texture profile, cooking weight loss (WLC), peroxide index and free fatty acids were evaluated on days 0 and 21. The treatments with propolis and reduced nitrite (EN150 and P1N75) showed a red color intensity (a*) similar to the treatment with erythorbate and the same nitrite content (EN75) at the end of storage, maintaining the characteristic reddish color of the sausages. The extract slowed down lipid oxidation during storage, especially P2N75, which showed the lowest level of TBARS (0.39 mg MDA/kg) and the peroxide index (2.13 mEq g O2) on day 21. The residual nitrite value in EN75 was the lowest (p < 0.05) on day 21, showing that synthetic antioxidants are more efficient than the extract in nitrite reduction reactions. The results for the counts of psychrotrophic microorganisms showed that the extract did not have the expected antimicrobial effect on the growth of this microorganisms, and leveling the results revealed no differences (p < 0.05) between the treatments. Despite the red propolis extract not showing a significant antimicrobial improvement in lamb sausages, it can be considered a healthy option with good prospects for replacing synthetic antioxidants with a natural product.

The compound paraquat dichloride hydrate significantly affects the in vitro growth rate of a Chromobacterium violaceum wild type strain / O composto hidrato-dicloreto de paraquat afeta a taxa de crescimento in vitro de uma cepa do tipo selvagem de Chromobaterium violaceum

Introduction: the toxicity of pesticides on bacterial cell growth is still limited. Objectives: The current study aimed to assess the in vitro growth rate of the C. violaceum wild type strain ATCC12472 exposed to the herbicide paraquat dichloride hydrate at different incubation times and final concentrations. Methodology: bacterial inocula were incubated in a nutrient broth medium containing the compound paraquat at final concentrations 100 and 1.000 µg mL-1 under aeration conditions. Spectrophotometric readings at different incubation times were carried out to estimate the in vitro bacterial growth rate. Moreover, the number of viable bacteria cells in the samples was also estimated in the presence of the paraquat at two concentrations tested based on colony-forming units grown on the nutrient broth agar. Results: significant decreases in the C. violaceum growth rate were detected, after one hour of paraquat exposure at a final concentration of 1,000 µg mL-1 (p<0.05) compared to all treatments tested. After two hours of paraquat exposure, significant decreases were progressively found at all final concentrations of 100 (p<0.01) and of 1,000 µg mL-1 (p<0.001). These data were also corroborated by counting the total number of colony-forming units at final concentrations tested. Conclusion: the findings described in current study suggest that the compound paraquat dichloride hydrate exerts significant effects on the in vitro growth rate of a C. violaceum wild type strain.

Introdução: a toxicidade de pesticidas sobre o crescimento de células bacterianas ainda é limitada. Objetivos: o presente estudo objetivou avaliar a taxa de crescimento in vitro de uma cepa selvagem de C. vilaceum ATCC12472 exposta ao herbicida hidratodicloreto de paraquat em diferentes tempos de incubação e concentrações finais. Metodologia: inóculos bacterianos foram incubados em um caldo nutritivo contendo o composto paraquat nas concentrações 100 e 1.000 µg mL-1 sob condições de aeração. Leituras espectrofotométricas em diferentes tempos de incubação foram realizadas para estimar a taxa de crescimento in vitro bacteriano. Além disso, o número de células bacterianas viáveis nas amostras foi também estimado na presença do paraquat nas duas concentrações testadas, baseado no número de unidades formadoras de colônias crescidas em meio nutritivo ágar. Resultados: diminuições significativas na taxa de crescimento da C. violaceum foram detectadas, após uma hora de exposição ao paraquat na concentração final de 1.000 µg mL-1 (p<0,05) em comparação aos demais tratamentos testados. Com duas horas de exposição ao paraquat, diminuições significativas foram progressivamente encontradas em todas as concentrações finais de 100 (p<0,01) e de 1.000 µg mL-1 (p<0,001). Tais dados foram corroborados pela contagem do número total de unidades formadoras de colônias nas concentrações analisadas. Conclusão: as descobertas descritas aqui sugerem que o composto hidrato-dicloreto de paraquat exerce efeitos significativos sobre a taxa de crescimento in vitro de uma cepa selvagem da bactéria C. violaceum

Características fermentativas na ensilagem de cana-de-açúcar com maniçoba / Fermentative characteristics in sugarcane silage with maniçoba

A utilização da silagem de cana-de-açúcar apresenta benefícios que têm despertado interesse de produtores e pesquisadores. No entanto, algumas limitações, principalmente relacionadas ao seu padrão de fermentação, têm constituído grande desafio para utilização desta forrageira. Com objetivo de avaliar a inclusão de maniçoba sobre as características fermentativas na silagem de cana-de-açúcar, foi elaborado experimento em delineamento inteiramente casualizado com quatro tratamentos (níveis de inclusão: 0, 20, 30 e 40%) e seis repetições. Após 90 dias do fechamento dos silos, foram determinadas as perdas na forma de gases, perda total e recuperação de matéria seca e produção de efluentes. Os silos então foram abertos e obtido o extrato aquoso das silagens, foram determinados os teores dos ácidos orgânicos (acético, butírico, lático e propiônico), etanol, N-NH3, NT e valores de pH. À medida que se aumentou o nível de inclusão de maniçoba, foi observada redução de 67% nas perdas por gases e de 23,3% na produção de efluente, enquanto a concentração de etanol foi reduzida de 25,6 a 2,7%. As máximas concentrações de ácido lático (2,4%), acético (2,2%) e propiônico (0,03%) foram encontradas em silagens contendo 40% de maniçoba, enquanto que, para o ácido butírico, decresceu linearmente. Em todas as silagens, o pH encontrado mostrou-se adequado ao processo de ensilagem (variação de 3,4 a 3,7). O maior nível de inclusão de maniçoba em silagens de cana-de-açúcar melhora a fermentação das silagens e reduz as perdas fermentativas.

The use of silage sugar cane has a benefit that has aroused the interest of producers and researchers. However, some limitations mainly related to its fermentation pattern, has become the challenge for forage use. To evaluate the inclusion of maniçoba on silage fermentation characteristics of sugar cane, it was prepared an experiment in a completely randomized design with four treatments (inclusion levels: 0, 20, 30 and 40% ) and six replications. After 90 days of the silos closing o were resoluted losses in the form of gases, total loss and recovery of dry matter production and effluent. The silos were opened and then obtained the aqueous extract of the silages, determined levels of organic acids (acetic, butyric, lactic and propionic), ethanol, NH3-N, NT and pH values. As the level of inclusion of maniçoba was increased, it was observed a 67% reduction in the losses of gases and 23.3% in the effluent production, while the ethanol concentration was reduced from 25.6 to 2.7%. The maximum concentration of lactic acid (2.4%), acetic acid (2.2%) and propionic (0.03%) were found in silages containing 40% of maniçoba, while for butyric acid it decreased linearly. In all silages the pH found was adequate to silage (range 3.4 to 3.7). The highest level of maniçoba inclusion in sugar cane silages improves the fermentation of the silage and reduces fermentation losses.