Janeeyre Ferreira Maciel

Changes in thermo-tolerance and survival under simulated gastrointestinal conditions of Salmonella Enteritidis PT4 and Salmonella Typhimurium PT4 in chicken breast meat after exposure to sequential stresses

This study assessed changes in thermo-tolerance and capability to survive to simulated gastrointestinal conditions of Salmonella Enteritidis PT4 and Salmonella Typhimurium PT4 inoculated in chicken breast meat following exposure to stresses (cold, acid and osmotic) commonly imposed during food processing. The effects of the stress imposed by exposure to oregano (Origanum vulgare L.) essential oil (OVEO) on thermo-tolerance were also assessed. After exposure to cold stress (5°C for 5h) in chicken breast meat the test strains were sequentially exposed to the different stressing substances (lactic acid, NaCl or OVEO) at sub-lethal amounts, which were defined considering previously determined minimum inhibitory concentrations, and finally to thermal treatment (55°C for 30min). Resistant cells from distinct sequential treatments were exposed to simulated gastrointestinal conditions. The exposure to cold stress did not result in increased tolerance to acid stress (lactic acid: 5 and 2.5μL/g) for both strains. Cells of S. Typhimurium PT4 and S. Enteritidis PT4 previously exposed to acid stress showed higher (p<0.05) tolerance to osmotic stress (NaCl: 75 or 37.5mg/g) compared to non-acid-exposed cells. Exposure to osmotic stress without previous exposure to acid stress caused a salt-concentration dependent decrease in counts for both strains. Exposure to OVEO (1.25 and 0.62μL/g) decreased the acid and osmotic tolerance of both S. Enteritidis PT4 and S. Typhimurium PT4. Sequential exposure to acid and osmotic stress conditions after cold exposure increased (p<0.05) the thermo-tolerance in both strains. The cells that survived the sequential stress exposure (resistant) showed higher tolerance (p<0.05) to acidic conditions during continuous exposure (182min) to simulated gastrointestinal conditions. Resistant cells of S. Enteritidis PT4 and S. Typhimurium PT4 showed higher survival rates (p<0.05) than control cells at the end of the in vitro digestion. These results show that sequential exposure to multiple sub-lethal stresses may increase the thermo-tolerance and enhance the survival under gastrointestinal conditions of S. Enteritidis PT4 and S. Typhimurium PT4.

A Chitosan Coating Containing Essential Oil from Origanum vulgare L. to Control Postharvest Mold Infections and Keep the Quality of Cherry Tomato Fruit

The efficacy of an edible chitosan coating (CHI; 4 mg/mL) and Origanum vulgare L. essential oil (OVEO; 1.25 μL/mL) for maintaining the quality of cherry tomato fruit during storage at room (25°C; 12 days) and cold (12°C; 24 days) temperatures was assessed. CHI and OVEO in combination showed in vitro fungicidal effects against R. stolonifer and Aspergillus niger. CHI-OVEO coating reduced the incidence of black mold and soft rot caused by these fungi in artificially contaminated cherry tomato fruit during storage at both temperatures. CHI-OVEO coating delayed the appearance of the first visible signs of black mold and soft rot in artificially contaminated cherry tomato fruit stored at room temperature by 6 days and by more than 9 days in those stored at cold temperature. At the end of storage at room and cold temperature fruit coated with CHI-OVEO showed higher firmness (>2 N/mm) and lower weight loss (>2%) compared to uncoated tomato fruit. CHI-OVEO coating delayed the decrease of lycopene, ascorbic citric acid, glucose and fructose during the storage time assessed at room or cold temperatures. The increase of catechin, myricetin, caffeic and syringic acids was higher (1–9 mg/g) in cherry tomato fruit coated with CHI-OVEO compared to uncoated fruit during the storage at both temperatures studied. CHI-OVEO coating is a feasible treatment for maintaining the storage quality of cherry tomato fruit.

Evaluation of quality of bread type french by instrumental and sensory methods

Na presente pesquisa, o objetivo foi avaliar a qualidade do pao tipo frances, comercializado em panificadoras de Joao Pessoa-PB, por meio de metodos instrumentais e sensoriais. Inicialmente, amostras de paes das doze panificadoras selecionadas nesse estudo foram submetidas as determinacoes de volume especifico, umidade, pH, acidez, cor da casca, cor do miolo e perfil de textura, tendo todas essas analises sido realizadas em triplicata, com 10 repeticoes. Em seguida, foi aplicado um teste de aceitacao sensorial, utilizando-se uma escala hedonica de nove pontos, com 65 provadores, que avaliaram as amostras quanto aos atributos aparencia, cor da casca, cor do miolo, crocância da casca, aroma, sabor, textura e aceitacao global. Nos testes instrumentais, foi observado que a maioria dos paes apresentou umidade abaixo de 26% e acidez acima de 4,5 mL de NaOH 0,1N/10 g de pao. Com relacao ao volume especifico, valores satisfatorios foram observados em 86,2% das amostras (entre 5,0 e 8,0 cm³/g), enquanto para a luminosidade da casca (60-78), e firmeza (2,87 a 6,32 N), esse percentual foi em torno de 80%. Para as demais caracteristicas de textura foi observado que a media da elasticidade variou de 0,91 – 1,93, da coesividade de 0,72 – 0,86 e da mastigabilidade de 1,91 –5,71 N. Em relacao a aceitacao sensorial, somente 50% das panificadoras tiveram seus paes aceitos em todos os atributos avaliados, com escores medios iguais ou superiores a 6. As demais amostras foram rejeitadas por falta de crocância, e uma destas teve seus paes rejeitados tambem nos atributos aroma, sabor e aparencia, apresentando, portanto, maior necessidade de adequacao.

Effects of Lactobacillus acidophilus LA-3 on physicochemical and sensory parameters of açaí and mango based smoothies and its survival following simulated gastrointestinal conditions

The effects of the incorporation of Lactobacillus acidophilus LA3 (inoculated at 9 log CFU/mL) on physicochemical parameters, contents of sugars and organic acids, phenolic profile and sensory aspects of açaí (AS) and mango based smoothies (MS) during 28 days of refrigerate storage were assessed. The survival of L. acidophilus in AS and MS under simulated human gastrointestinal conditions during storage was also monitored. Counts of L. acidophilus LA-3 were approximately 8.5 log CFU/mL in AS and 7.5 log CFU/mL in MS after 1 day of storage and no changes (p ≥ 0.05) were observed in later evaluated storage time periods. Fruit smoothies (AS or MS) with L. acidophilus LA-3 presented lower (p < 0.05) contents of glucose, fructose and maltose and higher (p < 0.05) contents of lactic and succinic acids compared to those without L. acidophilus LA-3. Phenolic contents increased or decreased (p < 0.05) after 1 day of storage in AS and MS with L. acidophilus LA-3 and did not change (p ≥ 0.05) in AS or MS without L. acidophilus LA-3. The incorporation of L. acidophilus LA-3 increased the acidic flavor and fermented aroma in AS and MS. Viable counts of L. acidophilus LA-3 were approximately 7.5 and 8.5 log CFU/mL in AS and MS, respectively, at the end of in vitro digestion just after the incorporation, as well as on days 14 and 28 of storage. These results show the feasibility of incorporating L. acidophilus LA-3 into AS or MS and suggest these fruit smoothies as matrices for formulation of non-dairy beverages containing potentially probiotic lactobacilli.