In the present study, 20 selected Lactobacillus strains already characterized in a previous research for their capability to grow in conditions simulating the intestinal environment, their resistance to antibiotics, t...In the present study, 20 selected Lactobacillus strains already characterized in a previous research for their capability to grow in conditions simulating the intestinal environment, their resistance to antibiotics, their antibacterial activity and their adhesion capability to intestinal human Caco-2 TC7 and HT-29 MTX cell lines, were further investigated to explore more their probiotic properties. Growth behaviour in the presence of prebiotic (fructooligosac-charides (FOS) and lactulose) at a concentration of 2%, cholesterol removal by measuring the residual cholesterol in medium supplemented with cholesterol, ability to deconjugate bile salts using BSH enzyme and antioxidant activity of culture supernatant of Lactobacillus strains by ABTS·+ and DPPH methods were analyzed. All probiotic strains demonstrated important prebiotic assimilation (P > 0.05) even with OD600 > 3 after 30 h of contact, cholesterol removal ability with maximum percentage of 57% after 24 h of contact and they were found to liberate significantly (P < 0.05) more cholic acid with maximum of 0.40 mM of sodium glycocholate, 0.33 mM of sodium taurocholate and 0.41 mM of their mixte and scavenge both radicals with 52% and 2.19% of ABTS·+ and DPPH respectively. This study confirmed the suitability of these probiotic strains for application in functional food formulations especially where cholesterol reduction and antioxidant activity in food are needed to assess possible in vivo human health benefits.展开更多
One hundred strains isolated from bovine raw milk, obtained from different farms, were subjected to different in vitro stress typical of gastrointestinal tract. Twelve strains were able to tolerate pepsin at pH 2, pan...One hundred strains isolated from bovine raw milk, obtained from different farms, were subjected to different in vitro stress typical of gastrointestinal tract. Twelve strains were able to tolerate pepsin at pH 2, pancreatin and bile salts (0.3%). These bacteria were identified using 16S rRNA gene sequencing. Eight isolates were Lactobacillus plantarum and four were Lactobacillus fermentum. They were not able to degrade mucin and they were γ-haemolytic. All strains had antibacterial activity against Staphylococcus aureus, Listeria monocytogenes and Salmonella thyphimirium. However, only six strains inhibited Escherchia coli. All these showed ability for autoaggregation and/or hydrophobicity properties. They were also characterized in respect to their technological properties. Important acidification and low proteolytic and lipolytic capacities were detected for all strains. In addition, they were able to produce exopolysaccharides and grow at hot and cold temperatures. These bacteria may be used further for manufacturing of functional foods and confirming their suitability as probiotic starter cultures.展开更多
The present work focused on the effects of the Modified Atmosphere Packaging (MAP) 1 (5% O2 and 10% CO2) or 2 (2% O2 and 5% CO2) and the previous addition of Lactoperoxidase System (LPS) and Oregano essential oil or c...The present work focused on the effects of the Modified Atmosphere Packaging (MAP) 1 (5% O2 and 10% CO2) or 2 (2% O2 and 5% CO2) and the previous addition of Lactoperoxidase System (LPS) and Oregano essential oil or chlorine washing on the quality of fresh-cut lettuce during refrigerated storage at +4?C. Our results showed the significant effect of this combined treatment on quality improvement during storage. Thus, mesophilic bacteria was reduced in treated samples compared to those untreated with number which not exceeded the critical of 5 × 107 UFC?g-1 (p 2 and CO2 levels created by both atmosphere were not significantly different between the two treatments (p > 0.05). Brightness of lettuce samples was significantly reduced during storage. Thereafter, the PCA data showed the effect of combined treatment on the preservation of hygienic, physico-chemical and sensory quality up to the 7th day of refrigerated storage of these treated samples. The results obtained draw attention to modified atmosphere packaging lettuce and the addition of bio-preservatives which could be an alternative of choice to replace chlorine to preserve the sanitary quality of green products.展开更多
Hydration represents the main unit operation in the industrial thermal process of dry dates.In this work,Tunisian Deglet Nour dates were hydrated experimentally at a laboratory scale by using saturated air as it is c...Hydration represents the main unit operation in the industrial thermal process of dry dates.In this work,Tunisian Deglet Nour dates were hydrated experimentally at a laboratory scale by using saturated air as it is commonly undertaken in industry.This study focuses on the modeling of this unit operation in order to control the moisture uptake phenomenon during processing.A physic-based simplified numerical model describing moisture transfer during hydration was implemented in COMSOL rMultiphysics software.The model considers the real geometry of dates instead of approaching the fruits by simplified shapes.Moisture diffusivities of two types of Deglet Nour dry dates characterized by different maturation stages were estimated.Results showed a good agreement between experimental and numerically computed values of average moisture content.Moisture profile in dates flesh was computed numerically using estimated moisture diffusivities.The numerical model proposed in this work could be therefore employed as a predictive tool to simulate and optimize the hydration operation of dates.展开更多
文摘In the present study, 20 selected Lactobacillus strains already characterized in a previous research for their capability to grow in conditions simulating the intestinal environment, their resistance to antibiotics, their antibacterial activity and their adhesion capability to intestinal human Caco-2 TC7 and HT-29 MTX cell lines, were further investigated to explore more their probiotic properties. Growth behaviour in the presence of prebiotic (fructooligosac-charides (FOS) and lactulose) at a concentration of 2%, cholesterol removal by measuring the residual cholesterol in medium supplemented with cholesterol, ability to deconjugate bile salts using BSH enzyme and antioxidant activity of culture supernatant of Lactobacillus strains by ABTS·+ and DPPH methods were analyzed. All probiotic strains demonstrated important prebiotic assimilation (P > 0.05) even with OD600 > 3 after 30 h of contact, cholesterol removal ability with maximum percentage of 57% after 24 h of contact and they were found to liberate significantly (P < 0.05) more cholic acid with maximum of 0.40 mM of sodium glycocholate, 0.33 mM of sodium taurocholate and 0.41 mM of their mixte and scavenge both radicals with 52% and 2.19% of ABTS·+ and DPPH respectively. This study confirmed the suitability of these probiotic strains for application in functional food formulations especially where cholesterol reduction and antioxidant activity in food are needed to assess possible in vivo human health benefits.
文摘One hundred strains isolated from bovine raw milk, obtained from different farms, were subjected to different in vitro stress typical of gastrointestinal tract. Twelve strains were able to tolerate pepsin at pH 2, pancreatin and bile salts (0.3%). These bacteria were identified using 16S rRNA gene sequencing. Eight isolates were Lactobacillus plantarum and four were Lactobacillus fermentum. They were not able to degrade mucin and they were γ-haemolytic. All strains had antibacterial activity against Staphylococcus aureus, Listeria monocytogenes and Salmonella thyphimirium. However, only six strains inhibited Escherchia coli. All these showed ability for autoaggregation and/or hydrophobicity properties. They were also characterized in respect to their technological properties. Important acidification and low proteolytic and lipolytic capacities were detected for all strains. In addition, they were able to produce exopolysaccharides and grow at hot and cold temperatures. These bacteria may be used further for manufacturing of functional foods and confirming their suitability as probiotic starter cultures.
文摘The present work focused on the effects of the Modified Atmosphere Packaging (MAP) 1 (5% O2 and 10% CO2) or 2 (2% O2 and 5% CO2) and the previous addition of Lactoperoxidase System (LPS) and Oregano essential oil or chlorine washing on the quality of fresh-cut lettuce during refrigerated storage at +4?C. Our results showed the significant effect of this combined treatment on quality improvement during storage. Thus, mesophilic bacteria was reduced in treated samples compared to those untreated with number which not exceeded the critical of 5 × 107 UFC?g-1 (p 2 and CO2 levels created by both atmosphere were not significantly different between the two treatments (p > 0.05). Brightness of lettuce samples was significantly reduced during storage. Thereafter, the PCA data showed the effect of combined treatment on the preservation of hygienic, physico-chemical and sensory quality up to the 7th day of refrigerated storage of these treated samples. The results obtained draw attention to modified atmosphere packaging lettuce and the addition of bio-preservatives which could be an alternative of choice to replace chlorine to preserve the sanitary quality of green products.
文摘Hydration represents the main unit operation in the industrial thermal process of dry dates.In this work,Tunisian Deglet Nour dates were hydrated experimentally at a laboratory scale by using saturated air as it is commonly undertaken in industry.This study focuses on the modeling of this unit operation in order to control the moisture uptake phenomenon during processing.A physic-based simplified numerical model describing moisture transfer during hydration was implemented in COMSOL rMultiphysics software.The model considers the real geometry of dates instead of approaching the fruits by simplified shapes.Moisture diffusivities of two types of Deglet Nour dry dates characterized by different maturation stages were estimated.Results showed a good agreement between experimental and numerically computed values of average moisture content.Moisture profile in dates flesh was computed numerically using estimated moisture diffusivities.The numerical model proposed in this work could be therefore employed as a predictive tool to simulate and optimize the hydration operation of dates.
