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- Effect of different conditions of growth and storage on the cell counts of two lactic acid bacteria after spray drying in orange juicePublication . Barbosa, Joana; Borges, Sandra; Teixeira, PaulaConsumers increasingly require innovative food products with health benefits. Thus, a dried orange juice incorporating probiotics could be a novel challenge. In this context, we investigated whether different sugars added to the culture media used for growth of two lactic acid bacteria contributed to their protection during spray drying in orange juice and subsequent storage under different conditions of temperature, light exposure and water activity. Cell viability during passage through simulated gastro-intestinal conditions was also investigated. Cells grown in culture medium containing fructose resulted in the worst survival rates during storage. High survival was observed for cells grown in the presence of lactose, followed by glucose. The survival of dried bacteria was enhanced at 4 C, water activity of 0.03 and absence of daylight. For cells grown in standard culture medium and after 12 months of storage at 4 C in orange juice powder (about 109 cfu/mL), there was a reduction of approximately 2 log-units for both lactic acid bacteria after gastro-intestinal tract passage simulation. Using the conditions of growth and storage investigated, it is possible to improve the survival rate of lactic acid bacteria and produce an orange juice powder with probiotic characteristics with shelf life of at least 12 months.
- The progress of essential oils as potential therapeutic agents: a reviewPublication . Baptista-Silva, Sara; Borges, Sandra; Ramos, Oscar. L.; Pintado, Manuela; Sarmento, BrunoEssential oils are products obtained from plants, by steam distillation, mechanical processes of citrus fruit epicarp, or dry distillation after separation of the aqueous phase by physical processes. They are usually composed of secondary metabolites of aromatic plants with oxygenated structures such as alcohols, ketones, aldehydes, and esters, presenting therapeutic properties such as antibacterial, antifungal and antioxidant activities. Essential oils are used in the pharmaceutical, food, and fragrance industries. The increasing use of plants by the pharmaceutical industry makes the study of essential oils crucial to design new bioactive delivery systems. This paper presents aliterature review that summarizes the best advanced data regarding the use of essential oils and their volatile constituents for biomedical applications with focuses on innovative pharmaceutical formulations. Nonetheless, it seems clear that more clinical evaluations are required until essential oils can be considered as possible applications in pharmacy or as adjuvants to current medications.
- Behavior of Listeria monocytogenes isolates through gastro-intestinal tract passage simulation, before and after two sub-lethal stressesPublication . Barbosa, J.; Borges, S.; Magalhães, R.; Ferreira, V.; Santos, I.; Silva, J.; Almeida, G.; Gibbs, P.; Teixeira, P.The effects of previous exposure to sub-lethal acidic and osmotic stresses on the survival of Listeria monocytogenes during exposure to gastro-intestinal (GI) tract simulation, was investigated. Six L. monocytogenes strains isolated from cheeses were selected and exposed to high salt concentrations or acidic conditions and their viability compared in quick and slow digestions. The results demonstrated that (i) all isolates were more sensitive to the exposure to acidic than to osmotic sub-lethal conditions (ii) significant differences (p < 0.05) between the two types of digestion were observed; in slow digestion, the log reduction was higher for all the tested isolates (iii) all isolates were inhibited in the presence of bile salts for both types of digestion (iv) differences between quick and slow digestion were not observed (p > 0.05) after exposure to either osmotic or acidic stress (v) a higher cellular inactivation (p < 0.001) was observed during the passage through the GI tract simulation after exposure to osmotic than to acidic stresses and (vi) neither osmotic nor acidic sub-lethal stresses conferred resistance to simulated GI tract conditions.
- Effects of encapsulation on the viability of probiotic strains exposed to lethal conditionsPublication . Borges, Sandra; Barbosa, Joana; Camilo, Rute; Carvalheira, Ana; Silva, Joana; Sousa, Sérgio; Gomes, Ana M.; Pintado, Maria M.; Silva, José P.; Costa, Paulo; Amaral, Maria H.; Teixeira, Paula; Freitas, Ana C.The effect of microencapsulation on the viability of Lactobacillus casei, L. paracasei, L. acidophilus Ki and Bifidobacterium animalis BB-12 during exposure to lethal conditions (25% NaCl, pH 3.0 and 55–60 ºC) was evaluated. Results demonstrated that survival of probiotic strains to the imposed lethal stress conditions was strain dependent. With the exception of exposure to 25% (w ⁄ v) NaCl, L. acidophilus Ki (free and encapsulated cells) demonstrated the highest survival rates through exposure to lethal conditions of temperature and pH. For this probiotic strain exposed to heat, microencapsulated cells expressed a higher heat tolerance at 55 ºC than free cells. For the other tested bacteria, in general, encapsulation had no positive effect on survival through the tested lethal conditions.
- Survival and biofilm formation by Group B streptococci in simulated vaginal fluid at different pHsPublication . Borges, Sandra; Silva, Joana; Teixeira, PaulaThe Group B Streptococcus (GBS, Streptococcus agalactiae) is an important cause of neonatal and maternal infection. GBS is a commensal organism of the lower gastrointestinal and vaginal tract. A frequent mode of neonatal infection is vertical transmission from pregnant women to their foetus or neonate. The aim of this study was to evaluate the survival and biofilm production of 10 GBS strains in simulated vaginal fluid at pH 4.2, 5.5 and 6.5. GBS survived longer at higher pH than at normal vaginal pH. At pH 4.2, with the exception of two isolates that were recovered up to 48 and 72 h, viable GBS numbers declined below the limit of detection by 24 h. At higher pH, GBS survived between 3 and 15 days. All isolates investigated were biofilm producers but biofilm production was greater in tryptone soy broth compared to simulated vaginal fluid. The quantity of biofilm produced increased with the rise in the pH. This study suggests that high vaginal pH may influence both GBS survival and biofilm production and thus could be a risk factor for GBS infection.
- Effects of processing and storage on Pediococcus pentosaceus SB83 in vaginal formulations: lyophilized powder and tabletsPublication . Borges, Sandra; Costa, Paulo; Silva, Joana; Teixeira, PaulaVaginal probiotics have an important role in preventing the colonization of the vagina by pathogens. This study aimed to investigate different formulations with Pediococcus pentosaceus SB83 (lyophilized powder and tablets with and without retarding polymer) in order to verify its stability and antilisterial activity after manufacture and during storage. The bacteriocinogenic activity of P. pentosaceus SB83 against Listeria monocytogenes was evaluated in simulated vaginal fluid. Suspension of Pediococcus pentosaceus SB83 reduced the pathogen only after 2 h and the lyophilized bacteria after 24 h of contact, and, in the tablets, P. pentosaceus SB83 lost the antimicrobial activity. The pH of simulated vaginal fluid decreased for all the tested conditions. As lyophilized powder demonstrated better results concerning antimicrobial activity, this formulation was selected to evaluate the antilisterial activity during the 12 months of storage. During storage at room temperature, lyophilized bacteria totally inhibited the pathogen only until one month of storage. At 4 degrees C, P. pentosaceus SB83 showed antimicrobial activity during all the time of storage investigated. Therefore, the better formulation of P. pentosaceus SB83 is the lyophilized powder stored at 4 degrees C, which may be administered intravaginally as a washing solution.
- Enzymatic hydrolysis of insect Alphitobius diaperinus towards the development of bioactive peptide hydrolysatesPublication . Sousa, Pedro; Borges, Sandra; Pintado, ManuelaEdible insects are a promising protein source for the future generation, due to their nutritional composition, sustainability and low environmental impact. Recent studies demonstrated their potential as a protein base to obtain bioactive peptides with potential applicability in the food industry. The aim of this study was to hydrolyze and analyze the potential of the edible insect Alphitobius diaperinus protein to develop an improved insect food ingredient with bioactive properties. After evaluating various conditions for the enzymatic hydrolysis with Alcalase 2.5L and Corolase PP, the best condition chosen for each enzyme was an enzyme : substrate ratio of 1.5% for 4 hours and a ratio of 3.0% for 6 hours, respectively. Insect protein hydrolysates are demonstrated to have relevant bioactive properties, namely antioxidant (by ABTS and ORAC methods) and antihypertensive activities (through the ability to inhibit the angiotensin converting enzyme, ACE), but no antimicrobial or antidiabetic properties were observed. Antioxidant activity values for hydrolysates obtained with Alcalase 2.5L and Corolase PP were 95.0 ± 0.8 and 95.7 ± 1.0 μmol Trolox equivalent per g insect powder by the ABTS method, 825.6 ± 85.5 and 944.8 ± 68.1 μmol Trolox equivalent per g insect powder by the ORAC method, respectively. Insect hydrolysates were able to inhibit the ACE and IC50 values for insect hydrolysates obtained with Alcalase 2.5L and Corolase PP were 55.5 ± 6.2 and 107.4 ± 9.7 μg of protein per mL, respectively. These insect protein hydrolysates can be used as a supplement/ingredient in the food industry with potential health benefits.
- Pediococcus acidilactici as a potential probiotic to be used in food industryPublication . Barbosa, Joana; Borges, Sandra; Teixeira, PaulaThe objective of this study was to compare the results obtained between a commercial probiotic bacterium and a strain of Pediococcus acidilactici isolated from a food matrix. Besides the characterisation of the isolates, the main focus of this work was to evaluate their ability to survive through simulated gastrointestinal tract passage as well as the effect of the spray drying process to be used as concentrated cultures in the food industry. Both lactic acid bacteria produced any of the virulence determinants investigated; they exhibited no significant antibiotic resistances and <1logunit reduction in viable counts was obtained after exposure to simulated gastrointestinal tract conditions. Concentrated cultures of P.acidilactici HA-6111-2 in 10% (w/v) of reconstituted skim milk were obtained by spray drying and, after 60days of storage at 4 degrees C, <1logunit reduction in viable count was recorded. In conclusion, from these preliminary characterisation tests and its extended viability in the dried form, this P.acidilactici strain should be considered as a potentially useful probiotic.
- Influence of sub-lethal stresses on the survival of lactic acid bacteria after spray-drying in orange juicePublication . Barbosa, J.; Borges, S.; Teixeira, P.The demand for new functional non-dairy based products makes the production of a probiotic orange juice powder an encouraging challenge. However, during drying process and storage, loss of viability of the dried probiotic cultures can occur, since the cells are exposed to various stresses. The influence of sub-lethal conditions of temperature, acidic pH and hydrogen peroxide on the viability of Pediococcus acidilactici HA-6111-2 and Lactobacillus plantarum 299v during spray drying in orange juice and subsequent storage under different conditions was investigated. At the end of storage, the survival of both microorganisms through simulated gastro-intestinal tract (GIT) conditions was also determined. The viability of cells previously exposed to each stress was not affected by the drying process. However, during 180 days of storage at room temperature, unlike P. acidilactici HA-6111-2, survival of L. plantarum 299v was enhanced by prior exposure to sub-lethal conditions. Previous exposure to sub-lethal stresses of each microorganism did not improve their viability after passage through simulated GIT. Nevertheless, as cellular inactivation during 180 days of storage was low, both microorganisms were present in numbers of ca. 10(7) cfu/mL at the end of GIT. This is an indication that both bacteria are good candidates for use in the development of an orange juice powder with functional characteristics.
- New insights on biopolymer sterilization using supercritical co2 technologyPublication . Soares, Gonçalo C.; Silva, Miguel; Borges, Sandra; Baptista-Silva, Sara; Freixo, Ricardo; Learmonth, David A.; Oliveira, Ana L.
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