Browsing by Author "Amaral, M. H."
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- Effect of storage conditions on stability of free and encapsulated in plain- or cysteine-supplemented alginate, Bifidobacterium animalis BB-12®Publication . Sousa, S. C.; Costa, E. A.; Gomes, A. M.; Pintado, M. M.; Malcata, F. X.; Silva, J. P.; Lobo, J. M. Sousa; Costa, P.; Amaral, M. H.; Bahia, M. F.; Rocha-Santos, T.; Rodrigues, D.; Freitas, A. C.The main objective of this research work was to study the viability of Bifidobacterium animalis BB-12® as free and calcium alginate-encapsulated cells, with or without cysteine, throughout storage, at four different temperatures. Extrusion by aerodynamically assisted flow was used to produce alginate and calcium alginate supplemented with L-cysteine·HCl microcapsules, containing B. animalis BB-12®. The microcapsules were suspended in Ringer solution in a 1:9 (g/mL) ratio, and stored at 21, 4, -20 and -80 ºC throughout six months, respectively. In parallel, the viability of free cells in cell suspension, was subjected to the same storage conditions and the corresponding viability assessed. Results showed that at 21, 4 and -20 ºC, the encapsulation did not have a protective effect—free cells maintained their viability throughout longer periods than encapsulated counterparts. At -80 ºC, encapsulation protected B. animalis BB-12® in comparison to the behavior of free cells. However, this effect was only observed in calcium alginate microcapsules supplemented with L-cysteine.HCl. After 180 days storage at -80 ºC, a 2 log cycle difference, in viable cells was observed between microcapsules with or without cysteine. The viable numbers of B. animalis BB-12® in microcapsules without cysteine was similar to that of free cells. In conclusion, alginate encapsulation revealed a protective effect on viability of B. animalis BB-12® stored at -80 ºC when supplemented with L-cysteine.HCl.
- Effects of encapsulation on the viability of probiotic strains exposed to lethal conditionsPublication . Borges, S.; Barbosa, J.; Camilo, R.; Carvalheira, A.; Sousa, S.; Gomes, A. M.; Pintado, M. M.; Silva, J. P.; Costa, P.; Amaral, M. H.; Silva, J.; Teixeira, P.; Freitas, A. C.The effect of microencapsulation in an alginate matrix on the viability of several potential probiotic strains (Lactobacillus paracasei LAFTI® L26, L. acidophilus Ki and Bifidobacterium animalis BB-12®), in the presence and absence of L-cysteine, during the exposure to lethal conditions of temperature (55 ºC for L. acidophilus Ki and 60 ºC for L. paracasei and B. animalis BB-12®, during 60 min), pH (3.0 during 6h) and salt (25% during 24h), was evaluated. The microcapsules were prepared via extrusion by aerodynamically-assisted flow. The effect of the disintegration of the microcapsules by mixing with sodium citrate in the enumeration of survivors was also evaluated. The lethal treatments were performed in whey protein concentrate medium and the survivors were enumerated accordingly. In general, the microencapsulated cells were more sensitive to the lethal conditions. The addition of L-cysteine to growth medium did not increase the viability of the tested strains except for B. animalis BB-12®. Furthermore, the disintegration in sodium citrate did not affect the viability. The survival of the probiotic strains was dependent on the lethal stress being imposed and planktonic cells were more resistant to the tested lethal conditions. Encapsulation of these probiotic bacteria did not improve their survival through lethal conditions.
- Encapsulation protective effect upon viability of probiotic bacteria throughout storage and gastrointestinal tractPublication . Rodrigues, D.; Sousa, S.; Rocha-Santos, T.; Gomes, A. M.; Pintado, M. M.; Malcata, F. X.; Silva, J. P.; Lobo, J. M. S.; Costa, P.; Amaral, M. H.; Freitas, A. C.Microcapsules (MC) with fresh cultures of potential probiotic strains (Lactobacillus paracasei LAFTI® L26, L. acidophilus Ki and Bifidobacterium animalisBB-12®) were produced by spray-drying using whey protein concentrate (WPC50) with or without L-cysteine (0.5 g/L). After microencapsulation, the MC were stored, in duplicate, at 5ºC over a period of 6 months during which the number of viable cells (VC) were evaluated. After 15, 60 and 120 days of storage, their resistance throughout gastrointestinal conditions was evaluated. In MC without L-cysteine, the VC numbers of L. acidophilus Ki and B. animalis BB-12® after 6 months of storage decreased from 108 to 106 cfu/g whereas no decrease was observed for L. paracasei. The presence of L-cysteine revealed a positive effect, especially for L. acidophilus Ki after 90 days of storage accounting for more than one logarithm cycle increase in viability. Encapsulation had a protective effect on the three probiotic strains when exposed to the gastrointestinal conditions in comparison to their free cells. This effect was particularly significant for L. acidophilus Ki in conditions similar to those of ileum/duodenum including the presence of pancreatin and bile salts. Storage time did not affect the resistance of the three probiotic strains to the gastrointestinal conditions.