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- A functional dried fruit matrix incorporated with probiotic strains: Lactobacillus Plantarum and Lactobacillus KefirPublication . Rêgo, A.; Freixo, R.; Silva, J.; Gibbs, P.; Morais, A. M. M. B.; Teixeira, P.The consumption of probiotic functional foods, i.e. processed foods enriched with microorganisms that confer health benefits to the host, shows a progressive increase in the last decade due to changes in habits and trends of consumers attracted by the benefits of these products. Currently, the development of fruits and vegetables with probiotic content is a topic of high interest for the probiotic-food consumers as these are a popular item perceived as healthy by consumers, and issues related with lactose intolerance are overcome. The aim of this research study was to develop a new healthy dry food that contains a source of probiotic strains providing some benefits to consumers. Apple was selected as an experimental food matrix and two different probiotic Lactobacillus species, L. plantarum and L. kefir, were tested separately. Samples were taken immediately before and after the drying process in order to determine the viability of bacteria adhered to the matrix. Dried apple cubes were stored in sterile closed glass containers or in sealed bags vacuum packed and normal atmosphere) at room temperature and at 4ºC. The bacterial viability in the dried product was tested at different storage times. For both probiotic strains, a decrease of approximately 2 log cycles in bacterial cell numbers was observed after drying. The bacterial number in apple cubes at the time of storage at room temperature and 4ºC was approximately 1x107 cfu/g. Both probiotic strains died after one month of storage at room temperature, while during storage at 4ºC the cells remained viable after 3 months, with bacterial number around 1x106 cfu/g.
- Survival of spray-dried Lactobacillus kefir is affected by different protectants and storage conditionsPublication . Golowczyc, Marina A.; Gerez, Carla L.; Silva, Joana; Abraham, Analía G.; Antoni, Graciela L. De; Teixeira, PaulaSurvival of two Lactobacillus kefir strains after spray drying in reconstituted skim milk with or without the addition of 12.5 g monosodium glutamate/ l, 20 g sucrose/l, or 20 g fructo-oligosaccharides (FOS)/l and during subsequent storage under different conditions of temperature (20 and 30 C) and relative humidity (RH) (0, 11 and 23%) was evaluated. After being dried, L. kefir 8321 and L. kefir 8348 had a decrease in viability of 0.29 and 0.70 log cfu/ml respectively, while the addition of different protectants improved the survival of both strains significantly. During storage, bacterial survival was significantly higher under lower conditions of RH (0–11%), and monosodium glutamate and FOS proved to be the best protectants.
- Preservation of probiotic strains isolated from kefir by spray dryingPublication . Golowczyc, M.A.; Silva, J.; Abraham, A.G.; Antoni, G.L. De; Teixeira, P.Aims: This work aims to investigate the survival of Lactobacillus kefir CIDCA 8348, Lactobacillus plantarum CIDCA 83114 and Saccharomyces lipolytica CIDCA 812, all isolated from kefir, during spray drying and subsequent storage. Methods and Results: Micro-organisms were grown in De Man, Rogosa, Sharpe (MRS) or yeast medium (YM) medium and harvested in the stationary phase of growth. The thermotolerance in skim milk (D and Z values), the survival of spray drying at different outlet air temperatures and subsequent storage in different conditions during 150 days were studied. The resistance to the heat treatments was higher in Lact. plantarum compared to Lact. kefir and S. lipolytica. The three micro-organisms studied varied considerably in their ability to survive to spray drying processes. Lactobacillus plantarum showed the highest survival rate for all the tested outlet air temperatures and also to the further storage in the dried state. The survival rates of Lact. kefir and S. lipolytica through drying and subsequent storage in the dried state decreased when the drying outlet air temperatures increased. Conclusions: Spray drying is a suitable method to preserve micro-organisms isolated from kefir grains. A high proportion of cells were still viable after 80 days of storage at refrigerated temperatures Significance and Impact of Study: It is the first report about spray-dried probiotic strains isolated from kefir grain and contributes to the knowledge about these micro-organisms for their future application in novel dehydrated products.
- Effect of stress on cells of lactobacillus delbrueckii sp. bulgaricusPublication . Silva, Joana; Carvalho, Ana Sofia; Teixeira, Paula; Gibbs, Paul A.Cultures of Lactobacillus delbrueckii sp. bulgaricus play an important role in the production of fermented foods and are frequently used as starter cultures for dairy fermentations combined with other species. It These cultures is are particularly used in the industrial production of yoghurt and cheeses. Large scale Pproduction methods of dried L. bulgaricus powders, for inoculating the production vat directly, involve treatments that stress cells in such a way that they lose some of their original activity. containing viable and active organisms which are long-term preserved during storage in the dried state, areis presented. This review covers the environmental stress responses in cells of L. bulgaricus which have been investigated. The responses of L. bulgaricus cells to heat, cold, acid, osmotic, oxygen, starvation, drying and during storage in the dried state are described. Attempts to improve the survival of L. bulgaricus during drying and subsequent storage in the dried state are also discussed in this review.