LISTERIA MONOCYTOGENES IN FOODS: CONTRIBUTING DATA FOR RISK ASSESSMENT

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Development of probiotic fruit juice powders by spray-drying: a review

Publication . Barbosa, Joana; Teixeira, Paula

The use of spray-drying for the production of powdered fruit juices has been a common practice in recent years since it is a simple, economic, and advantageous technique. The current knowledge on the different spray-drying parameters, allowing the best conditions to obtain high-quality powders, is presented in this review. The incorporation of probiotic cultures into fruit juices can enhance the functional characteristics of fruit juices. The selection of these probiotics and their benefits to consumers' health are briefly discussed. As maintaining the viability of probiotics is extremely important in the development of a probiotic functional product, the factors that influence and improve survival, in all pre- and post-spray-drying steps, are also detailed. Finally, a few studies on probiotic fruit juices obtained by spray-drying are cited. Industries should bet on their development and commercialization, since despite being challenging to develop, these are very innovative and attractive products meeting modern consumer demands.

2017Journal article

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Comparison of spray drying, freeze drying and convective hot air drying for the production of a probiotic orange powder

Publication . Barbosa, J.; Borges, S.; Amorim, M.; Pereira, M. J.; Oliveira, A.; Pintado, M. E.; Teixeira, P.

Survival of two LAB in orange powders obtained by spray-(SD), freeze-(FD) and convective hot air drying (CD) was investigated during drying and subsequent storage. Colour and vitamin C content of the powders were also evaluated. There was no decrease in the cell number during SD and FD, but a reduction of ~2 log cycles was obtained in CD. During storage at 4 °C no significant differences (p > 0.05) in the survival of Lactobacillus plantarum 299v were observed for the orange powder obtained by the different techniques. However, during storage at room temperature, its survival was better in orange powders prepared by CD. For Pediococcus acidilactici HA-6111-2, reductions during storage were minimal for most of the conditions investigated. Considering the initial cell number obtained after each drying process, SD and FD allowed survival of an increased number of cells after storage period. The best colour retention was obtained by FD, with no maltodextrin, and the higher total vitamin C retention was achieved in SD and FD powders. By the high production costs and long drying times of FD, it can be concluded that SD could be a good method to produce a new functional non-dairy product, such as a probiotic orange juice powder

2015Journal article

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Pediococcus acidilactici as a potential probiotic to be used in food industry

Publication . Barbosa, Joana; Borges, Sandra; Teixeira, Paula

The 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.

2015Journal article

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Influence of sub-lethal stresses on the survival of lactic acid bacteria after spray-drying in orange juice

Publication . 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.

2015Journal article

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Selection of potential probiotic Enterococcus faecium isolated from Portuguese fermented food

Publication . Barbosa, Joana; Borges, Sandra; Teixeira, Paula

Four Enterococcus faecium strains isolated from fermented products were evaluated for potential use as probiotic strains. In addition to efaAfm gene, commonly found in E. faecium food isolates, none of the isolates possessed virulence genes and none had positive reactions for the production of tyramine, histamine, putrescine and cadaverine in the screening medium used. All of these four isolates proved to be resistant to 65 °C. E. faecium 119 did not show antimicrobial activity against any of the target bacteria investigated. E. faecium 85 and 101 inhibited Listeria innocua and E. faecium DSMZ 13590. The strain E. faecium 120 inhibited seven target bacteria (Listeria monocytogenes 7946, L. monocytogenes 7947, L. innocua 2030c, L. innocua NCTC 11286, E. faecium DSMZ 13590, Enterococcus faecalis ATCC 29212 and Staphylococcus aureus ATCC 29213) and was chosen as the representative to assess the ability to survive gastrointestinal tract passage simulation, as well as the protective role of two food matrices (skim milk and Alheira) during its passage. For both matrices used, no significant differences (p < 0.05) were obtained between the types of digestion — quick and slow passage simulation. In the skim milk matrix the isolate was reduced to values below the detection limit of the enumeration technique by the end of the two digestions, in contrast to the Alheira matrix, for which isolate 120 showed a reduction of only ca. 1 log CFU/ml. The E. faecium strain 120 was shown to be a potential candidate for further investigations as a potential probiotic culture.

2014Journal article

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