Could pre-treatments with sub-lethal stresses enhance the ability of lactic acid bacteria to survive after spray-drying in orange juice?

Barbosa, Joana; Borges, Sandra; Teixeira, Paula

http://hdl.handle.net/10400.14/54360

Use this identifier to reference this record.

Name:	Description:	Size:	Format:
72719454.pdf		774.77 KB	Adobe PDF	Download

Send Feedback

Authors

Barbosa, Joana

Borges, Sandra

Teixeira, Paula

Abstract(s)

Introduction: The demand for new functional non-dairy based products makes the production of an orange juice powder with pre- and probiotic characteristics, an encouraging challenge. Spray drying is a simple and inexpensive way to produce a dried orange juice incorporating probiotics (Barbosa et al., 2015). However, drying processes, and subsequent storage, greatly affect the viability of the dried probiotic cultures due to the exposure to various stresses such as high temperatures and rapid dehydration (Tripathi and Giri, 2014). Solutions are required since probiotic microorganisms should be present in foods in numbers of about 106-107 cfu/g or cfu/mL until the time of consumption and must remain viable during passage through the gastro-intestinal tract (GIT) of the consumer (FAO/WHO, 2002; Sanz, 2007). The aim of this work was to investigate if the pre-exposure to sub-lethal conditions of temperature, acidic pH and hydrogen peroxide could influence the viability of Pediococcus acidilactici HA-6111-2 and Lactobacillus plantarum 299v during spray drying in orange juice and subsequent storage under different conditions. Also the survival of both lactic acid bacteria (LAB) through simulated GIT was determined at the end of storage. Conclusions: For all the sub-lethal conditions investigated, there were no significant (p>0.05) reductions in cell viability during the drying process (data not shown). Prior exposure of L. plantarum 299v to any of the sub-lethal stresses applied, increased their survival during 180 days of storage at room temperature (graph A); this effect was not observed (p>0.05) for cells stored at 4 ºC (graph B). At this temperature, cell inactivation was very low, as previously demonstrated by other researchers (Teixeira et al., 1995). For storage at room temperature, initially, reductions in viable cell numbers were greater for cells exposed to lactic acid (about -2 log units), but from 90 days until the end of the storage, the reduction in viable cells not exposed to sub-lethal stress was greater (more than 3 log units). Temperature conferred the highest protection, followed by treatment with HCl, H2O2, and finally by lactic acid. The exposure to any of the sub-lethal treatments prior to spray drying, did not result in the enhancement of survival of P. acidilactici HA-6111-2 during storage (graphs C and D). On the contrary, survival during storage was negatively influenced by previous exposure to all the sub-lethal conditions investigated. After simulation of GIT conditions for the spray dried cells at the end of storage at 4 ºC, L. plantarum 299v and P. acidilactici HA-6111-2 were present in numbers of ca. 107 cfu/mL, despite the exposure to sub-lethal stresses did not have improved their viability. As a conclusion of this study, the influence on the viability of two LAB after the exposure to different sub-lethal stress conditions prior spray drying and subsequent storage in orange juice was species/strain dependent. Considering that to have a beneficial effect on health, a probiotic must be present in minimum quantities of 107 cfu/mL in the product and remain viable during passage through the GIT, both L. plantarum 299v and P. adicilactici HA-6111-2 seem to be good candidates for use in the production of a new functional orange juice powder.