Comparative survival of probiotic lactobacilli spray-dried in the presence of prebiotic substances.
OBJECTIVE
Probiotic milk-based formulations were spray-dried with various combinations of prebiotic substances in an effort to generate synbiotic powder products.


RESULTS
To examine the effect of growth phase and inclusion of a prebiotic substance in the feed media on probiotic viability during spray-drying, Lactobacillus rhamnosus GG was spray-dried in lag, early log and stationary phases of growth in reconstituted skim milk (RSM) (20% w/v) or RSM (10% w/v), polydextrose (PD) (10% w/v) mixture at an outlet temperature of 85-90 degrees C. Stationary phase cultures survived best (31-50%) in both feed media and were the most stable during powder storage at 4-37 degrees C over 8 weeks, with 30-140-fold reductions in cell viability at 37 degrees C in RSM and PD/RSM powders, respectively. Stationary phase Lact. rhamnosus GG was subsequently spray-dried in the presence of the prebiotic inulin in the feed media, composed of RSM (10% w/v) and inulin (10% w/v), and survival following spray-drying was of the order 7.1-43%, while viability losses of 20,000-90,000-fold occurred in these powders after 8 weeks' storage at 37 degrees C. Survival of the Lactobacillus culture after spray-drying in powders produced using PD (20% w/v) or inulin (20% w/v) as the feed media was only 0.011-0.45%. To compare different probiotic lactobacilli during spray-drying, stationary phase Lact. rhamnosus E800 and Lact. salivarius UCC 500 were spray-dried using the same parameters as for Lact. rhamnosus GG in either RSM (20% w/v) or RSM (10% w/v) and PD (10% w/v). Lact. rhamnosus E800 experienced approx. 25-41% survival, yielding powders containing approximately 10(9) CFU g(-1), while Lact. salivarius UCC 500 performed poorly, experiencing over 99% loss in viability during spray-drying in both feed media. In addition to the superior survival of Lact. rhamnosus GG after spray-drying, both strains experienced higher viability losses (570-700-fold) during storage at 37 degrees C over 8 weeks compared with Lact. rhamnosus GG.


CONCLUSIONS
Stationary phase cultures were most suitable for the spray-drying process, while lag phase was most susceptible. The presence of the prebiotics PD and inulin did not enhance viability during spray-drying or powder storage.


CONCLUSIONS
High viability (approximately 10(9) CFU g(-1)) powders containing probiotic lactobacilli in combination with prebiotics were developed, which may be useful as functional food ingredients for the manufacture of probiotic foods.
Corcoran
B M
BM
Teagasc, Dairy Products Research Centre, Moorepark, Fermoy, Co. Cork, Ireland.
Ross
R P
RP
Fitzgerald
G F
GF
Stanton
C
C
D000818:Animals; D001431:Bacteriological Techniques / Q000379:methods; D015169:Colony Count, Microbial / Q000379:methods; D003470:Culture Media; D005503:Food Additives / Q000494:pharmacology; D005516:Food Microbiology; D005936:Glucans / Q000494:pharmacology; D006358:Hot Temperature; D007444:Inulin / Q000494:pharmacology; D007778:Lactobacillus / Q000187:drug effects / Q000254:growth & development*; D008892:Milk; D011208:Powders; D011309:Preservation, Biological / Q000379:methods; D019936:Probiotics
D003470:Culture Media; D005503:Food Additives; D005936:Glucans; D011208:Powders; D007444:Inulin; C033375:polydextrose