Comparative Survival Rates of Human-Derived Probiotic Lactobacillus paracasei and L. salivarius Strains during Heat Treatment and Spray Drying

Abstract

Spray drying of skim milk was evaluated as a means of preserving Lactobacillus paracasei NFBC 338 and Lactobacillus salivarius UCC 118, which are human-derived strains with probiotic potential. Our initial experiments revealed that NFBC 338 is considerably more heat resistant in 20% (wt/vol) skim milk than UCC 118 is; the comparable decimal reduction times were 11.1 and 1.1 min, respectively, at 59°C. An air outlet temperature of 80 to 85°C was optimal for spray drying; these conditions resulted in powders with moisture contents of 4.1 to 4.2% and viable counts of 3.2 ؋ 10 9 CFU/g for NFBC 338 and 5.2 ؋ 10 7 CFU/g for UCC 118. Thus, L. paracasei NFBC 338 survived better than L. salivarius UCC 118 during spray drying; similar results were obtained when we used confocal scanning laser microscopy and LIVE/DEAD BacLight viability staining. In addition, confocal scanning laser microscopy revealed that the probiotic lactobacilli were located primarily in the powder particles. Although both spray-dried cultures appeared to be stressed, as shown by increased sensitivity to NaCl, bacteriocin production by UCC 118 was not affected by the process, nor was the activity of the bacteriocin peptide. The level of survival of NFBC 338 remained constant at ϳ1 ؋ 10 9 CFU/g during 2 months of powder storage at 4°C, while a decline in the level of survival of approximately 1 log (from 7.2 ؋ 10 7 to 9.5 ؋ 10 6 CFU/g) was observed for UCC 118 stored under the same conditions. However, survival of both Lactobacillus strains during powder storage was inversely related to the storage temperature. Our data demonstrate that spray drying may be a cost-effective way to produce large quantities of some probiotic cultures.Given that probiotic microorganisms play a role in promoting and maintaining health (29) has stimulated considerable interest in incorporating these into functional foods and pharmaceutical products. By definition, probiotics are "living microorganisms, which upon ingestion in certain numbers, exert health benefits beyond inherent basic nutrition" (13), and it is recommended that probiotic products contain at least 10 7 live microorganisms per g or per ml (15). Therefore, from a commercial point of view, an inexpensive method for large-scale production of cultures containing high levels of viable probiotic cells in a form suitable for product applications is highly desirable.In previous studies researchers have investigated the production of freeze-dried powders and frozen concentrates of probiotic Bifidobacterium and Lactobacillus spp. (10,12,24). However, there are many disadvantages associated with this approach; freeze-drying is time-consuming and expensive, there are high transport and storage costs associated with frozen concentrated cultures, and the freeze-thaw process is associated with a loss of culture viability. In comparison, spray drying, one of the predominant processing tools used in the dairy industry, can be used to produce large amounts of dairy ingredients relatively inexpensively; it has been estimated th...

Presence of two Lactobacillus and Bifidobacterium probiotic strains in the neonatal ileum

“…This strain was identified as Lactobacillus paracasei according to 16S rRNA sequencing. Interestingly, this strain exhibited the same PFGE pattern as the probiotic strain Lactobacillus paracasei NFBC 338 (Figure 1c) (Gardiner et al, 1998(Gardiner et al, , 2000Desmond et al, 2005). This was further confirmed by plasmid profiling (Figure 1d).…”

Technology and potential applications of probiotic encapsulation in fermented milk products

“…bulgaricus or lactis have an advantage in withstanding higher temperatures during processing and storage (Gardiner et al, 1998;Gardiner et al, 2000;Rodtong and Tannock, 1993;Drake et al, 1996). For instance, L. paracasei NFBC 338 survived significantly better that L. salivarius UCC 118 at similar spray-drying conditions, which may be attributed to the greater thermal tolerance of L. paracasei compared to L. salivarius (Gardiner et al, 2000). Furthermore, it has been shown that B. animalis subsp.…”

“…The drying process causes this solution to shrink into a pure polymer envelope enclosing the core material. Spray drying can be used as a cost-effective method to produce large quantities of probiotic cultures when critical parameters such as the type of atomization, air pressure and outlet-air temperature have been controlled (Gardiner et al, 2000;Champagne and Møllgaard, 2008). Different polysaccharides were used as the matrix and the nozzle temperature of the spray dryer as well as the water activity of the microcapsules had an important impact on the survival of probiotic bacteria.…”

Cellular injuries on spray‐dried Lactobacillus rhamnosus GG and its stability during food storage

“…It was assumed that probiotics were encapsulated in the dried samples. Gardiner et al (2000) had similar observation and established the encapsulation of bacterial cells by confocal scanning laser microscopy technique. Skim milk had individual particles but with uniform appearances and surfaces (Figure 3(a)).…”

“…Although there is variability in the minimum recommended levels of probiotics in foods (Charteris et al, 1998), an official standard requiring a minimum of at least 10 7 live micro-organisms/g or ml have been introduced by several food organizations (IDF, 1992;Ishibashi and Shimamura, 1993). Therefore, from a commercial point of view, an inexpensive method for large-scale production of cultures containing high levels of viable probiotic cells in a form suitable for product application is highly desirable (Gardiner et al, 2000).…”