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Effects of sub-lethal high-pressure homogenization treatment on the outermost cellular structures and the volatile-molecule profiles of two strains of probiotic lactobacilli.

Tabanelli G, Vernocchi P, Patrignani F, Del Chierico F, Putignani L, Vinderola G, Reinheimer JA, Gardini F, Lanciotti R - Front Microbiol (2015)

Bottom Line: Moreover, the effect of HPH treatment on the metabolism of probiotic cells within a dairy product during its refrigerated storage was investigated using SPME-GC-MS.The results of this study will contribute to understanding the changes that occur in the outermost cellular structures and the metabolism of LAB in response to HPH treatment.The findings of this investigation may contribute to elucidating the relationships between these changes and the alterations of the technological and functional properties of LAB induced by pressure treatment.

View Article: PubMed Central - PubMed

Affiliation: Centro Interdipartimentale di Ricerca Industriale Agroalimentare, Università degli Studi di Bologna Cesena, Italy.

ABSTRACT
Applying sub-lethal levels of high-pressure homogenization (HPH) to lactic acid bacteria has been proposed as a method of enhancing some of their functional properties. Because the principal targets of HPH are the cell-surface structures, the aim of this study was to examine the effect of sub-lethal HPH treatment on the outermost cellular structures and the proteomic profiles of two known probiotic bacterial strains. Moreover, the effect of HPH treatment on the metabolism of probiotic cells within a dairy product during its refrigerated storage was investigated using SPME-GC-MS. Transmission electron microscopy was used to examine the microstructural changes in the outermost cellular structures due to HPH treatment. These alterations may be involved in the changes in some of the technological and functional properties of the strains that were observed after pressure treatment. Moreover, the proteomic profiles of the probiotic strains treated with HPH and incubated at 37°C for various periods showed different peptide patterns compared with those of the untreated cells. In addition, there were differences in the peaks that were observed in the low-mass spectral region (2000-3000 Da) of the spectral profiles of the control and treated samples. Due to pressure treatment, the volatile-molecule profiles of buttermilk inoculated with treated or control cells and stored at 4°C for 30 days exhibited overall changes in the aroma profile and in the production of molecules that improved its sensory profile, although the two different species imparted specific fingerprints to the product. The results of this study will contribute to understanding the changes that occur in the outermost cellular structures and the metabolism of LAB in response to HPH treatment. The findings of this investigation may contribute to elucidating the relationships between these changes and the alterations of the technological and functional properties of LAB induced by pressure treatment.

No MeSH data available.


PCA loading plots and variable factor coordinates for the two principal components relative to the aroma compounds of control or HPH-treated buttermilk inoculated with Lactobacillus paracasei A13 (A,B) and Lactobacillus acidophilus DRU (C,D) after 15 days of storage at 4°C. In PCA loading plots (A,C) the different samples are indicated by letters, an namely: C pH 7 (not acidified control samples), C pH 4.6 (acidified control samples), HPH pH 7 (not acidified treated samples) and HPH pH 4.6 (acidified treated samples).
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Figure 5: PCA loading plots and variable factor coordinates for the two principal components relative to the aroma compounds of control or HPH-treated buttermilk inoculated with Lactobacillus paracasei A13 (A,B) and Lactobacillus acidophilus DRU (C,D) after 15 days of storage at 4°C. In PCA loading plots (A,C) the different samples are indicated by letters, an namely: C pH 7 (not acidified control samples), C pH 4.6 (acidified control samples), HPH pH 7 (not acidified treated samples) and HPH pH 4.6 (acidified treated samples).

Mentions: To better evaluate the effect of HPH treatment on the aroma profile of buttermilk, a Principal Component Analysis (PCA) was conducted using the % of the peak area of the volatile compounds listed in Tables 1, 2. Figures 5A,C show PCA loading plots of the aroma profile data for buttermilk that was inoculated with L. paracasei A13 cells or L. acidophilus DRU cells, respectively, which demonstrated that the first two principal components (PC1 and PC2) explained more than 85% of the total variability. In both cases, PC1 accounted for the greater part of the variability (approximately 65.38 and 55.99% for the L. paracasei A13-containing samples and the L. acidophilus DRU-containing samples, respectively), and the samples could be grouped into four clusters according to whether they were HPH treated and the pH of the medium. The control buttermilk samples were grouped in the upper part of the plot, whereas the HPH-treated samples were grouped in the lower part. Moreover, the acidified samples were grouped on the left side of the plot, and the pH 7 buttermilk samples were grouped on the right side.


Effects of sub-lethal high-pressure homogenization treatment on the outermost cellular structures and the volatile-molecule profiles of two strains of probiotic lactobacilli.

Tabanelli G, Vernocchi P, Patrignani F, Del Chierico F, Putignani L, Vinderola G, Reinheimer JA, Gardini F, Lanciotti R - Front Microbiol (2015)

PCA loading plots and variable factor coordinates for the two principal components relative to the aroma compounds of control or HPH-treated buttermilk inoculated with Lactobacillus paracasei A13 (A,B) and Lactobacillus acidophilus DRU (C,D) after 15 days of storage at 4°C. In PCA loading plots (A,C) the different samples are indicated by letters, an namely: C pH 7 (not acidified control samples), C pH 4.6 (acidified control samples), HPH pH 7 (not acidified treated samples) and HPH pH 4.6 (acidified treated samples).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585067&req=5

Figure 5: PCA loading plots and variable factor coordinates for the two principal components relative to the aroma compounds of control or HPH-treated buttermilk inoculated with Lactobacillus paracasei A13 (A,B) and Lactobacillus acidophilus DRU (C,D) after 15 days of storage at 4°C. In PCA loading plots (A,C) the different samples are indicated by letters, an namely: C pH 7 (not acidified control samples), C pH 4.6 (acidified control samples), HPH pH 7 (not acidified treated samples) and HPH pH 4.6 (acidified treated samples).
Mentions: To better evaluate the effect of HPH treatment on the aroma profile of buttermilk, a Principal Component Analysis (PCA) was conducted using the % of the peak area of the volatile compounds listed in Tables 1, 2. Figures 5A,C show PCA loading plots of the aroma profile data for buttermilk that was inoculated with L. paracasei A13 cells or L. acidophilus DRU cells, respectively, which demonstrated that the first two principal components (PC1 and PC2) explained more than 85% of the total variability. In both cases, PC1 accounted for the greater part of the variability (approximately 65.38 and 55.99% for the L. paracasei A13-containing samples and the L. acidophilus DRU-containing samples, respectively), and the samples could be grouped into four clusters according to whether they were HPH treated and the pH of the medium. The control buttermilk samples were grouped in the upper part of the plot, whereas the HPH-treated samples were grouped in the lower part. Moreover, the acidified samples were grouped on the left side of the plot, and the pH 7 buttermilk samples were grouped on the right side.

Bottom Line: Moreover, the effect of HPH treatment on the metabolism of probiotic cells within a dairy product during its refrigerated storage was investigated using SPME-GC-MS.The results of this study will contribute to understanding the changes that occur in the outermost cellular structures and the metabolism of LAB in response to HPH treatment.The findings of this investigation may contribute to elucidating the relationships between these changes and the alterations of the technological and functional properties of LAB induced by pressure treatment.

View Article: PubMed Central - PubMed

Affiliation: Centro Interdipartimentale di Ricerca Industriale Agroalimentare, Università degli Studi di Bologna Cesena, Italy.

ABSTRACT
Applying sub-lethal levels of high-pressure homogenization (HPH) to lactic acid bacteria has been proposed as a method of enhancing some of their functional properties. Because the principal targets of HPH are the cell-surface structures, the aim of this study was to examine the effect of sub-lethal HPH treatment on the outermost cellular structures and the proteomic profiles of two known probiotic bacterial strains. Moreover, the effect of HPH treatment on the metabolism of probiotic cells within a dairy product during its refrigerated storage was investigated using SPME-GC-MS. Transmission electron microscopy was used to examine the microstructural changes in the outermost cellular structures due to HPH treatment. These alterations may be involved in the changes in some of the technological and functional properties of the strains that were observed after pressure treatment. Moreover, the proteomic profiles of the probiotic strains treated with HPH and incubated at 37°C for various periods showed different peptide patterns compared with those of the untreated cells. In addition, there were differences in the peaks that were observed in the low-mass spectral region (2000-3000 Da) of the spectral profiles of the control and treated samples. Due to pressure treatment, the volatile-molecule profiles of buttermilk inoculated with treated or control cells and stored at 4°C for 30 days exhibited overall changes in the aroma profile and in the production of molecules that improved its sensory profile, although the two different species imparted specific fingerprints to the product. The results of this study will contribute to understanding the changes that occur in the outermost cellular structures and the metabolism of LAB in response to HPH treatment. The findings of this investigation may contribute to elucidating the relationships between these changes and the alterations of the technological and functional properties of LAB induced by pressure treatment.

No MeSH data available.