Production of Functional Amino Acids in Okara by Mixed Culture of Lactic Acid Bacteria

Swiss-type cheeses such as Emmental are characterized by the successive development of thermophilic lactic acid bacteria (TLAB) and propionibacteria. The aim of this study was to determine whether the choice of TLAB strain influenced propionibacteria. TLAB and propionibacteria were cultured sequentially under the conditions prevailing in cheese. Firstly, 11 Emmental juice-like media were prepared by fermenting casein-enriched milk with pure or mixed cultures of TLAB (Lactobacillus helveticus, Lb. delbrueckii subsp. lactis and Streptococcus thermophilus), differing in their proteolytic activities. TLAB cells were then removed by microfiltration. Finally, five strains of Propionibacterium freudenreichii were grown on these media at 24°C under anaerobiosis and their growth characteristics and lactate consumption determined. The media mainly differed in their contents of peptides (1·9–5·3 g/kg) and free amino acids (1·0–5·6 g/kg) and the proportions of lactate isomers (42–92% of the L(+) isomer). Propionibacteria were significantly (P<0·05) influenced by TLAB strains (differences in doubling times of up to 20% and differences in lactate consumption after 600 h culture of up to 52%). The influence of TLAB was similar for all the propionibacteria tested, depended on the TLAB strains and could not be generalized to the TLAB species. Propionibacteria were stimulated by high peptide levels, low levels of free amino acids and NaCl, a low proportion of L(+)-lactate and other undetermined factors. However, variations due to TLAB were less than those between propionibacteria strains.

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Diversity in growth and protein degradation by dairy relevant lactic acid bacteria species in reconstituted whey

Journal of Dairy Research ◽

10.1017/s0022029912000040 ◽

2012 ◽

Vol 79 (2) ◽

pp. 201-208 ◽

Cited By ~ 17

Author(s):

Micaela Pescuma ◽

Elvira M. Hébert ◽

Elena Bru ◽

Graciela Font de Valdez ◽

Fernanda Mozzi

Keyword(s):

Amino Acids ◽

Lactic Acid ◽

Lactic Acid Bacteria ◽

Protein Degradation ◽

Proteolytic Activity ◽

Starter Culture ◽

Whey Proteins ◽

Principal Component ◽

Fermented Foods ◽

Small Peptides

The high nutritional value of whey makes it an interesting substrate for the development of fermented foods. The aim of this work was to evaluate the growth and proteolytic activity of sixty-four strains of lactic acid bacteria in whey to further formulate a starter culture for the development of fermented whey-based beverages. Fermentations were performed at 37°C for 24 h in 10 and 16% (w/v) reconstituted whey powder. Cultivable populations, pH, and proteolytic activity (o-phthaldialdehyde test) were determined at 6 and 24 h incubation. Hydrolysis of whey proteins was analysed by Tricine SDS-PAGE. A principal component analysis (PCA) was applied to evaluate the behaviour of strains. Forty-six percent of the strains grew between 1 and 2 Δlog CFU/ml while 19% grew less than 0·9 Δlog CFU/ml in both reconstituted whey solutions. Regarding the proteolytic activity, most of the lactobacilli released amino acids and small peptides during the first 6 h incubation while streptococci consumed the amino acids initially present in whey to sustain growth. Whey proteins were degraded by the studied strains although to different extents. Special attention was paid to the main allergenic whey protein, β-lactoglobulin, which was degraded the most byLactobacillus acidophilusCRL 636 andLb. delbrueckiisubsp.bulgaricusCRL 656. The strain variability observed and the PCA applied in this study allowed selecting appropriate strains able to improve the nutritional characteristics (through amino group release and protein degradation) and storage (decrease in pH) of whey.

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On the Nitrogen Nutrition of Silage Strains of Lactic Acid Bacteria

Australian Journal of Biological Sciences ◽

10.1071/bi9660105 ◽

1966 ◽

Vol 19 (1) ◽

pp. 105 ◽

Cited By ~ 3

Author(s):

CJ Brady

Keyword(s):

Amino Acids ◽

Lactic Acid ◽

Lactic Acid Bacteria ◽

Free Amino Acids ◽

Free Amino ◽

Nitrogen Nutrition ◽

Synthetic Medium ◽

Post Harvest ◽

Synthetic Media ◽

Time Of Harvest

Consideration is given to the adequacy of the free amino acids in plant juices at the time of harvest as nitrogen substrate for strains of lactic acid bacteria isolated from silage. The requirements of several strains of the bacteria for free amino acids in synthetic media were compared with the concentration of these acids in the liquid phase of plants at the time of harvest; this comparison suggested that several amino acids, and particulady lysine, may at times be rate.limiting. Ethanolic extracts of plants, sampled before and after a period of post-harvest wilting, were assayed as nitrogen substrates for the bacteria. A marked response to additions of lysine, some response to arginine, and evidence of deficiency of other acids were noted. The importance of post-harvest proteolysis to the amino acid nutrition of the bacteria in the silage environment is discussed. Certain fractions of the plant extracts were found to promote early growth of the bacteria in the synthetic medium, and the distribution of this activity in different fractions is described.

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Accelerated ripening of Pecorino Umbro cheese

Journal of Dairy Research ◽

10.1017/s0022029998003161 ◽

1998 ◽

Vol 65 (4) ◽

pp. 631-642 ◽

Cited By ~ 22

Author(s):

ALDO CORSETTI ◽

MARCO GOBBETTI ◽

EMANUELE SMACCHI ◽

MARIA DE ANGELIS ◽

JONE ROSSI

Keyword(s):

Amino Acids ◽

Lactic Acid ◽

Lactic Acid Bacteria ◽

Free Amino ◽

Trichloroacetic Acid ◽

Short Peptides ◽

Accelerated Ripening ◽

Total Free Amino Acids ◽

Biochemical Analyses ◽

Dipeptidase Activities

We have investigated accelerating the ripening of Pecorino Umbro cheese by adding crude cytoplasmic extract from Pseudomonas fluorescens, non-starter lactic acid bacteria (NSLAB) or cheese slurry. Microbiological and biochemical analyses and sensory evaluation were carried out on control and experimental cheeses over 28 d ripening. In the cheeses containing NSLAB or slurry, counts of mesophilic lactobacilli ranged from log 7·6 at day 1 to ∼log 8·6 cfu/g after 28 d ripening, ∼2 log cycles higher than in the control cheese. All the experimental cheeses contained higher levels than the control of total free amino acids and N soluble at pH 4·6 and in 120 g trichloroacetic acid/l. Compared with the control, higher aminopeptidase and dipeptidase activities were found in the cheeses containing NSLAB and slurry, and especially in those containing the Pseudomonas enzyme. The cheeses containing NSLAB or slurry were characterized by an accumulation of short peptides (Mr<2000) detected by FPLC. Although the cheese containing enzyme had an atypical flavour, the addition of mesophilic lactobacilli reduced from 60 to 28 d the ripening period of Pecorino Umbro cheese, without the appearance of off flavour.

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