Catalytic isomerization of dihydroxyacetone to lactic acid by heat treated zeolites

ABSTRACT Two types of white wheat bread (high- and low-type loaves) were investigated for rope spoilage. Thirty of the 56 breads tested developed rope spoilage within 5 days; the high-type loaves were affected by rope spoilage more than the low-type loaves. Sixty-one Bacillus strains were isolated from ropy breads and were characterized on the basis of their phenotypic and genotypic traits. All of the isolates were identified as Bacillus subtilis by biochemical tests, but molecular assays (randomly amplified polymorphic DNA PCR assay, denaturing gradient gel electrophoresis analysis, and sequencing of the V3 region of 16S ribosomal DNA) revealed greater Bacillus species variety in ropy breads. In fact, besides strains of B. subtilis, Bacillus licheniformis, Bacillus cereus, and isolates of Bacillus clausii and Bacillus firmus were also identified. All of the ropy Bacillus isolates exhibited amylase activity, whereas only 32.4% of these isolates were able to produce ropiness in bread slices after treatment at 96°C for 10 min. Strains of lactic acid bacteria previously isolated from sourdough were first selected for antirope activity on bread slices and then used as starters for bread-making experiments. Prevention of growth of approximately 104 rope-producing B. subtilis G1 spores per cm2 on bread slices for more than 15 days was observed when heat-treated cultures of Lactobacillus plantarum E5 and Leuconostoc mesenteroides A27 were added. Growth of B. subtilis G1 occurred after 7 days in breads started with Saccharomyces cerevisiae T22, L. plantarum E5, and L. mesenteroides A27.

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STUDY ABOUT THE INFLUENCE OF SOME FACTORS ABOUT THE LACTIC ACID FERMENTATION OF CARROT JUICES

Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca Agriculture ◽

10.15835/buasvmcn-agr:795 ◽

2008 ◽

Vol 65 (2) ◽

Author(s):

Magda Gabriela Bratu ◽

Lavinia Buruleanu ◽

Daniela Avram

Keyword(s):

Amino Acids ◽

Ascorbic Acid ◽

Lactic Acid ◽

Raw Materials ◽

Lactic Acid Fermentation ◽

Total Acidity ◽

Acid Fermentation ◽

Heat Treated ◽

Initial Content

The influence of the storage time of vegetables - raw materials, the influence of fermentationÂ temperature and the influence of the glucose addition about the lactic acid fermentation unfolding has beenÂ studied.Â Fresh carrots and carrots stored five months were pressed to raw juice and heat-treated at 70 degrees C forÂ 20 minutes in the aim of destroy the undesirable microorganisms.Â Carrot juices were inoculated with lactic acid bacteria isolated from epiphytic microbiota at theÂ concentration of 4x105Â UFC/ml and fermented in a thermostat for 96 hours. During the fermentation theÂ following analytical parameters were established: reducing sugars, total acidity, pH, amino acids content, nitritesÂ content, ascorbic acid content.Â During fermentation the pH of carrot juices decreases from 6,15 to 3,99, while the total acidity increasesÂ from 0,06 to 1,62% (as lactic acid). Less than 25% of the initial content of ascorbic acid rests in the juices afterÂ 96 hours of fermentation.Â The amino acids content of juices, expressed as g N2/100g, increase with a middle of 50% in 96 hours,Â due of the proteins decomposition. The pre-digestion of these compounds improve the nutritional quality of theÂ lactofermented juices.Â We found that the glucose supplement hasnâ€™t a significant influence about the lactic acid accumulation.Â Also, at the end of the period of study, we found that the substratum metabolization was difficult in the sampleÂ with 1% glucose initial added.Â The quality of the raw materials, especially concerning the sugars content and the total acidity at theÂ beginning of the fermentation process is important because a rapidly increase of acidity minimizes the influenceÂ of spoilage bacteria.Â To proceed from the results of the sensory analysis and the results of the chemical analysis weÂ recommend stopping the fermentation of these juices after 72 hours.

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A postbiotic consisting of heat-treated lactobacilli has a bifidogenic effect in pure culture and in human fermented faecal communities

Applied and Environmental Microbiology ◽

10.1128/aem.02459-20 ◽

2021 ◽

Author(s):

Alicja K. Warda ◽

Adam G. Clooney ◽

Feargal Ryan ◽

Pedro H. de Almeida Bettio ◽

Giulio Di Benedetto ◽

...

Keyword(s):

Lactic Acid ◽

Lactic Acid Bacteria ◽

Gut Microbiota ◽

Pure Culture ◽

Bifidobacterium Longum ◽

Lactobacillus Delbrueckii ◽

Therapeutic Interventions ◽

Major Constituent ◽

Human Gut ◽

Heat Treated

The gut microbiota has a significant impact on host health. Dietary interventions using probiotics, prebiotics and postbiotics have the potential to alter microbiota composition and function. Other therapeutic interventions such as antibiotics and faecal microbiota transplantation have also been shown to significantly alter the microbiota and its metabolites. Supplementation of a faecal fermentation model of the human gut with a postbiotic product Lactobacillus LB led to changes in microbiome composition (i.e. increase in beneficial bifidobacteria) and associated metabolic changes (i.e. increased acid production). Lactobacillus LB is a heat-treated preparation of cellular biomass and a fermentate generated by Limosilactobacillus fermentum CNCM MA65/4E-1b (formerly known as Lactobacillus fermentum CNCM MA65/4E-1b) and Lactobacillus delbrueckii ssp. delbrueckii CNCM MA65/4E-2z, medically relevant strains used to produce antidiarrheal preparations. In pure culture, Lactobacillus LB also stimulates the growth of a range of bifidobacterial species and strains. Lactobacillus LB-like preparations generated using other Lactobacillaceae, including commercially available probiotic bacteria, did not have the same impact on a model strain (Bifidobacterium longum subsp. infantis ATCC 15697). This bifidogenic activity is heat- and enzyme-stable and cannot be attributed to lactose, which is a major constituent of Lactobacillus LB. L. fermentum CNCM MA65/4E-1b is largely responsible for the observed activity and there is a clear role for compounds smaller than 1 kDa. Importance In general, disruptions to the gut microbiota are associated with multiple disorders in humans. The presence of high levels of Bifidobacterium spp. in the human gut is commonly considered to be beneficial. Bifidobacteria can be supplemented in the diet (as probiotics) or those bifidobacteria already present in the gut can be stimulated by the consumption of prebiotics such as inulin. We demonstrate that Lactobacillus LB (a product consisting of two heat-killed lactic acid bacteria and their metabolites) can stimulate the growth of bifidobacteria in human fermented faecal communities and in pure culture. Given the heat-treatment applied during the production process, there is no risk of the lactic acid bacteria colonising (or causing bacteraemia) in vulnerable consumers (infants, immunocompromised, etc). Lactobacillus LB has the potential to affect human health by selectively promoting the growth of beneficial bacteria.

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Physical Adsorption of Aflatoxin B1 by Lactic Acid Bacteria and Saccharomyces cerevisiae: A Theoretical Model

Journal of Food Protection ◽

10.4315/0362-028x-70.9.2148 ◽

2007 ◽

Vol 70 (9) ◽

pp. 2148-2154 ◽

Cited By ~ 86

Author(s):

DANTE J. BUENO ◽

CÉSAR H. CASALE ◽

ROMINA P. PIZZOLITTO ◽

MARIO A. SALVANO ◽

GUILLERMO OLIVER

Keyword(s):

Saccharomyces Cerevisiae ◽

Lactic Acid ◽

Lactic Acid Bacteria ◽

Aflatoxin B1 ◽

Physical Adsorption ◽

Adsorption Efficiency ◽

Adsorption Model ◽

Heat Treated ◽

Number Of Binding Sites ◽

Two Parameters

The ability of lactic acid bacteria (LAB) and Saccharomyces cerevisiae to remove aflatoxin B1 (AFB1) from liquid medium was tested. The experimental results indicated that (i) AFB1 binding to microorganisms was a rapid process (no more than 1 min); (ii) this binding involved the formation of a reversible complex between the toxin and microorganism surface, without chemical modification of the toxin; (iii) the amount of AFB1 removed was both toxin- and bacteria concentration–dependent; and (iv) quantitatively similar results were obtained with viable and nonviable (heat-treated) bacteria. According to these details, a physical adsorption model is proposed for the binding of AFB1 to LAB and S. cerevisiae, considering that the binding (adsorption) and release (desorption) of AFB1 to and from the site on the surface of the microorganism took place (AFB1 + S ↔ S − AFB1). The model permits the estimation of two parameters: the number of binding sites per microorganism (M) and the reaction equilibrium constant (Keq) involved, both of which are useful for estimating the adsorption efficiency (M × Keq) of a particular microorganism. Application of the model to experimental data suggests that different microorganisms have similar Keq values and that the differences in toxin removal efficiency are mainly due to differences in M values. The most important application of the proposed model is the capacity to select the most efficient microorganism to remove AFB1. Furthermore, it allows us to know if a modification of the adsorption efficiency obtained by physical, chemical, or genetic treatments on the microorganism is a consequence of changes in M, Keq, or both.

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Assessment of Microbiological Quality and Physicochemical Parameters of Fruhe Made by Ovine and Goat Milk: A Sardinian (Italy) Cheese

Fermentation ◽

10.3390/fermentation6040119 ◽

2020 ◽

Vol 6 (4) ◽

pp. 119

Author(s):

Marco A. Murgia ◽

Pietrino Deiana ◽

Anna Nudda ◽

Fabio Correddu ◽

Luigi Montanari ◽

...

Keyword(s):

Lactic Acid ◽

Physicochemical Parameters ◽

Pathogenic Bacteria ◽

Microbiological Quality ◽

Goat Milk ◽

Total Solid ◽

Heat Treated ◽

Nutritional Characteristics ◽

Average Residual ◽

Fresh Cheese

Fruhe (Casu axedu) is a fresh cheese, traditionally manufactured in Sardinia (Italy) from sheep or goat milk, characterized by a compact coagulum obtained from raw or heat-treated whole milk. The objective of this study was to investigate the microbiological quality and physicochemical parameters of the sheep and goat Fruhe types of cheese at 21 days of cold storage. Chemical analyses showed that all Fruhe cheese samples were characterized by a pH below 4.4 and a variable content of total solid (22.75–21.06 g/100 g) proteins (5.4–10 g/100 g) and fat (3.9–15.7 g/100 g). The average residual lactose content was 2.6 g/100 g, while lactic acid content was 1.8 g/100 g. Microbial analyses revealed a high number of Lactic Acid Bacteria for both thermophilic and mesophilic streptococci (9 log CFU/g), and no pathogenic bacteria were found. The content of Free Amino Acids and Free Fatty acids point out that a good activity of rennet and microbial enzymes occurred, although Fruhe cheese is not subject to a ripening process. The present research reports the microbiological and nutritional characteristics of the sheep and goat Fruhe cheese that could represent the basis for further investigations, needful to improve its nutritional quality and to preserve its peculiarities.

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Rheological Monitoring of Structure Development and Rebodying of Set-Style Yoghurt

Applied Rheology ◽

10.1515/arh-2000-0005 ◽

2000 ◽

Vol 10 (2) ◽

pp. 73-79 ◽

Cited By ~ 8

Author(s):

I. M. Afonso ◽

J. M. Maia

Keyword(s):

Lactic Acid ◽

Storage Time ◽

Shear Thickening ◽

Protein Network ◽

Shear Stresses ◽

Structure Development ◽

Full Development ◽

Heat Treated ◽

Strong Shear ◽

Structural Breakdown

AbstractThe present work was undertaken in order to evaluate the rheological changes of set-style yoghurt at different incubation times, during production. The study of rheological changes of milk destined to set-style yoghurt production, in different processing stages prior to fermentation was accomplished using steady and oscillatory shear, while the study of the influence of storage time was also carried out using steady shear. Set-style yoghurt samples with 2 and 3 hours of fermentation exhibited a major structural breakdown during upward shear rate sweep experiments as expected, since the protein network was initially intact. Both samples exhibited two points of sudden decay. For T2 the these points occured at shear stresses of 38 Pa and 77 Pa and for T3 at 47 Pa and 80-83 Pa. The first point corresponds to the main break-up of protein network and the second one to the disruption of primary-aggregates, breaking the portion of casein network that was associated with exopolyssacharides produced by lactic acid bacteria. Structural analysis performed by means of oscillatory measurements indicate that the protein network is already partially formed after 2 hours, albeit full development is only achieved after longer periods. Heat-treated milk, evaporated milk and set-style yoghurt samples with 0 and 1 hour incubation times showed an apparent yield stress value of approximately 0.4 Pa and a strong shear-thinning behaviour afterwards. At higher shear stresses (approximately 1.6 Pa), however, the behaviour changed to shear-thickening, this effect being attributed to flow-induced interactions between the milk components. For the latter sample, a further change in flow behaviour occurred at a stress of 8 Pa, which is probably due to the breakdown of the weak protein network that had formed during incubation.

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Effective Use of Nisin to Control Lactic Acid Bacterial Spoilage in Vacuum-Packed Bologna-type Sausage

Journal of Food Protection ◽

10.4315/0362-028x-62.9.1004 ◽

1999 ◽

Vol 62 (9) ◽

pp. 1004-1010 ◽

Cited By ~ 67

Author(s):

E. ALISON DAVIES ◽

CATHERINE F. MILNE ◽

HELEN E. BEVIS ◽

RICHARD W. POTTER ◽

JO M. HARRIS ◽

...

Keyword(s):

Growth Rate ◽

Lactic Acid ◽

Lactic Acid Bacteria ◽

Shelf Life ◽

Antibacterial Effects ◽

Predominant Species ◽

Lactobacillus Sake ◽

Heat Treated ◽

Effective Use ◽

Nisin Activity

Lactic acid bacteria (LAB) commonly cause spoilage in minimal heat-treated vacuum-packed cured delicatessen meats. Predominant species are Lactobacillus sake and L. curvatus. LAB strains isolated from spoiled products of this type (liver sausage, ham and bologna sausage) were found to be sensitive to low nisin concentrations (maximum of 1.25 μg g−1). Addition of 25 μg g−1 nisin (as Nisaplin) inhibited the growth of LAB spoilage organisms inoculated into vacuum-packed pasteurized bologna-type sausages stored at 8°C. Control sausages became spoiled (>108 LAB CFU g−1) by day 7, whereas sausages containing nisin remained unspoiled for >50 days. The effect of three types of phosphates (used as emulsifiers) on nisin activity in the sausages was compared. LAB growth rate was fastest in samples containing orthophosphate, and slowest in sausages containing diphosphate. The shelf life was also greatly extended in the latter. Fat content also affected nisin activity. Nisin activity (as indicated by LAB inhibition) was greatest in samples containing 15% > 25% > 37% (wt/wt) fat. In a sausage formulation containing 37% fat and incorporating diphosphate as emulsifier, levels of nisin as low as 2.5 μg g−1 showed antibacterial effects. A nisin level of 6.25 μg g−1 totally inhibited LAB growth for over 4 weeks and 25 μg g−1 for 5 weeks. Spoilage control was achieved in the same sausage formulation but with 25% (wt/wt) fat; 12.5 μg g−1 nisin prevented LAB growth for 5 weeks.

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