High Pressure Homogenization versus Heat Treatment: Effect on Survival, Growth, and Metabolism of Dairy Leuconostoc Strains

2012 ◽  
Vol 75 (9) ◽  
pp. 1634-1641 ◽  
Author(s):  
D. M. GUGLIELMOTTI ◽  
F. PATRIGNANI ◽  
R. LANCIOTTI ◽  
M. E. GUERZONI ◽  
J. A. REINHEIMER ◽  
...  
Keyword(s):  
Heat Treatment ◽  
High Pressure ◽  
Skim Milk ◽  
Viable Cell ◽  
Inhibitory Effect ◽  
Microbial Inactivation ◽  
High Pressure Homogenization ◽  
Cell Counts ◽  
Total Destruction ◽  
Aldehydes And Ketones

The effect of high pressure homogenization (HPH) with respect to a traditional heat treatment on the inactivation, growth at 8°C after treatments, and volatile profile of adventitious Leuconostoc strains isolated from Cremoso Argentino spoiled cheeses and ingredients used for their manufacture was evaluated. Most Leuconostoc strains revealed elevated resistance to HPH (eight passes, 100 MPa), especially when resuspended in skim milk. Heat treatment was more efficient than HPH in inactivating Leuconostoc cells at the three initial levels tested. The levels of alcohols and sulfur compounds increased during incubation at 8°C in HPH-treated samples, while the highest amounts of aldehydes and ketones characterized were in heated samples. Leuconostoc cells resuspended in skim milk and subjected to one single-pass HPH treatment using an industrial-scale machine showed remarkable reductions in viable cell counts only when 300 and 400 MPa were applied. However, the cell counts of treated samples rose rapidly after only 5 days of storage at 8°C. The Leuconostoc strains tested in this work were highly resistant to the inactivation treatments applied. Neither HPH nor heat treatment assured their total destruction, even though they were more sensitive to the thermal treatment. To enhance the inhibitory effect on Leuconostoc cells, HPH should be combined with a mild heat treatment, which in addition to efficient microbial inactivation, could allow maximal retention of the physicochemical properties of the product.

Microbial inactivation by high pressure homogenization: Effect of the disruption valve geometry

2013 ◽  
Vol 115 (3) ◽  
pp. 362-370 ◽  
Author(s):  
Francesco Donsì ◽  
Marianna Annunziata ◽  
Giovanna Ferrari
Keyword(s):  
High Pressure ◽  
Microbial Inactivation ◽  
High Pressure Homogenization

Inhibition of the Antibacterial Lactoperoxidase-Thiocyanate-Hydrogen Peroxide System by Heat-Treated Milk

1985 ◽  
Vol 48 (6) ◽  
pp. 494-498 ◽  
Author(s):  
B. EKSTRAND ◽  
W. M. A. MULLAN ◽  
A. WATERHOUSE
Keyword(s):  
Heat Treatment ◽  
Hydrogen Peroxide ◽  
Skim Milk ◽  
Inhibitory Effect ◽  
Sulfhydryl Groups ◽  
Inhibitory Factor ◽  
Casein Micelle ◽  
Heated Milk ◽  
Heat Treated

The antibacterial system, lactoperoxidase-H2O2-SCN− was affected by the presence of heated milk or skim milk reconstituted from powders having received severe heat treatment. This inhibitory effect was related to the increase in exposed sulfhydryl groups and to the redistribution of protein between micellar and whey phases. Chromatographic analyses of heat-treated milk showed that the inhibitory factor was associated with the casein micelle fraction. The inhibition, however, was overcome by addition of unheated skim milk.

scholarly journals Effect of Ultra High Pressure Homogenization on Alkaline Phosphatase and Lactoperoxidase Activity in Raw Skim Milk

2011 ◽  
Vol 1 ◽  
pp. 874-878 ◽  
Author(s):  
Cláudia R.G. Pinho ◽  
Mark A. Franchi ◽  
Alline A.L. Tribst ◽  
Marcelo Cristianini
Keyword(s):  
High Pressure ◽  
Alkaline Phosphatase ◽  
Skim Milk ◽  
High Pressure Homogenization ◽  
Ultra High Pressure

Quality of Mango Nectar Processed by High-Pressure Homogenization with Optimized Heat Treatment

2011 ◽  
Vol 76 (2) ◽  
pp. M106-M110 ◽  
Author(s):  
Alline Artigiani Lima Tribst ◽  
Mark Alexandrow Franchi ◽  
Pilar Rodriguez de Massaguer ◽  
Marcelo Cristianini
Keyword(s):  
Heat Treatment ◽  
High Pressure ◽  
High Pressure Homogenization

scholarly journals The Effect of pH and High-Pressure Homogenization on Droplet Size

2017 ◽  
Vol 2 (4) ◽  
pp. 110-122
Author(s):  
Ah Pis Yong ◽  
Md. Aminul Islam ◽  
Nurul Hasan
Keyword(s):  
High Pressure ◽  
Light Scattering ◽  
Droplet Size ◽  
Skim Milk ◽  
Egg Yolk ◽  
Continuous Phase ◽  
High Pressure Homogenization ◽  
Emulsion Droplets ◽  
Droplet Sizes ◽  
Basil Oil

The aims of this study are to revisit the effect of high pressure on homogenization and the influence of pH on the emulsion droplet sizes. The high-pressure homogenization (HPH) involves two stages of processing, where the first stage involves in blending the coarse emulsion by a blender, and the second stage requires disruption of the coarse emulsion into smaller droplets by a high-pressure homogenizer. The pressure range in this review is in between 10-500 MPa. The homogenised droplet sizes can be reduced by increasing the homogenization recirculation, and there is a threshold point beyond that by applying pressure only, the size cannot be further reduced. Normally, homogenised emulsions are classified by their degree of kinetic stability. Dispersed phase present in the form of droplets while continuous phase also known as suspended droplets. With a proper homogenization recirculation and pressure, a more kinetically stable emulsion can be produced. The side effects of increasing homogenization pressure are that it can cause overprocessing of the emulsion droplets where the droplet sizes become larger rather than the expected smaller size. This can cause kinetic instability in the emulsion. The droplet size is usually measured by dynamic light scattering or by laser light scattering technique. The type of samples used in this reviews are such as chocolate and vanilla based powders; mean droplet sizes samples; basil oil; tomato; lupin protein; oil; skim milk, soymilk; coconut milk; tomato homogenate; corn; egg-yolk, rapeseed and sunflower; Poly(4-vinylpyridine)/silica; and Complex 1 until complex 4 approaches from author case study. A relationship is developed between emulsion size and pH. Results clearly show that lower pH offers smaller droplet of emulsion and the opposite occurs when the pH is increased.

scholarly journals Mechanisms of Inactivation of Dry Escherichia coli by High-Pressure Carbon Dioxide

2017 ◽  
Vol 83 (10) ◽  
Author(s):  
Yuan Yao Chen ◽  
Feral Temelli ◽  
Michael G. Gänzle
Keyword(s):  
Escherichia Coli ◽  
Carbon Dioxide ◽  
High Pressure ◽  
Water Activity ◽  
Microbial Inactivation ◽  
Dominant Factor ◽  
Cyclopropane Fatty Acid ◽  
Content Type ◽  
E Coli ◽  
Cell Counts

ABSTRACT High-pressure carbon dioxide processing is a promising technology for nonthermal food preservation. However, few studies have determined the lethality of high-pressure CO2 on dry bacterial cells, and the mechanism of inactivation remains unknown. This study explored the mechanisms of inactivation by using Escherichia coli AW1.7 and mutant strains differing in heat and acid resistance, in membrane composition based on disruption of the locus of heat resistance, and in genes coding for glutamate decarboxylases and cyclopropane fatty acid synthase. The levels of lethality of treatments with liquid, gaseous, and supercritical CO2 were compared. The cell counts of E. coli AW1.7 and mutants with a water activity (aW) of 1.0 were reduced by more than 3 log10 (CFU/ml) after supercritical CO2 treatment at 35°C for 15 min; increasing the pressure generally enhanced inactivation, except for E. coli AW1.7 ΔgadAB. E. coli AW1.7 Δcfa was more susceptible than E. coli AW1.7 after treatment at 10 and 40 MPa; other mutations did not affect survival. Dry cells of E. coli were resistant to treatments with supercritical and liquid CO2 at any temperature. Treatments with gaseous CO2 at 65°C were more bactericidal than those with supercritical CO2 or treatments at 65°C only. Remarkably, E. coli AW1.7 was more susceptible than E. coli AW1.7 Δcfa when subjected to the gaseous CO2 treatment. This study identified CO2-induced membrane fluidization and permeabilization as causes of supercritical mediated microbial inactivation, and diffusivity was a dominant factor for gaseous CO2. IMPORTANCE The safety of dry foods is of increasing concern for public health. Desiccated microorganisms, including pathogens, remain viable over long periods of storage and generally tolerate environmental insults that are lethal to the same organisms at high water activity. This study explored the use of high-pressure carbon dioxide to determine its lethality for dried Escherichia coli and to provide insight into the mechanisms of inactivation. The lethality of high-pressure CO2 and the mechanisms of CO2-mediated inactivation of dry E. coli depended on the physical state of CO2. Liquid and supercritical CO2 were ineffective in reducing the cell counts of dry E. coli isolates, and the effectiveness of gaseous CO2 was related to the diffusivity of CO2. Results provide a novel and alternative method for the food industry to enhance the safety of low aW products.

scholarly journals Inactivation of Bacillus spores in reconstituted skim milk by combined high pressure and heat treatment

2006 ◽  
Vol 101 (1) ◽  
pp. 172-180 ◽  
Author(s):  
K.J. Scurrah ◽  
R.E. Robertson ◽  
H.M. Craven ◽  
L.E. Pearce ◽  
E.A. Szabo
Keyword(s):  
Heat Treatment ◽  
High Pressure ◽  
Skim Milk ◽  
Bacillus Spores
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