Benefits and effectiveness of high pressure processing on cheese: a ricotta case study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Roberta Stefanini ◽  
Anna Ronzano ◽  
Giulia Borghesi ◽  
Giuseppe Vignali
Keyword(s):  
High Pressure ◽  
Microbial Growth ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
High Pressure Processing ◽  
Lag Phase ◽  
Starting Point ◽  
Volatile Organic ◽  
Parmigiano Reggiano

Abstract Today High Pressure Processing (HPP) is receiving interest thanks to its ability to stabilize foods preserving nutritional and sensorial characteristics. This work applies HPP on nutrient ricottas created in the Parmigiano Reggiano area and demonstrates not only its benefits, but also disadvantages, testing different pressures and packaging. Moreover, the ability of HPP to prolong the lag phase and reduce the maximum growth rate of bacteria is illustrated with a mathematical model. Results show the influence of HPP parameters on microbial growth, volatile organic compounds, syneresis, softness and colour, and demonstrate that not all packaging are suitable for the treatment. Obtained data highlight the effectiveness of HPP, which results the best stabilization method to sell safe and nutritive ricottas on the market with a long shelf life. Of course, the work can be a starting point for food companies who want to test an innovative and promising non-thermal technology.

High pressure processing controls microbial growth and minimally alters the levels of health promoting compounds in grapefruit (Citrus paradisi Macfad) juice

2013 ◽  
Vol 18 ◽  
pp. 7-14 ◽  
Author(s):  
Ram M. Uckoo ◽  
Guddadarangavvanahally K. Jayaprakasha ◽  
Jeremy A. Somerville ◽  
V.M. Balasubramaniam ◽  
Monica Pinarte ◽  
...  
Keyword(s):  
High Pressure ◽  
Microbial Growth ◽  
High Pressure Processing ◽  
Citrus Paradisi ◽  
Health Promoting

Inhibition of Listeria monocytogenes in Cooked Ham through Active Packaging with Natural Antimicrobials and High-Pressure Processing

2007 ◽  
Vol 70 (11) ◽  
pp. 2498-2502 ◽  
Author(s):  
ANNA JOFRÉ ◽  
MARGARITA GARRIGA ◽  
TERESA AYMERICH
Keyword(s):  
High Pressure ◽  
Listeria Monocytogenes ◽  
Active Packaging ◽  
High Pressure Processing ◽  
The Other ◽  
Lag Phase ◽  
Natural Antimicrobials ◽  
Cooked Ham ◽  
Potassium Lactate

Enterocins A and B and sakacin K at 200 and 2,000 activity units (AU)/cm2, nisin at 200 AU/cm2, 1.8% potassium lactate, and a combination of 200 AU/cm2 of nisin and 1.8% lactate were incorporated into interleavers, and their effectiveness against Listeria monocytogenes spiked in sliced, cooked ham was evaluated. Antimicrobial-packaged cooked ham was then subjected to high-pressure processing (HPP) at 400 MPa. In nonpressurized samples, nisin plus lactate–containing interleavers were the most effective, inhibiting L. monocytogenes growth for 30 days at 6°C, with counts that were 1.9 log CFU/g lower than in the control after 3 months. In the other antimicrobial-containing interleavers, L. monocytogenes did not exhibit a lag phase and progressively grew to levels of about 8 log CFU/g. HPP of actively packaged ham slices reduced Listeria populations about 4 log CFU/g in all batches containing bacteriocins (i.e., nisin, sakacin, and enterocins). At the end of storage, L. monocytogenes levels in the bacteriocin-containing batches were the lowest, with counts below 1.51 log CFU/g. In contrast, HPP moderately reduced L. monocytogenes counts in the control and lactate batches, with populations gradually increasing to about 6.5 log CFU/g at the end of storage.

Evaluating the Growth of Listeria monocytogenes in Refrigerated Ready-to-Eat Frankfurters: Influence of Strain, Temperature, Packaging, Lactate and Diacetate, and Background Microflora

2008 ◽  
Vol 71 (9) ◽  
pp. 1806-1816 ◽  
Author(s):  
AMIT PAL ◽  
THEODORE P. LABUZA ◽  
FRANCISCO DIEZ-GONZALEZ
Keyword(s):  
High Pressure ◽  
Listeria Monocytogenes ◽  
Shelf Life ◽  
Growth Rates ◽  
Maximum Growth ◽  
Lag Time ◽  
Lag Phase ◽  
Potassium Lactate ◽  
Plate Counts ◽  
Data Log

This research was conducted to study the growth of Listeria monocytogenes inoculated on frankfurters stored at different conditions as a basis for a safety-based consume by shelf life date label. Three L. monocytogenes strains were separately inoculated at 10 to 20 CFU/cm2 onto frankfurters that were previously formulated with or without high pressure and with or without added 2% potassium lactate (PL) and 0.2% sodium diacetate (SD). Inoculated frankfurters were air or vacuum packaged; stored at 4, 8, or 12°C; and L. monocytogenes and psychrotrophic plate counts were determined for 90, 60, and 45 days, respectively, or until the stationary phase was reached. The data (log CFU per square centimeter versus time) were fitted using the Baranyi-Roberts model to determine maximum growth rates and lag-phase time. The maximum growth rates and the lag time under each growth condition were used to calculate the time to reach 100-fold the initial Listeria population. In frankfurters lacking PL and SD, the count of all strains increased by 2 log after 18 to 50 days at 4°C and 4 to 13 days at 8°C. The growth was inhibited at 4 and 8°C in frankfurters containing PL and SD, but one ribotype was capable of growing, with the time to reach 100-fold the initial Listeria population ranging from 19 to 35 days at 12°C. In most cases, the time to reach 100-fold the initial Listeria population of L. monocytogenes was significantly longer in vacuum-packaged frankfurters as compared with air-packaged samples. Inclusion of PL and SD also inhibited the growth of psychrotrophs, but at all temperatures the psychrotrophic plate counts were greater than 4 log CFU/cm2 at the end of the experiments. These results indicated that despite the use of antimicrobials, certain L. monocytogenes strains could be capable of growing under storage-abuse conditions. Growth kinetics data could be useful for establishing a shelf life date label protocol under different handling scenarios.

Comparison of Enrichment Broths for the Recovery of Healthy and Heat-Injured Salmonella Typhimurium on Raw Duck Wings

2013 ◽  
Vol 76 (11) ◽  
pp. 1963-1968 ◽  
Author(s):  
QIANWANG ZHENG ◽  
CAROLINE BUSTANDI ◽  
YISHAN YANG ◽  
KEITH R. SCHNEIDER ◽  
HYUN-GYUN YUK
Keyword(s):  
Growth Rate ◽  
Salmonella Typhimurium ◽  
Doubling Time ◽  
Growth Parameters ◽  
False Negative ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Detection Methods ◽  
Lag Phase ◽  
Peptone Water

This study was performed to optimize Salmonella Typhimurium recovery from raw duck wings with five nonselective broths (buffered peptone water, tryptic soy broth, lactose broth, universal preenrichment broth, nutrient broth) and four selective broths (selenite broth, BAX System MP media [MP], Salmonella AD media [AD], ONE broth-Salmonella [OB]). Healthy or heat-injured (50 and 85% injury) cells were inoculated at a level of 102, 101, or 100 CFU/25 g on raw duck wings. Growth was modeled using DMfit with four growth parameters: lag-phase duration, maximum growth rate, doubling time, and maximum population density. Most enrichments were able to recover Salmonella Typhimurium to greater than 6 log CFU/ml. AD, MP, and OB had significantly (P < 0.05) higher maximum growth rate (0.9 to 1.0/h) and lower doubling time (0.7 to 0.8 h). Buffered peptone water, AD, MP, and OB recovered healthy and 50%-injured cells at low inoculum levels to more than 6.0 log CFU/ml; OB achieved the greatest recovery (7.6 and 7.9 log CFU/ml), following 24 h of incubation. The 85%-injured cells at 100 and 101 CFU/25 g, however, were only recovered in OB, reaching 7.3 and 7.5 log CFU/ml, respectively. These results suggest that OB may be an appropriate enrichment broth for the recovery of Salmonella Typhimurium from raw duck wings in standard diagnostic tests or other rapid detection methods, to avoid false-negative results.

Modelling the growth kinetic of spoilage microorganisms in a packaged cow’s ricotta processed with high pressure

2019 ◽  
Author(s):  
Roberta Stefanini ◽  
Giuseppe Vignali ◽  
Fabio Coloretti
Keyword(s):  
High Pressure ◽  
Dairy Products ◽  
Nutritional Value ◽  
High Pressure Processing ◽  
Food Preservation ◽  
Omega 3 ◽  
Food Components ◽  
Fresh Foods ◽  
Spoilage Microorganisms ◽  
Parmigiano Reggiano

Today consumers demand fresh foods without additives, preservatives and health risks: that is why non-thermal food preservation methods are receiving more interest, among them High Pressure Processing is able to avoid thermal degradation of food components, extend their shelf life and preserve colour, flavour and nutritional value. HPP is often used on dairy products because of its impact on physicochemical and sensory characteristics, its ability to improve their structure and texture and inactivate some microorganisms. The aim of this work is to evaluate the effect of HPP on a packaged ricotta rich in Conjugated Linoleic Acid (CLA) and Omega-3, resulting from cows fed with linseed in the Parmigiano Reggiano area, and processed with a hydrostatic pressure of 600 MPa for 5 minutes. The ultimate goal is to find a mathematical model able to show the treatment’s effect on spoilage microorganisms that grow spontaneously in this product during a month of refrigerated storage.

Growth of a Methane-Utilizing Mixed Culture HD6T on Methanol and Poly-β-Hydroxybutyrate Biosynthesis

2010 ◽  
Vol 160-162 ◽  
pp. 171-175 ◽  
Author(s):  
Jing Dong ◽  
Jia Ying Xin ◽  
Ying Xin Zhang ◽  
Lin Lin Chen ◽  
Hong Ye Liang ◽  
...  
Keyword(s):  
Mixed Culture ◽  
Mineral Salt Medium ◽  
Biomass Concentration ◽  
Dry Weight ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Production Costs ◽  
Lag Phase ◽  
Phase Duration ◽  
Phb Production

Methane-utilizing mixed culture HD6T was successfully cultivated in a brief non-sterile process using methanol as a sole carbon and energy source for the production of poly-β-hydroxybutyrate(PHB). Shake-flask experiments showed HD6T could grow well in the mineral salt medium with the addition of methanol exposed to the air directly. This non-sterile process and the use of cheap substrates (methanol) can reduce the production costs of PHB. It was found that HD6T grew better and PHB production in a more effective way with an initial liquid methanol concentration of 0.15%(v/v).The lag phase duration, the maximum growth rate, the biomass concentration and the PHB yield, for the optimal conditions were, respectively, 12.03h, 0.04h-1(OD600), 1.54g/l(dry weight), 0.424g/l(dry weight). Methane-utilizing mixed culture HD6T appears to be a promising organism for PHB production.

Growth of Stressed Strains of Four Non-O157 Shiga Toxin–Producing Escherichia coli Serogroups in Five Enrichment Broths

2015 ◽  
Vol 78 (11) ◽  
pp. 1960-1966 ◽  
Author(s):  
BAVO VERHAEGEN ◽  
KOEN DE REU ◽  
MARC HEYNDRICKX ◽  
INGE VAN DAMME ◽  
LIEVEN DE ZUTTER
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Growth Dynamics ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Lag Phase ◽  
Sodium Pyruvate ◽  
Peptone Water ◽  
Pure Cultures ◽  
Freeze Stress

The purpose of this study was to evaluate (i) the behavior of several strains of non-O157 Shiga toxin–producing Escherichia coli (STEC) serogroups (O26, O103, O111, and O145) exposed to different stress conditions and (ii) the growth dynamics of stressed and nonstressed non-O157 STEC cells in five enrichment media. STEC strains were exposed to acid, cold, and freeze stresses. Lethal and sublethal injuries were determined by plating in parallel on selective and nonselective agar media. Freeze stress (8 days, −20°C) caused the most lethal (95.3% ± 2.5%) injury, as well as the most sublethal (89.1% ± 8.8%) injury in the surviving population. Growth of stressed and nonstressed pure cultures of non-O157 STEC on modified tryptic soy broth, buffered peptone water (BPW), BPW with sodium pyruvate, Brila, and STEC enrichment broth (SEB) was determined using total viable counts. To compare growth capacities, growth after 7 and 24 h of enrichment was measured; lag phases and maximum growth rates were also calculated. In general, growth on BPW resulted in a short lag phase followed by a high maximum growth rate during the enrichment of all tested strains when using all three stress types. Furthermore, BPW ensured the highest STEC count after 7 h of growth. Supplementing the medium with sodium pyruvate did not improve the growth dynamics. The two selective media, Brila and SEB, were less efficient than BPW, but Brila's enrichment performance was remarkably better than that of SEB. This study shows that irrespective of the effect of background flora, BPW is still recommended for resuscitation of non-O157 STEC.

scholarly journals Tolerance of Benthic Diatoms to Severe Environmental Stress: A Case Study in Shatt Al-Arab River, Basrah, Iraq

2021 ◽  
Vol 5 (2) ◽  
pp. 222-247
Author(s):  
Rehab Al-Saedy
Keyword(s):  
Environmental Stress ◽  
Variable Temperature ◽  
Maximum Growth ◽  
Marine Species ◽  
Maximum Growth Rate ◽  
Diatom Species ◽  
Nitzschia Palea ◽  
Temperature Regimes ◽  
A New Species

The present work aims at investigating the ability of diatoms to re-establish their community after a severe environmental stress such desiccation. Diatoms were subjected to extreme environmental stress to observe their survival capability. Samples of sediment were collected from three sites, Maqal, Abu Flos and Al-Faw along the course of Shatt Al-Arab river. Different temperature regimes were implemented for testing the ability of diatoms to recover desiccation. Experiments were performed at various temperatures, 10, 15, 20, 25, 30, 35 and 40 ℃. A total of 67 diatom species were identified and included freshwater forms (25%), brackish water forms (25%) and marine species (26%), as well as 24% of taxa with undefined ecological preferences. The recovery rate of diatom species at all sites appeared to be rather similar. 40%, 38% and 37% of all taxa encountered were able to recover desiccation at sites 1, 2 and 3, respectively. Recovering ability of those species varies with variable temperature. Favourable temperature for most species to regrow ranged between 15 and 25 oC. Nitzschia palea exhibited the maximum growth rate at all temperatures (10-35 oC). 32% of all epiphytic species encountered were able to recover at 20 oC. Five species: Craspedostauros britannicus, Nitzschia invisitata, Pinnularia quadratarea, Simonsenia sp. and Tryblionella plana were not previously reported in Iraq and considered as new to the region. A new species, Synedropsis abuflosensis, was found. The outcome of the present work clearly indicates that some species of diatoms can recover after exposure to sever environmental stress.

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