Effect of High-Pressure Treatment on the Survival of Listeria monocytogenes Scott A in Sliced Vacuum-Packaged Iberian and Serrano Cured Hams

2006 ◽  
Vol 69 (10) ◽  
pp. 2539-2543 ◽  
Author(s):  
PILAR MORALES ◽  
JAVIER CALZADA ◽  
MANUEL NUÑEZ
Keyword(s):  
High Pressure ◽  
Listeria Monocytogenes ◽  
Detrimental Effect ◽  
Vacuum Packaging ◽  
Sensory Characteristics ◽  
Pressure Treatment ◽  
High Pressure Treatment ◽  
Microbiological Safety ◽  
Holding Period ◽  
And Control

High-pressure treatment is useful for increasing the microbiological safety of ready-to-eat foods. With dry-cured hams, this treatment can be applied to the finished product after slicing and vacuum packaging. The effect of high-pressure treatment on the survival of inoculated Listeria monocytogenes Scott A and on the sensory characteristics of two Spanish dry-cured hams, Iberian and Serrano, was investigated. Ham slices were inoculated with L. monocytogenes at 6 × 106 CFU/g and held at 4°C for 20 h before high-pressure treatment. During this holding period, the population of the pathogen declined by 0.44 and 0.51 log CFU/g in Iberian and Serrano hams, respectively. Treatment at 450 MPa for 10 min at 12°C reduced L. monocytogenes populations by 1.50 and 1.16 log CFU/g in Iberian and Serrano hams, respectively. During the first week of storage at4or 8°C, L. monocytogenes populations declined by an average 0.89 log CFU/g in pressurized Iberian ham and 2.09 log CFU/g in pressurized Serrano ham. After 60 days at 4 or 8°C, the respective populations in pressurized and control hams were 3.24 and 4.70 log CFU/g for Iberian ham and 2.73 and 5.07 log CFU/g for Serrano ham. The color parameters L* and a* were not influenced by high-pressure treatment, and parameter b* was increased only in Iberian ham. Sensory characteristics of hams were not affected by high-pressure treatment. Treatment of Iberian and Serrano hams at 450 MPa for 10 min significantly reduced the population of L. monocytogenes Scott A without a detrimental effect on the sensory characteristics of the hams.

scholarly journals Changes in selected vitamins, microorganism counts, and sensory quality during storage of pressurised sprouted seed of alfalfa (Medicago sativa L.)

2011 ◽  
Vol 23 (No. 6) ◽  
pp. 246-250 ◽  
Author(s):  
GabrovskáD ◽  
I. Paulíčková ◽  
E. Mašková ◽  
V. Fiedlerová ◽  
K. Kocurová ◽  
...  
Keyword(s):  
High Pressure ◽  
Vitamin C ◽  
Sensory Quality ◽  
Pantothenic Acid ◽  
Storage Period ◽  
Pressure Treatment ◽  
High Pressure Treatment ◽  
Microbiological Safety ◽  
Alfalfa Seed

The aim of this study was to examine the changes of nutritional and sensory quality of sprouted alfalfa seed treated by high pressure, that take place during storage. Along with this, microbiological safety was also observed. Sprouted alfalfa seed in citric acid pickle, packed in transparent laminated bags PA/PE 80, was treated with 500 MPa high pressure for 10 minutes. The processed seed in bags was stored in a refrigerator for 21 days. The bags were sampled in regular intervals to perform analyses. The changes in the contents of vitamin C, riboflavin, niacin, and pantothenic acid were observed during storage. The same samples were also checked for microbiological safety and sensory quality. Vitamin C showed a significant decrease during storage. The content of vitamin C fell markedly after high pressure treatment (by 77%) and further decreased by 10&ndash;20% during storage. The values of riboflavin content did not change very much as a consequence of pressurisation or the storage period. The contents of niacin and pantothenic acid kept decreasing until the 3<sup>rd</sup> day of storage by some 60% in total and then remained unchanged. Sensory descriptors indicated quality decrease. High pressure treatment damaged the tissues of sprouted alfalfa seed which subsequently manifested itself particularly in the deterioration of appearance and texture quality. An additional overall impairment of the seed appearance and texture occurred during its storage. Microbiological safety of sprouted alfalfa seed was preserved throughout the storage time. &nbsp;

Effects of high-pressure treatment on free fatty acids release during ripening of ewes' milk cheese

2007 ◽  
Vol 74 (4) ◽  
pp. 438-445 ◽  
Author(s):  
Bibiana Juan ◽  
Victoria Ferragut ◽  
Martin Buffa ◽  
Buenaventura Guamis ◽  
Antonio-José Trujillo
Keyword(s):  
Fatty Acids ◽  
High Pressure ◽  
Fatty Acid ◽  
Free Fatty Acid ◽  
Free Fatty Acids ◽  
Pressure Treatment ◽  
High Pressure Treatment ◽  
Effect Of Pressure ◽  
Two Stages ◽  
And Control

The free fatty acid (FFA) profile of high pressure treated ewes' milk cheeses were studied to assess the effect of pressure treatment on cheese lipolysis. Cheeses were treated at 200, 300, 400 or 500 MPa (2P to 5P) at two stages of ripening (after 1 and 15 days of manufacturing; P1 and P15) and FFA were assayed at 1, 15 and 60 d ripening. On the first day of ripening, 3P1-cheeses showed levels of FFA twice that of the control cheeses. However, no significant differences were found between 3P1 and control cheeses at 60 d ripening. On the contrary, 4P1 and 5P1-cheeses had the lowest total FFA levels. The point at which pressure treatment was applied influenced the FFA profile of cheeses; cheeses pressurized at pressures <400 MPa on the first day of ripening were more similar to untreated cheeses than their homologues treated at 15 d.

Effect of Cheese Water Activity and Carbohydrate Content on the Barotolerance of Listeria monocytogenes Scott A

2006 ◽  
Vol 69 (6) ◽  
pp. 1328-1333 ◽  
Author(s):  
PILAR MORALES ◽  
JAVIER CALZADA ◽  
BUENAVENTURA RODRÍGUEZ ◽  
MÁXIMO de PAZ ◽  
PILAR GAYA ◽  
...  
Keyword(s):  
High Pressure ◽  
Listeria Monocytogenes ◽  
Water Activity ◽  
Dry Matter ◽  
High Pressure Processing ◽  
Carbohydrate Content ◽  
Pressure Treatment ◽  
High Pressure Treatment ◽  
Log Reduction ◽  
Fresh Cheese

High-pressure processing is an appropriate technique for improving the microbiological safety of packaged ready-to-eat foods. The effect of high-pressure treatment on Listeria monocytogenes Scott A inoculated into fresh Hispánico-type cheese and ripe Mahón cheese was investigated. A 3.8-log reduction in the counts of L. monocytogenes Scott A in fresh cheese was recorded after 3 min at 400 MPa and 12°C, whereas 18 min under the same conditions was required to obtain a 1-log reduction in ripe cheese. Dry matter values were 48.96% for fresh cheese and 58.79% for ripe cheese, and water activity (aw) values were 0.983 and 0.922, respectively. In dehydrated fresh cheese (58.20% dry matter) in which 5% NaCl was added to achieve a 0.904 aw value, L. monocytogenes Scott A counts were lowered by only 0.4 log after treatment for 10 min at 400 MPa. On the other hand, in a 60:40 mixture of ripe cheese:distilled water with a 0.976 aw value, the reduction under the same conditions was 3.9 log. Within the aw range of 0.945 to 0.965, L. monocytogenes Scott A barotolerance was significantly higher in fresh cheese than in ripe cheese for equivalent aw values. Carbohydrate content was higher in fresh cheese than in ripe cheese. The addition of lactose at a concentration of 5 mg/g to an 85:15 mixture of ripe cheese:distilled water did not influence L. monocytogenes Scott A barotolerance during treatment for 10 min at 400 MPa. Galactose at a concentration of 5 mg/g had a protective effect during high-pressure treatment, and glucose at a concentration of 5 mg/g favored L. monocytogenes Scott A survival during refrigerated storage of pressurized samples at 8°C for 5 days.

scholarly journals Extension of the Shelf Life of Prawns (Penaeus japonicus) by Vacuum Packaging and High-Pressure Treatment

2000 ◽  
Vol 63 (10) ◽  
pp. 1381-1388 ◽  
Author(s):  
M. E. LÓPEZ-CABALLERO ◽  
M. PÉREZ-MATEOS ◽  
J. A. BORDERÍAS ◽  
P. MONTERO
Keyword(s):  
High Pressure ◽  
Shelf Life ◽  
High Pressures ◽  
Vacuum Packaging ◽  
Point Of View ◽  
Pressure Treatment ◽  
High Pressure Treatment ◽  
Penaeus Japonicus ◽  
Muscle Color ◽  
Number Of Bacteria

The present study has investigated the application of high pressures (200 and 400 MPa) in chilled prawn tails, both conventionally stored (air) and vacuum packaged. Vacuum packaging and high-pressure treatment did extend the shelf life of the prawn samples, although it did affect muscle color very slightly, giving it a whiter appearance. The viable shelf life of 1 week for the air-stored samples was extended to 21 days in the vacuum-packed samples, 28 days in the samples treated at 200 MPa, and 35 days in the samples pressurized at 400 MPa. Vacuum packaging checked the onset of blackening, whereas high-pressure treatment aggravated the problem. From a microbiological point of view, batches conventionally stored reached about 6 log CFU/g or even higher at 14 days. Similar figures were reached in total number of bacteria in vacuum-packed samples and in pressurized at 200-MPa samples at 21 days. When samples were pressurized at 400 MPa, total numbers of bacteria were below 5.5 log CFU/g at 35 days of storage. Consequently, a combination of vacuum packaging and high-pressure treatment would appear to be beneficial in prolonging freshness and preventing spotting.

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