Modeling the effect of temperature on survival rate of Salmonella Enteritidis in yogurt

2014 ◽  
Vol 17 (3) ◽  
pp. 479-485 ◽  
Author(s):  
J. Szczawiński ◽  
M. E. Szczawińska ◽  
A. Łobacz ◽  
A. Jackowska-Tracz
Keyword(s):  
Survival Rate ◽  
Salmonella Enteritidis ◽  
Storage Time ◽  
Storage Temperature ◽  
Effect Of Temperature ◽  
Polynomial Equations ◽  
Natural Logarithm ◽  
Primary Model ◽  
Different Temperatures ◽  
Number Of Bacteria

Abstract The aim of the study was to determine the inactivation rates of Salmonella Enteritidis in commercially produced yogurt and to generate primary and secondary mathematical models to predict the behaviour of these bacteria during storage at different temperatures. The samples were inoculated with the mixture of three S. Enteritidis strains and stored at 5oC, 10oC, 15oC, 20oC and 25oC for 24 h. The number of salmonellae was determined every two hours. It was found that the number of bacteria decreased linearly with storage time in all samples. Storage temperature and pH of yogurt significantly influenced survival rate of S. Enteritidis (p < 0.05). In samples kept at 5oC the number of salmonellae decreased at the lowest rate, whereas at 25°C the reduction in number of bacteria was the most dynamic. The natural logarithm of mean inactivation rates of Salmonella calculated from primary model was fitted to two secondary models: linear and polynomial. Equations obtained from both secondary models can be applied as a tool for prediction of inactivation rate of Salmonella in yogurt stored under temperature range from 5 to 25°C; however, polynomial model gave the better fit to the experimental data.

Modeling the effect of temperature on survival rate of Listeria monocytogenes in yogurt

2016 ◽  
Vol 19 (2) ◽  
pp. 317-324 ◽  
Author(s):  
J. Szczawiński ◽  
M.E. Szczawińska ◽  
A. Łobacz ◽  
A. Jackowska-Tracz
Keyword(s):  
Listeria Monocytogenes ◽  
Survival Rate ◽  
Storage Time ◽  
Ph Value ◽  
Effect Of Temperature ◽  
Natural Logarithm ◽  
Primary Model ◽  
Different Temperatures ◽  
Mathematical Equations ◽  
And Storage

Abstract The aim of the study was to (i) evaluate the behavior of Listeria monocytogenes in a commercially produced yogurt, (ii) determine the survival/inactivation rates of L. monocytogenes during cold storage of yogurt and (iii) to generate primary and secondary mathematical models to predict the behavior of these bacteria during storage at different temperatures. The samples of yogurt were inoculated with the mixture of three L. monocytogenes strains and stored at 3, 6, 9, 12 and 15°C for 16 days. The number of listeriae was determined after 0, 1, 2, 3, 5, 7, 9, 12, 14 and 16 days of storage. From each sample a series of decimal dilutions were prepared and plated onto ALOA agar (agar for Listeria according to Ottaviani and Agosti). It was found that applied temperature and storage time significantly influenced the survival rate of listeriae (p<0.01). The number of L. monocytogenes in all the samples decreased linearly with storage time. The slowest decrease in the number of the bacteria was found in the samples stored at 6°C (D-10 value = 243.9 h), whereas the highest reduction in the number of the bacteria was observed in the samples stored at 15°C (D-10 value = 87.0 h). The number of L. monocytogenes was correlated with the pH value of the samples (p<0.01). The natural logarithm of the mean survival/inactivation rates of L. monocytogenes calculated from the primary model was fitted to two secondary models, namely linear and polynomial. Mathematical equations obtained from both secondary models can be applied as a tool for the prediction of the survival/inactivation rate of L. monocytogenes in yogurt stored under temperature range from 3 to 15°C, however, the polynomial model gave a better fit to the experimental data.

scholarly journals Influence of different method and different storage life on moisture and senzorial evaluation of durable salamis

2008 ◽  
Vol 56 (4) ◽  
pp. 183-196
Author(s):  
Hana Šulcerová ◽  
Jiří Štencl ◽  
A. Šulcová
Keyword(s):  
Storage Time ◽  
Storage Temperature ◽  
Heat Treated ◽  
Different Temperatures ◽  
The Difference ◽  
Total Difference ◽  
Cut Surface ◽  
Sausage Casing ◽  
General Appearance

Heat-treated salamis “Vysočina“ were produced with standard way in a meat factory; their diameter was 55 mm. Samples were stored under laboratory conditions at different temperatures: 5, 10, 15, 20, and 25 °C and sensory analysed every week during one month storage. The dry matter (d.m.) was measured, too. Descriptors of general appearance, sausage casing, texture, cut surface, dry edge, smell, taste, and salty were monitored. Biggest changes were in descriptors general appearance and sausage casing (P < 0.001) and also in dry edge (P < 0.010) during the month period. Germs of moulds were found only at 5 and 10 °C. Rapid increase of d.m. in samples was noticeable in the first week of the storage time. It was 3 % d.m. at 5 °C and 11 % d.m. at 25 °C. Increase of d.m. of salamis continues slowly in the next three weeks period; the total difference was about 10 % d.m. in the temperature range measured. Decrease of d.m. at 5 °C was noticed in the last week of the measurement. The difference was 3.5 % d.m. This change means that the equilibrium moisture content of the samples of salamis has been reached at the temperature 5 °C. The best sensorial quality of salamis “Vysočina” was in the storage temperature ranged from 15 to 20 °C.

scholarly journals Study on Changes of Textural and Biochemical Properties of Tuna during Ultra-Low Temperature Storage

2016 ◽  
Vol 6 (2) ◽  
pp. 51 ◽  
Author(s):  
Yu-ying PAN ◽  
Xiao-hua QIU ◽  
Jin-sheng YANG
Keyword(s):  
Soluble Protein ◽  
Storage Time ◽  
Storage Temperature ◽  
Frozen Storage ◽  
Biochemical Properties ◽  
Texture Profile ◽  
Low Temperature Storage ◽  
Different Temperatures ◽  
Temperature Storage

<p class="1Body">The effect of TPA and biochemical properties of Yellow Tuna during frozen storage at different temperatures(-18°C, -25°C, -35°C, -45°C<em>, </em>-55°C<em>, </em>-65°C) were studied by measuring the textural characteristics (the hardness, Springiness) salt-solubility of myofibrillar proteins, Ca<sup>2+</sup>ATPase activities. The results indicated that the hardness, springiness, actomyosin salt-solubility, Ca<sup>2+</sup>ATPase activities decreased during the process of frozen storage. Meanwhile, the frozen stored temperature showed great effect on the freezing denaturation of protein (P &lt; 0.05). For the same longer of the storage time, the lower frozen temperature, the less extent of freeze denaturation; Stored in -18°C for three months, the content of Salt soluble protein reduced to zero; Stored in -25°C for 120 <em>days</em>, the content of salt soluble protein also reduced to zero; But stored in -55°C and -65°C, the change is very little. Ca<sup>2+</sup>ATPase activities also reduced to zero after stored in -18°C and -25°C for three months. But stored in -55°C and -65°C, there is no obvious change. Moreover, there is a Positive relationship between the change of texture profile and the content of Salt soluble protein, the lower the storage temperature, the less of the change of texture profile. Therefore, when it is stored in -55°C, the quality of Yellow Tuna can be maintained to the maximum extent within six months.</p>

scholarly journals Effect of temperature on the growth kinetics of Salmonella Enteritidis in cooked ham

2014 ◽  
Vol 58 (1) ◽  
pp. 47-56 ◽  
Author(s):  
Małgorzata Ewa Szczawińska ◽  
Jacek Szczawiński ◽  
Adriana Łobacz
Keyword(s):  
Growth Kinetics ◽  
Salmonella Enteritidis ◽  
Goodness Of Fit ◽  
Effect Of Temperature ◽  
Goodness Of Fit Test ◽  
Bacterial Counts ◽  
Logistic Equations ◽  
Cooked Ham ◽  
Number Of Bacteria ◽  
Microbiological Data

Abstract The aim of the study was to determine a growth rate of Salmonella Enteritidis in cooked ham stored under different temperatures and to compare usefulness of the mathematical models for describing the microbiological data. The samples of cooked pork ham were inoculated with the mixture of three Salmonella Enteritidis strains and stored at 5°C, 10°C, 15°C for 21 d, and at 20°C and 25°C for 5 d. The number of salmonellae was determined at 10 periods of storage at each temperature. From each sample a series of decimal dilutions were prepared and plated onto Brilliant Green Agar. The plates were incubated at 37°C for 24-48 h under aerobic conditions. The colonies grown on culture media were counted, bacterial counts were multiplied by the appropriate dilutions, and number of bacteria (colony-forming units) was calculated. The bacterial counts were transformed into logarithms and analysed using IBM SPSS Statistics 20. The experiment was performed in five replicates. The obtained growth curves of bacteria were fitted to primary growth models, namely Gompertz, logistic, and Baranyi models. The goodness-of-fit test was evaluated by calculating mean square error and Akaike’s criterion. Growth kinetics values from the modified Gompertz and logistic equations were calculated. It was found that in samples of ham stored at 5°C and 10°C for 21 d, the number of bacteria remained almost at the same level during storage. In samples stored at 15°C, 20°C, and 25°C growth of salmonellae was observed. It was found that logistic model gave in most cases the best fit to obtained microbiological data describing the behaviour of S. Enteritidis in cooked ham. The growth kinetics values calculated in this study from logistic equations can be used to predict potential S. Enteritidis growth in cooked ham stored at 15°C, 20°C, and 25°C.

scholarly journals Changes in Biochemical Characteristics and Activities of Ripening Associated Enzymes in Mango Fruit during the Storage at Different Temperatures

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Md. Anowar Hossain ◽  
Md. Masud Rana ◽  
Yoshinobu Kimura ◽  
Hairul Azman Roslan
Keyword(s):  
Shelf Life ◽  
Biochemical Parameters ◽  
Storage Time ◽  
Storage Temperature ◽  
Starch Content ◽  
Titratable Acidity ◽  
Different Temperatures ◽  
Soluble Solid ◽  
Storage Temperatures ◽  
Carbohydrate Contents

As a part of the study to explore the possible strategy for enhancing the shelf life of mango fruits, we investigated the changes in biochemical parameters and activities of ripening associated enzymes of Ashwina hybrid mangoes at 4-day regular intervals during storage at −10°C, 4°C, and30±1°C. Titratable acidity, vitamin C, starch content, and reducing sugar were higher at unripe state and gradually decreased with the increasing of storage time at all storage temperatures while phenol content, total soluble solid, total sugar, and nonreducing sugar contents gradually increased. The activities of amylase,α-mannosidase,α-glucosidase, and invertase increased sharply within first few days and decreased significantly in the later stage of ripening at30±1°C. Meanwhile polyphenol oxidase,β-galactosidase, andβ-hexosaminidase predominantly increased significantly with the increasing days of storage till later stage of ripening. At −10°C and 4°C, the enzymes as well as carbohydrate contents of storage mango changed slightly up to 4 days and thereafter the enzyme became fully dormant. The results indicated that increase in storage temperature and time correlated with changes in biochemical parameters and activities of glycosidases suggested the suppression ofβ-galactosidase andβ-hexosaminidase might enhance the shelf life of mango fruits.

scholarly journals Study on Varying Salt Level and Storage Time on Physico-Chemical and Sensory Quality of Beef Nugget

2014 ◽  
Vol 24 (1-2) ◽  
pp. 149-158
Author(s):  
MAK Talukder ◽  
MA Hashem ◽  
SME Rahman ◽  
MS Islam ◽  
MM Hossain ◽  
...  
Keyword(s):  
Storage Time ◽  
Sensory Quality ◽  
Storage Temperature ◽  
Chemical Properties ◽  
Salt Level ◽  
Physico Chemical ◽  
Significant Difference ◽  
Different Temperatures ◽  
And Storage

The experiment was conducted to find out the effect of salt and storage temperature on the physico-chemical properties of beef nugget. For this purpose nugget samples were divided into two parts; one is called fresh nugget and another is preserved nugget at different temperatures. Then the fresh samples as well as the preserved samples were divided into four subdivisions. Then these are treated with different salt levels (0, 1.5, 3 and 5% salt level). The preserved samples were stored at 4oC and -20oC. Samples preserved at 4oC were stored in the refrigerator for 21 days and were analyzed on 7th day, 14th day and 21th day and samples preserved at -20oC were stored in the refrigerator for 60 days and were analyzed on 15th day, 30th day, 45th day and 60th day of preservation. Dry matter and Ash content of all the samples increased significantly (P<0.01) with the advancement of storage time and salt level. CP% of fresh samples was 22.31, 20.55, 20.13 and 20.55 at 0, 1.5, 3 and 5% salt concentration. CP, DM, Ash and Fat also varied among the samples significantly (P<0.01). Highly significant difference is observed in preserved samples than in fresh samples at different salt levels. Fresh nugget treated with 1.5% salt found to be more acceptable in terms of sensory evaluation. So we recommend fresh nugget to be best for consumption.DOI: http://dx.doi.org/10.3329/pa.v24i1-2.19280 Progress. Agric. 24(1&2): 149 - 158, 2013

scholarly journals Effect of temperature on the survival and growth of freshwater prawns Macrobrachium borellii and Palaemonetes argentinus (Crustacea, Palaemonidae)

2011 ◽  
Vol 101 (3) ◽  
pp. 233-238 ◽  
Author(s):  
Marcela C. Montagna
Keyword(s):  
Growth Rate ◽  
Survival Rate ◽  
Anthropogenic Impact ◽  
Effect Of Temperature ◽  
Freshwater Environment ◽  
Intermolt Period ◽  
Different Temperatures ◽  
Cephalothorax Length ◽  
Survival And Growth ◽  
Size Increment

During the two-month rearing period, the effect of four water temperatures (15°C, 20°C, 25°C and 30°C) on survival rate, number of molts, and growth rate (molt increment and intermolt period) of juvenile Macrobrachium borellii Nobili, 1896 and Palaemonetes argentinus Nobili, 1901 prawns was evaluated in laboratory conditions. The two species showed some similarities in their both survival and growth pattern at different temperatures. The survival rate was highest at 20°C and 25°C, decreasing at the lowest temperature. The number of molts increased at higher temperatures, ranging the intermolt period from 22.2 days to 9.9 days, for M. borellii, and from 20.8 to 9.5 days for P. argentinus, corresponding those values to 15°C and 30°C, respectively. No difference between species was noted in the intermolt period. The size increment by molting increased significantly from 15°C to 25°C, whereas a reduction in the growth of prawns was observed at 30°C. Significant differences among temperatures were found in the slope of regressions between the size increment by molting and the cephalothorax length. M. borellii showed a significantly higher tolerance to elevated temperature and a faster growth (about twice at 25°C) than P. argentinus. These differences could provide M. borellii a competitive advantage for a better adaptation to the dynamic of freshwater environment, especially in areas with anthropogenic impact.

Effect of storage time and temperature on infectivity, reproduction and development of Heterorhabditis megidis in Galleria mellonella

Nematology ◽  
2000 ◽  
Vol 2 (6) ◽  
pp. 635-644 ◽  
Author(s):  
Gerrie Wiegers ◽  
Mari I.C. Boff ◽  
Peter Smits
Keyword(s):  
Body Length ◽  
Storage Time ◽  
Galleria Mellonella ◽  
Storage Temperature ◽  
Storage Period ◽  
Reproductive Capacity ◽  
Effect Of Temperature ◽  
Inoculum Level ◽  
Heterorhabditis Megidis ◽  
And Storage

AbstractThe effect of temperature, dose and storage period on the infectivity and development of Heterorhabditis megidis (strain NLH-E 87.3) infective juveniles (IJ) was studied in the laboratory. IJ were stored at 5, 10, 15 and 20°C for a period of up to 70 days (10 weeks). Every second week, mortality, infectivity, reproductive capacity, time to emergence and length of IJ were examined. Galleria mellonella larvae were infested with doses of one and 30 IJ. As the period of storage increased, the number of active nematodes, the infectivity and the reproduction of IJ decreased both at low and high temperatures. Time to first emergence and body length of IJ were significantly affected by time, storage temperature and inoculum level. Independent of the dose and storage periods, highest infectivity and optimal development were observed when IJ were stored at 10 and 15°C. Effets de la durée du stockage et de la température sur le pouvoir infestant, la reproduction et le développement d'Heterorhabditis megidis parasitant Galleria mellonella - Les effets de la température, de la dose d'inoculum et de la durée du stockage sur le pouvoir infestant et le développement des juvéniles infestants (JI) d'Heterorhabditis megidis ont été étudiés au laboratoire. Les JI ont été stockés à 5, 7, 10, 15 et 20°C pendant une période allant jusqu'à 70 jours (10 semaines). Toutes les 2 semaines ont été examinées: la mortalité, le pouvoir infestant, la capacité de reproduction, la durée de l'émergence et la longueur de ces JI. Les larves de Galleria mellonella ont été infestées à deux doses: un et 30 JI. Lorsque la durée du stockage augmente, le nombre de nématodes actifs, le pouvoir infestant et la reproduction des JI diminuent, aussi bien à basse qu'à haute température. La durée de la première émergence et la longueur du corps des JI ont été significativement affectées par la durée et la température du stockage, ainsi que par la valeur de l'inoculum. De façon indépendante de cette dernière valeur et de la durée de stockage, le pouvoir infestant la plus élevée et le développement optimal ont été observés lorsque les JI sont stockés à 10 et 15°C.

scholarly journals Decrease in the Antioxidant Capacity in Beverages Containing Tea Extracts during Storage

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Tomas Nekvapil ◽  
Vladimir Kopriva ◽  
Vladimir Boudny ◽  
Martin Hostovsky ◽  
Petr Dvorak ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Antioxidant Capacity ◽  
Green Tea ◽  
Storage Time ◽  
Fruit Juice ◽  
Storage Temperature ◽  
Mean Value ◽  
Fruit Juices ◽  
Significant Dependence ◽  
Different Temperatures

The aim of this work was to determine antioxidant capacity of beverages containing black, white, and green tea extracts using the photochemiluminescence method, and to monitor its changes based on the storage temperature and time. Samples were stored at two different temperatures (refrigerated at 4°C and laboratory temperature 22°C), analyzed after opening of the original package, and consequently after 4 and 7 days. Results of the antioxidant capacity are expressed as the standard equivalents, that is, ascorbic acid in mmol/L. The highest mean value of the antioxidant capacity was found after opening of the original package in fruit-juice-enriched samples and totaled 9.793 mmol/L. This group revealed significant dependence (P<0.05) not only on the storage time, but also temperature. In samples without added fruit juices containing preservatives the value was 0.428 mmol/L. This group showed significant dependence (P<0.05) on the decrease of antioxidant capacity only when based on the storage time. Samples without fruit juices or preservatives showed significant decrease in the antioxidant capacity (P<0.05) after 4 days of storage based on the storage time. The dependence on temperature was revealed only after 7 days of storage.

scholarly journals PENANGANAN IKAN NILA (Oreochromis niloticus) HIDUP DENGAN DENGAN MENGGUNAKAN ES SEBAGAI PENGAWET

2017 ◽  
Vol 5 (3) ◽  
pp. 80
Author(s):  
Mafrian Kris Maraja ◽  
Netty Salindeho ◽  
Jenki Pongoh
Keyword(s):  
Mortality Rate ◽  
Storage Time ◽  
Storage Temperature ◽  
Cold Chain ◽  
Optimum Time ◽  
Live Fish ◽  
Randomized Design ◽  
Different Temperatures ◽  
Completely Randomized Design ◽  
And Storage

Imotilization of fish is one way of handling techniques by using low temperature (cooling). Cooling (cold chain) is applied to transport live fish so that the weight of the load during transportation could be reduced and fish do not experience stress during transportation. This technique is more advantageous when compared with the wet transportation system by using water. After the fish fainted, fish could be re-awakened by returning the fish to the pond with the aid of sufficient aeration to facilitate fish regain consciousness. This study aims to determine the rate of stunning, the speed of awareness, and mortality of nile tilapia fish which was treated and stored at different temperatures and times. This study used a factorial completely randomized design (RAL) with 2 treatments namely, storage method (A) treatment consisting of 2 storage levels (Temperature 10-12 ° C and 14-16 ° C); and storage time (B) consisting of 4 levels (2, 4, 6 and 8 hours). The optimum time of fainting fish is at a temperature of 14-16 ° C that is 8.19 min. For re-awakening, the optimum time is 48 seconds when fish was stored for 2 hours. The best mortality rate was achieved at storage temperature ± 14-16 ° C because after 6 hours storage the mortality rate was only 20.8%, but by the maximum storage (8 hours) the mortality has reached 87.5%, Meanwhile at a storage temperature of ± 10-12 ° C, the mortality has reached 50% after 6 hours and 100% at 8 hours.Pemingsanan ikan merupakan salah satu cara teknik penanganan dengan pengunaan suhu rendah (pendinginan). Pemingsanan dengan suhu rendah diaplikasikan untuk transportasi ikan hidup dengan tujuan mengurangi berat beban selama transportasi dan supaya ikan tidak mengalami stress selama transportasi. Teknik ini lebih menguntungkan jika dibandingkan dengan transportasi sistem basah dengan menggunakan air. Setelah dipingsankan ikan kembali disadarkan dengan mengembalikan ikan ke kolam air habitatnya dengan dibantu aerasi yang cukup agar ikan kembali sadar. Penelitian ini bertujuan untuk mengetahui kecepatan pemingsanan, kecepatan penyadaran, dan mortalitas ikan nila yang dipingsankan dan disimpan pada suhu dan waktu berbeda. Penelitian ini menggunakan rancangan acak lengkap (RAL) faktorial dengan 2 perlakuan yaitu, perlakuan metode penyimpanan (A) yang terdiri atas 2 taraf penyimpanan (Suhu 10–12°C dan 14–16°C); perlakuan lama penyimpanan (B) yang terdiri atas 4 taraf (2, 4, 6 dan 8 jam). Waktu optimum kecepatan pingsan adalah pada suhu 14–16°C yaitu 8,19. Untuk penyadaran kembali, waktu optimumnya adalah 48 detik, pada ikan nili yng disimpan 2 jam. Pada penyimpanan suhu ±14-16°C didapat tingkat mortalitas terbaik karena sampai penyimpanan 6 jam tingkat mortalitasnya hanya 20,8%, namun sampai penyimpanan maksimum ( 8 jam) sudah mencapai 87,5%, sedangkan pada suhu penyimpanan ±10-12°C , setelah 6 jam mortalitasnya sudah mencapai 50% dan saat 8 jam tingkat mortalitasnya sudah mencapai 100%.

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