Behavior of Listeria monocytogenes in the Presence of Streptococcus lactis in a Medium with Internal pH Control

1990 ◽  
Vol 53 (11) ◽  
pp. 918-923 ◽  
Author(s):  
JANE M. WENZEL ◽  
ELMER H. MARTH
Keyword(s):  
Listeria Monocytogenes ◽  
Starter Culture ◽  
Ph Control ◽  
Experimental Conditions ◽  
Initial Inoculum ◽  
Dairy Foods ◽  
Streptococcus Lactis ◽  
Significant Difference ◽  
Internal Ph ◽  
Before And After

Growth of Listeria monocytogenes strains V7, Scott A, and California (initial inoculum 103/ml) at 21 or 30°C in the presence of Streptococcus Iactis (initial inoculum 0.25 or 1.0%) was determined using a medium with internal pH control (IPCM-1). The pH of the uninoculated medium (control) was 7.0 before and after incubation. Populations of L. monocytogenes in IPCM-1 without S. lactis after 30 h at 21°C were ca. 107/ml for strains V7 and Scott A and ca. 106/ml for strain California, and at 30°C they were ca. 108/ml for all three strains. When data were plotted, areas of graphs between curves representing controls and treatments were calculated to quantitate the extent of inhibition of L. monocytogenes caused by S. lactis. Each such area is called the “area of inhibition” (AI). Growth of the pathogen was inhibited by S. lactis; the degree was dependent on temperature and concentration of lactic culture and, in some instances, strain of Listeria. Greatest inhibition of each strain occurred with the largest inoculum of S. lactis and at the highest temperature. No significant difference (p>0.05) in AI or pH among the three strains was observed at 21°C. At 30°C, strain California was inhibited significantly more (p<0.05) than V7 or Scott A by both concentrations of S. lactis at 24 and 30 h of incubation. No significant difference (p>0.05) in pH was found at this temperature regardless of concentration of S. lactis or strain of Listeria. IPCM-1 inoculated with a lactic starter culture is ready for use at pH 5.5 after 15–18 h of incubation. Inhibition of Listeria was not complete at this pH under any of the experimental conditions. Substantial numbers of L. monocytogenes (103–105 CFU/ml) were present when this medium was ready for use to produce cultured dairy foods.

Behavior of Listeria monocytogenes in the Presence of Lactic Acid Bacteria in an Agitated Medium with Internal pH Control

1991 ◽  
Vol 54 (3) ◽  
pp. 183-188 ◽  
Author(s):  
JANE M. WENZEL ◽  
ELMER H. MARTH
Keyword(s):  
Lactic Acid ◽  
Statistical Analysis ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Lactococcus Lactis ◽  
Ph Control ◽  
Lactococcus Lactis Subsp ◽  
Streptococcus Lactis ◽  
Streptococcus Cremoris ◽  
Internal Ph

An agitated medium with internal pH control (IPCM-2) was inoculated to contain Listeria monocytogenes (strain V7, Scott A or California) at ca. 103 CFU/ml and Streptococcus cremoris (Lactococcus lactis subsp. cremoris) or Streptococcus lactis (Lactococcus lactis subsp. lactis) at 0.25 or 1.0% The inoculated medium was incubated with shaking in a waterbath at 30°C for 30 h. L. monocytogenes and lactic acid bacteria were enumerated and pH was determined at appropriate intervals. The area on a figure between curves for the control and treatment and designated as the area of inhibition (AI) was calculated and used to quantify inhibition of each strain of L. monocytogenes for a particular set of conditions in IPCM-2. Statistical analysis of AI values calculated from data obtained at 6, 24, and 30 h of incubation revealed no significant (p < 0.05) difference in inhibition among the three strains of L. monocytogenes for each type of lactic streptococcus present. Streptococcus cremoris was significantly (0.01 < p < 0.05) more inhibitory to all three strains of L. monocytogenes than was S. lactis at 24 and 30 h of incubation. IPCM-2 is considered ready for use at a pH of 5.4 or less, which was reached between 12 and 15 h of incubation in samples containing 0.25 or 1.0% S. cremoris. Populations of L. monocytogenes in such samples were ca. 104 to 106 CFU/ml regardless of strain of Listeria or percentage of S. cremoris added as inoculum. In samples initially containing 0.25 or 1.0% S. lactis, pH 5.4 was not reached until after 18–24 h of incubation. At this point all three strains of L. monocytogenes had grown to ca. 105 CFU/ml regardless of percentage of S. lactis added as inoculum. Despite the inhibition seen, substantial numbers of the pathogen were present when the medium was ready for use.

scholarly journals Consumer Perception Towards the Enhanced Color of Atypical Dark-Cutting Beef by Nitrite-Embedded Packaging

2019 ◽  
Vol 3 (2) ◽  
Author(s):  
C. Edmundson ◽  
A. Cassens ◽  
G. Mafi ◽  
D. Stein ◽  
A. Riggs ◽  
...  
Keyword(s):  
Ph Control ◽  
Consumer Perception ◽  
State University ◽  
Self Assessment ◽  
Surface Color ◽  
Instrumental Color ◽  
Significant Difference ◽  
Before And After ◽  
Beef Steaks ◽  
Sliding Scale

ObjectivesMeat color is often seen by consumers as an indicator of freshness and wholesomeness. Nitrite-embedded (NE) packaging forms nitric oxide myoglobin, which imparts a bright red color similar to oxymyoglobin. However, limited research has determined the effects of NE packaging to improve the appearance of atypically dark cutting beef. Consumers’ perception of NE packaging ultimately determines its success in the market. Educating consumers through infographics can transfer knowledge more effectively than text alone, potentially being a useful method to introduce and simplify the complexity of NE packaging’s role in improving the surface color of beef steaks. The objectives of this study were to evaluate FreshCase® nitrite-embedded packaging’s effect on atypical dark-cutting beef steaks and to evaluate student consumer perception of nitrite-embedded packaging improving the surface color of beef before and after exposure to infographics containing equal content.Materials and MethodsAtypical dark-cutting (n = 13, pH 5.70 ± 0.09) and normal-pH (n = 13, pH = 5.57 ± 0.1) USDA Low Choice beef strip loins were selected 3 d postharvest. Atypical dark-cutting loins were cut into 2.54 cm thick steaks and randomly packaged in polyvinyl chloride film (PVC) or NE film. Normal-pH control loins were cut 2.54 cm and randomly packaged in PVC overwrap. Packages were placed in a coffin-style retail case under fluorescent lighting for 6 d. Instrumental color was observed every 24 h using a HunterLab MiniScan XE spectrophotometer. The color was determined as a* values and chroma. In the second objective, surveys using a ten-point Likert sliding scale (0 = not familiar at all, 10 = extremely familiar) were randomly allocated and emailed via Qualtrics to students enrolled in the Introduction to Animal Science course at Oklahoma State University. These surveys used a pre-questionnaire to evaluate students’ pre-perception of their knowledge of beef color and NE packaging. After the pre-perception questionnaire students were provided one of the following: a static infographic presented as a still image with annotated graphics, a 46 s video infographic with audio and animated graphics, or both infographic formats. A post-questionnaire followed exposure to students’ respective infographic to evaluate changes in the perception of knowledge.ResultsAtypical dark-cutting steaks treated in NE packaging had higher (P < 0.05, more red intensity) chroma and a* values compared to atypical dark-cutting steaks in PVC on d 4, 5, and 6. There was a significant difference (P < 0.05) in the students’ (n = 288) pre- and post-questionnaire self-assessment of their familiarity with NE packaging. Prior to randomly viewing infographics, students were less familiar (= 3.18) with NE packaging than after viewing infographics (= 6.46). However, there was no significant difference in perceptions (P = 0.22) between viewing the different infographic formats.ConclusionThe results suggest that NE packaging with consumer education can improve their perceptions and knowledge and enhance the appearance of atypical dark-cutting beef.

Fate of Listeria monocytogenes during the Manufacture, Ripening and Storage of Feta Cheese

1989 ◽  
Vol 52 (2) ◽  
pp. 82-87 ◽  
Author(s):  
DEMETRIOS K. PAPAGEORGIOU ◽  
ELMER H. MARTH
Keyword(s):  
Listeria Monocytogenes ◽  
Ph Value ◽  
Standard Procedure ◽  
Starter Culture ◽  
Lactobacillus Bulgaricus ◽  
Cheese Making ◽  
Initial Inoculum ◽  
Feta Cheese ◽  
Salt Brine ◽  
And Storage

The ability of Listeria monocytogenes to grow during the Feta cheese-making process, and to survive during ripening, and storage of the cheese was examined. Pasteurized whole cow's milk was inoculated to contain ca. 5.0 × 103 L. monocytogenes [strain Scott A or California (CA)] cfu/ml and made into Feta cheese according to standard procedure. Lactobacillus bulgaricus, and Streptococcus thermophilus (1:1, v/v) were used as starter culture (1%, v/v). Fresh cheese was placed into sterile 12% salt brine and was held at 22°C for 24 h. Then it was placed into sterile 6% salt brine and held 4 d at 22°C after which it was stored in the same brine at 4°C. Milk, curd, whey, cheese, and brine were tested for numbers of L. monocytogenes and pH. Duplicate samples were used to enumerate L. monocytogenes by surface-plating on McBride Listeria Agar. Selected Listeria colonies were confirmed biochemically, L. monocytogenes was entrapped in curd during cheese-making with the population in curd being 0.92 Log10 cfu/g greater than in the inoculated milk; the whey contained an average of 3.2% of the initial inoculum. L. monocytogenes in cheese increased in numbers by ca. 1.5 Log10 cfu/g during the first 2 d of ripening, the population was 2.33 (S.D. ± 0.12) Log10 cfu/g greater in cheese than in the inoculated milk, with a maximum number of 1.5 × 106 cfu/g. The pH value of 2-d-old cheese decreased to 4.6 and then growth of L. monocytogenes ceased. Both strains of L. monocytogenes survived in Feta cheese for more than 90 d even at the low pH of 4.30 (S.D. ± 0.05) that Feta cheese had after ripening. Strain CA was significantly (P&lt;0.006) less tolerant than strain Scott A, of conditions in the cheese during storage at 4°C.

Enhanced Control of Listeria monocytogenes by Enterococcus faecium KE82, a Multiple Enterocin–Producing Strain, in Different Milk Environments

2016 ◽  
Vol 80 (1) ◽  
pp. 74-85 ◽  
Author(s):  
ELPINIKI VANDERA ◽  
ALEXANDRA LIANOU ◽  
ATHANASIA KAKOURI ◽  
JINBO FENG ◽  
ANNA-IRINI KOUKKOU ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Enterococcus Faecium ◽  
Starter Culture ◽  
Streptococcus Thermophilus ◽  
Raw Milk ◽  
Pcr Analysis ◽  
Dairy Foods ◽  
Reverse Transcription Pcr

ABSTRACT Enterococcus faecium KE82, isolated from traditional Greek Graviera cheese, was identified in pure broth cultures in vitro as a multiple enterocin–producing bacterial strain possessing the structural entA, entB, and entP enterocin genes. E. faecium KE82 was further assessed for in situ antilisterial activity in raw milk (RM) and commercially thermized milk (TM; 63°C for 30 s) in the presence of the indigenous microbiota and in sterile raw milk (SRM; 121°C for 5 min) with or without the addition of two commercial starter culture (CSC) strains Streptococcus thermophilus and Lactococcus lactis. Growth of Listeria monocytogenes was completely inhibited in RM incubated at 37°C for 6 h, whereas the pathogen was significantly inactivated in RM+KE82 samples during further incubation at 18°C for 66 h. In contrast, L. monocytogenes levels increased by approximately 2 log CFU/ml in TM, but in TM+KE82 samples, pathogen growth was retarded during the first 6 h at 37°C followed by growth cessation and partial inactivation at 18°C. After 48 to 72 h, growth of L. monocytogenes in SRM+CSC samples decreased by 4 to 5 log CFU/ml compared with the SRM control, whereas additional 10-fold decreases in the pathogen were observed in SRM+CSC+KE82 samples. Reverse transcription PCR analysis of SRM+KE82 and SRM+CSC+KE82 samples confirmed that the entA and entB genes were transcribed, but entP gene transcription was not detected. All RM and SRM samples inoculated with E. faecium KE82 displayed strong in situ inhibitory activity against L. monocytogenes in well diffusion bioassays, whereas activity was weaker to undetectable in comparable or additional TM+KE82 samples; no milk sample without E. faecium KE82 had activity against L. monocytogenes. The findings of this study indicate that E. faecium KE82 is an antilisterial agent that could be used in traditional dairy foods because it concomitantly produces enterocins A and B in situ in milk.

Relevance Predictability in Information Retrieval Systems

1967 ◽  
Vol 06 (02) ◽  
pp. 45-51 ◽  
Author(s):  
A. Kent ◽  
J. Belzer ◽  
M. Kuhfeerst ◽  
E. D. Dym ◽  
D. L. Shirey ◽  
...  
Keyword(s):  
Information Retrieval ◽  
Experimental Conditions ◽  
Treatment Groups ◽  
Retrieval Systems ◽  
Significant Difference ◽  
Information Retrieval Systems ◽  
High Predictability ◽  
Intermediate Response ◽  
Quantitative Indicators ◽  
Level Of Processing

An experiment is described which attempts to derive quantitative indicators regarding the potential relevance predictability of the intermediate stimuli used to represent documents in information retrieval systems. In effect, since the decision to peruse an entire document is often predicated upon the examination of one »level of processing« of the document (e.g., the citation and/or abstract), it became interesting to analyze the properties of what constitutes »relevance«. However, prior to such an analysis, an even more elementary step had to be made, namely, to determine what portions of a document should be examined.An evaluation of the ability of intermediate response products (IRPs), functioning as cues to the information content of full documents, to predict the relevance determination that would be subsequently made on these documents by motivated users of information retrieval systems, was made under controlled experimental conditions. The hypothesis that there might be other intermediate response products (selected extracts from the document, i.e., first paragraph, last paragraph, and the combination of first and last paragraph), that would be as representative of the full document as the traditional IRPs (citation and abstract) was tested systematically. The results showed that:1. there is no significant difference among the several IRP treatment groups on the number of cue evaluations of relevancy which match the subsequent user relevancy decision on the document;2. first and last paragraph combinations have consistently predicted relevancy to a higher degree than the other IRPs;3. abstracts were undistinguished as predictors; and4. the apparent high predictability rating for citations was not substantive.Some of these results are quite different than would be expected from previous work with unmotivated subjects.

The influence of osteopathic correction on the rate of various rhythms of the body

2019 ◽  
pp. 64-71 ◽  
Author(s):  
A. E. Chernikova ◽  
Yu. P. Potekhina
Keyword(s):  
Heart Rate ◽  
Respiratory Rate ◽  
Age Groups ◽  
Biomechanical Properties ◽  
Dispersion Analysis ◽  
The Body ◽  
Body Tissues ◽  
Age Related ◽  
Significant Difference ◽  
Before And After

Introduction. An osteopathic examination determines the rate, the amplitude and the strength of the main rhythms (cardiac, respiratory and cranial). However, there are relatively few studies in the available literature dedicated to the influence of osteopathic correction (OC) on the characteristics of these rhythms.Goal of research — to study the influence of OC on the rate characteristics of various rhythms of the human body.Materials and methods. 88 adult osteopathic patients aged from 18 to 81 years were examined, among them 30 men and 58 women. All patients received general osteopathic examination. The rate of the cranial rhythm (RCR), respiratory rate (RR) heart rate (HR), the mobility of the nervous processes (MNP) and the connective tissue mobility (CTM) were assessed before and after the OC session.Results. Since age varied greatly in the examined group, a correlation analysis of age-related changes of the assessed rhythms was carried out. Only the CTM correlated with age (r=–0,28; p<0,05) in a statistically significant way. The rank dispersion analysis of Kruskal–Wallis also showed statistically significant difference in this indicator in different age groups (p=0,043). With the increase of years, the CTM decreases gradually. After the OC, the CTM, increased in a statistically significant way (p<0,0001). The RCR varied from 5 to 12 cycles/min in the examined group, which corresponded to the norm. After the OC, the RCR has increased in a statistically significant way (p<0,0001), the MNP has also increased (p<0,0001). The initial heart rate in the subjects varied from 56 to 94 beats/min, and in 15 % it exceeded the norm. After the OC the heart rate corresponded to the norm in all patients. The heart rate and the respiratory rate significantly decreased after the OC (р<0,0001).Conclusion. The described biorhythm changes after the OC session may be indicative of the improvement of the nervous regulation, of the normalization of the autonomic balance, of the improvement of the biomechanical properties of body tissues and of the increase of their mobility. The assessed parameters can be measured quickly without any additional equipment and can be used in order to study the results of the OC.

Validation of a monetary Taylor Aggression Paradigm: Associations with trait aggression and role of provocation sequence

2020 ◽  
Author(s):  
J Konzok ◽  
L Kreuzpointner ◽  
GI Henze ◽  
L Wagels ◽  
C Kärgel ◽  
...  
Keyword(s):  
Random Sequence ◽  
Reactive Aggression ◽  
Reaction Time Task ◽  
Competitive Reaction ◽  
Experimental Conditions ◽  
Fixed Sequence ◽  
Taylor Aggression Paradigm ◽  
Trait Aggression ◽  
Significant Difference ◽  
In Series

© 2020 Elsevier Inc. The Taylor Aggression Paradigm (TAP) is widely used to measure reactive aggression in laboratory settings. While modified versions (mTAPs) with various stimulus characteristics (shocks, noise, pressure, heat) have already been established, a modified version with monetary stimuli has only been introduced very recently. In this experiment, 209 young healthy participants (104 males, 105 females) completed a mock Competitive Reaction Time Task (CRTT) with a fictional opponent with preprogrammed 40 win and 60 lose trials. In lose trials, participants were provoked by subtracting a low (0–20 euro cents), medium (30–60 cents) or high (70–90 cents) amount of money from their fictitious account. Provocation stimuli were either presented randomly or in a fixed sequence (experimental conditions). In contrast to a random sequence, the fixed sequence was generated by repeating trials from the same provocation category in series of three. Linear mixed models (LMMs) considering aggression trajectories revealed significant effects of provocation (low, medium, high) and trait aggression (K-FAF) on reactive aggression. Men showed significantly higher reactive aggression levels than women. In regard to provocation sequence, we found no significant difference in reactive aggression between the random vs. fixed stimulus sequences. The findings provide new evidence supporting the view that the monetary mTAP is able to induce as well as capture reactive aggression in the laboratory. Additionally, we found no advantage of a fixed sequence as the level of reactive aggression in a given trial appeared to be mainly predicted by the preceding provocation trial.

Melatih Kepemimpinan Perangkat Desa Kebonharjo Kulonprogo: Membangun Sikap Anti Korupsi

2018 ◽  
Vol 1 ◽  
pp. 107
Author(s):  
Adi Heryadi ◽  
Evianawati Evianawati
Keyword(s):  
Transformational Leadership ◽  
Data Collection ◽  
Paired Samples ◽  
Significant Difference ◽  
Before And After ◽  
Post Test ◽  
Sample Test ◽  
Corruption Perception ◽  
Measuring Tool

This study aims to prove whether transformational leadership training is effective for building anti-corruption attitudes of villages in Kebonharjo village, subdistrict Samigaluh Kulonprogo. This research is an experimental research with one group pre and posttest design.Subject design is 17 people from village of 21 candidates registered. Measuring tool used in this research is the scale of anti-corruption perception made by the researcher referring to the 9 anti-corruption values with the value of reliability coefficient of 0.871. The module used as an intervention made by the researcher refers to the transformational leadership dimension (Bass, 1990). The data collected is analyzed by statistical analysis of different test Paired Sample Test. Initial data collection results obtained sign value of 0.770 which means> 0.05 or no significant difference between anti-corruption perception score between before and after training. After a period of less than 1 (one) month then conducted again the measurement of follow-up of the study subjects in the measurement again using the scale of anti-corruption perception. The results of the second data collection were analysed with Paired Samples Test and obtained the value of 0.623 sign meaning p> 0.05 or no significant difference between post test data with follow-up data so that the hypothesis of this study was rejected.

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