PLEROCERCOID GYMNORHYNCHUS (CESTODA: TRYPANORHYNCHA) IN LEPIDOPUS CAUDATUS: INTERFERENCE ON TMA-N AND TVB-N DETERMINATION

Total Volatile Basic Nitrogen (TVB-N) and Trimethylamine Nitrogen (TMA-N) are the most important freshness indicators in fish. The present report demonstrates that the Gymnorhynchus gigas plerocercoid may interfere on TVBN and TMA-N determination. The study was carried-out on 101 samples: 37 Mp (muscle portions around the parasite), 32 P (larvae of Gymnorynchus gigas extracted from muscle) and 32 Mnp (muscle portions parasite-free), obtained from 10 specimens of Lepidopus caudatus kept at several temperature for different time. The TVB-N and TMA-N contents of each sample were measured using the Conway microdiffusion method. Statistically significant differences (p < 0.05) between Mp and Mnp for TMA-N were found from 24h of storage at 4 and 15°C. No significant differences (p < 0.05) between Mp and Mnp for TVB-N were observed from 48h of storage at 4 and 15°C. TVB-N and TMA-N content was variable in larvae

A new approach to modelling the shelf life of Gilthead seabream (Sparus aurata)

A total of 217 Gilthead seabreams were subdivided in four groups, according to four different storage conditions. All fish were evaluated by both Quality Index Method (QIM) and microbiological analysis, sampling skin, gills and flesh, separately. A QIM score predictive system was set by modelling the growth of microflora of skin, gills and flesh and coupling these predictions to each related partial QIM score (QIMSkin, QIMGills, QIMFlesh). The expression of QIM score as a function of bacterial behaviour was carried out by the employment of two coefficients. The predicted mean bacterial concentrations corresponding to the QIM score at 14 days were always near to Log 8 CFU g^{ -1} in the case of 'S' (skin) and 'G' (gills) series. Moreover, predicted QIM scores were in a good agreement with observed data, reproducing the observed mean time of rejection as well as the bacterial spoilage level (Log 8 CFU g^{ -1}), for all kinds of storage condition

Development of a predictive model for the shelf-life of Atlantic mackerel (Scomber scombrus)

Despite its commercial value, the shelf-life of the Atlantic mackerel (Scomber scombrus) during refrigerated storage was poorly investigated. In this regard, the Quality Index Method (QIM) was proposed as a suitable scoring system for freshness and quality sensorial estimation of fishery products. This study aims to develop a deterministic mathematical model based on dynamic temperatures conditions and a suc-cessive statistical analysis of the results obtained. This model will be exploited to predict the shelf-life of the Atlantic mackerel based on specific storage temperatures. A total of 60 fresh fishes were subdivided into two groups and respectively stored in ice for 12 days at a constant temperature of 1±0.5°C (Group A) and a fluctuating temperature ranging between 1 and 7°C (Group B). Microbiological analysis and sensory evaluation through the QIM were performed on each fish at regular time inter-vals. A critical value of 6 Log cfu/g of spoilage bacteria (mainly psychotropic) associated with a significant decay of the sensorial characteristics was exceeded after 9 days of storage for Group A and 3 days for Group B. A reliable prediction of fish freshness was obtained by modelling the QIM as a function of the spoilage bacteria behaviour. A coefficient β of correlation was determined to convert the spoilage bacteria load into a Quality Index score. The adoption of mathematical predictive models to assess microbial behaviour under different environmental conditions is an interest-ing tool for food industries to maximize production and reduce waste

EFFECT OF SIDEROPHORES AGAINST E. COLI O157:H7

In this study, the inhibiting activity of siderophores produced by Pseudomonas fluorescens against Escherichia coli O157:7 was assayed. Siderophores were extracted from P. fluorescens cultures and preliminarily tested by C.A.S. reagent and UV. The siderophores activity against E. coli O157:H7 was characterised by the determination of Minimal Inhibiting Concentration (MIC). Furthermore, E. coli O157:H7 growth tests with and without siderophores were prepared at 12°C, pH 7 and 5, aw 0.997 and 0,988. The MIC was assessed at 7 μg/ml whereas the growth test showed a high inhibiting activity with the exception of tests at pH 5

Modelling Bacterial Dynamics in Food Products: Role of Environmental Noise and Interspecific Competition

In this paper we review some results obtained within the context of the predictive microbiology, which is a specific field of the population dynamics. In particular we discuss three models, which exploit tools of statistical mechanics, for bacterial dynamics in food of animal origin. In the first model, the random fluctuating behaviour, experimentally meas- ured, of the temperature is considered. In the second model stochastic differential equations are introduced to take into account the influence of physical and chemical variables, such as temperature, pH and activity water, subject to deter- ministic and random variations. The third model, which is an extended version of the second one, neglects the environ- mental fluctuations, and concentrates on the role of the interspecific bacterial interactions. The comparison between expected results and observed data indicates that the presence of noise sources and interspecific bacterial interactions improves the predictive features of the models analyzed

BEHAVIOUR OF Aeromonas hydrophila IN SALTED SWORDFISH SAMPLES

A challenge test for Aeromonas hydrophila in salted swordfish samples was carried out. Particularly, 24 samples (250g) were experimentally contaminated, salted and stored at two different temperature regimes (fluctuating – F group - and non fluctuating – NF group – regime). The count of A. hydrophila, Enterobacteria and Lactic acid bacteria (LAB) as well as the determination of pH and aw were performed at 0, 19 43, 163, 187, 230, 320 and 368 hours whereas the temperature was monitored continuously by using 6 data-loggers. In both group, the mean concentrations of A. hydrophila did not exceed Log 3 cfu/g and decreased below the mean value of Log 1 cfu/g after 368 hours. However in the F group the A. hydrophila growth was slower and the decrease appeared slightly higher than NF group and this suggests the temperature fluctuations induces a more pronounced behaviour variability of A. hydrophila under stressing conditions

Neural bases of reward anticipation in healthy individuals with low, mid, and high levels of schizotypy

A growing body of research has placed the ventral striatum at the center of a network of cerebral regions involved in anticipating rewards in healthy controls. However, little is known about the functional connectivity of the ventral striatum associated with reward anticipation in healthy controls. In addition, few studies have investigated reward anticipation in healthy humans with different levels of schizotypy. Here, we investigated reward anticipation in eighty-four healthy individuals (44 females) recruited based on their schizotypy scores. Participants performed a variant of the Monetary Incentive Delay Task while undergoing event-related fMRI.Participants showed the expected decrease in response times for highly rewarded trials compared to non-rewarded trials. Whole-brain activation analyses replicated previous results, including activity in the ventral and dorsal striatum. Whole-brain psycho-physiological interaction analyses of the left and right ventral striatum revealed increased connectivity during reward anticipation with widespread regions in frontal, parietal and occipital cortex as well as the cerebellum and midbrain. Finally, we found no association between schizotypal personality severity and neural activity and cortico-striatal functional connectivity. In line with the motivational, attentional, and motor functions of rewards, our data reveal multifaceted cortico-striatal networks taking part in reward anticipation in healthy individuals. The ventral striatum is connected to regions of the salience, attentional, motor and visual networks during reward anticipation and thereby in a position to orchestrate optimal goal-directed behavior