Search

In this work, we develop a kinetic model of tumour growth taking into account the effects of clinical uncertainties characterising the tumours' progression. The action of therapeutic protocols trying to steer the tumours' volume towards a target size is then investigated by means of suitable selective-type controls acting at the level of cellular dynamics. By means of classical tools of statistical mechanics for many-agent systems, we are able to prove that it is possible to dampen clinical uncertainties across the scales. To take into account the scarcity of clinical data and the possible source of error in the image segmentation of tumours' evolution, we estimated empirical distributions of relevant parameters that are considered to calibrate the resulting model obtained from real cases of primary glioblastoma. Suitable numerical methods for uncertainty quantification of the resulting kinetic equations are discussed and, in the last part of the paper, we compare the effectiveness of the introduced control approaches in reducing the variability in tumours' size due to the presence of uncertain quantities. • New kinetic model for tumour growth with clinical uncertainties. • The action of therapeutic protocols steers the tumours' volume towards a target size. • The introduced therapies reduce the variability due to uncertain quantities. • Calibration of the model based on MRI scans. • Examples based on UQ methods for kinetic equations. [ABSTRACT FROM AUTHOR]

Highlights: [•] The kinetics of phenolic content of some fresh-cut produce during storage was modeled. [•] A model based on two-irreversible consecutive reactions was used to fit experimental data. [•] Literature data and specific experimental trials were used to validate the model. [•] The model precisely fitted the trend of phenolic compounds of all fresh-cut fruit and vegetable samples studied. [•] The model could be used to understand the change of phenolic compounds due to wounding and to better predict shelf-life. [Copyright &y& Elsevier]

Abstract: Fresh-cut artichokes were treated with cysteine in the form of aqueous solutions of l-cysteine hydrochloride monohydrate at 0.5% (w/v) normal pH 2.2 adjusted to different pH values with NaOH (from 2 to 7). General appearance and colour measurements during storage at 5°C showed different degrees of suppression of darkening on cut surfaces. Cysteine pre-treatments caused an increase in the yellow index (b* value) of fresh-cut artichokes compared to untreated samples, which was more pronounced at lower pH (47.9 versus the initial value of 28.3 after 1 day). Artichokes treated at lower pH values also had a lower appearance score and higher PPO activity than artichokes treated at higher values, closer to neutrality. Starting from 3 days of storage a negative correlation between solution pH and PPO activity was also observed, that for artichokes treated with cysteine at pH 7 was lower than for control samples. l-cysteine pre-treatments did not affect total phenolic content and antioxidant activity of fresh-cut artichokes, which showed an increasing pattern after 8 days. These data may represent an important step in prevention of browning in fresh-cut artichokes. [Copyright &y& Elsevier]

The aim of this paper was to obtain a more realistic shelf life estimation of fresh-cut lettuce by considering several sensorial, physical and chemical attributes. The Multivariate Accelerated Shelf Life Testing (MASLT) approach was applied, comparing the use of the traditional zero- and first- order reactions with the Weibullian logistic model in describing score change kinetics over time. A total variance of 79.6% was explained by two principal components (PC): PC1 (68.8%) and PC2 (10.8%). The multivariate degradation kinetics was better described by a zero-order reaction, yielding an r 2 value greater than 0.97, while the temperature dependence of the multivariate rate constant, k m , was well-fitted by the log-logistic model. A cut-off criterion of −1.52 was calculated, leading to shelf life estimations of ∼12.4, ∼10.4 and ∼3.7 days for fresh-cut lettuce stored at 0, 5 and 15 °C, respectively. This method provides an overall and accurate description of the degradation phenomena occurring during the storage of fresh-cut lettuce. [ABSTRACT FROM AUTHOR]

The shelf life (SL) of fresh rocket leaves stored at 0, 5 and 15 °C was studied using a non-linear model. In particular, the cumulative form of the Weibull equation and a log-logistic model were, respectively, used to fit the experimental data over time and to study the temperature dependence of the degradation rates for several sensorial, chemical and physical attributes. The Weibullian model fit the experimental data, exhibiting correlation coefficients between 0.950 and 0.996; when using traditional first-order kinetics, this value ranged from 0.902 to 0.985. Additionally, a log-logistic model that could accurately describes the temperature dependence of the Weibull parameters also accounting for the thermal history of the product. Due to the different degradation patterns of the degradation curves, the definition of the shelf life significantly changed based on the quality attributes and the storage temperatures. In particular, when the samples were stored at 5 °C, the appearance score limited the shelf life, exhibiting value of 5.8 days; when non-isothermal conditions were considered, the ascorbic acid content became the critical factor due to its major sensitivity toward temperature abuse. Results may be useful for planning produce logistics with fully automated distribution steps and better managing stocks, according to thermal history and, possibly, the priorities of potential customers. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this research was to identify, quantify and compare the main quality parameters and functional compounds of ‘Parthenon’ broccoli florets stored at two different conditions. The first condition consisted in a modified atmosphere packaging (MAP) using microperforated polypropylene plastic. Then, the second one was in an unpackaged storage (Control). The main quality parameters assessed in this research were the overall appearance, odour, weight loss and colour. While, the functional compounds evaluated in this study were the chlorophyll and carotenoid pigments, vitamin C, total phenol content and intact glucosinolates, as well as the in vitro antioxidant activity. The results indicated that the loss of quality was lower in MAP than in Control samples when comparing with Fresh sample. In addition, the weight loss in MAP samples was 0.75% while in the Control samples was 3.36% at the end of storage. Besides, the losses of external attributes were also more pronounced in Control than in the MAP samples. Moreover, this degradation tendency was also observed for bioactive compounds, where their retention in the MAP was higher than in Control samples. In fact, the loss of total phenol content and intact glucosinolates content in MAP samples was about 20 and 23%, respectively, while in Control samples was about 48% and 57% correspondingly. This was also observed in the antioxidant activity (AA) values, since AA is correlated with these functional compounds. [Copyright &y& Elsevier]

Abstract: Fresh-cut processing can add convenience to artichoke consumption, although post-cutting browning is still a major problem. Different compounds (ascorbic acid, citric acid, cysteine, and their combination, ethanol, sodium chloride, 4-hexylresorcinol) were tested at different concentrations in two experiments. An algorithm for rapid colour measurements by means of image analysis was implemented, and allowed measurement of L*, a*, and b* values from the whole quarter surface and from the browned areas, while the external appearance of artichoke quarters was evaluated using an anchored subjective scale. Cysteine (0.5%) was the most effective treatment to prevent browning as evaluated by colour attributes and appearance score. Its effectiveness was improved by increasing the pH of the solution from the natural pH (2.1) to pH 3, resulting in L* values of browned areas about 30% higher than controls (27.4 and 21.5 respectively). The mean values of appearance scores for cysteine treated samples were all above the limit of marketability (score 3), significantly higher than in control samples which had mean values below this limit. All colour parameters were significantly correlated with appearance scores, and L* of the whole quarter surface had the highest correlation. The results represent a step forward in research on anti-browning treatments for fresh-cut artichokes, also providing an objective tool for colour evaluation. [Copyright &y& Elsevier]