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Occupation of shallow environments by rhynchonelliform brachiopods is rare during the early late Tremadocian (Tr2). However, in the NW Argentina basin the plectorthoidean Tarfaya purmamarcaensis occupied high-energy environments during this time interval. This species forms up to 15 cm thick monospecific concentrations in shoreface and offshore transition settings, and polytypic pavements in relatively deeper water offshore environments. Generation of such concentrations could be linked to the population dynamics of T. purmamarcaensis. A geometric morphometrics analysis allowed us to recognize four growth stages in the ontogeny of the species. The juvenile phases are absent in high-energy proximal environments and are scarce in the shoreface; in contrast, no representatives of the fourth phase (hypermature adults) have been found in the open platform deposits, and adults are almost absent. Although shell concentrations are usually linked to physical processes (i.e., storm events), the low taphonomic alteration of the shells suggests that transport was not a highly influential factor. Morphological differences (i.e., development of cardinal canals, ribs incurved posterolaterally) in specimens from different environments suggest that the population dynamics could have been the main cause in generating different concentrations. According to the source-sink model, high productivity of brachiopods in the shoreface environment and a passive transport of larvae to the offshore might explain not only the thicker shallow-water concentrations but also the differences in shell growth of populations inhabiting these environments. [ABSTRACT FROM AUTHOR]

Electrical microcurrent therapy (EMT) consists of the application of low intensity (μA) currents that are similar to endogenous electric fields generated during wound healing. To examine the effectiveness and safety of EMT for improving wound healing and pain in people with acute or chronic wounds. Randomized clinical trials (RCTs) assessing the effectiveness of EMT in wound healing published up to August 1st, 2020 were included. The main outcomes were wound surface area, healing time, and number of wounds healed. Secondary outcomes were pain perception and adverse events. A quantitative analysis was conducted using the inverse variance and Mantel-Haenszel methods. Eight RCTs were included in the qualitative summary and seven in the quantitative analysis (n = 337 participants). EMT plus standard wound care (SWC) produced a greater decrease in wound surface [mean difference (MD) = -8.3 cm2; CI 95%: −10.5 to −6.0] and healing time (MD = -7.0 days; CI 95%: −11.9 to −2.1) that SWC alone, showing moderate and low certainty in the evidence, respectively. However, no differences were observed in the number of healed wounds [risk ratio = 2.0; CI 95%: 0.5 to 9.1], with very low quality of evidence. EMT decreased perceived pain (MD = -1.4; CI 95%: −2.7 to −0.2), but no differences in adverse effects were noted between groups (risk difference = 0.05; CI 95%: −0.06 to 0.17). EMT is an effective, safe treatment for improving wound area, healing time, and pain. Further clinical trials that include detailed intervention parameters and protocols should be designed to lower the risk of bias. • First meta-analysis evaluating the effectiveness of external microcurrents devices. • Microcurrents are more effective than standard wound care alone. • Microcurrents are effective and safe in improving wound area, healing time, and pain. • Microcurrents can be equally effective as negative pressure wound therapy. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to examine the effect of dry needling (DN) on the biomechanical properties of a latent medial myofascial trigger point (MTrP) of the soleus muscle compared with an adjacent point within the taut band (TB) measured by myotonometry. Fifty asymptomatic volunteers were randomly assigned to an intervention group (n = 26) or control group (n = 24). One session of DN was performed in every group as follows: 10 needle insertions into the MTrP area (intervention group) or TB area (control group). Myotonometric measurements (frequency, decrement, and stiffness) were performed at baseline (pre-intervention) and after the intervention (post-intervention) in both locations (MTrP and TB areas). The results showed that stiffness outcome significantly decreased with a large effect size after DN in the MTrP when measured in the MTrP location (P =.002; d = 0.928) but not when measured in the TB location. In contrast, no significant changes were observed in any location when the TB was needled (P >.05). The findings suggest that only DN into the MTrP area was effective in decreasing stiffness outcome, therefore a specific puncture was needed to modify myofascial muscle stiffness. [ABSTRACT FROM AUTHOR]

The main aim of this work was to investigate the difference in the excitability of the soleus H-reflex in healthy volunteers following spinal transcutaneous electrical nerve stimulation (TENS) and high-frequency alternating current (HFAC) at a frequency of 10 kHz applied at the lower thoracic spinal level (T10-T12). A double-blind, randomized, crossover, controlled clinical trial was designed. Participants received three randomized interventions (TENS, 10 kHz, and sham stimulation) during 40 min. The amplitude and latency of the soleus H-reflex were registered prior to, during, and 10 min following stimulation. Twenty-four participants completed the study. A significant inhibition of H-reflex amplitude was observed following transcutaneous spinal TENS (12.7%; 95% CI 1.5-22.2%) when compared with sham stimulation (5.5%; 95% CI 3.6-14.5%; p = 0.03). An increase in H-reflex latency was also observed following transcutaneous spinal stimulation at 10 kHz (2%; 95% CI 1.4-2.5%) as compared with sham stimulation (0.7%; 95% CI 0.07-1.3%; p < 0.01). No differences were found between TENS and 10 kHz for H-reflex modulation. Transcutaneous spinal TENS and HFAC at a frequency of 10 kHz had a modulatory effect on the soleus H-reflex when compared to sham stimulation; however, no differences were found between these two interventions. [ABSTRACT FROM AUTHOR]

The purpose of this study was to develop and validate a Spanish version of the Whiplash Disability Questionnaire (WDQ) for the Spanish population with acute whiplash-associated disorder (WAD). This was a cross-sectional questionnaire validation study. Adults with acute WAD (grade I to III) were enrolled within 3 weeks of their injury. A blinded forward and back translation of the WDQ was made from English to Spanish, and the resulting back-translation version was compared with the original. Patients with WAD completed the Spanish version of the 13-item WDQ. The developed questionnaire was assessed using psychometric statistical analysis including correlation with the numerical rating score for pain, Northwick Park Neck Pain Questionnaire, Neck Disability Index, and 36-item Short Form Health Survey. Fifty-six patients completed the questionnaire, the mean age was 33.9 years (standard deviation [SD] = 10.5), and 76.8% were women. Participants were enrolled 13.9 days (SD 4.9) after the injury, with 14.3% presenting with WAD grade I and 85.7% with WAD grade II. The mean WDQ score was 62 (SD = 31). Two factors were detected, and the factor structure remained stable after translation. Positive correlations were identified between the total WDQ score and the numerical rating score, Neck Pain Questionnaire, and Neck Disability Index results, with a strong negative correlation with the 36-item Short Form Health Survey. The Spanish version of WDQ is psychometrically reliable and a valid instrument to measure the disability status in patients with acute WAD within the clinic. [ABSTRACT FROM AUTHOR]

The Patagonian Continental Shelf (PCS) is a dynamic region characterized by the confluence of two western boundary currents (the Brazil and Malvinas currents) and the presence of several oceanographic fronts, giving rise to a large and rich biological area. In this study we analyze the distribution pattern of brachiopod assemblages along a latitudinal range between 39°S and 55°S, including the relationship with different physical factors of the benthic zone, either measured in situ (depth, sediment, water temperature, and salinity) or provided by the Bio-ORACLE database (water temperature, salinity, phosphate concentration, nitrate concentration, dissolved oxygen concentration, primary productivity, phytoplankton, and current velocity). Data show that articulate brachiopods were not homogeneous in terms of species composition, body size, relative abundance and taphonomic signatures along the latitudinal gradient, thus indicating environmental sensitivity. The brachiopod assemblages throughout the gradient are characterized by the dominance of Magellania venosa , especially in the internal sector of the platform, accompanied by Terebratella dorsata towards the slope, and Liothyrella uva in the southern sector. Based on all available information, it appears that the main physical factors that affect the distribution of articulate brachiopods from the PCS were sediment grain size and water flow velocities. Also, in M. venosa shells, sediment grain size is also associated with fragmentation, abrasion and encrusting by invertebrates. Finally, the larger sizes of M. venosa appear to be associated with higher productivity areas rich in phytoplankton and suitable environmental water energy. [ABSTRACT FROM AUTHOR]

The attractiveness of airlines is a topic of great interest to researchers and professionals wishing to understand the ability of airlines to attract and satisfy air passengers. However, there is a lack of consensus on which attributes of the airline are important for attracting and satisfying passengers. In general, previous studies have mostly focused on a limited number of attributes affecting a passenger's choice of airline, satisfaction, behaviour and loyalty. This study aims to develop a model to measure the importance of airline attributes, a model which could be adopted by future research on airline attractiveness. Besides a review of previous empirical research on the topic, an empirical study was conducted among air passengers at a major international airport in Spain. Results revealed the existence of eight categories of attributes that are important for airline passengers. The most important categories were: ‘safety and punctuality’, ‘ticket price’, and ‘attention and service during the customer journey’. In addition, air travel frequency and socio-demographic characteristics affected the perceived importance of the categories of attributes. For instance, air travel frequency had a positive influence on the importance passengers attach to ‘safety and punctuality’, ‘flight schedule and connections’, and ‘in-flight space’. [ABSTRACT FROM AUTHOR]

Background Many substances poured out from industries can be toxic to humans and can impair physical performance. Besides, physical training may modify the body concentrations of these substances as a result of physiological adaptations. Objectives The aim of the study was to determine if different modalities of exercise might affect serum concentrations of toxic trace elements in sportsmen. Methods 80 Spanish national sportsmen were recruited before the start of their training period. All the athletes had been training regularly for the previous two years with a rigorous training target at high-level competition. 31 sedentary participants from the same geographic area formed the control group. Serum arsenic, beryllium, cadmium, cesium and lead samples were analyzed with an ICP-MS. Results Serum concentrations were higher among the sportsmen group than among the control group, being highly significant in cases of Be from 0.043 ± 0.019 to 0.074 ± 0.029 μg/L, Cs from 0.693 ± 0.305 to 1.358 ± 0.569 μg/L and Pb from 0.162 ± 0.171 to 2.375 ± 1.699 μg/L; and significant in the case of Cd from 0.046 ± 0.027 to 0.067 ± 0.059 μg/L. However, if they were separated according to different sport modalities, it was found that, although they had higher concentrations than controls, there were elements that changed their concentrations in relation to the metabolic type of activity performed. Conclusions In some cases physical exercise induces favorable adaptations to avoid environmental pollution damage. Endurance training (65–75% VO 2max ) can be considered the most effective exercise to prevent toxicity effects. However, integral-matrixes analysis are required in further research to overcome some controversial behaviors of some elements. [ABSTRACT FROM AUTHOR]

Omega-3 polyunsaturated fatty acids (PUFAs), such as docosaexaenoic acid (DHA) and eicosapentaenoic acid (EPA), mediate neuroactive effects in experimental models of traumatic peripheral nerve and spinal cord injury. Cellular mechanisms of PUFAs include reduced neuroinflammation and oxidative stress, enhanced neurotrophic support, and activation of cell survival pathways. Bioactive Omega-9 monounsaturated fatty acids, such as oleic acid (OA) and 2-hydroxy oleic acid (2-OHOA), also show therapeutic effects in neurotrauma models. These FAs reduces noxious hyperreflexia and pain-related anxiety behavior following peripheral nerve injury and improves sensorimotor function following spinal cord injury (SCI), including facilitation of descending inhibitory antinociception. The relative safe profile of neuroactive fatty acids (FAs) holds promise for the future clinical development of these molecules as analgesic agents. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá. [ABSTRACT FROM AUTHOR]

This study aims to identify the different needs for accommodation renovation at mature destinations, as well as to analyse the effect of these needs on a tourist's overall impression regarding the need to renovate the accommodation. From the literature review, six categories of accommodation renovation are identified and tourist attitudes towards them are assessed using the case of Gran Canaria, a mature coastal destination in Spain. Results include a model explaining tourists’ overall impression concerning the need to rejuvenate the accommodation based on the different categories of renovation. A significant negative association between a tourist's evaluation of the overall need for renovation and his/her overall satisfaction is also confirmed. Professional implications in terms of policies and strategies for rejuvenating accommodation on Gran Canaria are suggested, most of which could be of interest for other mature destinations. [ABSTRACT FROM AUTHOR]

Highlights: [•] We propose a fully consistent two-layer dynamic real-time architecture for a special class of hybrid systems. [•] The arising challenges for solution methods are discussed when (hybrid) eNMPC is applied. [•] The fast hybrid neighboring-extremal controller (NEC) on the lower layer ensures consistency by considering the same economic optimal control problem as the hybrid eNMPC. [•] The NEC avoids infeasibilities and steers the process to its operational bounds under disturbances. [•] An important step towards integrated scheduling and control is taken. [Copyright &y& Elsevier]

Abstract: This work focuses on control design for input-output feedback linearizable nonlinear systems with bounded inputs and state constraints in the presence of uncertainty. Controllers based on Lyapunov’s direct method have been synthesized before for this class of nonlinear systems to enforce asymptotic stability in the presence of bounded inputs. However, none of these controllers accounts explicitly for state constraints. In order to address this task, we propose an optimization-based design method for which two properties will be guaranteed simultaneously despite parametric uncertainty, namely, closed-loop stability with bounded inputs and feasibility of the transient in the presence of state constraints. [Copyright &y& Elsevier]

Abstract: In this work the normal vector method is extended to the simultaneous treatment of parametric uncertainty and disturbances. This method ensures that desired dynamic properties hold despite parametric uncertainty by maintaining a minimal distance between the operating point and so-called critical manifolds where the process behavior changes qualitatively. Here, unknown exogeneous disturbances and uncertain model and process parameters are considered simultaneously. To address this simultaneous problem formulation, the augmented systems developed for only parameterized disturbances in previous works have to be modified and extended. A generalized formulation of the robust optimization problem results, which includes normal vector constraints on critical manifolds of steady states and of bounds on the state transient. The numerical methods are further developed to prepare for the treatment of high-dimensional problems. Illustrative case studies considering the design of a continuous mixed-suspension mixed-product removal crystallization process and the Tennessee Eastman process are presented. [Copyright &y& Elsevier]

Abstract: Trees dispersed in pastures are a prominent feature of many Central American landscapes, particularly in cattle producing regions where farmers retain trees to serve as shade, fodder, timber and firewood. The presence of dispersed trees in pastures is often considered as important for the conservation of biodiversity by providing habitat and enhancing landscape connectivity. However, despite their critical productive and environmental roles, little is known about tree distribution within pastures or how farmers’ management decisions influence the trees themselves and their impact on farm productivity and biodiversity conservation. Here, we present a synthesis of (a) the abundance, composition, and size of dispersed trees in four important cattle producing regions of Costa Rica (Caňas and Río Frío) and Nicaragua (Rivas and Matiguás), based on inventory of 18,669 trees on 1492ha of pasture, (b) the local knowledge, management and use of trees by cattle farmers, and (c) opportunities for ensuring sustainable management of dispersed trees in pasture-dominated landscapes. Dispersed trees were common in all four landscapes, with mean frequency ranging from 8.0treesha−1 in Caňas to 33.4treesha−1 in Matiguás. A total of 255 tree species were found in pastures across the four landscapes. The total number of tree species per landscape varied from 72 in Rivas to 101 in Caňas and Rio Frio, with mean species richness per farm ranging from 22.9 in Rio Frio to 45.9 in Matiguás. In all four landscapes, a handful of tree species dominated the pastures, with the ten most abundant species in each landscape accounting for >70% of all trees recorded. Most of these common tree species provide fruits or foliage eaten by cattle, or are important timber or firewood species, and are deliberately retained by farmers for these uses. In all four landscapes, farmers had a detailed knowledge of tree attributes affecting pasture and animal productivity, and influenced tree cover through pasture management activities and occasional tree cutting. Current farm management practices are gradually decreasing the diversity of trees in pastures, and in some cases also tree density, reducing their contribution to farm productivity and biodiversity conservation. To reverse this trend, incentives are required to encourage cattle farmers to retain and enhance tree cover in pastures, through the adoption of pasture management practices that favor the regeneration and persistence of a diverse range of tree species. [Copyright &y& Elsevier]

The aim of this study was to compare serum vanadium (V) concentrations between athletes of different sports modalities and people who did not practise physical exercise regularly. One hundred and twenty-one subjects divided into a control group (CG; n = 37; 1.75 ± 0.03 m; 79.45 ± 10.20 kg; 24.72 ± 6.06 years) and an athletes' group (AG; n = 84; 1.77 ± 0.05 m; 66.34 ± 6.12 kg; 19.57 ± 1.95 years) participated in this research. AG were classified by sports modality: aerobic (AE; n = 26), anaerobic (ANA; n = 22); aerobic-anaerobic (AE-ANA; n = 36). Serum V concentrations were analysed by inductively coupled plasma mass spectrometry. AG showed higher V concentrations compared to CG (p < 0.01). AE obtained higher concentrations compared to ANA and AE-ANA (p < 0.05). Physical training could increase serum V levels. Specifically, aerobic sports modalities could increase serum V levels to a greater extent than other sports modalities. [ABSTRACT FROM AUTHOR]

Abstract: Measuring conductivity in aqueous solutions is a problem which is not easy to solve due to the differences in mass and mobility that exist between ions conduction and electrons. Additionally, it is necessary to keep in mind the interaction processes electrode-solution. As a consequence, the electrolytic conductivity cell has to be polarized with alternating voltage of adequate amplitude and frequency in order to extract the correct information. In this paper an electronic conditioning circuit is presented which converts electric conductivity into a value of continuous voltage. A hardware solution is proposed to do the conductivity temperature compensation. Experimental results obtained in KCl solutions are also offered by following a close discussion of them. [Copyright &y& Elsevier]

Accommodation companies offer a product of strategic interest to tour operators insofar as it determines to a great extent the cost of a package vacation, while it also significantly influences the degree of satisfaction of the tourists who purchase such packages. That, together with the increasingly competitive rivalry among European tour operators, suggests how important it is for the tour operators to exercise some control over the accommodation companies with which they deal. This study describes the control that German and British tour operators exercise over the accommodation companies with whom they do business and the characteristics of the two types of companies that influence that control. [Copyright &y& Elsevier]

This study aims to determine the changes induced by a maximal exercise test until exhaustion on the serum and urinary concentrations of Magnesium (Mg), Phosphorous (P), Rubidium (Rb) and Strontium (Sr) in athletes (AG) and sedentary students (SG). Fifty subjects participated in the study divided into two groups. In AG there were twenty-five male athletes and in SG there were twenty-five male sedentary students. Both groups performed an exercise test until exhaustion, starting at 8 or 10 km/h respectively, and increasing the speed at 1 km/h every 400 m. Serum and urine samples were obtained from all participants before and after the test. Regarding the basal status, AG showed lower values of Mg in serum (p < 0.05) and urine (p < 0.01), but higher concentrations of serum P (p < 0.05) in comparison to SG. Comparing the pre and post-test values, corrected or non-corrected for hemoconcentration in serum and for creatinine in urine, AG showed a decrease in serum Mg (p < 0.05), in serum P (p < 0.01) and in urinary Sr (p < 0.01) while an increase was observed in urinary P (p < 0.05) and in urinary Rb (p < 0.05). It can be concluded that a treadmill test until exhaustion leads to changes in serum and urinary concentrations of minerals in both AG and SG males. This may reflect an adaptive response of the body to overcome the physical stress and, in some cases, to avoid loss of these elements. [ABSTRACT FROM AUTHOR]

In chocolate manufacturing, the conching process is one of the main stages during which rheological and sensorial characteristics of the chocolate are developed. Additionally, it is one of the most extensive stages, which reflects the high levels of energy consumption and limited capacities of the equipment used in production plants. To reduce operating time guaranteeing the desired chocolate quality, it is necessary to understand the phenomena that govern the dynamic behavior of the conching process. Thus, the aim of this work is to construct a phenomenological based semi-physical model to predict an indicator of the chocolate's sensory quality, namely "Conching Degree" (CD). The CD is calculated using the concentrations of two key volatile compounds: tetramethylpyrazine (TMP) and benzaldehyde (BA). Concentration profiles of TMP and BA, as well as moisture content (H%), are predicted by the model for the duration of the conching process of a semi-sweet chocolate. The chocolate quality is validated analyzing the chocolate's sensory profile. The obtained results allow to establish a model for predicting of the CD of the product with a value of 0.60 (mg∕kg) − 1 during 750 min of processing with an error rates of less than 10%. According to the sensory results, a greater CD improves the general quality and increases the chocolate notes in the product. Furthermore, we propose that reducing the conching time from 750 to 630 min does not significantly modify the sensory quality of the product, and results in the optimization of 100 h processing per month. • Mathematical model for predicting the "Conching Degree" evolution of chocolate. • The model predicts "Conching Degree", a key chocolate's sensorial quality indicator. • The model predicts chocolate flavor properties with an error rate of less than 10%. • The model contributes to the development of chocolate products.. • The model is a tool for proposing possible process modifications for optimization. • The model enables standardize processses to maintain the product's sensorial quality [ABSTRACT FROM AUTHOR]

• A stochastic strategic public transport equilibrium model was developed. • The approach captures the variability in users' choices due to uncertainty. • User choices of access/alighting stops, line, and transfer/egress are modelled. • The model is calibrated with passive data from smart cards transactions and GPS. • The model predicts correctly the assignments observed in a massive system dataset. A strategic public transport equilibrium model is developed that considers each user's trip decision, covering the choices of access stop, mode and line, alighting stop, and transfer or egress. At each stage, these choices are considered to be stochastic and made under capacity constraints resulting in waiting time increases at stops and stations due to demand levels and/or arriving vehicle loads. The modeling strategy is based on the hyper-path concept, but rather than evaluate user strategies, the approach models transitions at all individual nodes, thus facilitating computational efficiency. In this approach, we develop a recursive method different from resolving explicitly a recursion based on Bellman´s equation, which is suitable for large and dense transit networks. A method is presented for estimating the model parameters, which was applied to the real case of the Santiago, Chile transit system based on passive transaction datasets generated by users' smart cards and GPS technology aboard the system's buses. These data were used to estimate alighting stops and an exhaustive and disaggregate reconstruction of all user trips. Once calibrated, the model proved able to predict the trip assignments observed in the calibration dataset as well as datasets from later periods, making predictions that closely fit the observations and adapting well to changes in network topology, operating patterns, and user demand. Therefore, the model should have considerable potential as a powerful, flexible, and highly useful tool for system regulators and operators who define public transport structures, operations, and policies. [ABSTRACT FROM AUTHOR]

Meat color is attributed to myoglobin concentration and redox state. Myoglobin is a water-soluble hemoprotein with iron in its prosthetic group, which defines myoglobin's redox state via its valence state and ligand linked to the free coordination site. In fresh meat, myoglobin can be in one of three states in dynamic equilibrium: deoxymyoglobin, oxymyoglobin, and metmyoglobin. Myoglobin can chemically interact with numerous components in meat products, affecting its redox state. These structural alterations in myoglobin caused by processing conditions will affect its thermal stability and consequently meat product color. Presently, cured meat products are made with sodium nitrite, a curing agent that reacts with myoglobin in meat, forming nitrosomyoglobin, a stable compound that gives the final meat product a distinctive pink color. This work proposes a mathematical model for understanding myoglobin structural changes during the production of a cured meat product. Because of the phenomenological structure of the established model, valuable knowledge is obtained, allowing new possibilities to be explored in the color of meat products while considering the chemical state of myoglobin. The proposed phenomenological model is validated with an error of roughly 10%. • Mathematical model for understanding myoglobin structural changes of meat products. • Relationships between myoglobin structural changes and color in the meat product. • Reducing NaNO_2 employed in color generation and residual nitrite in meat products. • The model allows new possibilities to be explored in the color of meat products. [ABSTRACT FROM AUTHOR]

The conching process is one of the main stages of chocolate manufacture involving the development of sensory attributes and the product rheological properties. At the current operation of the conching process, the on-line estimation of quality properties that define an optimal development of the chocolate is not possible. In that sense, the on-line estimation of the "Conching Degree" (CD) as a flavor quality indicator and the chocolate viscosity as a textural quality attribute are fundamental tasks for guaranteeing process monitoring and real-time decision making. To this aim, this paper proposes a Moving Horizon Estimator (MHE) for the on-line estimation, instead of measurement, of the CD and the viscosity of chocolate. In this formulation, only available physical measurements of process variables easy to obtain are required, avoiding time-consuming and extensive conventional laboratory methods to quantify these chocolate's quality indicators. The estimator is designed as an optimization problem over a moving horizon, constrained to a Phenomenological Based Semi-Physical Model (PBSM) describing the conching process main phenomena. The performance of the proposed estimator is evaluated by simulation with data from a real plant. Finally, the proposed optimization-based estimation structure allows estimating the CD and the viscosity of chocolate with estimation indices errors lower than 6% considering only two available measurements in the process. • Moving Horizon Estimator (MHE) for the estimation of CD and viscosity of chocolate. • CD and viscosity of chocolate are estimated considering only two measurements. • The estimator is constrained to a Phenomenological Based model describing the conching process. • The estimation of CD and viscosity allows real-time process monitoring. • The estimator uses easy-to-obtain measurements avoiding extensive laboratory methods. [ABSTRACT FROM AUTHOR]

The conching process is a crucial stage in chocolate manufacturing involving the development of sensory attributes and rheological properties of the product in three phases: dry, plastic, and liquid. This research creates a Phenomenological Based Semi-Physical Model for predicting the chocolate structural changes during conching process. The model was constructed by applying the methodology proposed by Álvarez etal. (2009). Sampling involved all phases of conching for semi-sweet chocolate. The study of the rheological behavior of the chocolate, in the dry and plastic phases involved the extrusion test for the semi-solid samples. For the liquid phase, the rheological data was generated through a bob-cup rheometer. Rheological parameters of the Herschel–Bulkley model including yield stress (σ o), consistency index (k), and flow index (n) were determined for all samples. A microstructural analysis was conducted to qualitatively validate the structural changes. This analysis revealed coating of the solid particles by fat released from the mechanical impacts on the product. Additionally, the strong relationships between rheological parameters and structural changes are due to the released fat. The created model predicts the viscosity within the accepted range for guaranteeing the rheological quality of product, i.e, 5.3 [ Pa*s] for shear rate of 40 s − 1 , measured by rheometer. Additionally, operational conditions were varied during the simulation to evaluate the viscosity behavior. The model provides a tool for proposing possible process modifications for optimization without affecting the rheological quality of the product. • Mathematical model to predict the evolution of chocolate's rheological variables. • The model predicts viscosity accepted values for the product's rheological quality. • The model establishes strong relationships between rheology and microstructure. • The model contributes for the development of chocolate products. • The model is a tool for proposing possible process modifications for optimization. • The model enables standardize process to maintain the product's rheological quality. [ABSTRACT FROM AUTHOR]