Modelling volume change and deformation in food products/processes: An overview

Volume change and large deformation occur in different solid and semi-solid foods during processing, e.g., shrinkage of fruits and vegetables during drying and of meat during cooking, swelling of grains during hydration, and expansion of dough during baking and of snacks during extrusion and puffing. In addition, food is broken down during oral processing. Such phenomena are the result of complex and dynamic relationships between composition and structure of foods, and driving forces established by processes and operating conditions. In particular, water plays a key role as plasticizer, strongly influencing the state of amorphous materials via the glass transition and, thus, their mechanical properties. Therefore, it is important to improve the understanding about these complex phenomena and to develop useful prediction tools. For this aim, different modelling approaches have been applied in the food engineering field. The objective of this article is to provide a general (non-systematic) review of recent (2005–2021) and relevant works regarding the modelling and simulation of volume change and large deformation in various food products/processes. Empirical-and physics-based models are considered, as well as different driving forces for deformation, in order to identify common bottlenecks and challenges in food engineering applications.Fil: Purlis, Emmanuel. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Cevoli, Chiara. Università di Bologna; ItaliaFil: Fabbri, Angelo. Università di Bologna; Itali

Can the outside-in half-tunnel technique reduce femoral tunnel widening in anterior cruciate ligament reconstruction? A CT study

There are different techniques for drilling the femoral tunnel in the anterior cruciate ligament reconstruction (ACLR), but their influence in the bone tunnel enlargement in unknown. The purpose of this study was to compare two different surgical techniques for evaluating femoral tunnel enlargement in ACLR. The hypothesis was that tunnel placement using the outside-in technique leads to less tunnel enlargement compared to the transtibial technique. METHODS: Forty-four patients treated for ACLR between March 2013 and March 2014 were prospectively enrolled in this study. According to the surgical technique, subjects were assigned to Group A (Out-in) or Group B (Transtibial). All patients underwent CT examination in order to evaluate the femoral tunnel enlargement at four different levels. Moreover, all patients were evaluated with the Lachman test and pivot shift test, and the KT1000 arthrometer was used to measure the anterior laxity of the knee. A subjective evaluation was performed using the 2000 International Knee Documentation Committee Subjective Knee score, Lysholm knee score and Tegner activity scale. All patients were assessed after 24 months of follow-up. RESULTS: At the final follow-up, there were statistically significant differences (p 0.05). CONCLUSIONS: In ACLR with a suspension system, the outside-in technique leads to less enlargement of the femoral tunnel lower than the transtibial technique. KEYWORDS: Anterior cruciate ligament reconstruction; CT imaging; Drilling technique; Femoral tunnel enlargement PMID: 28389757 DOI: 10.1007/s00590-017-1950-8 Share on FacebookShare on TwitterShare on Google+ LinkOut - more resource

NUMERICAL SIMULATION OF PHYSICAL SYSTEMS IN AGRI-FOOD ENGINEERING

In agri-food engineering many complex problems arise in plant and process design. Specifically the designer has to deal with fluid dynamics, thermal or mechanical problems, often characterized by physics coupling, non-linearity, irregular geometry, anisotropy and in definitive rather high complexity. In recent years, the ever growing availability of computational power at low cost, made these problems more often approached with numerical simulation techniques. Mainly in terms of finite elements and finite volumes. In this paper the fundamentals of numerical methods are briefly recalled and a discussion about their possibility of application in the food and agricultural engineering is developed

Estimation of rheological properties of ice cream unfrozen liquid phase by FT-NIR spectroscopy

The control of ice cream powder mixture production is carried out evaluating the ice cream liquid phase. The present study was conduced on ice cream and unfrozen liquid phase in order to indirectly evaluate the rheological properties by measuring the powder mixture. The calibration set was formed by samples with different percentage of thickeners, maintaining constant the concentration of the other remaining compounds. After the NIR acquisitions the powders were mixed with warm milk, blended and than settled in order to obtain the unfrozen liquid phase needed for the rheological measurements. For each recipe three batches were prepared. The flow curves were evaluated by using the Ostwald de Waele’s equation and the goodness of fit was evaluated by the R2, which was above 0.95. Predictive models of rheological parameters were set up by means of PLS regressions in order to predict the consistency coefficient (K) and the flow behavior index (n) from spectral acquisitions. High correlation of calibration was found for both parameters and NIR spectra obtaining R2 of 0.884 for K and 0.874 for n. The good prediction of the models encourages applying them to reduce significantly the time of the powder mixing control during production

Simulazione di processo: i numeri applicati agli alimenti

Il prodotto agricolo che diventa alimento, nel passaggio dalla fase di raccolta in campo, attraverso la successiva selezione ed eventuale trasformazione, fino a quella finale di confezionamento e distribuzione, incontra macchine ed impianti. In tale percorso dunque si evidenziano elementi tecnici di natura ingegneristica. Gli specifici problemi di progettazione di tali processi e delle macchine che li implementano coinvolgono diversi aspetti fisici e chimico-fisici, soprattutto di natura termica, meccanica, elettrica o fluidodinamica. Dunque assieme ai classici metodi di progettazione basati su bilanci di massa ed energia, integrati eventualmente con la realizzazione di prototipi o comunque con elementi di sperimentazione, è sempre più frequente l'integrazione con lo sviluppo di modelli matematici, capaci di simulare con una certa approssimazione, il processo in studio. Ciò è molto evidente nei settori industriali a maggiore marginalità ma, data la sempre maggiore disponibilità di mezzi hardware e software per il calcolo automatico, si osserva un crescente interesse anche nel settore dell'ingegneria agraria, testimoniato da una produzione scientifica internazionale in significativa e costante espansione. In tale contesto, lo scopo principale del presente lavoro è quello di presentare una rassegna dei modelli di simulazione di interesse agroalimentare, sviluppati in ambito DISTAL. Il modello, che costituisce la base della simulazione, consiste sostanzialmente in un insieme di equazioni differenziali, in grado di descrivere la geometria e la fisica del problema, risolto attraverso un metodo numerico. Tale modello può essere pensato come una rappresentazione, più o meno fedele, di un prototipo fisico, avendo però rispetto a quest’ultimo i seguenti vantaggi (V) e problemi (P): V1) è possibile una verifica o comunque un affinamento del progetto attraverso una procedura per tentativi successivi, con tempi e costi generalmente ridotti rispetto a quelli di una completa campagna di sperimentazione; V2) si dispone di una descrizione dettagliata e completa del processo, rendendo spesso possibile ottenere informazioni non osservabili per via sperimentale; P1) sussiste la necessità di personale specificamente formato. In tale ottica l’Università può giocare un ruolo importante; P2) i materiali biologici sono complessi e non sempre è possibile descriverne opportunamente la disomogeneità e l’anisotropia. Inoltre le loro proprietà fisiche (p.e. densità, conducibilità termica ed elettrica, calore specifico, viscosità, permeabilità, umidità, diffusività, composizione) possono variare ampiamente in funzione della temperatura, dell’umidità, della storia delle deformazioni, del tempo; P3) le geometrie sono spesso irregolari e difficili da descrivere

Theoretical and experimental study on mechanical characterisation of a water drop impact on a solid surface

The drop impact phenomenon can be used to study many agricultural aspects related to the rainfall, runoff and irrigation, such as the stability of aggregated and the detachment of fine particles. The aim of this study was to study experimentally and numerically the water drop impact on a solid wall. In a first phase a simple experimental apparatus and basic theoretical concepts were used to investigate the influence of the drop speed on the impact pressure. In the second section, a finite element model able to reproduce the complex phenomenon observed in the experimental phase, was developed. The pressure values obtained by experimental measurement are similar to those calculated on the base of the energy conservation principle (average percentage difference of 15.6%). Numerical model was useful to obtain important information on pressure profile inside the drop and the impact pressure during the splash, at present hard to achieve experimentally. The model was used to estimate also an almost realistic dynamic behaviour of the spreading drop

Numerical models of mass transfer during ripening and storage of salami

Ripening, in the dry sausages manufacturing process, has an influence over the main physical, chemical and microbiological transformations that take place inside these products and that define the final organoleptic properties of dry sausages. A number of study about the influence of ripening conditions on the main chemical and microbiological characteristics of dry sausages is available today. All these studies indicate that the final quality and safety standards achieved by the sausage manufacturing process can be considered to be strictly dependent from the specific ripening conditions. The water diffusion inside a seasoned sausage is surely an aspect of primary importance with regard to the quality of final product. As a consequence the aim of this research was to develop two parametric numerical models, concerning the moisture diffusion physics, describing salami ripening and storage. Mass transfer equations inside the sausage volume were numerically solved using a finite element technique. A first model describes diffusion phenomena occurring inside the salami and the exchange phenomena involving the surface of the product and the environment. After the ripening, the salami are stored in waterproof packaging, consequently an additional model able to describe also the evaporation and condensation phenomena occurring between the salami surface and the air in the package, was developed. The moisture equilibrium between salami surface and conservation atmosphere is mainly ruled by the temperature changes during storage. Both models allow to analyze the history of the moisture content inside the salami and are parametrised on product size and maturation/storage conditions. The models were experimentally validated, comparing the numerical outputs of the simulations with experimental data, showing a good agreement

Screening of grated cheese authenticity by nir spectroscopy

Parmigiano–Reggiano (PR) cheese is one of the oldest traditional cheeses produced in Europe, and it is still one of the most valuable Protected Designation of Origin (PDO) cheeses of Italy. The denomination of origin is extended to the grated cheese when manufactured exclusively from whole Parmigiano-Reggiano cheese wheels that respond to the production standard. The grated cheese must be matured for a period of at least 12 months and characterized by a rind content not over 18%. In this investigation the potential of near infrared spectroscopy (NIR), coupled to different statistical methods, were used to estimate the authenticity of grated Parmigiano Reggiano cheese PDO. Cheese samples were classified as: compliance PR, competitors, non-compliance PR (defected PR), and PR with rind content greater then 18%. NIR spectra were obtained using a spectrophotometer Vector 22/N (Bruker Optics, Milan, Italy) in the diffuse reflectance mode. Instrument was equipped with a rotating integrating sphere. Principal Component Analysis (PCA) was conducted for an explorative spectra analysis, while the Artificial Neural Networks (ANN) were used to classify spectra, according to different cheese categories. Subsequently the rind percentage and month of ripening were estimated by a Partial Least Squares regression (PLS). Score plots of the PCA show a clear separation between compliance PR samples and the rest of the sample was observed. Competitors samples and the defected PR samples were grouped together. The classification performance for all sample classes, obtained by ANN analysis, was higher of 90%, in test set validation. Rind content and month of ripening were predicted by PLS a with a determination coefficient greater then 0.95 (test set). These results showed that the method can be suitable for a fast screening of grated cheese authenticity

High-Temperature ceramic coatings with geopolymeric binders

High-temperature (HT) resistant coatings represent an updating subject of high industrial interest on account of their relevant applications (turbines, engines, aeronautic, ecc.). While many HT resistant products are known, not simple appears to satisfy the requirement of their high and stable adhesion on the support. The aim of this work was to develop novel HT resistant ceramic coatings based on silicon carbide and/or zirconium oxide, using geopolymeric resins as binders. Geopolymers show many advantages respect to organic polymers, first of all their high heat resistance and refractoriness. Moreover, they are fully inorganic, do not require organic solvents and are not off-gassing. During the geopolymerization step, the polymineral resin (alumino-silicate binders) is formed, acting as glue sticking together the unreacted Al-Si source materials and fillers (ceramic powders), forming the ceramic-geopolymer composite coatings. In order to optimize the geopolimeric binders, different raw materials have been tested (caolins, meta-kaolins and alumina/silica fine powders), while the alkali aqueous solution was KOH/K2SiO3, fixing the ratios SiO2/Al2O3 = 4 and SiO2/K2O = 2. Setting conditions, microstructural evolution as a function of the temperature and thermal evolution either in air or inert atmosphere were deeply investigated in order to set-up the best preparation conditions. HT resistant coatings were prepared by mixing the ceramic fillers (90 wt%) with geopolimeric binders, then applying the obtained mixture on ceramic substrates by brushing. After a first setting, coatings were stabilized by a thermal treatment in inert atmosphere at 1350?C and then the oxidation behaviour and adhesion level on the substrates were studied. A key role of new glass-ceramic phases formed during the thermal treatments has been evidenced