Classical thermo-analytical micro methods (DTA, DSC) are still very useful for process work, but medium scale instruments based on heat flow measurement are attaining an increasingly important role in this domain.
As in many areas, development of reaction calorimetry for industrial applications was driven by needs and by available means (technical capabilities).
The needs have been fairly constant over the past decades. There are data needs:
-Heat release rates
-Heat of desired reactions and decompositions
-Heat capacities and heat transfer capacities
It took the specialists of calorimetry a long time to recognize and to accept the operational needs, namely:
-Working under controlled temperature conditions (constant temperature, temperature ramps)
-Adding components during runs (continuously or in portions)
-Simulation of industrial mixing conditions
The main driving force for the development of process oriented calorimetric instruments was the evolution of electronic hardware which made the control of heat flow on a (non micro) laboratory scale easy.
The paper gives an overview on the principles of heat flow control and reviews the developments of the fifties and sixties, when the matching of heat flow with heat release by reactions was the goal.
With the advent of fast and powerful laptop computers, the focus has shifted. Now, the deduction of true heat release rates from signals which may be badly distorted, is the goal.
Some recent developments are reviewed and the hope is expressed that calorimetric equipment, inexpensive enough to be affordable for every laboratory engaged in process work, will be available soon.
Authors:C. S. Raina, S. Singh, A. S. Bawa, and D. C. Saxena
Rice brokens were utilized in the development of pasta products. Response surface methodology (RSM) was used to analyze the effect of pre-gelatinized rice flour (from rice brokens), vital gluten, water, glycerol monostearate (GMS) and sodium alginate on the quality responses (sensory, cooking quality, rehydration ratio and solids loss) of the pasta product. A rotatable central-composite design was used to develop models for the responses. Responses were affected most by changes in rice flour and vital gluten levels and to a lesser extent by water, GMS and sodium alginate levels. The maximum sensory score (39.69), cooking quality (12.38), rehydration ratio (3.11) and minimum solids loss (15.64) were identified at 671.05 g kg-1rice flour, 242.40 g kg-1water, 74.70 g kg-1vital gluten, 2.14 g kg-1GMS and 9.71 g kg-1sodium alginate levels.
Authors:A. Sipos, P. Agachi, X. Meyer, and P. Strehaiano
Based on a nonlinear model, this article realizes an investigation of dynamic behaviour of a batch fermentation process using direct sensitivity analysis (DSA). The used nonlinear mathematical model has a good qualitative and quantitative description of the alcoholic fermentation process. This model has been discussed and validated by authors in other studies. The DSA of dynamic model was used to calculate the matrix of the sensitivity functions in order to determine the influence of the small deviations of initial state, control inputs, and parameters from the ideal nominal values on the state trajectory and system output in time. Process optimization and advanced control strategies can be developed based on this work.
Reaction calorimetry strongly penetrated process development laboratories in the fine chemicals industry. Applications of calorimetry to different fields of process optimization, chemical reactions and physical unit operations were developed. Applications were first developed in the field of process safety. The thermal data of reaction obtained in the calorimeters allow us to check if a reaction will be controllable at full scale under normal operating conditions and in case of equipment failure. Further, the accurate temperature control and heat flow measurement opened the door to more engineering related data, in the fields of phase equilibria like vapour liquid, solubilities, crystallization and also in the mixing techniques. Some examples of developments in these different fields will be reviewed.
Authors:M. Nagy-Gasztonyi, Á. Kardos-Neumann, and P. Á. Biacs
Blanching of vegetables before freezing has some advantages as well as a number of disadvantages. Process optimization involves measuring the rate of enzyme destruction, such that the blanching time is just long enough to destroy the indicator enzyme. Eventually, peroxidases were almost universally the enzymes of choice, as they are usually the most heat-stable enzymes found in vegetables and fruits, so by the time they are inactivated no other enzymes or micro-organisms remain. But there is no evidence that peroxidases are involved in deteriorative reactions in the food. The aim of this work was to improve blanching technology in Hungarian frozen food industry with special emphasis on broccoli treatment. Instead of peroxidases, lipoxygenases were chosen to determine the adequate blanching parameters. Usually, lipoxygenases accompany lipases, so lipase activity is measured, too. On the basis of model blanching experiments, the conclusion is that lipoxygenase could be used as indicator enzyme. Being less heat stable than peroxidase, this enzyme requires shorter heat treatment, hence its inactivation should result in minimum quality deterioration and economic loss.
Authors:Moh Moh Zin, Fruzsina Borda, Edit Márki, and Szilvia Bánvölgyi
Since significant percentage of fruits and vegetables go to waste during processing, investigation of how to improve the valuable products of extraction from the wastes is an undeniably effective way to save the planet. Beetroot (root, peel, and stalk) is a chief source of natural betalain color compounds and phenolic compounds with copious radical scavenging activity. The major emphasis of this work is to optimize process variables which are extraction time (10–60 min), operating temperature (20–50 °C), and aqueous ethanol solvent with the concentration of (25–75%) for effective extraction of valuable compounds such as betalains, total polyphenols, and antioxidant activity from beetroot peel. Spectrophotometric analysis was applied for quantification of those compounds. Amongst which, lowest solvent concentration (25% v/v) together with the highest temperature (50 °C) and extraction time (50 min) brought yielded higher results. The process optimization was carried out using Design Expert (11.0.3) statistical software. Overall, it can be noted that extraction process can be improved by controlling operating time and temperature, avoiding unnecessary overuse of costly solvent.
Modern thermal analysis, microcalorimetry and new emerging combined techniques which deliver calorimetric, microscopic and
spectroscopic data offer a powerful analytical battery for the study of pharmaceuticals. These techniques are very useful
in all steps of development of new drug products as well as methods for quality control in production. The characterization
of raw materials enables to understand the relationships between polymorphs, solvates and hydrates and to choose the proper
development of new drug products with very small amount of material in a very short time. Information on stability, purity
is valuable for new entities as well as for marketed drug substances from different suppliers. Excipients which vary from
single organic or inorganic entity to complexes matrixes or polymers need to be characterized and properly controlled. The
thermodynamic phase-diagrams are the basis of the studies of drug-excipients interactions. They are very useful for the development
of new delivery systems. A great number of new formulations need proper knowledge of the behaviour of the glass transition
temperature of the components. Semi-liquid systems, interactions in aqueous media are also successfully studied by these techniques.
Authors:Bence Döbrőssy, Attila Kovács, András Budai, Ágnes Cornides, and Lajos Döbrőssy
A szűrővizsgálat elutasításának okai között szerepelnek a szűrés nemkívánatos lélektani mellékhatásai. Ennek lehetséges okai három csoportba sorolhatók: 1.
okok, mint például az egészségügyi szolgáltatások igénybevételét meghatározó emberi magatartás. Különösen azoknak a szolgáltatásoknak az elutasítása gyakori, amelyek nem a jelenben is kínzó tünetek és panaszok orvoslását célozzák, hanem a jövőben majd esetleg fellépő betegségek megelőzését szolgálják; ilyen „jövőre irányuló” szolgáltatás a szűrővizsgálat is. 2. A
rákbetegségnek a közfelfogásban rögzült negatív képe
és a gyógyíthatóságát illető kételyek. Szóba jönnek továbbá 3. a
szűrővizsgálat szubjektív megtapasztalásával közvetlenül összefüggő okok.
A szolgáltatóknak törekedniük kell az okok kiküszöbölésére: a) a különböző korú, társadalmi helyzetű és műveltségi szintű rétegekhez szóló
feladata, hogy kialakítsa a betegségmegelőzés szükségességét elfogadó magatartást, és változtasson az embereknek a rákkal szemben eltúlzottan negatív, a vereséget előre elkönyvelő szemléletén; b) a szűrővizsgálatot szolgáltató szakemberek kötelessége, hogy minden tőlük telhetőt megtegyenek a szűrővizsgálattól visszatartó tényezők mérséklése érdekében. Ennek módja a jó munkaszervezés és a szakmai munka minőségének optimalizálása, valamint a jó kommunikáció: a szűrővizsgálat előtti, alatti és utáni felvilágosítás, információszolgáltatás és tanácsadás.