Modeli određivanja vremena potrebnog za odmrzavanje hrane ovisno o uvjetima prerade i karakteristikama gotovog proizvoda

Determining thawing times of frozen foods is a challenging problem as the thermophysical properties of the product change during thawing. A number of calculation models and solutions have been developed. The proposed solutions range from relatively simple analytical equations based on a number of assumptions to a group of empirical approaches that sometimes require complex calculations. In this paper analytical, empirical and graphical models are presented and critically reviewed. The conditions of solution, limitations and possible applications of the models are discussed. The graphical and semi-graphical models are derived from numerical methods. Using the numerical methods is not always possible as running calculations takes time, whereas the specialized software and equipment are not always cheap. For these reasons, the application of analytical-empirical models is more useful for engineering. It is demonstrated that there is no simple, accurate and feasible analytical method for thawing time prediction. Consequently, simplified methods are needed for thawing time estimation of agricultural and food products. The review reveals the need for further improvement of the existing solutions or development of new ones that will enable accurate determination of thawing time within a wide range of practical conditions of heat transfer during processing.Toplinska i fizikalna svojstva proizvoda mijenjaju se tijekom odmrzavanja, pa je određivanje vremena odmrzavanja oduvijek predstavljalo problem. Razvijeni su različiti matematički modeli za rješavanje tog problema, počevši od relativno jednostavnih analitičkih funkcija koje polaze od niza pretpostavki, pa sve do raznih empirijskih modela što uključuju složene izračune. U ovom su radu kritički prikazani analitički, empirijski i grafički modeli. Osim toga, raspravlja se o uvjetima potrebnim za rješavanje problema, ograničenju i mogućoj primjeni modela. Grafički i polugrafički modeli izvedeni su iz numeričkih metoda. Numeričke metode nisu uvijek primjenjive jer izračuni oduzimaju puno vremena, a specijalizirani su programi i oprema uglavnom skupi. Zbog toga su za primjenu u inženjerstvu prikladniji analitičko-empirijski modeli. Ovaj revijalni prikaz potvrđuje da ne postoji jednostavna, točna i u praksi lako izvediva analitička metoda određivanja vremena odmrzavanja prehrambenih proizvoda, te da treba razviti jednostavnije metode. Zaključeno je da postojeća rješenja treba poboljšati ili treba razviti nove modele koji će omogućiti precizno određivanje vremena odmrzavanja u različitim uvjetima prijenosa topline prilikom obrade hrane

2 nd Brazilian Consensus on Chagas Disease, 2015

Abstract Chagas disease is a neglected chronic condition with a high burden of morbidity and mortality. It has considerable psychological, social, and economic impacts. The disease represents a significant public health issue in Brazil, with different regional patterns. This document presents the evidence that resulted in the Brazilian Consensus on Chagas Disease. The objective was to review and standardize strategies for diagnosis, treatment, prevention, and control of Chagas disease in the country, based on the available scientific evidence. The consensus is based on the articulation and strategic contribution of renowned Brazilian experts with knowledge and experience on various aspects of the disease. It is the result of a close collaboration between the Brazilian Society of Tropical Medicine and the Ministry of Health. It is hoped that this document will strengthen the development of integrated actions against Chagas disease in the country, focusing on epidemiology, management, comprehensive care (including families and communities), communication, information, education, and research

A simple technique to improve the firmness of cooked potato tissue

Potato tissue samples with varying cell turgor pressures were prepared by soaking in mannitol solutions (0 to 0.5 M). Increased concentration of mannitol in the soaking solutions decreased the cell turgor pressure in potato tissues providing samples with varying degrees of turgidity or plasmolysis. Firmness changes in potato tissues of differing turgor pressure during cooking were examined using a Zwick universal testing machine and also by chewing tests. A modified device attached to a Zwick machine facilitated complete immersion of a potato disc in circulating boiling water, providing rapid and reproducible heat transfer in the tissue during firmness measurements. Tissue firmness expressed as the force required to cause 10% strain in the sample varied in potato discs treated with differing mannitol solutions. Potato discs soaked in 0 to 0.3 M mannitol solutions were more turgid at 20°C than other samples and showed higher tissue firmness. However, when discs of potato were heated in the range of 2090°C, samples treated with 0.4 and 0.5 M mannitol solutions showed some increase in tissue firmness while all other samples exhibited a rapid decline. Bite-force measurements on potato discs also indicated a rapid loss of tissue firmness in turgid samples. Potato tissues when cooked after soaking in 0.4 or 0.5 M mannitol solution showed more intact and inflated cells than other samples