Termalna svojstva proteina mesa u procesu osmotske dehidratacije u melasi šećerne repe

Abstract

Termalne osobine svinjskog mesa (Longissimus dorsi) osmotski dehidratisanog u melasi šećerne repe i svežeg svinjskog mesa praćene su metodama termalne analize: Diferencijalnom skenirajućom kalorimetrijom (DSC), termogravimetrijskom analizom (TGA), modulovanom diferencijalnom skenirajućom kalorimetrijom (MDSC). Dobijeni rezultati pokazuju postojanje novonastale proteinske osnove osmotski dehidratisanog svinjskog mesa koji je posledica smanjenja količine vode i interakcije komponenti melase s proteinima mesa. Nađeno je da osmotskom dehidratacijom dolazi do promene i pregrupisavanja preostale slobodne vode u dva oblika, što ukazuje na mehaničko strukturne promene u interfibrilarnoj mreži i pojednostavljivanje strukture proteinske osnove. Definisani su nastali strukturni nivoi proteinske osnove: strukturni nivo vode vezane na protein tj. postojanje proteinske strukture i posle osmotske dehidratacije -strukturni nivo I; strukturni nivo mreže sa ujednačeno manjim porama tj. nivo energetski jače vezane imobilizirane -strukturni nivo II; strukturni nivo mreže sa ujednačeno većim porama tj. nivo energetski slabije vezane imobilizirane -strukturni nivo III. Ispitivanjem termalnih osobina uzoraka osmotski dehidratisanog mesa sa smanjenom vlagom ( ispod 20%) nađeno je postojanje staklastog prelaza pošto je najveća količina vode vezana za čvrsti matriks. Definisani su optimalni uslovi rehidratacije osmotski dehidratisanog svinjskog mesa, te su određene Pelegove konstante rehidratacije. Nađeno je postojanje nativnih struktura proteina u osmotski dehidtiranom mesu i određeni su kinetički parametri denaturacije (Ea, kb) svežeg i osmotski dehidriranog mesa. Određen je sadržaj makroelemenata osmotski sušenog svinjskog mesa. Radi objašnjenja složenosti interakcija proteina mesa i sastojaka osmotskog rastvora melase koje se odvijaju pri dehidrataciji, kao model sistem poslužila je interakcija proteina albumina goveđeg seruma (BSA) s jonima nekih makroelemenata prisutnih u melasi.

Thermal properties of pork meat (Longissimus dorsi) osmotically dehydrated in sugar beet molasses and fresh pork were followed by the methods of thermal analysis: Differential Scanning Calorimertry (DSC), Thermogravimetric Analysis (TGA), Modulated Differential Scanning Calorimetry (MDSC). The results indicate the existence of newly formed protein matrix as a consequence of osmotic dehydration of pork meat: reducing the amount of water and the interaction of the components of molasses and meat proteins. It has been found that changes were induced by the process of osmotic dehydration, and rearrangeement of the remaining free water in two forms. Also as a consequence of the osmotic dehydration, structural changes in the interfibrilar network and simplifying of the original structure of the meat protein matrix were occurred. A structural levels of protein matrix were defined: as structural level of the water bound to the protein, meaning the existence of protein structure and after osmotic dehydration Structural level I; a structural level with uniformly small pores in the network of formed protein matrix: energy level of more tightly immobilized water –Structural level II; and structural level of network with uniformly larger pores, energy level of lower bound immobilized water - Structural level III. By characterization of the thermal properties of the samples of osmotically dehydrated meat with reduced moisture (below 20%) the glass transition was found, as most of the water bound to a solid matrix.The optimal conditions for rehydration of dehydrated pork meat were defined, and Peleg‘s rehydration constants were obtained. It was found that the existence of the native structure of the protein in the osmotically dehydrated meat, and the kinetic parameters of protein denaturation (Ea, kb) of fresh and dehydrated meat were obtained. The content of macroelements in the osmotically dehydrated, fresh pork meat and in the sugar beet molasses were obtained. In order to explain the complexity of the interaction of meat proteins with the components of the osmotic solution -molasses that occur in the dehydration process, the model-system of the protein bovine serum albumin (BSA) interaction with the ions were implied to present simple interaction of some major elements with a protein matrix followed by DSC and ITC .