Glassy state in relation to the thermal inactivation of enzyme invertase in amorphous dried matrices of trehalose, maltodextrin and PVP

CAROLINA SCHEBOR; MARÍA DEL PILAR BUERA; JORGE CHIRIFE

JOURNAL OF FOOD ENGINEERING

Elsevier

Año: 1996 vol. 30 p. 269 - 282

0260-8774

<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> The stabilization of invertase by its incorporation in aqueous trehalose and polymer solutions, followed by freeze-drying and desiccation to ´zero´ moisture content, was studied. The dried amorphous preparations of trehalose, maltodextrina (MD, DE=10.9), and poly(vinyl)pyrrolidone (PVP), molecular weights 360000, 40000 and 10000, greatly protected invertasa – as compared with its behavior in liquid solution- from heat inactivation at elevated temperatures. Significant invertasa inactivation was observed in heated PVP and MD matrices kept well below their glass-transition temperature (Tg) since systems of higher Tg afforded better protection. However, the data for trehalose deviated from this behavior since invertasa stabilization was higher than that expected on the basis of the results obtained with polymer matrices. Present results suggest that invertasa inactivation in dried amorphous systems cannot be adequately explained by the glass-transition theory and this is particularly true for trehalose, for which some additional mechanism of enzyme protection is likely to operate.