91E-6 |
Compression heating characteristics of proteins during high pressure processing |
V. KESAVAN1, V. M. Balasubramaniam1, C. Adhikari1, G. Narayanaswamy1, and S. J. Parulekar2. (1) Illinois Institute of Technology, Moffett Campus, National Center for Food Safety and Technology, 6502 S. Archer Road, Summit-Argo, IL 60501, (2) Department of Chemical and Env. Eng., Illinois Institute of Technology, Chicago, IL 60616 The temperature of the food material increases as a result of compression applied during high pressure processing (HPP) of foods. The temperature increase depends on compressibility of solutes and media. Very limited data are available on the compression heating (CH) of proteins. The objective of our research was to study the compression heating of selected protein-water (soy, egg albumin and gelatin) solutions under HPP. The compression heating system consists of a 25-HP high-pressure pump, a temperature controlled pressure chamber, and 20 mL sample holder equipped with a type K thermocouple. The system had nearly instantaneous pressure come-up and depressurization times. CH characteristics of the three proteins dissolved in water at two concentrations 5%, 10% w/v, were studied. Experiments were conducted at two initial temperatures, 25°C and 70°C, and various pressures from 150 to 600 MPa. The compression heating values were calculated as a difference between maximum temperature of the sample under pressure and the initial temperature of the sample at atmospheric pressure. Among the proteins tested, soy protein had the highest CH values and gelatin the lowest. Increasing the initial temperatures of the proteins from 25°C to 70°C increased the compression heating values from 2.7-3.3 °C per 100MPa to 4.1-5.1 °C per 100MPa respectively. Because, the hydrophobic and hydrophilic amino acids in soy protein are randomly distributed in the primary structure, the molecules is more flexible and has the highest CH values. In contrast, gelatin consists of large number of hydrophobic amino acids and there is more association of the molecules and tighter structures are formed. Thus, the gelatin molecule is more compact and has the lowest CH value. This study should allow the prediction of CH values of complex food matrices using the behavior of individual substances. It will also measure the impact of HPP on protein functionality.
Session 91E, Nonthermal Processing: Nonthermal processing of foods
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