HIGH‐PRESSURE DIFFERENTIAL SCANNING CALORIMETRY (DSC): EQUIPMENT AND TECHNIQUE VALIDATION USING WATER–ICE PHASE‐TRANSITION DATA

Abstract

ABSTRACT Understanding phase transition during high‐pressure (HP) processing of foods is important both with respect to optimizing the process and improvement of product quality, but scientific information available in this area is very limited. In this study, the phase‐transition behavior of water was evaluated using a HP differential scanning calorimetry (DSC). Tests were carried out under both isothermal pressure‐scan (P‐scan) and isobaric temperature‐scan (T‐scan) modes with distilled water prefrozen in the sample cell. P‐scan was carried out at 0.3 MPa/min at two temperatures, −10 and −20C, and T‐scan was carried out at 0.15C/min at two pressures, 0.1 and 115 MPa. The pressure‐induced phase transition of water was accurately reproduced by the P‐scan test. Ice melting latent heat during P‐scan showed no significant difference (P > 0.05) from the available reference data in literature. The relationship between P‐scan tested (Lm) and reference latent heat was Lm = 0.987 L (R2 = 0.99, n = 6) suggesting a mean error less than 2%. T‐scan mode was less appropriate and did not yield promising result. Measured values were less accurate than P‐scan probably because of the influence of large heat capacity of sample cell. However, reliable and reproducible results obtained under P‐scan mode suggested that the HP DSC can be used for the calorimetric determination of pressure‐dependent water‐phase transition in real food systems during HP freezing/thawing operations.