Pressure‐shift freezing and its influence on texture, colour, microstructure and rehydration behaviour of potato cubes

Abstract

SummaryTemperature changes during pressure-shift freezing (400 MPa) of potato cubes and its effects on the drip loss (weight and conductivity), texture (shear and compression tests), colour (L, a, b values), drying behaviour, rehydration properties (water uptake, texture after rehydration) and visible cell damage after thawing (micrographs) were investigated and compared with conventional freezing (0.1 MPa, -30 "C), subsequent frozen storage (-18 "C) or pressure treatment (400 MPa) at + 15 "C. Pressure-shift freezing resulted in increased crystallization rates compared to conventional freezing at -30 "C. Crystallization and cooling to -8 "C took 2.5 min during and after pressure release versus 17 min at atmospheric pressure. Drip loss was reduced from 12.0 to 10.8 g/100 g. Water uptake during 10 min of rehydration (93.9 g/100 g compared to 77.4 g/100 g and incomplete rehydration) and texture values were improved. Browning after thawing or after fluidized bed drying was reduced (increased a value, lower L value), suggesting partial enzyme inactivation during pressure treatment. Differences in colour and texture to the untreated controls were smaller after pressure-shift freezing than after conventional freezing. Cooling to -30 "C after pressure-shift freezing did not significantly affect the results, whereas subsequent frozen storage at -18 "C resulted in quality deterioration, as observed after frozen storage of conventionally frozen samples. The improved preservation of cell structure was demonstrated using scanning electron microscopy.

High-pressure-shift freezing: Main factors implied in the phase transition time

“…Phase transition times (plateau times) are thus considerably reduced, and resulting ice crystals are granular-shaped and homogeneously distributed rather than typical dendritic structures (Martino, Otero, Sanz, & Zaritzky, 1998). Improvements in structure, texture and water holding capacity have been reported by many authors in different high-pressure-shift frozen products such as gels (Fuchigami & Teramoto, 1998;Kanda, Aoki, & Kosugi, 1992), vegetables (Koch, Seyderhelm, Wille, Kalichevsky, & Knorr, 1996;Otero, Solas, Sanz, de Elvira, & Carrasco, 1998) or meat products (Fernández-Martín, Otero, Solas, & Sanz, 2000;Martino et al, 1998). However, deteriorations in color, water holding capacity and texture of muscle tissues have also been described, depending on the level of applied pressure (Chevalier, Sentissi, Havet, & Le Bail, 2000;Fernández-Martín et al, 2000;Massaux, Berá, Steyer, Sindic, & Deroanne, 1999).…”

High pressure–low temperature processing of foods: impact on cell membranes, texture, color and visual appearance of potato tissue

“…In consequence, the process time as well as the quality of the frozen material is improved. Besides other materials, examinations of plant tissue materials have been carried out with peach and mango (Otero, Martino, Zaritzky, Solas, & Sanz, 2000), eggplant , potato (Koch, Seyderhelm, Wille, Kalichevsky, & Knorr, 1996), Chinese cabbage (Fuchigami, Kato, & Teramoto, 1998a) and carrots (Fuchigami, Kato, & Teramoto, 1997a;Fuchigami, Miyazaki, Kato, & Teramoto, 1997b), indicating a better texture and microstructure of the tissue after pressureshift freezing.…”

Metastable phases during high-pressure–low-temperature processing of potatoes and their impact on quality-related parameters

“…Due to the rate of the process, the size of the resulting crystals is smaller than for conventional freezing, leading to a prevention of structural damages. Tofu Kanda, Aoki, & Kosugi, 1992), carrots Fuchigami, Miyazaki, et al, 1997), potatoes (Koch et al, 1996;Luscher et al, 2005), aubergines (Otero, Solas, Sanz, de Elvira, & Carrasco, 1998), peach and mango (Otero, Martino, Zaritzky, Solas, & Sanz, 2000) or turbot fish have been shown to maintain a better structural quality of frozen products after PSF. The reduction of the phase transition time for PSF, as well as the crystallisation in the whole sample volume has been demonstrated in oil-in-water emulsions (Levy, Dumay, Kolodziejczyk, & Cheftel, 1999) and potatoes (Urrutia Benet et al, in press).…”

“…High pressure (HP) has been used during last years as a ''third dimension'', together with temperature and time, to be considered for freezing and thawing processes to avoid dramatic damages, such as texture disruption in vegetal (Cheftel, Thiebaud, & Dumay, 2002;Fuchigami, Kato, & Teramoto, 1998;Fuchigami, Miyazaki, Kato, & Teramoto, 1997;Fuchigami, Teramoto, & Ogawa, 1998;Koch, Seyderhelm, Wille, Kalichevsky, & Knorr, 1996;Luscher, Schlueter, & Knorr, 2005;Smout, Sila, Vu, Van Loey, & Hendrickx, 2005;Teramoto & Fuchigami, 2000) and animal tissues (Chevalier, Le Bail, Chourot, & Chantreau, 1999;Chevalier, Sentissi, Havet, & Le Bail, 2000;Chevalier, Sequeira-Munoz, Le Bail, Simpson, & Ghoul, 2000;Zhao, Flores, & Olson, 1998;Zhu, Ramaswamy, & Simpson, 2004), and to achieve enzymatic inactivation (Ashie & Simpson, 1996;Indrawati, Ludikhuyze, Van Loey, & Henrickx, 2000;Indrawati, van Loey, Denys, & Hendrickx, 1998;Préstamo, Palomares, & Sanz, 2005).…”