Location: Healthy Processed Foods ResearchTitle: Effects of isochoric freezing conditions on cut potato quality
|ZHAO, YUANHENG - University Of California|
|Wood, Delilah - De|
|POWELL-PALM, MATTHEW - University Of California|
|CHEN, LIUBIAO - Chinese Academy Of Sciences|
|RUBINSKY, BORIS - University Of California|
Submitted to: Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/27/2021
Publication Date: 4/29/2021
Citation: Zhao, Y., Bilbao-Sainz, C., Wood, D.F., Chiou, B., Powell-Palm, M., Chen, L., McHugh, T.H., Rubinsky, B. 2021. Effects of isochoric freezing conditions on cut potato quality. Foods. 10(5). Article 974. https://doi.org/10.3390/foods10050974.
Interpretive Summary: Minimally processed products are one of the major growing segments in the food industry. However, fresh-cut fruits and vegetables have limited shelf life due to excessive tissue softening and cut surface browning. Isochoric freezing is considered a high-pressure freezing technique that allows low-temperature storage without ice formation. In this study, we examined the effects of isochoric freezing conditions (procedure, temperature/pressure and compression rate) on the quality properties (mass change, volume change, water holding capacity, color and texture) of cut potatoes after thawing. Results showed that the freezing temperature/pressure and the processing procedure had the greatest effects on the quality of thawed potatoes. Samples treated at high subfreezing temperatures with pressures below 71MPa retained their overall quality, independent of the processing procedure. The samples showed increased losses in mass, volume, water holding capacity and texture at higher pressures. However, samples immersed in an isotonic solution of 5% ascorbic acid showed improved quality retention.
Technical Abstract: Isochoric freezing is a pressure freezing technique that could be used to retain the beneficial effects of food storage at temperatures below their freezing point without ice damage. In this study, potato cylinders were frozen in an isochoric system and examined using full factorial combinations of three processing procedures (immersed in water, vacuum packed and immersed in ascorbic acid solution), four freezing temperatures/pressures (-3°C/37MPa, -6°C/71MPa, -9°C/101MPa and -15°C/156MPa) and two average compression rates (less than 0.02 and more than 0.16 MPa/s). The effects of process variables on critical quality attributes of frozen potatoes after thawing were investigated, including mass change, volume change, water holding capacity, color and texture. Processing procedure and freezing temperature/pressure were found to be highly significant factors, whereas the significance of the compression rate was lower. For the processing procedures, immersion in an isotonic solution of 5% ascorbic acid best preserved quality attributes. At the highest-pressure level of 156 MPa and low compression rate of 0.02 MPa/s, potato samples immersed in ascorbic acid retained their color, 98.5% mass and 84% elasticity modulus value. These samples also showed a 1% increase in volume and 13% increase in maximum stress due to pressure-induced hardening.