Rheological properties of fresh-cut apple as affected by ascorbic acid/CaCl2 dipping and ultraviolet light radiation.

GÓMEZ, P.; SALVATORI, D.; ALZAMORA, S.

Anaheim/OC, CA, USA

Congreso; The 2009 Institute of Food Technologists Annual Meeting (IFT); 2009

Institute of Food Technologists

Short wave ultraviolet light (UV-C) has been proposed as a germicidal factor to inactivate microorganisms and increase shelf life of fresh-cut fruit and vegetables. Irradiation at higher doses has been reported to produce an increase of the surface browning, which can be prevented by application of a suitable antibrowning agent prior to irradiation. This work evaluated the changes on linear viscoelastic properties of fresh-cut apples dipped in an antibrowning solution and irradiated with UV-C light. Apple slices (3 cm diameter and 0.6 cm thickness) were dipped in a 1% (w/v) ascorbic acid + 0.1 % (w/v) calcium chloride solution for 5 min at 4ºC. For UV-C irradiation, they were placed at 10 cm distance from two germicidal lamps (253.7 nm, 15 W) during 20 min (UV-C dose: 11.2 KJ/m2). Slices pretreated with the antibrowning solution with or without irradiation were compared to a control (fresh apple) throughout a week of storage at 4-5ºC. Dynamic oscillatory shear and creep/recovery tests were performed at 0 and 7 day. Creep behavior was fitted with a mechanical model (a spring, two Kelvin-Voigt elements and a dashpot). LM and ESEM observations were made after processing and storage. Storage moduli (G’) of apples immersed in the antibrowning solution and subjected or not to UV-C treatment were lower than those of the fresh fruit, both at 0 and 7 day. The instantaneous compliance (J0) and the retarded compliances (J1 and J2)  increased after 7 day storage in samples treated with the antibrowning agent. This increase was more pronounced when the apples were also irradiated. Rheological response of apple tissue was correlated with microstructure and ultrastructure features. Acid ascorbic/CaCl2 dipping and ultraviolet light exposure produced changes in viscoelastic properties of fresh-cut apple throughout storage in refrigeration.