Influence of maturity degree, modified atmosphere and anti-browning dipping on texture changes kinetics of fresh-cut apples

Consumer acceptability of fresh-cut apples is affected by texture characteristics, mainly by crispness attribute. The use of combined instrumental acoustic-mechanical techniques and the measurement of the absorption coefficient at 670 nm (μa670) by time-resolved reflectance spectroscopy (TRS) have been shown useful to assess fruit crispness and the maturity degree. The aim of this work was to evaluate the influence of the maturity degree measured by TRS, modified atmosphere and anti-browning dipping on the texture of fresh-cut apples as measured by means of an instrumental mechanical-acoustic test and the rheological behavior of the cell wall material. Apples were measured at harvest by TRS at 670 nm, ranked on the basis of decreasing μa670 (increasing maturity) and classified as less mature (LeM), medium mature and more mature (MoM). Only LeM and MoM apples were peeled and cut, half of them were dipped in the antibrowning solution and the other were not dipped. All samples were packed using air or 80% Ar + 20% CO2 modified atmosphere (MA). Ethylene concentration and instrumental mechanical-acoustic characteristic were evaluated after 1, 4, 8, 11 and 15 d of refrigerated storage (4 °C). The rheological behavior of cell wall material was evaluated after 1 and 15 d. LeM and MoM samples showed a different ethylene evolution for fresh-cut apples packed in air. The mechanical-acoustic results showed that the maturity degree influenced the texture significantly, with LeM apples firmer and more rigid and producing also a higher number of acoustic events with more elevated maximum signal amplitude than MoM fruit. However maturity degree did not affect the evolution of texture throughout storage. Both dipping treatment and MA did not affect texture clearly. The rheological behavior of the cell wall material suggested an increase of elastic behavior with storage time. In order to obtain a fresh-cut product with homogeneous texture characteristics, these results suggest that it would be beneficial to process fruits of a homogeneous maturity class, which could be achieved by sorting using TRS.