Spraying treatment of fresh-cut apples as a sustainable alternative to dipping for browning inhibition: a preliminary lab-scale study

Several fresh-cut apple snacks are available on the market, and their color is highly relevant for consumers. As apple slices brown very quickly after cutting, dipping them in an antioxidant solution for a few minutes is common to avoid this phenomenon. However, this procedure has some limitations. Using the same solution for several immersion cycles over several hours can lead to cross-contamination and microbial growth. In addition, osmotic exchange phenomena in the immersion tank lead to a reduction in the concentration of the active ingredients of the antioxidant solution over time, which requires continuous readjustment of the concentrations. These aspects, together with the large quantities of exhausted antioxidant solution to be disposed of, are limiting factors that drive the search for alternative and more sustainable methods than dipping. In this work, a comparison between a conventional dipping treatment of fresh-cut apples and spraying at increasing volume of antioxidant solution was performed. Color, considered as the quality reference parameter, was visually assessed (occurrance of dark spots) and CIE Lab colorimetric indices were measured over a five-day experimental period. Based on dark spots and the changes in brightness (Δ L*), hue angle (Δ h) and chroma (Δ C*), some of the spraying treatments applied were found to be comparable to dipping in controlling browning. For all treatments, high intra- and inter-batch variability and within slices of the same apple was observed concerning both instrumental data and dark spots development, indicating that further investigation is needed to validate this result and to apply this procedure at an industrial level.