Effect of Dipping Pre-treatment with Unripe Grape Juice on Dried “Golden Delicious” Apple Slices

The consumption of apple chips is increasing in the last decades because of the consumer’s preferences towards healthy snacks. However, the enzymatic browning, which is attributed mainly to polyphenol oxidase (PPO, EC 1.10.3.1) activity, negatively affectsthesensory,nutritional,andantioxidantpropertiesofdriedapplesasaconsequenceoftheoxidationofphenolicsubstrates duringpost-harveststages.Theantibrowningandantioxidanteffectsofdippingpre-treatmentswithunripegrapejuiceaswellas reference formulations including a mixture of 1% w/v ascorbic acid and 1% w/v citric acid, 6% w/v NatureSeal®, and 0.1% w/v sodium metabisulfite were evaluated by spectrophotometric and colorimetric assays on dried BGolden Delicious^ apple slices. Based on HPLC analysis, the treated apple slices were enriched with bioactive compounds which effectively improved antioxidant capacity and limited enzymatic browning by increasing lightness, reducing color change, and inhibiting PPO activity. Hence,thejuiceofunripegrapesrecoveredasagriculturalwastesduringbunchthinningofvineyardscouldbeproposedasasafe, inexpensive, and eco-friendly alternative to conventional antibrowning treatments in apple processing.