Use of vacuum impregnation for the production of high quality fresh-like apple products

• VI was optimized to achieve high quality fresh-like apple products.
• VI at 738 mbar-10 s determined limited changes in composition, colour and firmness.
• VI-treated apples in isotonic sorbitol solution showed a higher firmness and crispness.
• Colour of VI-treated apples with sorbitol and trehalose solutions was preserved.
• VI in isotonic sucrose solutions positively affected the sensory properties of apples.

The application of vacuum impregnation (VI) for the production of high quality fresh like apple products has been investigated. Preliminary tests were carried out to select the optimal VI treatment conditions (P: 857–50 mbar; VI time: 10–1000 s). The use of isotonic sorbitol, glucose, fructose, sucrose, trehalose and maltose solutions was then studied to keep quality and improve stability of the VI treated apples. VI at 738 mbar for 10 s allowed the penetration of the impregnation agent (water) with minimal effects on fruit composition and quality. VI isotonic solutions determined a limited solute increase while affected mechanical properties positively; firmness of apples processed with sorbitol solution was higher than that of the fresh fruit. Moreover, they contributed to preserve apples from browning. After 7 days, h° values significantly higher than the untreated samples were obtained with trehalose > sorbitol > glucose > sucrose > maltose. Sensory analysis confirmed the positive effect of isotonic VI solution on apples quality.