The impact of drying (air‐, oven‐ and vacuum‐drying) on bioactive polyphenolics, vitamin C and antioxidant capacity of slices of “Redfield” apple, a red‐fleshed apple cultivar, was investigated. The drying process significantly impacted the concentration of specific phenolic compounds and vitamin C concentration in dried slices. The loss of epicatechin, cyanidin‐3‐O‐galactoside, phloridzin and quercetin glycosides occurred during oven‐drying. The concentration of all the phenolic compounds in vacuum‐dried apple slices at 20C for 24 h was comparable to that of fresh apple slices. Antioxidant capacity measured by oxygen radical absorption capacity was significantly reduced by the oven‐drying as compared to other drying methods. PRACTICAL APPLICATIONS These results suggested that vacuum‐drying offers a great potential for preserving bioactive compounds during dehydration process for obtaining nonfried apple chips. Red‐fleshed apples have potential for use in value‐added snack product manufacturing because of the presence of anthocyanins in the flesh. However, nonuniform color distribution in red‐fleshed apples is an issue for quality measurement.

S. 2007. Biochemical characterization of enzymatic browning in selected apple genotypes. Can. J. Plant Sci. 87: 1067-1074. Enzymatic browning in apples (Malus × domestica Borkh.) caused by polyphenol oxidases (PPO) is the major factor responsible for the deterioration of quality in processed apple products such as juice, fresh-cut slices, and chips. Selected apple genotypes with a range of low post-cut enzymatic browning were investigated to understand the biochemical mechanisms leading to enzymatic browning. Post-cut enzymatic browning, polyphenolic profiles using LC-MS/MS, PPO activity, vitamin C, total antioxidant capacity using the Ferric Reducing Antioxidant Power (FRAP) and the Oxygen Radical Absorbance Capacity (ORAC), and elemental composition were determined in two recently released cultivars [Eden TM (also known as SJCA38R6A74) and SuperMac], and one new advanced line (SJCA16) and compared with two commercial cultivars (Empire and Cortland). Eden TM exhibited the least post-cut enzymatic browning as estimated by Whiteness Index. SJCA16 possessed a characteristic yellowish flesh color. Whiteness Index (WI) values were inversely related to chlorogenic acid, catechin and epicatechin contents present in apple slices. Vitamin C content showed a strong positive correlation with WI. Among the mineral elements, the content of copper had a strong positive correlation with PPO activity.

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The purpose of the present study was to evaluate the sensory and nutritional quality aspects of dried apple slices that had been prepared by giving three different pretreatments (vacuum impregnation [VI] treatment, antibrowning treatment and untreated control). Descriptive sensory analysis carried out by trained panelists revealed that chip crispiness and crunchiness were improved by the VI in comparison to the other treatments. As compared to untreated apple slices, incorporation of calcium and vitamin E in dipping solution resulted in uptake of calcium (760 mg/100 g) and vitamin E (168 mg/ 100 g) in the fruit matrix, which can be used to meet the daily requirement for calcium and vitamin E in the consumer's diet. PRACTICAL APPLICATIONSThe eco-friendly processes like vacuum impregnation can be utilized in developing dried apple snacks to improve the sensory attributes and introduce quality-enhancing food additives, such as calcium salt and natural flavors, as well as minerals, vitamins and bioactives for meeting the daily dietary requirements and promoting health benefits to the consumer. 1

The study was carried out to evaluate the selected quality attributes of a prototype nonfried apple snack produced by application of vacuum impregnation (VI) of maple syrup and vacuum drying. When maple syrup concentration was adjusted to 20-40% in the VI solution, vacuum-dried apple slices are resulted in the greatest textural attributes, whiteness index, and desirable moisture content and water activity. Comparison of the VI-treated, vacuum-dried apple slices with commercially fried apple and potato snacks revealed that the consumer acceptability was greater for the fried snack products due to their flavor and texture; however, in addition to higher oil content (>30%), commercial fried apple and potato snacks possessed lower antioxidant capacity than nonfried apple snacks. VI process enhanced the calcium content of the nonfried apple snack products.

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