Effect of Apple Juice Enrichment with Selected Plant Materials: Focus on Bioactive Compounds and Antioxidant Activity

Abstract

Using a multi-analytical approach, this paper aimed to investigate the effect of apple juice enrichment with Arbutus unedo and Diospyros kaki fruits, Myrtus communis berry extract, Acca sellowiana, or Crocus sativus flower by-products on both bioactive compounds content and antioxidant activity. Physico-chemical parameters, vitamin C, sugars, organic acids, total polyphenol content, antioxidant activity, and sensory attributes were evaluated. An LC-PDA/MS QTof analysis allowed for the identification of 80 different phenolic compounds. The highest polyphenol content (179.84 and 194.06 mg of GAE/100 g fw) and antioxidant activity (CUPRAC, 6.01 and 7.04 mmol of Fe²⁺/100 g fw) were observed in products with added A. sellowiana and D. kaki, respectively. Furthermore, the study showed a positive correlation between polymeric procyanidins and antioxidant activity (0.7646-0.8539). The addition of A. unedo fruits had a positively significant influence on the increment of vitamin C (23.68 ± 0.23 mg/100 g fw). The obtained products were attractive to consumers, especially those with 0.1% C. sativus flower juice, M. communis berry extract, and persimmon D. kaki fruits. The synergy among the different analytical techniques allowed us to obtain a complete set of information, demonstrating that the new apple smoothies were enriched in both different beneficial molecules for human health and in antioxidant activity.

Keywords: HPLC-ELSD; LC-PDA/MS QTof; Malus domestica L.; UPLC-PDA; by-products; phenolic compounds; sensory evaluation.

Figure 1

Quantification of phenolic compounds by UPLC-PDA method (mg/100 g fw) in apple juice and enriched apple smoothies. Mean values of the total polyphenolic compounds with different letters (a–f) are significantly different (homogenous groups) at p ≤ 0.05.

Figure 2

Consumer evaluation of enriched apple juices (5° hedonic scale). Sensory evaluation was carried out in analysed juices immediately after processing. The presented values are the average of all evaluations. AJ—apple juice; AJ+S01—apple juice + 0.1% saffron flower juice; AJ+S05—apple juice + 0.5% saffron flower juice; AJ+M5—apple juice + 5% myrtle berry extract; AJ+F5—apple juice + 5% feijoa flowers; AJ+P—apple juice + 5% persimmon purée; AJ+C—apple juice + 5% strawberry tree fruits.