Effects of blackcurrant and apple mash blending on the phenolics contents, antioxidant capacity, and colour of juices

https://doi.org/10.17221/20/2008-CJFSCitation:Oszmiański J., Wojdyło A. (2009): Effects of blackcurrant and apple mash blending on the phenolics contents, antioxidant capacity, and colour of juices. Czech J. Food Sci., 27: 338-351.
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The objective of this research was to evaluate the effect of blackcurrant mash blended with apple pulp during juice production and storage on its phenolic composition, antioxidant activity, L-ascorbic acid, and colour. Five variants of samples were prepared: apple juices from two cultivars: the Shampion and Idared cultivars without and with 20% of blackcurrant pulp and blackcurrant juice which were stored at 4°C and 30°C for 6 months. The apple juices prepared from the Idared and Shampion cultivars had a very low L-ascorbic acid contents (1.32 mg/l and 6.26 mg/l, respectively) whereas blackcurrant juice showed the highest amount of L-ascorbic acid, i.e. 704.3 mg/l. The addition of 20% of blackcurrant pulp before apple crashing resulted in a great difference between L-ascorbic acid contents in juices. The addition of blackcurrant fruits before apple crushing had a statistically significantly different (P < 0.05) influence on phenolic compounds, especially in Idared blended pulp. As compared with the control samples, flavan-3-ol concentration increased 4 times in juices made from 80% of Idared apples blended with 20% of blackcurrant fruits. Apple pulp blended with blackcurrant was richer in hydroxycinnamic acids (especially caffeic, p-coumaric, and neochlorogenic acids) than juices made only from apples. The results ranged from 83.05 to 3297.6µM T/100 ml for DPPH (1,1-diphenyl-2-picrylhydrazyl radical), from 20.64 to 490.93µM T/100 ml for ABTS (2,2’azinobis-(3-ethylbenzthiazoline-6-sulphonic acid)), and from 1.52 to 37.35µM T/ml for FRAP (Ferric reducing antioxidant power assay) for apple juice made from the Idared cultivar and for blackcurrant juice, respectively. The highest level of the antioxidant capacity (P < 0.05) observed in the blackcurrant sample was due to the effect of the high anthocyanin and ascorbic acid contents. The apple juice colour showed a moderate degradation with time as indicated by the slight reduction of L* values in the samples stored at 4°C for 6 months, and a much higher decrease of L* values in the samples stored at 30°C. The lightness of the apple blended with blackcurrant increased during storage as a result of the coloured anthocyanin degradation. The temperature during the sample storage (30°C) had a significant influence, resulting in a higher degradation of all phenolics compounds analysed, colour and antioxidant activity.
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