Chokeberries () are rarely used in diet in Croatia but they have high content of polyphenolic compounds and one of the highest antioxidant activities among fruits. The aim of this study is to compare the quality, phenolic content and antioxidant capacity of different chokeberry products (juices, powders, fruit tea, capsules and dried berries). It can be expected that processing influences antioxidant activity and phenolic content of final products reaching consumers. Characterisation of phenolic compounds was carried out by using spectroscopic methods (Folin-Ciocalteu and pH differential methods). Antioxidant activity of chokeberry products was determined using 2,2-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods. The results show that the investigated products contain high amount of phenols (3002 to 6639 mg per L and 1494 to 5292 mg per 100 g of dry matter) and lower amount of total anthocyanins (150 to 1228 mg per L and 141 to 2468 mg per 100 g of dry matter). The examined juices and other chokeberry products possess high antioxidant capacity (12.09 to 40.19 mmol per L or 58.49 to 191.31 mmol per 100 g of dry matter, respectively) and reducing power (38.71 to 79.86 mmol per L or 13.50 to 68.60 mmol per 100 g of dry matter, respectively). On the basis of phenolic content and antioxidant activity, capsules and powders stand out among other products. The study indicates that there are significant differences (p<0.05) in the quality, phenolic content and antioxidant capacity among examined products.

A number of studies have shown that the consumption of cocoa and chocolate products has positive health effects on humans. The object of this research was to monitor changes of total and individual phenolics and antioxidant capacity during the cocoa bean manufacturing. The loss of cocoa phenolics and their antioxidant activity vary with the degree of technological process. The process of roasting and cocoa nib alkalisation had the major influence on phenolic compounds as well as on antioxidant capacity. The roasting treatment resulted in 14% loss of the total phenolics content, while alkalisation resulted in 64% loss of total phenolics content. Procyanidins B1 and B2 as well as ())-epigallocatechin were the unstable components, while caffeic acid derivate showed the greatest stability in all technological process. Furthermore, PCA showed that phenolic contents, antioxidant capacity and non-fat cocoa solids parts of the samples were classified in groups according technological conditions.

Abstract:The antioxidant activities and total phenolic content of 30 samples of acacia honey from Croatian territory were analysed. Phenolics were determined by the modified Folin-Ciocalteu method, antiradical activity by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and potential antioxidant activity using the ferric reducing antioxidant power (FRAP) method. In all samples, physicochemical parameters (water content, electrical conductivity, total reducing sugars, sucrose content, acidity, hydroxymethylfurfural content, prolin content, optical rotation, diastase activity and invertase activity) were measured according to Croatian legislation and International regulatory standards. Honey can be considered as a dietary supplement as it contains some important components including α-tocopherol, ascorbic acid, flavonoids and phenolics. The composition and properties of honey are dependent on floral origins, climatic conditions of the produced area, processing and storage methods. The results of physicochemical analyses showed that all the values of investigated parameters are in agreement with the current legislation. Phenolic content ranged from 31.72 mg/kg to 80.11 mg/kg, antiradical activity expressed as IC 50 ranged from 61.28% to 253.47% and antioxidant activity expressed as FRAP value from 6.95 to 142.43. A positive correlation was observed between total phenolic content and antioxidant activity, indicating that phenolic compounds are mainly responsible for the antioxidant power of acacia honey.

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