The objective of this study was to determine the polyphenol content (total phenols, flavonoids, nonflavonoids, anthocyanins) and antioxidant capacity in selected fruits (apple, ‘Idared’; apricot, ...‘Madjarska najbolja’; blueberry, ‘Bluecrop’; mandarin, ‘Kuno’; orange, unknown; sour cherry, ‘Marasca’; strawberry, ‘Maya’ and peach, ‘Redhaven’) and vegetables (broccoli, ‘Belstar’ -flower and steam; cauliflower, ‘Favola’; kale, ‘Melissa’ and leek-leaf and root -unknown) commonly consumed in the Croatian diet. Total phenols, flavonoids and nonflavonoids were measured calorimetrically by using the Folin-Ciocalteu reagent with gallic acid as the standard; anthocyanins were determined using bisulphite bleaching method using cyanidin-3-diglucoside as standard, whereas antioxidant capacity was measured using DPPH method. The highest total polyphenols were observed in sour cherry as 2560 mg GAE/kg fresh weight (FW), followed by blueberry, orange, mandarin, strawberry, apple, apricot, and peach. Among vegetables the highest concentration of total polyphenols was determined in kale (1039 mg GAE/kg FW) followed by broccoli flower, broccoli steam, leek leaf, leek root and cauliflower. In all investigated fruits, as well as vegetables, total flavonoids were predominant polyphenols. Total nonflavonoids were present in low concentration especially in leek leaf, broccoli flower and leek root. The highest antioxidant capacity in fruit and vegetables was determined in samples with higher concentration of flavonoids. In selected fruits, there was a distinct correlation between total phenols or flavonoids and antioxidant capacity, while in vegetable the correlation was not observed.
The influence of processing wild elderberry into concentrated juice on polyphenols (total phenols, flavonoids, non-flavonoids, anthocyanins, flavan-3-ols, hydrolysed tannins) stability, activity of ...polyphenol oxidase (PPO) and peroxidase (POD), and changes of physico-chemical parameters (total and soluble dry matter, total acidity, pH, sugars) were investigated. The amounts of total phenols, flavonoids, non-flavonoids, falvan-3-ols and hydrolysed tannins were analyzed using Folin-Ciocalteu colorimetric method, while the total anthocyanins were determined by bisulphite bleaching method. Total phenols ranged from 25.87 mg/g DM to 38.87 mg/g DM. Total anthocyanins were the most abundant polyphenols in all investigated samples (raw elderberries, elderberries after blanching, elderberry juice after disintegration and pressing, concentrated elderberry juice) and their concentration ranged from 13.12 mg/g DM to 25.67 mg/g DM. Other polyphenols determined in high concentration were hydrolysed tannins, followed by fl avan-3-ols, flavonoids and nonfavonoids. After blanching, the concentration of all polyphenols did not decrease significantly. After disintegration of elderberries the concentration of all polyphenols increased, probably due to inactivation of PPO and POD and better isolation of polyphenols from homogenized puree. During processing of elderberry juice into concentrated juice most polyphenols were stable. Total acidity and pH value were not changed during processing, whereas the amounts of total and reducing sugar increased after pressing and additionally after concentration. The obtained results suggest that raw elderberries as well as elderberry concentrated juice are high potential source of polyphenols especially anthocyanins.
The aim of this research was to investigate the influence of several parameters on quality of Clementine (Citrus clementine) jam. Thermal treated and nontreated Clementine purée, two types of sugar ...(sucrose and fructose) and three different amounts of added pectin were used for the jam producing. Accordingly, twelve jams were prepared and sorted in four groups, two of nontreated purées and two of treated purées, and each one with sucrose and fructose within. The quality of jams was evaluated through gel strength measurement, sensory evaluation and level of polyphenols. The results of gel strength measurement showed that the treated purée jams were less firm than nontreated ones, the jams with sucrose were firmer than the ones with fructose and the gel strength of jams increased with amount of added pectin increase. Jams of nontreated purée contained higher level of polyphenols in comparison with jams of treated purée. Regarding to sensory evaluation, the nontreated purée jams were higher rated in comparison to treated ones. Furthermore, jams with fructose were better evaluated than jams with sucrose. Based on obtained results, it is revealing that nontreated purée jam with fructose and 0.7 % added pectin was the best sensory evaluated sample.
Pressing of plum fruit in producing cloudy juices is difficult due to high amount of pectic substances in plum. Maceration of pulp with enzymes is usual way to make pressing more effective but ...provided that no negative impact on juice quality and biological value e.g. antioxidant capacity (AC). Content of anthocyanins and other phenolic compounds in juices are related with its AC so better extraction of these compounds from fruit to juice is of great importance to obtain juice with nice colour, health benefi ts and excellent sensory characteristics. The aim of this work was to investigate the influence of enzyme concentration, maceration temperature and duration on the yield, content of phenolic compounds, anthocyanins, AC and sensory perception in producing cloudy juices. Plum fruit (Prunus domestica L.), cultivar Bistrica, was used to produce cloudy juices on small scale equipment. Before pressing, fruits were pitted and treated with maceration enzymes in concentration of 100 or 140 ppm at 20 or 48oC for one or two hours (eight samples). Anthocyanins were determined by method based on bisulfite bleaching, total phenolics (TP) by Folin-Ciocalteu reagent, the AC by FRAP (Ferric Reducing Antioxidant Power) method and sensory evaluation by Quantitative descriptive method. The higher yields were obtained with pre-treatments by 140 ppm of enzyme on 48oC during 1 and 2h, and also in the same juices the highest amount of TP was found. In general, anthocyanin contents increased with enzyme concentration, temperature and duration. Despite some exceptions increasing trend of AC with enzyme concentration and temperature of treatment was observed. Sensory all juices were
high evaluated without significant differences. Enzyme treatment on 48oC/2h could be recommended to produce high quality cloudy plum juice due to high yield, high anthocyanin contents and total phenolics, antioxidant capacity and sensory evaluation.
The biologically active compounds, especially fruit phenolics, are responsible for reduced risk of developing chronic diseases (cardiovascular disease, cancer, diabetes, etc.), due to their ...antioxidant activities. Th is study summarized some chemical principles of antioxidant capacity assays and the antioxidant capacity of selected fruit varieties (strawberry, sour cherry, cornelian cherry, blackthorn). We determined the contents of total phenolics (TPC), total flavonoids (TF), total non-flavonoids (TNF) and total anthocyanins (TA) in selected fruits. The content of TPC, TF and TNF in fruits was analyzed by Folin-Ciocalteu colorimetric method, while the TA content of extracts was determined by bisulphite bleaching method. Total antioxidant capacity (TAC) of selected fruits were analyzed using 2,2-azinobis(3-ethylbenzothiazoline- 6-sulfonic acid) radical cation (ABTS), 2,2-diphenil-1-picrylhydrazyl radical scavenging capacity (DPPH), ferric ion reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC). Cornelian cherry had the highest content of TPC, while sour cherry cv. Marasca had the highest content of TA. TAC was the highest in cornelian cherry fruits and decreased in other fruits as follow: sour cherry, blackthorn and strawberry. The fruit extracts had different TAC in relation to the method applied, and the different TAC of fruits can be ascribed to their TPC, TF, TNF or TA content. There was a direct correlation between the TAC determined using DPPH and ORAC methods and the TA content of fruit extracts. Using FRAP method correlation was weaker, but using ABTS method correlation was not observed. The ripping correlation between TF or TNF and TAC was observed using ABTS and ORAC methods.
Sensory quality is important in assessing cultivars for fresh consumption as well as for the processing industry. Important quality attributes for fresh consumption were found to be colour, taste, ...flavour and texture attributes. Strawberries (Fragaria x ananassa Duch.) have unique, highly desirable taste and flavour and are one of the most important cultivated berry fruits in Croatia. Today, consumers are increasingly better informed about diet and health, and as a result, desire more “healthy“ food, which offer high quality, safety and optimum nutrient balance. The increasing demand for organic food has focused interest based on claims that an organic product tastes “different“, is “preferred“ and is “more healthy“. It has implicit expectation that the improvement is due to the way the food is grown. The topic of organic food and organic agriculture attracts considerable public, commercial and research interest. The purpose of the present investigation was to profile the sensory characteristics of fresh fruit and its purées in two strawberry cultivars, ‘Maya’ and ‘Queen Elisa’, conventionally and organically grown in Croatia. Quantitative descriptive analysis (QDA) was used to describe the sensory properties of fresh fruit as well as its purées. All obtained results were statistically evaluated. Conducted sensory evaluation indicated that there were slightly expressed
some differences in sensory attributes observed by panelists between two different cultivars and two type of cultivation but they did not show significant differences in any sensory attribute when dealing with two different strawberry cultivars or two types of cultivation.
