Next Article in Journal
The Effects of a Natural Citrus Phenolic Extract on the Quality Attributes and Oxidative Stability of Pariza-Type Meat Emulsion Product
Previous Article in Journal
Diclofenac Degradation in Aqueous Solution Using Electron Beam Irradiation and Combined with Nanobubbling
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Applied Sciences
Volume 14
Issue 14
10.3390/app14146029
applsci-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Compositional Characteristics of Currant Juices Prepared by Different Processes and Other Selected Currant Products

by
Tereza Podskalská
*,
Novel Kishor Bhujel
,
Martina Hraničková
,
Filip Beňo
,
Adam Tobolka
and
Helena Čížková
*
Department of Food Preservation, Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague, Czech Republic
*
Authors to whom correspondence should be addressed.
Appl. Sci. 2024, 14(14), 6029; https://doi.org/10.3390/app14146029
Submission received: 26 May 2024 / Revised: 24 June 2024 / Accepted: 8 July 2024 / Published: 10 July 2024
(This article belongs to the Section Food Science and Technology)
Browse Figures
Versions Notes

Abstract

The quality of black/red currant products, which are valuable components of a healthy diet, depends on many aspects, e.g., natural variability, climatic conditions, degree of ripeness, processing technology, and recipe. The aim of the study was to assess the effect of the harvest year (2020 and 2021) and different processes (with or without prepress enzymatic treatment) on the chemical composition of 38 laboratory-prepared black/red currant (BC/RC) juices and to compare them with 19 selected commercial products, using 20 compositional and quality markers. Significant differences (p < 0.01) were observed for BC in sucrose, Dp-3-glu, and Cy-3-glu content within the different processes, as well as fructose and ascorbic acid content within the harvest year (p < 0.05). The greatest differences between BC and RC juices were observed in ascorbic acid content (1567 mg/kg in BC and 261 mg/kg in RC), citric acid content (34.6 g/kg in BC and 23.2 g/kg in RC), and in the anthocyanin profile. The major anthocyanins of the currant products were identified as Dp-3-rut (39.1–50.4%), Cy-3-rut (30.1–39.1%), Cy-3-glu (3.6–18.2%), and Dp-3-glu (9.4–13.5%) in BC and Cy-3-glu (59.3–67.2%) and Cy-3-rut (14.2–19.8%) in RC. The chemical composition of commercial products was found to be highly variable and dependent on the recipe used.

1. Introduction

The currant belongs to the genus Ribes of the higher dicotyledonous plants, family Grossulariaceae, including about 150 species and hybrids of currants and gooseberries. The commercially cultivated species include black currants (Ribes nigrum L.), red currants (Ribes rubrum L.), and white currants (colour forms of R. rubrum L.), which are a white variety of the red currant. The world’s most grown cultivars of black currants are Roodknop, Öjebyn, Tiben, Mortti, Ola, Ben Lomond, Ben Alder, Ben Nevis, Ben Hope, Bona, Magnus, Boskoop Giant, and Titania; those of red currants are Jonkheer van Tets, Red Dutch, Heinemann’s R.S., Rondom, Stanza, Red Lake, Rovada, Rolan, Hron, Rosetta, and Redpoll [1,2,3,4].
The total world currant production in 2022 was almost 764.5 thousand tonnes. According to FAOSTAT, the Czech Republic ranked among the top 10 currant producers in the world in 1993–2022, along with Russia, Poland, Germany, Ukraine, Great Britain, Austria, France, Hungary, and Denmark. On average over this period, the Czech Republic produced 8 118 tonnes of currants [5].
Currants are primarily grown to produce fruit juices, nectars, non-alcoholic beverages (fruit drinks, teas, flavoured mineral waters), alcoholic beverages (like the French ‘Crème de cassis’), fruit drink concentrates, jams, purees, fillings, toppings, ice creams, candies, jelly, functional foods, nutraceutical ingredients, or to be eaten fresh [1,2,3,4,6].
The industrial production of currant juices involves several steps, such as thawing and crushing the berries (to obtain the homogenate of the fruit), heating them to a certain temperature, enzymatic maceration, pressing, filtering, clarification, pasteurisation, and filling. The production of concentrates is like the production of currant juice, but the final product is concentrated by the evaporation of water. In general, the reasons for the different steps in berry processing are to maximise juice yield, inactivate microorganisms, deactivate enzymes, and maintain the sensory characteristics of the final product The use of pectolytic enzymes in juice production is quite common, because these treatments improve juicing, prevent the gelatinisation of the juice, increase juice yield, reduce viscosity, and significantly increase the extraction of bioactive compounds such as polyphenols. Commonly used enzymes usually contain mixtures of endo-polygalacturonase, pectin lyase, and pectinesterase, as well as other enzymes with cellulolytic and hemicellulolytic effects, mostly originating from fungal sources (notably from A. niger spp.). The purpose is to break up polymeric structures such as pectin, cellulose, and hemicellulose in the flesh of berries. The degradation of pectin changes physico-chemical properties such as the total soluble solids, pH, turbidity, aroma, and increased bitterness (astringency) due to a significant increase in polyphenol content [4,6,7,8,9,10].
The quality of black currant and red currant juices depends on many aspects. The correct choice of variety (the suitability of the raw material for industrial processing, adaptation to climatic conditions, and resistance to diseases and microorganisms) is essential. The processing technology itself is also crucial, as each step affects the chemical composition of the final product and therefore its nutritional and sensory properties [4,11,12]. Laaksonen et al. (2020) investigated the effects of enzymatic and non-enzymatic treatments on the chemical composition of juices. For the black currant cultivar Mortti, the total anthocyanin concentration was 152 ± 12 mg/100 g without enzymatic assistance and 229 ± 1 mg/100 g with enzymatic assistance [6]. It also depends on the harvest year, as confirmed in a paper by Šimerdová et al. (2021). For the black currant variety Ben Lomond, the total anthocyanin content was 217 mg/100 g, 131 mg/100 g, and 283 mg/100 g in a three-year period [13]. In study by Rachtan-Janicka et al. (2021), the vitamin C content of three currant varieties (Titania, Ben Adler, and Tiben) was determined at concentrations of 147 ± 5 mg/100 g in 2014 and 135 ± 4 mg/100 g in 2015 [14].
Current studies on the complex determination of the chemical composition of black currant and especially red currant juices are insufficient. The aim of this work is to expand/update the database of quality markers of black and red currants (or selected commercial currant products), because there are very few literature sources for the selected markers (formol number, d-isocitric acid, and minerals). Also limited is the number of recent studies analysing more than three varieties of black currants and especially red currants. This work verifies the influence of selected factors—natural variability, harvest year (2020 and 2021), and different processes (with/without enzyme addition)—on the chemical composition of black/red currant juices and compares the quality with selected commercially available products. In order to compare the chemical composition, quality markers (sugars, organic acids (including ascorbic acid and d-isocitric acid), titratable acidity, formol number, ash, minerals, and anthocyanins) were determined. Eventually, this study could be helpful for breeders, scientists, or specialised food industries.

2. Materials and Methods

2.1. Berries and Commercial Products

The analysis was carried out on 38 laboratory-produced juices (more precisely, on 22 samples of black currant juice (16 samples of enzyme juice and 6 samples of non-enzyme juice) and 16 samples of red currant juice (10 samples of enzyme juice and 6 samples of non-enzyme juice)). The juices were laboratory-prepared from hand-picked berries of black currant (cultivars Öjebyn, Titania, Othello, Ben Hope, Red Hube, Viola, and unknown) and red currant (cultivars Rovada, Heinemann’s R.S., Jonkheer van Tets, and unknown) collected from various geographic locations in the Czech Republic between 2020 and 2021 (see Table 1). Immediately after harvesting, the fruits were frozen and stored at −18 °C until processing. Unfortunately, due to crop frost or low yields of currant berries, it was not possible to compare all varieties from the first year of the study. Therefore, the samples were replaced by other varieties, but the number of samples with and without enzyme addition in the two-year experiment was maintained (Table 1).
Furthermore, we controlled the chemical composition of 19 samples of commercial products (more precisely, 8 homogenates, 4 concentrates, and 7 nectars; see Table 2), which were purchased on the Czech market or directly from the Czech producers: Pepsico CZ Ltd. (Prague, Czech Republic), Mattoni 1873 a.s. (Kyselka, Czech Republic), and Hamé Ltd. (Kunovice, Czech Republic). All samples were stored in a freezer (−18 °C) before processing or/and analysis.

Juice Preparation

For the laboratory preparation of currant juices, the addition of a solution of the enzyme preparation (pectinase) Rohapect MC (AB Enzymes GmbH, Darmstadt, Germany) and the juicer Sana Supreme 727 (Mipam bio Ltd., České Budějovice, Czech Republic), with homogenising attachment and juicing sieve attachment, were used. A solution of the enzyme preparation Rohapect MC was prepared by weighing 2 g into a 50 mL volumetric flask and making up to the mark with distilled water. The berry samples stored in the freezer were thawed to room temperature before processing (cleaning, defrosting). First, a homogenate was prepared from the black/red currant berries (800 g, 40 rpm, ≈20 °C), followed by tempering (50 °C, 30 min), enzyme addition (pectinase), Rohapect MC (mixing 4 mL solution/800 g berries), a second tempering (50 °C, 90 min), juicing (40 rpm), and finally, the freezing of the laboratory-prepared currant juices (enzyme juice) before analysis. For currant juices without enzyme addition (non-enzyme juice), they were prepared from the homogenate tempering (50 °C, 120 min), juicing (40 rpm), and subsequent freezing before analysis (Figure 1). The residues of currant seeds and skins after juicing were not further used. The dosage, temperature, and maceration time were defined according to the enzyme producer’s instructions. The temperature was set using the thermostat Memmert UN110 SingleDisplay (Verkon Ltd., Prague, Czech Republic). The currant juice production procedure was partially reproduced from the studies of Laaksonen et al. (2014) and Kidón and Narasimhan (2022) [10,11]. The juice yields are shown in Table 1.

2.2. Chemicals and Reagents

The chemical standards used in this study were obtained from Sigma-Aldrich (St. Louis, MO, USA): sucrose (≥99.5%), d-(+)-glucose (≥99.5%), d-(-)-fructose (≥99%), sorbitol (≥98%), citric acid monohydrate (≥99%), dl-isocitric acid trisodium salt hydrate (≥93%), l-cysteine (97%), potassium dihydrogen phosphate (≥98%), potassium dihydrogen phthalate (≥99.5%), and ethylenediaminetetraacetic acid disodium salt dihydrate (98.5–101.5%). The d-isocitric assay kit (K-ISOC) was obtained from Megazyme (Bray, Ireland). dl-malic acid (≥99%) and TRIS hydrochloride (pufferan, ≥99%) were obtained from Carl Roth (Karlsruhe, Germany). The standards of anthocyanins (delphinidin 3-rutinoside (>97%), cyanidin 3-glucoside (>97%), and cyanidin 3-rutinoside (>97%)) were obtained from Polyphenols AS (Sandnes, Norway). Sulphuric acid (96%), formic acid (85%), sodium hydroxide pellets (p.a.), sodium hydroxide ready-to-use volumetric solution 0.25 mol/L, formaldehyde (36–38%, p.a.), and methanol (99.9%) were obtained from Penta (Prague, Czech Republic). Ascorbic acid (p.a.), oxalic acid dihydrate (≥99%), hydrochloric acid (35%, p.a.), acetonitrile (≥99.5%), active carbon powder (<40 μm), and ammonium molybdate tetrahydrate (≥99%) were obtained from Lach-Ner (Neratovice, Czech Republic). The following chemicals were obtained from Merck (Darmstadt, Germany): cesium chloride (99.995%) and cesium chloride–lanthanum chloride buffer solution according to Schinkel for atomic absorption spectrometry (AAS; 10 g/L CsCl + 100 g/L La), standard solution with 1 g/L concentration of potassium (KNO3 in HNO3 0.5 mol/L), magnesium (Mg(NO3)2 in HNO3 0.5 mol/L), and calcium (Ca(NO3)2 in HNO3 0.5 mol/L). Rohapect MC (declared activity min. 650 PE/g) was obtained from AB Enzymes (Darmstadt, Germany).

2.3. Methods

2.3.1. Soluble Solids Analysis

The soluble solids (Rf) content was determined by refractometry according to DIN EN 12143, using a digital refractometer (RM40, Mettler-Toledo, Columbia, MD, USA) [15]. The soluble solids value (°Brix) was read from the digital display at 20.0 ± 0.1 °C (vs. distilled water).

2.3.2. Sugar Analysis

Major sugars (saccharose (Sach), glucose (Glc), fructose (Fru), and sorbitol) were determined by high-performance liquid chromatography (HPLC) with a refractive index detector (RID) according to DIN EN 12630 [16]. Samples for the HPLC analysis of sugars are first diluted with distilled water and filtered through syringe filters (Nylon, ø 25 mm, 0.45 µm; Verkon Ltd., Prague, Czech Republic) before HPLC analysis (chromatograph Thermo Scientific™ Dionex™ UltiMate™ 3000 (Thermo Scientific, Norristown, PA, USA) (Chromeleon® Version 6.80)), with the detector Shodex RI-101, column Shodex™ SUGAR™ SC1011 series (Shodex, Tokyo, Japan) (8.0 mm × 300 mm, 6 μm, 80 °C), and an analysis time of 17 min. The mobile phase was filtered and degassed distilled water at a flow rate of 1.0 mL/min. The injection volume was 20 μL. Samples were diluted as follows: juices, homogenates, and nectars 20 times and concentrates 100 times. The external standard method was used for quantitative evaluation. The standards of sucrose, glucose, fructose, and sorbitol in a 1 g/L mixed solution were used for the determination, from which a single-point calibration was performed.

2.3.3. Organic Acids Analysis

Major acids (malic (MA) and citric (CA) acid) were determined by HPLC with a diode-array detector (DAD) according to Scherer et al. and Rajchl et al. [17,18]. Samples for the HPLC analysis of organic acids are first diluted with distilled water and filtered through syringe filters (Nylon, ø 25 mm, 0.45 µm; Verkon Ltd., Prague, Czech Republic) before HPLC analysis (chromatograph Thermo Scientific™ Dionex™ UltiMate™ 3000 (Chromeleon® Version 6.80)) with detector UltiMate 3000 Series: Photodiode-Array Detector—210 nm; column Phenomenex Luna C18 (2) 100 A (4.6 mm × 250 mm, 5 μm, 20 °C); and an analysis time of 35 min. The mobile phase was 0.02 mol/L KH2PO4 at pH 2.5 (adjusted with H3PO4) at a flow rate of 1.0 mL/min. The injection volume was 20 μL. Samples were diluted as follows: juices, homogenates, and nectars 20 times and concentrates 100 times. The external standard method was used for quantitative evaluation. Malic and citric acid standards were used for quantification, from which calibration, a series of concentrations (0.2, 0.1, 0.05, and 0.025 g/L) were prepared.

2.3.4. d-Isocitric Acid Content

d-isocitric acid (ICA) was determined by the enzymatic method (Megazyme) according to Podskalská et al. [19]. The determination of d-isocitric acid is based on the oxidation of ICA by reaction with NADP+ to form 2-oxoglutarate, CO2, and the reduced form NADPH + H+. This reaction is catalysed by the enzyme NADP-isocitrate dehydrogenase (ICDH, EC 1.1.1.42). The amount of NADPH (stoichiometric with the amount of d-isocitric acid) is determined spectrophotometrically at 340 nm. The sample weight for juices, homogenates, and nectars was 25 g and for concentrates 5 g [19,20].

2.3.5. Titratable Acidity and Formol Number Analysis

The titratable acidity (TA) and formol number (FN) were determined by titration according to DIN EN 12147 and DIN EN 1133, respectively [21,22]. The determination of TA is based on titration with sodium hydroxide solution (NaOH, c = 0.25 mol/L) up to pH 8.1 using potentiometric indication. The volume of NaOH consumed is then converted to the equivalent amount of the predominant acid; in the case of currant juices, this is citric acid. The determination of FN is based on the release of H+ ions from amino acids present in the sample after the addition of formaldehyde solution. The released H+ ions are then titrated with NaOH solution (c = 0.25 mol/L). Automatic titrator (Titrator Excellence T5, Mettler-Toledo, Columbia, MD, USA) was used for the TA and FN analysis. The sample weight for juices and homogenates was 10 g, for nectars 20 g, and for concentrates 2.5 g [21,22].

2.3.6. Ash and Mineral Substances Analysis

Ash content was determined by gravimetry according to DIN EN 1135 [23]. The content of phosphorus (P) was assessed by the spectrophotometric method according to DIN EN 1136 [24] using a UV–VIS spectrophotometer (SPEKOL® 1300, Analytic Jena AG, Jena, Germany). Mineral substances (potassium (K), magnesium (Mg), and calcium (Ca)) were determined by atomic absorption spectrometry (AAS, Agilent 240FS AA, Agilent Technologies, Inc., Santa Clara, CA, USA) according to DIN EN 1134 [25]. For the determination of ash content, the sample weight of juices, homogenates, and nectars was 5 g and 1 g for concentrates. For the determination of phosphorus concentration, the pipetted sample volume (after the conversion of ash to a solution, 50 mL volumetric flask) was 2 mL for juices, homogenates, and concentrates and 5 mL for nectars [24]. For the determination of mineral substances concentration, the pipetted sample volume was 2 mL for all samples [25].

2.3.7. Ascorbic Acid Content

Ascorbic acid (AA) was determined by HPLC/DAD according to Iwase and Ono [26]. Samples for the HPLC analysis of ascorbic acid are first diluted with a solution of 0.5% oxalic acid with 0.25% l-cysteine (the solution was prepared by weighing 5 g oxalic acid plus 2.5 g l-cysteine into a 1000 mL volumetric flask and making it up to the mark with distilled water) and filtered through syringe filters (Nylon, ø 25 mm, 0.45 µm; Verkon Ltd., Prague, Czech Republic) before HPLC analysis (chromatograph Thermo Scientific™ Dionex™ UltiMate™ 3000 (Chromeleon® Version 6.80)) with the detector UltiMate 3000 Series: Photodiode-Array Detector—254, 360 nm and column Phenomenex Luna 10u C18 (2) 100 A (4.6 mm × 250 mm, 10 μm, 20 °C). The mobile phase was 5.5 mmol/L H2SO4 at a flow rate of 1.0 mL/min and an analysis time of 15 min. The injection volume was 5 μL. Samples were diluted as follows: juices and homogenates from black currants 100 times, juices and homogenates from red currants 10 times, nectars 10–25 times (by ingredients), and concentrates 200 times. The external standard method was used for quantitative evaluation. Ascorbic acid standard was used for determination and quantification, and a calibration range was prepared from it at concentrations of 1, 5, 10, 20, 40, and 60 mg/L.

2.3.8. Anthocyanins Analysis

The profile of anthocyanins was determined by reversed-phase HPLC/DAD with a gradient elution according to the International Federation of Fruit Juice Producers (IFU) Method No 71—Anthocyanins by HPLC [27]. Samples for the HPLC analysis of anthocyanins are first diluted with distilled water and filtered through syringe filters (PTFE, ø 25 mm, 0.2 µm; Verkon Ltd., Prague, Czech Republic) to HPLC vials with darkened glass (chromatograph Thermo Scientific™ Dionex™ UltiMate™ 3000 (Chromeleon® Version 6.80)), with the detector UltiMate 3000 Series: Photodiode-Array Detector—518, 520, 525 nm; column Purospher® STAR RP-8 Endcapped (Merck, Darmstadt, Germany) (4.6 mm × 250 mm, 5 μm, 40 °C); and an analysis time of 46 min. The mobile phase consisted of A—distilled water/formic acid in a volume ratio of 9:1 (v/v) and B—distilled water/formic acid/acetonitrile in a volume ratio of 4:1:5 (v/v/v) at a flow rate of 1.0 mL/min and gradient (0–1 min and 43–46 min 88% A + 12% B, 26 min 70% A + 30% B, 35–38 min 100% B) according to the IFU Method No 71 [27]. The injection volume was 10 μL. Samples were diluted as follows: juices and homogenates 10 times, nectars 5 times, and concentrates 50 times. The external standard method was used for quantitative evaluation. Anthocyanin standards (Cy-3-glu, Cy-3-rut, and Dp-3-rut) were used for determination and quantification, from which calibration, a series of concentrations (5, 25, 50, and 100 mg/L) were prepared.

2.4. Statistical Analysis

Statistical analyses were performed to compare the obtained quality parameters and anthocyanin content and profile in black and red currant juices. The results are expressed as mean values (from at least two measurements) ± standard deviations. The F-test and Student’s t-test were used to determine the statistical differences between harvest years, as well as to compare the produced (enzyme/non-enzyme) juices. Different types of currant juices, enzymatic or non-enzymatic, were subjected to one-way ANOVA, followed by the Tukey HSD test and principal component analysis (PCA). MS Excel (Microsoft; Redmond, WA, USA) and Statistica 12.0 (StatSoft; Tulsa, OK, USA) were used, with α = 0.05.

3. Results and Discussion

3.1. Chemical Composition of Black and Red Currant Juices

The effect of different processes (enzymatic (E) and without enzymatic (WE) juice pressing) and harvest year (2020 and 2021) on the chemical composition of the currant juices was studied on a laboratory scale, using berries of black and red currant. The analysis was based on 20 selected quality parameters (e.g., sugars, organic acids, mineral substances, and anthocyanin content). Of the four groups of currant juices, the average juice yield was highest for RC with enzyme addition (79%), followed by RC without enzyme addition (76%) and BC with/without enzyme addition (approximately 70%). No effect (p > 0.05) was observed for the yield with/without enzyme addition. The juice yields for the individual currant samples are shown in Table 1. For varieties from the same farmers, yields were similar over the two years. Only the Red Hube variety had a 3% higher yield in 2021. According to the literature sources, yields for black currant juice with enzyme addition range from 66 to 79% and from 58 to 72% without enzyme addition, and those for red currant juice with enzyme addition and ultrasound effect range from 86 to 88%. The reason for the low yield of juice could be attributed to the high pectin content of the berries [4,8,10].
The chemical compositions (f.w.) of BC and RC juices are presented in Table 3. It should be noted that the values for sorbitol are not shown in Table 3 and Table 5 as it was not detected in all samples. The statistical difference (p < 0.01) between black currant (BC) samples with enzyme addition (E) and without enzyme addition (WE) is only in sucrose content (at 0.2–1.8 g/kg E vs. <0.1 g/kg WE). The cut-off values for BC E/WE were for the FN (p = 0.061) and magnesium content (p = 0.053). The effect of the harvest year (2020–2021) of BC was observed (p < 0.05) for fructose and ascorbic acid content. The average ascorbic acid content was higher in 2020 (1756 mg/kg) than in 2021 (1377 mg/kg). In contrast, the average fructose content was lower in 2020 (45.6 g/kg) than in 2021 (53.1 g/kg). The cut-off values for BC 2020/2021 were for glucose (p = 0.056). The same varieties (Titania, Öjebyn, Red Hube) had a higher sugar content in 2021 than in 2020. The Red Hube variant even had almost double the glucose and fructose content (Glc: 29.6 g/kg versus 55.5 g/kg and Fru: 35.0 g/kg versus 66.8 g/kg). This may be due to climatic conditions or a higher maturity at harvest. There were no significant differences (p > 0.05) in the chemical composition of RC juices depending on harvest year or different processes (E/WE). The cut-off values for RC 2020/2021 were for fructose (p = 0.058). In contrast, minimal differences (p > 0.9) were observed in malic acid, d-isocitric acid, phosphorus, magnesium, and calcium content. The greatest differences (p < 0.001) between black and red currant were in the content of ascorbic acid (1567 ± 436 mg/kg in BC and 261 ± 101 mg/kg in RC), titratable acidity (37.9 ± 4.2 g/kg in BC and 25.5 ± 3.8 g/kg in RC), soluble solids (16.1 ± 1.8°Brix in BC and 12.3 ± 2.3°Brix in RC), and citric acid (34.6 ± 6.4 g/kg in BC and 23.2 ± 7.0 g/kg in RC) and in the anthocyanin profile (Table 3 and Table 4 and Figure 4).
The Code of Practice (CoP) reference guidelines are commonly used in European countries to verify the quality of black currant juices. The Association of the Fruits and Vegetable Juice and Nectar Industry of the European Union (AIJN), an organisation dedicated to standardising quality rules and assessing the authenticity of fruit juices, established the Code of Practice [28]. However, some of our results (see Table 3), such as titratable acidity values, fall outside this range, as do phosphorus, formol number, and citric acid for WE samples and ash for E samples. Similar TA results were obtained by the authors Kidón and Narasimhan [10] during the evaluation of black and red currant. The average values of potassium are at the lower CoP limit, which may be due to the maturity level of the berries. Cosmulescu et al. [29] investigated the mineral content of currants and measured potassium concentrations of 1711–1867 mg/kg for black currant. The high variability of the results limits the applicability of the standard values given in the CoP for black currant; therefore, the values (especially for mineral substances) might have been updated or reevaluated. The Code of Practice does not define the chemical composition (limit values) of red currant juice, so the values are compared with the range given in the food composition and nutrition tables for red currants (Souci et al., 2015) [30]. Contrary to our results, Souci et al. (2015) reported the standard value of the chemical composition for red currant juice: 0.9–5.0 g/kg for sucrose, 7.3–29.0 g/kg for glucose, 18.7–30.0 g/kg for fructose, 2.4–6.4 g/kg for malic acid, 16.9–23.0 g/kg for citric acid, and 260–470 mg/kg for ascorbic acid [30]. On the other hand, consistent with our results for sugars and organic acids are the published results from Stój and Targonski (2005 and 2006a), Nour et al. (2011), and Bazzarini et al. (1986) [31,32,33,34]. Compared to black currants, red currant varieties are highly variable in malic acid (0.6–11.4 g/kg) and potassium (466–3493 mg/kg) content. The average values of mineral substances correspond to the values given in the nutritional tables [30]. Similar results for phosphorus and potassium content in six different red currant varieties were documented by Štursa et al. (2016) [35]. A lower ash content may indicate increased water content and decreased mineral content due to climatic conditions or natural variability. Titratable acidity and citric acid decrease rapidly during maturation and react to climatic factors like high temperatures. Different type of cultivation soils and regional climates might affect mineral composition. The content of sugars, organic acids, formol number, mineral substances, and anthocyanins can be highly variable and influenced by several factors: climatic conditions (temperature, day length, UV irradiation, pH), natural variability in cultivars, ripeness level, latitude, technological processing, and storage conditions [10,12,31].
Table 3. Chemical composition (f.w.) of black currant (BC) and red currant (RC) juices (with (E)/without (WE) enzyme addition).
Table 3. Chemical composition (f.w.) of black currant (BC) and red currant (RC) juices (with (E)/without (WE) enzyme addition).
Marker Black Currant (BC)Red Currant (RC)ANOVA
p-Values		Literature DataReference
E
(n = 16)		WE
(n = 6)		E
(n = 10)		WE
(n = 6)		BCRC
Soluble solids [°Brix]16.2 ± 1.7 cd15.9 ± 1.8 c12.0 ± 1.7 ab12.9 ± 2.8 a<0.0018.9–20.08.0–15.3[2,4,10,11,12,28,33,34,36,37,38,39]
Sucrose [g/kg]0.8 ± 0.5 bcd<0.1 a<0.1 a<0.1 a<0.0050.0–36.90.0–11.6[4,6,11,12,28,30,32,38,39,40,41]
Glucose [g/kg]39.1 ± 7.937.0 ± 8.233.1 ± 7.836.5 ± 8.0NS21.0–82.87.0–46.6[4,6,11,12,28,30,32,38,39,40,41]
Fructose [g/kg]50.2 ± 8.2 c47.2 ± 9.537.3 ± 7.5 a39.6 ± 7.4<0.00523.0–85.418.0–55.4[4,11,12,28,30,32,38,39,40,41]
Ratio Glc/Fru0.8 ± 0.1 cd0.8 ± 0.1 cd0.9 ± 0.1 ab0.9 ± 0.1 ab<0.0010.6–0.90.7–1.2[28,32,34]
Malic acid [g/kg]2.9 ± 0.73.0 ± 0.73.7 ± 3.32.2 ± 0.8NS0.6–10.00.3–19.0[4,6,11,12,28,30,31,33,34,38,40]
Citric acid [g/kg]33.8 ± 6.2 c37.0 ± 6.1 cd22.0 ± 7.4 ab25.2 ± 5.8 b<0.00118.0–59.89.9–38.0[4,6,11,12,28,30,31,33,34,38,40]
d-isocitric acid [mg/kg]266 ± 39281 ± 62213 ± 53257 ± 51NS125–500130–313[28,31,34,42]
Ratio CA/ICA132 ± 43143 ± 57103 ± 3298 ± 13NS80–20075–188[28,31]
Titratable acidity [g/kg]37.6 ± 4.3 cd38.8 ± 3.5 cd25.8 ± 3.2 ab25.2 ± 4.3 ab<0.0018.7–48.012.0–39.0[2,10,28,33,34,37,39,43]
Formol number
[mL 0.1 M NaOH/100 g]		15.7 ± 6.622.5 ± 7.623.0 ± 13.217.3 ± 9.1NS7.0–30.01.5–2.6[28,34]
Ash [g/kg]5.2 ± 0.55.5 ± 0.54.4 ± 1.64.2 ± 1.5NS5.0–11.04.7–7.2[28,30,34,41,43]
Phosphorus [mg/kg]274 ± 81302 ± 97246 ± 110262 ± 138NS160–606156–440[28,30,34,35,41,43]
Potassium [mg/kg]1717 ± 4412046 ± 3011685 ± 8271544 ± 657NS1711–41001272–3000[28,30,33,34,35,41,43]
Magnesium [mg/kg]145 ± 30 cd115 ± 25102 ± 20 a100 ± 22 a<0.00180–67921–393[28,30,33,34,35,41,43]
Calcium [mg/kg]370 ± 94 cd324 ± 90232 ± 42 a257 ± 28 a<0.001160–74990–380[28,30,33,34,35,41,43]
Ascorbic acid [mg/kg]1631 ± 387 cd1396 ± 475 cd241 ± 100 ab295 ± 85 ab<0.001171–3960121–768[2,4,8,10,11,12,14,28,30,33,34,36,37,38,39,40,41,43,44]
Note: Data are expressed as mean value ± standard deviation (SD); n = number of samples; SDs followed by different lowercase letter in row are significantly different (p < 0.05), as analysed by one-way ANOVA; NS = not significant.
The anthocyanin content (f.w.) of BC and RC juices is presented in Table 4 and Figure 4. In agreement with other studies on BC juices, the four main anthocyanins, delphinidin-3-glucoside (Dp-3-glu), delphinidin-3-rutinoside (Dp-3-rut), cyanidin-3-glucoside (Cy-3-glu), and cyanidin-3-rutinoside (Cy-3-rut), were identified (see Table 4). Other authors found trace amounts of petunidin, peonidine, pelargonidine, cyanidin, delphinidin, and malvinidine derivatives. The HPLC analysis revealed 3–5 peaks in RC juices. According to the standard, the retention time and spectra characteristics of Cy-3-glu and Cy-3-rut were confirmed (RC, Table 4). Other peaks of unknown anthocyanins in RC could probably be cyanidin-3-sophoroside, cyanidin-3-glucosyl-rutinoside, cyanidin-3-xylosyl-rutinoside, and cyanidin-3-sambubioside [13,45,46]. The value of total anthocyanins in our case is calculated as the sum of all anthocyanins, as many authors do [4,10,13,14,44,47]. In some studies, it is calculated as the equivalent of cyanidin-3-glucoside [8,13,33], but this can be assumed to underestimate the results, because Cy-3-glu is one of the least abundant anthocyanins in black currant [13].
Table 4. Anthocyanin content [mg/100 g f.w.] in BC and RC juices (E/WE).
Table 4. Anthocyanin content [mg/100 g f.w.] in BC and RC juices (E/WE).
Black Currant (BC)Student’s
t-Test
p-Values		Reference
MarkerE
(n = 16)		WE
(n = 6)		Literature Data
Dp-3-glu
(*Cy-3-glu)		33.7 ± 10.1 b19.9 ± 6.3 a2.1–113.2<0.01[4,10,11,13,14,36,38,40,44,45,46,47,48]
Dp-3-rut243.6 ± 89.5 b151.1 ± 61.9 a11.5–311.4<0.05[4,10,11,13,14,36,38,40,44,45,46,47,48]
Cy-3-glu16.7 ± 4.6 b10.3 ± 3.0 a0.6–28.6<0.01[4,10,11,13,14,36,38,40,44,45,46,47,48,49]
Cy-3-rut117.9 ± 49.0102.8 ± 50.711.4–211.4NS[4,10,11,13,14,36,38,40,44,45,46,47,48,49]
Sum of unknown (*Cy-3-glu)ndnd0.0–14.4-[10,38,40,45,46,47]
TACy *411.9 ± 140.7284.1 ± 117.729.4–586.6NS[4,6,8,10,11,13,14,28,33,36,38,44,45,47,48]
Red currant (RC)Student’s
t-test
p-Values		Reference
MarkerE
(n = 10)		WE
(n = 6)		Literature data
Dp-3-glu
(*Cy-3-glu)		ndnd0.0–0.2-[10,38,45,46,47]
Dp-3-rutndnd<LOD-[10,38,45,46,47]
Cy-3-glu20.7 ± 8.020.9 ± 4.60.2–28.9NS[10,38,45,46,47,49]
Cy-3-rut10.2 ± 4.410.0 ± 3.51.6–17.5NS[10,38,45,46,47,49]
Sum of unknown (*Cy-3-glu)11.9 ± 10.15.1 ± 2.20.0–12.5NS[10,38,46,47]
TACy *42.8 ± 14.336.1 ± 7.14.7–31.7NS[2,10,33,38,39,47]
Note: Data are presented as mean ± SD; n = number of samples. * The concentration of delphinidin-3-rutinoside and sum of unknown anthocyanin were calculated using a calibration series from the cyanidin-3-glucoside standard; the total anthocyanins (TACy) were calculated as the sum of all anthocyanins. nd = not detected. SDs followed by a different lowercase letter in a row are significantly different (p < 0.05), as analysed by Student’s t-test. NS = not significant.
Student’s t-test revealed significant differences (p < 0.01) in the anthocyanin profile of black currant juices depending on different treatments (E/WE) for two anthocyanins, Dp-3-glu and Cy-3-glu, and significant differences (p < 0.05) for Dp-3-rut (Table 4). In contrast, Student’s t-test showed no significant differences (p > 0.05) in the anthocyanin content of BC juices depending on the year of harvest. The total amount of anthocyanins (TACy) and the content of individual anthocyanins (except Cy-3-rut) are approximately 1.5 times higher in enzyme juice samples than in non-enzyme juices. Anthocyanins are more abundant in the skin than in the flesh, so enzyme preparations are used to release them [8,38]. Student’s t-test showed no significant differences (p > 0.05) in the anthocyanin content of RC juices depending on the year of harvest or different processes. The cut-off values for RC 2020/2021 were for Cy-3-rut (p = 0.068).
The PCA analysis (Figure 2 and Figure 3) shows the relationship between chemical composition and the year of harvest (2020/2021) and technological processing (E/WE). For blackcurrant, the distribution of the PCA analysis was within minerals against other markers, and for red currant, sugars and ash were selected. For red currant juices, 16 chemical compounds were used for the PCA analysis, as no sucrose was detected (<0.1 g/kg) in RC juices. In Figure 2, the same varieties are shown in coloured ellipses—Red Hube (green), Titania (grey), and Öjebyn (yellow). As most of the red currant varieties are unknown, the orange ellipses (in Figure 3) show the same berry samples with and without enzyme addition (E/WE) for the harvest years 2020 and 2021.

3.2. Chemical Composition of Commercial Products

The chemical compositions (f.w.) of black and red currant (BC and RC) commercial products are presented in Table 5. BC homogenates had a higher mineral content (phosphorus, magnesium, and calcium) than BC juices and the CoP. This may be due to the skin content of the samples after homogenisation (Figure 1). Nevertheless, the average values are consistent with those published by Nour et al. (2011), Marjanovic-Balaban et al. (2012), and Cosmulescu et al. (2015) [29,33,43]. To compare the concentrates with 100% juice, the resulting values of concentrates were converted to 100% juice for a refraction of 16.1°Brix (with an average of 16.2°Brix for E samples and 15.9°Brix for WE samples, Table 3). The values of all measured markers for BC concentrates comply with the requirements of the AIJN Code of Practice (CoP) [28]. The concentrates contain lower amounts of phosphorus, a lower formol number, and lower citric acid compared to BC juices, and a higher d-isocitric acid content, which may be due to the individual choice of variety or the production process. The ascorbic acid content of BC homogenates and concentrates is lower than that of BC juices. This difference can be associated with several factors, such as choice of variety for processing, climatic conditions, ripeness level, the effect of temperature, access to oxygen, and storage conditions [39,44]. The chemical composition of nectars is highly variable (Table 5), particularly in terms of the content of sugars, citric acid, and ascorbic acid, as these substances may be present in the composition of the products (see Table 2). The chemical markers obtained for RC homogenates present a similar trend to that described for RC juices. The contents of phosphorus, calcium, sugars, and the main acids (citric, malic, and ascorbic acid) do not correspond to the range of values given in the nutritional tables by Souci et al. (2015) [30], but these contents are consistent with the published literature [1,11,32,33]. As with the BC homogenates, RC homogenates have a higher ash and mineral content compared to RC juices, which is due to the skin and seeds content of the product (Figure 1).
The anthocyanin content (f.w.) of selected commercial products from black and red currants is presented in Table 6 and Figure 4. The anthocyanin content is highly variable (Table 6), especially for concentrates and nectars, as anthocyanin stability can be affected by a high temperature (pasteurisation) and pH. The total and individual anthocyanin content are affected by the genetic predisposition of the currants, the conditions and method of cultivation, the harvest maturity of the berries, methods of fruit processing (recipe), and storage conditions [13,14]. The occurrence of unknown anthocyanins (derivatives of cyanidin, delphinidin, petunidin, pelargonidin, or peonidin) in black currant concentrates may be due to cultivar selection, natural variability, and formation during chemical transformation due to the production process and storage (elevated temperature and pH, access to oxygen) [40,45,47].
The most represented anthocyanins in this study were Dp-3-rut (39.1–50.4%), Cy-3-rut (30.1–39.1%), Cy-3-glu (3.6–18.2%), and Dp-3-glu (9.4–13.5%) in BC and Cy-3-glu (59.3–67.2%) and Cy-3-rut (14.2–19.8%) in RC (Figure 4). The representation of anthocyanins in the RC homogenates is like that of the WE RC juice samples. This is not the case for BC homogenate samples, which have three times higher amounts of anthocyanin Cy-3-rut than BC juice samples. In contrast, the representation of anthocyanins in nectars is very similar to that of BC juices.
Applsci 14 06029 g004
Figure 4. Representation of anthocyanins [%] in BC and RC juices with/without enzyme addition (E/WE) in the years 2020–2021 and in commercial products (homogenates, concentrates, and nectars).
Figure 4. Representation of anthocyanins [%] in BC and RC juices with/without enzyme addition (E/WE) in the years 2020–2021 and in commercial products (homogenates, concentrates, and nectars).
Applsci 14 06029 g004
The PCA diagram (Figure 5) shows a clear difference between homogenates and other commercial products (concentrates and nectars). The blackcurrant and redcurrant homogenates are expressed by negative values of the principal component (F1), while the concentrates and nectars show positive values. In particular, the mineral and sugar content led to the division into categories (homogenates, concentrates, and nectars).

4. Conclusions

Technological processing, harvest year, and natural variability influence the chemical composition of currant juices and commercial currant products. The greatest differences between BC and RC juices were in ascorbic acid content (1567 ± 426 mg/kg in BC and 261 ± 98 mg/kg in RC), citric acid content (34.6 ± 6.4 g/kg in BC and 23.2 ± 7.0 g/kg in RC), and the anthocyanin profile. Significant differences were observed for BC juices in the content of sucrose and anthocyanins (Dp-3-glu, Cy-3-glu, and Dp-3-rut) within the different processes (enzyme/non-enzyme juice) and the content of fructose and ascorbic acid within the harvest year (2020/2021). The fructose content of black and red currants was higher in 2021, while the ascorbic acid content was lower in that year than in 2020. For RC, there were differences in the fructose content within the harvest year. The chemical composition of commercial products is highly variable (especially for concentrates and nectars), which is influenced not only by the choice of variety but also by the production process and recipe. Homogenates have a higher ash and mineral content than juices due to the peel content of the product. Concentrates and nectars have a lower ascorbic acid content and a highly variable anthocyanin content than juices, which is probably due to the choice of raw material, the production process (increased temperature and pH, access to oxygen) and storage time. The data obtained could be useful in the compositional characterisation of authentic black and red currant varieties and selected commercial currant products for breeders, scientists, or specialised food industries.

Author Contributions

Conceptualisation, T.P. and H.Č.; methodology, T.P., A.T. and H.Č.; software, T.P. and F.B.; validation, T.P., F.B. and H.Č.; formal analysis, T.P., N.K.B., M.H., F.B. and A.T.; investigation, T.P., N.K.B. and M.H.; resources, T.P., M.H. and H.Č.; data curation, T.P.; writing—original draft preparation, T.P.; writing—review and editing, N.K.B., F.B. and H.Č.; visualisation, T.P.; supervision, T.P. and H.Č.; project administration, T.P.; funding acquisition, T.P. and H.Č. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the University of Chemistry and Technology, Prague, Czech Republic—grant No. A1_FPBT_2024_008.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy reasons.

Acknowledgments

We would like to thank AB Enzymes GmbH (Darmstadt, Germany) for providing the enzyme preparation.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Heiberg, M.; Maage, F. CURRANTS AND GOOSEBERRIES. In Encyclopedia of Food Sciences and Nutrition, 2nd ed.; Caballero, B., Ed.; Academic Press: Cambridge, MA, USA, 2003; pp. 1708–1712. ISBN 9780122270550. [Google Scholar] [CrossRef]
  2. Zdunić, G.; Šavikin, K.; Pljevljakušić, D.; Djordjević, B. Chapter 5—Black (Ribes nigrum L.) and Red Currant (Ribes rubrum L.) Cultivars. In Nutritional Composition of Fruit Cultivars, 1st ed.; Simmonds, M.S.J., Preedy, V.R., Eds.; Academic Press: Cambridge, MA, USA, 2016; pp. 101–126. ISBN 9780124081178. [Google Scholar] [CrossRef]
  3. Jasrotia, A.; Bakshi, P.; Kour, K.; Preet, M.S. Chapter 14—Currants (Ribes spp.). Minor Fruits: Nutraceutical Importance and Cultivation, 1st ed.; Ghosh, S.N., Ed.; Jaya Publications House: Delhi, India, 2017; pp. 257–286. ISBN 9789386110299. [Google Scholar]
  4. Laaksonen, O.; Mäkilä, L.; Tahnoven, R.; Kallio, H.; Yang, B. Sensory quality and compositional characteristics of blackcurrant juices produced by different processes. Food Chem. 2013, 138, 2421–2429. [Google Scholar] [CrossRef]
  5. Food and Agriculture Organization of the United Nations (FAO). 2023. Available online: https://www.fao.org/faostat/en/#data/QCL/visualize (accessed on 25 April 2024).
  6. Laaksonen, O.; Mäkilä, L.; Jokinen, M.; Metz, T.; Kallio, H.; Yang, B. Impact of storage on sensory quality of blackcurrant juices prepared with or without enzymatic treatment at industrial scale. Eur. Food Res. Technol. 2020, 246, 2611–2620. [Google Scholar] [CrossRef]
  7. Matthews, C. SOFT DRINKS/Production. In Encyclopedia of Food Sciences and Nutrition, 2nd ed.; Caballero, B., Ed.; Academic Press: Cambridge, MA, USA, 2003; pp. 5352–5358. ISBN 9780122270550. [Google Scholar] [CrossRef]
  8. Landbo, A.-K.; Meyer, A.S. Effects of different enzymatic maceration treatments on enhancement of anthocyanins and other phenolics in black currant juice. Innov. Food Sci. Emerg. Technol. 2004, 5, 503–513. [Google Scholar] [CrossRef]
  9. Mäkilä, L.; Laaksonen, O.; Kallio, H.; Yang, B. Effect of processing technologies and storage conditions on stability of black currant juices with special focus on phenolic compounds and sensory properties. Food Chem. 2017, 221, 422–430. [Google Scholar] [CrossRef] [PubMed]
  10. Kidoń, M.; Narasimhan, G. Effect of Ultrasound and Enzymatic Mash Treatment on Bioactive Compounds and Antioxidant Capacity of Black, Red and White Currant Juices. Molecules 2022, 27, 318. [Google Scholar] [CrossRef] [PubMed]
  11. Laaksonen, O.A.; Mäkilä, L.; Sandell, M.A.; Salminen, J.-P.; Liu, P.; Kallio, H.P.; Yang, B. Chemical-Sensory Characteristics and Consumer Responses of Blackcurrant Juices Produced by Different Industrial Processes. Food Bioprocess Technol. 2014, 7, 2877–2888. [Google Scholar] [CrossRef]
  12. Zheng, J.; Yang, B.; Tuomasjukka, S.; Ou, S.; Kallio, H. Effects of Latitude and Weather Conditions on Contents of Sugars, Fruit Acids, and Ascorbic Acid in Black Currant (Ribes nigrum L.) Juice. J. Agric. Food Chem. 2009, 57, 2977–2987. [Google Scholar] [CrossRef] [PubMed]
  13. Šimerdová, B.; Bobríková, M.; Lhotská, I.; Kaplan, J.; Křenová, A.; Šatínský, D. Evaluation of Anthocyanin Profiles in Various Blackcurrant Cultivars over a Three-Year Period Using a Fast HPLC-DAD Method. Foods 2021, 10, 1745. [Google Scholar] [CrossRef] [PubMed]
  14. Rachtan-Janicka, J.; Ponder, A.; Hallmann, E. The Effect of Organic and Conventional Cultivations on Antioxidants Content in Blackcurrant (Ribes nigrum L.) Species. Appl. Sci. 2021, 11, 5113. [Google Scholar] [CrossRef]
  15. DIN EN 12143; Fruit and Vegetable Juices—Estimation of Soluble Solids Content—Refractometric Method. Deutsches Institut für Normung: Berlin, Germany, 1996.
  16. DIN EN 12630; Fruit and Vegetable Juices—Determination of Glucose, Fructose, Sorbitol and Sucrose Contents—Method Using High Performance Liquid Chromatography. Deutsches Institut für Normung: Berlin, Germany, 1999.
  17. Scherer, R.; Rybka, A.C.P.; Ballus, C.A.; Meinhart, A.D.; Filho, J.T.; Godboy, H.T. Validation of a HPLC method for simultaneous determination of main organic acids in fruits and juices. Food Chem. 2012, 135, 150–154. [Google Scholar] [CrossRef]
  18. Rajchl, A.; Čížková, H.; Ševčík, R.; Jodasová, A.; Voldřich, M. Analytical data for plum paste as a tool for evaluation of plum paste authenticity. J. Food Nutr. Res. 2013, 52, 71–77. [Google Scholar]
  19. Podskalská, T.; Kvasnička, F.; Čížková, H. Metody stanovení d-isocitronové kyseliny ve výrobcích z ovoce/Methods for Determination of d-Isocitric Acid in Fruit Products. Chem. Listy 2021, 115, 615–622. [Google Scholar]
  20. Booklet d-Isocitric Acid (d-Isocitrate), Assay Procedure; K-ISOC 04/20; Megazyme Ltd., Bray, Co.: Wicklow, Ireland, 2020; pp. 1–11.
  21. DIN EN 12147; Fruit and Vegetable Juices—Determination of Titratable Acidity. Deutsches Institut für Normung: Berlin, Germany, 1997.
  22. DIN EN 1133; Fruit and Vegetable Juices—Determination of the Formol Number. Deutsches Institut für Normung: Berlin, Germany, 1994.
  23. DIN EN 1135; Fruit and Vegetable Juices—Determination of Ash. Deutsches Institut für Normung: Berlin, Germany, 1994.
  24. DIN EN 1136; Fruit and Vegetable Juices—Determination of Phosphorus Content; Spectrophotometric Method. Deutsches Institut für Normung: Berlin, Germany, 1994.
  25. DIN EN 1134; Fruit and Vegetable Juices—Determination of Sodium, Potassium, Calcium and Magnesium Content by Atomic Absorption Spectrophotometry (AAS). Deutsches Institut für Normung: Berlin, Germany, 1994.
  26. Hiroshi, I.; Ono, I. Determination of ascorbic acid and dehydroascorbic acid in juices by high-performance liquid chromatography with electrochemical detection using l-cysteine as precolumn reluctant. J. Chromatogr. A 1993, 654, 215–220. [Google Scholar] [CrossRef]
  27. IFU Method No. 71; Fruit Juices and Nectars—Detection of Anthocyanins by HPLC. International Federation of Fruit Juice Producers: Paris, France, 1998.
  28. The AIJN Code of Practice for evaluation of fruit and vegetable juices. In Reference Guidelines, 6.11 Reference Guideline for Blackcurrant Juice/Purée; A.I.J.N—European Fruit Juice Association: Belgium, Brussels, 2019.
  29. Cosmulescu, S.; Trandafir, I.; Nour, V. MINERAL COMPOSITION OF FRUIT IN BLACK AND RED CURRANT. South West J. Hortic. Biol. Environ. 2015, 6, 43–51. [Google Scholar]
  30. Souci, S.; Fachmann, W.; Kraut, H. Food Composition and Nutrition Tables, 8th ed.; Medpharm Scientific Publishers: Stuttgart, Germany, 2015; p. 1182. ISBN 9783804750729. [Google Scholar]
  31. Stój, A.; Targoński, Z. Use of content analysis of selected organic acids for the detection of berry juice adulterations. Pol. J. Food Nutr. Sci. 2006, 56, 41–47. [Google Scholar]
  32. Stój, A.; Targoński, Z. Use of sugar content analysis for the estimation of berry juice authenticity. Pol. J. Food Nutr. Sci. 2005, 55, 403–409. [Google Scholar]
  33. Nour, V.; Trandafir, I.; Ionica, M.E. Ascorbic acid, anthocyanins, organic acids and mineral content of some black and red currant cultivars. Fruits 2011, 66, 353–362. [Google Scholar] [CrossRef]
  34. Bazzarini, R.; Bigliardi, D.; Gherardi, S.; Castaldo, D.; Andrea, L.V.; Trifirò, A. Caratterizzazione analitica di lamponi, mirtilli, more di rovo e ribes rosso di diversa provenienza. Industria Conserve 1986, 61, 22–28. [Google Scholar]
  35. Štursa, V.; Diviš, P.; Jurečková, Z.; Matějíček, A. ANALYSIS OF RED CURRANT (RIBES RUBRUM) AND RED GOOSEBERRY (RIBES UVA-CRISPA) VARIETIES BY INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION SPECTROSCOPY. In Proceedings of the Conference MendelNet 2016, Brno, Czech Republic, 9–10 November 2016; Faculty of AgriSciences, Mendel Uvinersity: Brno, Czech Republic, 2016; pp. 669–674, ISBN 9788075094438. [Google Scholar]
  36. Djordjević, B.; Djurović, D.; Zec, G.; Zagorac, D.D.; Natić, M.; Meland, M.; Akšić, M.F. Does Shoot Age Influence Biological and Chemical Properties in Black Currant (Ribes nigrum L.) Cultivars? Plants 2022, 11, 866. [Google Scholar] [CrossRef]
  37. Vagiri, M.; Ekholm, A.; Öberg, E.; Johansson, E.; Andersson, S.C.; Rumpunen, K. Phenols and Ascorbic Acid in Black Currants (Ribes nigrum L.): Variation Due to Genotype, Location, and Year. J. Agric. Food Chem. 2013, 61, 9298–9306. [Google Scholar] [CrossRef]
  38. Zheng, J. Sugars, Acids and Phenolic Compounds in Currants and Sea Buckthorn in Relation to the Effects of Environmental Factors; University of Turku: Turku, Finland, 23 September 2013; ISBN 9789512954933. [Google Scholar]
  39. Djordjević, B.; Šavikin, K.; Zdunić, G.; Janković, T.; Vulić, T.; Oparnica, Č.; Radivojević, D. Biochemical Properties of Red Currant Varieties in Relation to Storage. Plant Foods Hum. Nutr. 2010, 65, 326–332. [Google Scholar] [CrossRef] [PubMed]
  40. Bordonaba, J.G.; Terry, L.A. Biochemical Profiling and Chemometric Analysis of Seventeen UK-Grown Black Currant Cultivars. J. Agric. Food Chem. 2008, 56, 7422–7430. [Google Scholar] [CrossRef]
  41. USDA Food and Nutrient Database for Fietary Studies. 2019. Available online: https://fdc.nal.usda.gov/fdc-app.html#/?query=currant (accessed on 18 April 2024).
  42. Wallrauch, S.; Greiner, G. Bestimmung der d-Isocitronensäure in Fruchtsäften und alkoholfreien Erfrischungsgetränken. Flüssiges Obst. 1977, 44, 241–245. [Google Scholar]
  43. Marjanović-Balaban, Z.; Grujić, S.; Jasic, M.; Vujadinović, D. TESTING OF CHEMICAL COMPOSITION OF WILD BERRIES. In Proceedings of the Third International Scientific Symposium “Agrosym Jahorina 2012”, Jahorina, Bosnia and Herzegovina, 15–17 November 2012; Kovačević, D., Ed.; Faculty of Agriculture, University of East Sarajevo: Lukavica, Bosnia and Herzegovina, 2012; pp. 154–160. [Google Scholar]
  44. Iversen, C.K. Black Currant Nectar: Effect of Processing and Storage on Anthocyanin and Ascorbic Acid Content. J. Food Sci. 1999, 64, 37–41. [Google Scholar] [CrossRef]
  45. Wu, X.; Gu, L.; Prior, R.L.; McKay, S. Characterization of Anthocyanins and Proanthocyanidins in Some Cultivars of Ribes, Aronia, and Sambucus and Their Antioxidant Capacity. J. Agric. Food Chem. 2004, 52, 7846–7856. [Google Scholar] [CrossRef] [PubMed]
  46. Veberic, R.; Slatnar, A.; Bizjak, J.; Stampar, F.; Mikulic-Petkovsek, M. Anthocyanin composition of different wild and cultivated berry species. LWT Food Sci. Technol. 2015, 60, 509–517. [Google Scholar] [CrossRef]
  47. Ponder, A.; Hallmann, E.; Kwolek, M.; Srednicka-Tober, D.; Kazimierczak, R. Genetic Differentiation in Anthocyanin Content among Berry Fruits. Curr. Issues Mol. Biol. 2021, 43, 36–51. [Google Scholar] [CrossRef] [PubMed]
  48. Jakobek, L.; Seruga, M.; Medvidović-Kosanović, M.; Novak, J.I. Anthocyanin content and antioxidant activity of various red fruit juices. Dtsch. Lebensm. Rundsch. Z. Leb. Leb. 2007, 103, 58–64. [Google Scholar]
  49. Stój, A.; Malik, A.; Targoński, Z. Comparative analysis of anthocyanin composition of juices obtained from selected species of berry fruits. Pol. J. Food Nutr. Sci. 2006, 56, 401–407. [Google Scholar]
Applsci 14 06029 g001
Figure 1. Scheme for juice production (with and without enzymatic treatment).
Figure 1. Scheme for juice production (with and without enzymatic treatment).
Applsci 14 06029 g001
Applsci 14 06029 g005
Figure 5. PCA biplot analysis of the selected commercial products (homogenates (BC/RC), concentrates, and nectars, 19) and chemical compounds (17)—soluble solids (Rf), sucrose (Sach), glucose (Glc), fructose (Fru), ratio of Glc/Fru, malic acid (MA), citric acid (CA), d-isocitric acid (ICA), ratio of CA/ICA, titratable acidity (TA), formol number (FN), ash, phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), and ascorbic acid (AA).
Figure 5. PCA biplot analysis of the selected commercial products (homogenates (BC/RC), concentrates, and nectars, 19) and chemical compounds (17)—soluble solids (Rf), sucrose (Sach), glucose (Glc), fructose (Fru), ratio of Glc/Fru, malic acid (MA), citric acid (CA), d-isocitric acid (ICA), ratio of CA/ICA, titratable acidity (TA), formol number (FN), ash, phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), and ascorbic acid (AA).
Applsci 14 06029 g005
Applsci 14 06029 g002
Figure 2. PCA biplot analysis of the black currant juices (with (E)/without (WE) enzyme addition, 22) and chemical compounds (17)—soluble solids (Rf), sucrose (Sach), glucose (Glc), fructose (Fru), ratio of Glc/Fru, malic acid (MA), citric acid (CA), d-isocitric acid (ICA), ratio of CA/ICA, titratable acidity (TA), formol number (FN), ash, phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), and ascorbic acid (AA).
Figure 2. PCA biplot analysis of the black currant juices (with (E)/without (WE) enzyme addition, 22) and chemical compounds (17)—soluble solids (Rf), sucrose (Sach), glucose (Glc), fructose (Fru), ratio of Glc/Fru, malic acid (MA), citric acid (CA), d-isocitric acid (ICA), ratio of CA/ICA, titratable acidity (TA), formol number (FN), ash, phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), and ascorbic acid (AA).
Applsci 14 06029 g002
Applsci 14 06029 g003
Figure 3. PCA biplot analysis of red currant juices (with (E)/without (WE) enzyme addition, 16) and chemical compounds (16)—soluble solids (Rf), glucose (Glc), fructose (Fru), ratio of Glc/Fru, malic acid (MA), citric acid (CA), d-isocitric acid (ICA), ratio of CA/ICA, titratable acidity (TA), formol number (FN), ash, phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), and ascorbic acid (AA).
Figure 3. PCA biplot analysis of red currant juices (with (E)/without (WE) enzyme addition, 16) and chemical compounds (16)—soluble solids (Rf), glucose (Glc), fructose (Fru), ratio of Glc/Fru, malic acid (MA), citric acid (CA), d-isocitric acid (ICA), ratio of CA/ICA, titratable acidity (TA), formol number (FN), ash, phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), and ascorbic acid (AA).
Applsci 14 06029 g003
Table 1. Samples of black and red currant juices (with/without enzyme addition).
Table 1. Samples of black and red currant juices (with/without enzyme addition).
Black Currant (BC, Ribes nigrum L.)
Sample No.CultivarHarvest PeriodEnzyme AdditionJuice Yield [%]Sample No.CultivarHarvest PeriodEnzyme AdditionJuice Yield [%]
1/20Öjebyn2020with69.21/21Red Hube ’2021with73.2
2/20Titania71.22/21Titania *67.7
3/20Titania *68.13/21Öjebyn °67.2
4/20Othello72.44/21-74.4
5/20Öjebyn °67.75/21Viola65.3
6/20Ben Hope72.76/21Titania69.3
7/20Red Hube ’69.87/21-70.7
8/20-56.48/21-73.6
9/20-without78.99/21-without72.7
10/20Othello64.610/21-67.7
11/20Ben Hope65.111/21-72.8
Red currant (RC, Ribes rubrum L.)
Sample No.CultivarHarvest periodEnzyme additionJuice yield [%]Sample No.CultivarHarvest periodEnzyme additionJuice yield [%]
12/20Rovada2020with71.312/21Heinemann’s R.S.2021with77.9
13/20-75.913/21Jonkheer van Tets80.9
14/20-79.414/21-80.0
15/20-83.015/21-76.2
16/20-80.816/21-80.0
17/20-without81.717/21-without78.5
18/20-78.118/21-73.6
19/20-70.619/21-75.8
Note: *, °, ’ = varieties from the same farmer.
Table 2. Samples of selected commercial products.
Table 2. Samples of selected commercial products.
Black Currant (BC)
Sample No.Product TypeProduct Composition
20homogenatesfrozen berries
21frozen berries
22frozen berries
23frozen berries
28concentratesjuice concentrate 65°Brix
29juice concentrate 65°Brix
30juice concentrate 65°Brix
31juice concentrate 68.95°Brix
32nectarswater, fructose-glucose syrup, sugar, black currant juice concentrate (25%)
33water, fructose-glucose syrup, sugar, black currant juice concentrate (25%)
34water, black currant juice concentrate (25%), sugar, citric acid, ascorbic acid
35water, black currant juice concentrate (25%), sugar, citric acid, ascorbic acid
36water, black currant juice concentrate (25%), sugar, citric acid, ascorbic acid
37water, sugar, black currant concentrate (25%), black currant flavouring, ascorbic acid
38water, sugar, black currant concentrate (25%), black currant flavouring, ascorbic acid
Red currant (RC)
24homogenatesfrozen berries
25frozen berries
26frozen berries
27frozen berries
Table 5. Chemical composition of selected commercial products.
Table 5. Chemical composition of selected commercial products.
MarkerBlack Currant (BC)Red Currant (RC)
HomogenatesConcentrates *NectarsHomogenates
(n = 4)(n = 4)(n = 7)(n = 4)
Soluble solids [°Brix]16.9 ± 1.516.1 ± 0.012.1 ± 0.512.0 ± 1.9
Sucrose [g/kg]<0.13.4 ± 0.739.0 ± 32.8<0.1
Glucose [g/kg]39.0 ± 6.435.0 ± 1.621.9 ± 16.133.4 ± 6.9
Fructose [g/kg]49.3 ± 7.943.4 ± 1.224.4 ± 18.136.8 ± 7.1
Ratio Glc/Fru0.8 ± 0.00.8 ± 0.00.9 ± 0.10.9 ± 0.0
Malic acid [g/kg]2.7 ± 0.82.4 ± 0.20.6 ± 0.24.5 ± 4.0
Citric acid [g/kg]29.0 ± 2.428.3 ± 1.26.0 ± 1.921.5 ± 4.8
d-isocitric acid [mg/kg]297 ± 29363 ± 2640 ± 18222 ± 57
Ratio CA/ICA98 ± 378 ± 4167 ± 5698 ± 6
Titratable acidity [g/kg]34.4 ± 3.233.9 ± 1.66.7 ± 0.925.3 ± 4.1
Formol number
[mL 0.1 M NaOH/100 g]		18.6 ± 4.68.8 ± 0.73.2 ± 1.127.6 ± 5.8
Ash [g/kg]7.4 ± 0.56.0 ± 0.31.1 ± 0.46.2 ± 0.2
Phosphorus [mg/kg]449 ± 35185 ± 2939 ± 11320 ± 19
Potassium [mg/kg]2593 ± 1302219 ± 371282 ± 622185 ± 155
Magnesium [mg/kg]239 ± 64141 ± 931 ± 10151 ± 18
Calcium [mg/kg]660 ± 211430 ± 27114 ± 41354 ± 91
Ascorbic acid [mg/kg]1290 ± 4731022 ± 307258 ± 211149 ± 83
Note: Data are expressed as mean ± standard deviation (SD); n = number of samples. * To compare the concentrates with 100% juice, the resulting values were converted to 100% juice (at a refraction of 16.1°Brix).
Table 6. Anthocyanin content [mg/100 g f.w.] of selected commercial products.
Table 6. Anthocyanin content [mg/100 g f.w.] of selected commercial products.
MarkerBlack Currant (BC)Red Currant (RC)
Homogenates
(n = 4)		Concentrates
(n = 4)		Nectars
(n = 7)		Homogenates
(n = 4)
Dp-3-glu
(*Cy-3-glu)		11.7 ± 4.526.7 ± 26.65.1 ± 4.2nd
Dp-3-rut130.4 ± 20.1247.8 ± 233.427.2 ± 17.3nd
Cy-3-glu31.1 ± 26.713.0 ± 12.01.8 ± 1.313.9 ± 6.6
Cy-3-rut82.7 ± 34.199.5 ± 97.213.1 ± 8.95.4 ± 3.7
Sum of unknown
(*Cy-3-glu)		nd2.7 ± 1.4nd2.8 ± 1.0
TACy *255.8 ± 60.5388.3 ± 365.747.2 ± 31.622.1 ± 10.7
Note: Data are presented as mean ± SD; n = number of samples. * The concentration of delphinidin-3-rutinoside and sum of unknown anthocyanin were calculated using a calibration series from the cyanidin-3-glucoside standard; the total anthocyanins (TACy) were calculated as the sum of all anthocyanins. nd = not detected.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Podskalská, T.; Bhujel, N.K.; Hraničková, M.; Beňo, F.; Tobolka, A.; Čížková, H. Compositional Characteristics of Currant Juices Prepared by Different Processes and Other Selected Currant Products. Appl. Sci. 2024, 14, 6029. https://doi.org/10.3390/app14146029

AMA Style

Podskalská T, Bhujel NK, Hraničková M, Beňo F, Tobolka A, Čížková H. Compositional Characteristics of Currant Juices Prepared by Different Processes and Other Selected Currant Products. Applied Sciences. 2024; 14(14):6029. https://doi.org/10.3390/app14146029

Chicago/Turabian Style

Podskalská, Tereza, Novel Kishor Bhujel, Martina Hraničková, Filip Beňo, Adam Tobolka, and Helena Čížková. 2024. "Compositional Characteristics of Currant Juices Prepared by Different Processes and Other Selected Currant Products" Applied Sciences 14, no. 14: 6029. https://doi.org/10.3390/app14146029

APA Style

Podskalská, T., Bhujel, N. K., Hraničková, M., Beňo, F., Tobolka, A., & Čížková, H. (2024). Compositional Characteristics of Currant Juices Prepared by Different Processes and Other Selected Currant Products. Applied Sciences, 14(14), 6029. https://doi.org/10.3390/app14146029

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop