© 2016 Ewemen Resources Limited / EJAEC. All rights reserved.

2016 | Vol. 2 | Issue 2 | Pg. 89 - 91

Ewemen Journal of Analytical & Environmental Chemistry ISSN 2488-913X

Available online at http://ewemen.com/category/ejaec/

Full Length Research

ASSESSMENT OF ASCORBIC ACID CONTENT OF COMMON COMMERCIAL FRUIT JUICES IN NIGERIAN MARKET

BABA A., OCHALA A.U., *OCHENI A.

Luminescence, Materials and Inorganic Research Unit Department of Chemistry, Kogi State University, P.M.B 1008, Anyigba, Kogi State, Nigeria.

ABSTRACT

Received 5 October, 2016 Revised 15 October, 2016 Accepted 31 October, 2016 *Corresponding Author’s Email: ochenades@yahoo.com

Commercial fruit juices are often enriched with ascorbic acid (vitamin C) because of its antioxidant potentials, among other nutritional benefits. In this present studies, the ascorbic acid content of commonly marketed fruit beverages in the Nigerian market were determined using titrimetric and spectrophotometric methods. The results indicate that the ascorbic acid of the investigated juices range from 8.0 to 22.2 mg in 100 mL, which differs slightly from the values reported on the product packaging label. Keywords: Ascorbic acid, Titrimetric method, Spectrophotometric methods, Fruit juice.

INTRODUCTION

Ascorbic Acid (Vitamin C) is a water soluble vitamin, found in many biological systems and fruits. It plays important roles in collagen biosynthesis, iron absorption and immune response activation (Lee and Abel, 2000). It is also an essential antioxidant in numerous in vivo protocols as scavengers of free radicals that are implicated in ageing, neurodegenerative and some non-transmissible chronic disease (De Ritter, 1971). Ascorbic Acid is therefore added to common fruit juices to enhance their nutritional benefits (Kabasakalis et al., 2000; Alan, 1996; Delcaro, 2004). Different analytical methods can be used to determine the quantity of ascorbic acid in fruit juices or beverages. These methods include titrimetry (AOAC, 1980), ultra violet spectrophotometry, high performance liquid chromotography (HPLC), electrophoresis, enzymatic methods, amperometry

method (Lee and Abel, 2000) The present investigation is aimed at determining the ascorbic acid content of ten (10) ready to drink beverages (fruit juices) marketed in Anyigba, Dekina LGA of Kogi State using both titrimetric and spectrophotometric methods. MATERIALS AND METHODS

Materials

All regents used were of analytical grades. 98% 2,6-dichlorophenol indiphenol and 99% oxalic acid both from Kermel Chemical co. Ltd., 99% Ascorbic Acid from BDH (Analar), 98% Ethanol from JHD Chemicals Guangdong Guanghua Sci-Tech Co., Ltd., and UV spectrophotometer Genesys 20 model were used in the study.

Ewemen Journal of Analytical & Environmental Chemistry 2016, 2(2): 89 - 91 Baba et al.

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Sampling

Ten (10) commercially packaged fruit juices were purchased from three (3) shops in Anyigba. The expiration dates and conditions of packaging were noted and found to comply with the national quality standards for beverage production. Determination of ascorbic acid content

Titrimetric Method

2,6–dichlorophenolindophenol method was used to determine the quantity of the ascorbic acid by titrimetric method. The dye stock was prepared by dissolving 0.05 g (2,6,-dichlorophenolindophenol sodium salt) in 50 mL water containing 42 mg sodium bicarbonate. The solution was diluted to 200 mL with water-ethanol (1:1) mixture and then filtered. The filtrate was standardized by titration against 2 mL of standard ascorbic acid solution which was added to 5 mL of diluted beverage solution. In a similar way the extracted solution was diluted with 4% oxalic acid. A standard ascorbic acid solution was prepared by dissolving 0.05 g in 45 mL of the beverage solution, made up to 50ml and used immediately. 10 g (w/v) of each of the sample (fruit juices) was extracted with 10 mL of 4% oxalic acid into a 100 mL volumetric flask and made up to the mark. 5 mL of the diluted solution was then combined with 10 mL of oxalic acid added and titrated with the dye, to the brisk pink end point. The Vitamin C content was obtained by substituting the average titre values into the equation below.

𝑣𝑖𝑡 𝑐 =𝑠𝑎𝑚𝑝𝑙𝑒 𝑤𝑡

𝑑𝑦𝑒 𝑡𝑖𝑡𝑟𝑒𝑋 𝑇𝑖𝑡𝑟𝑒 𝑣𝑜𝑙. 𝑜𝑓

𝑠𝑎𝑚𝑝𝑙𝑒

𝑒𝑥𝑡𝑟𝑎𝑐𝑡 𝑋

100

𝑠𝑎𝑚𝑝𝑙𝑒 𝑤𝑡𝑋 100

UV-Vis spectrophotometric method.

Standard ascorbic acid was prepared by dissolving 0.05 g standard crystalline ascorbic acid in 100 mL of distilled water. This is 500 ppm standard stock solution. In order to prepare the sample, 10 mL of each blended sample was homogenized with 40 mL of the mixture of 5% metaphosporic acid and 10% acetic acid solution (Arya et al., 2000). It was quantitatively transferred into a 100 mL volumetric flask and shaken vigorously. This was diluted further to the mark with a 50 mL mixture of 5% metaphosphoric and 50 mL of 10% acetic acid solutions (Raiman et al., 2005). It was filtered and the filtrate was treated with a few drops of bromine water. The solution turned brown which confirm the completion of the oxidation

of ascorbic acid to dehydroascorbic acid. A few drops of thiourea was later added, to remove excess bromine and, resulted in a clear solution. Finally, 2,4–dinitrophenyhydrazinic solution was mixed thoroughly with the solution and the absorbance of the standard and samples were recorded at 521 nm using uv Spectrophotometer. Using Beer Lambert’s Law, molar absorbtivity = 0.0323 Lmol-1cm-1 RESULTS AND DISCUSSION

Ten samples of fruit juices from the local market were investigated, to ascertain the accuracy of the ascorbic acid content reported on the product packaging label. Table 1 shows the summary of data obtained from the study. Table 1: Ascorbic acid content determined by titrimetric and spectrophotometric methods, in mg/100 mL.

Sample No. Description AAIL AATM AASM 1. 5-alive Berry blast 12.0 15.6 12.0 2. 5-alive citrus burst 12.0 17.0 20.0 3. 5-alive purpy orange 10.8 27.0 18.0 4. Chi exotic necter, bamar 12.0 17.0 12.0 5. Chivita Active Fortified 12.0 13.3 9.0 6. Chi happy hour 12.0 22.2 18.0 7. La Casera - 22.2 18.0 8. Capri sonne - 13.3 8.0 9. Liquifruit Berry 30 18.0 17.0

10. Liquifruit mango 12 18.0 8.0 Key: AAIC = Ascorbic Acid indicated on Label, AATM = Ascorbic Acid determined by titrimetric method, AASM = Ascorbic acid determined by spectrophotometric method

A student t-test analysis of the experimental results showed there was no significant difference (p = 0.05) in the Vitamin C content determined by titrimetric and spectrophotometric methods among the ten samples (Quires et al., 2009). The measured ascorbic acid content in fruit juices and soft drinks using redox titrations show that the amount declared on the labels were very different from that determined experimentally. In a similar way, the spectrophotometric determinations showed a 20% agreement with the values on the label, 30% lower and the remaining 50% showed higher values than those specify on the label. Although the values of the ascorbic acid from the titrimetric and spectrophotometric methods showed slight variations, statistically, the t-critical value at p = 0.05 indicate that the vitamin C values obtained from the two analytical methods were not significantly different. The observed difference in the two methods could be attributed to the level of sensitivity of the methods.

Ewemen Journal of Analytical & Environmental Chemistry 2016, 2(2): 89 - 91 Baba et al.

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Santos et al (2009) also reported similar findings in their study. Among the six brands of mango nectar studied by Santos and his team, only two had lower values of determined ascorbic acid than those provided on the label, while other nectars presented higher levels (up to 60%) than the value indicated on the label. Wide variation in the vitamin C contents of fruit had earlier been reported by Kabasakalis et al (2000) who ascertained that the ascorbic acid content in different commercial fruit juices marketed in Greece ranged from 2.4 to 43 mg/100 mL. Such wide ascorbic acid content was also observed in this study. There is the need therefore for local regulatory authorities like the National Agency for Food and Drug Administration and Control (NAFDAC) and the Standards Organisation of Nigeria (SON) to regularly monitor the ascorbic acid content of fruit juices in the market, and ascertain if the amount reported on the label actually corresponds to the actual packaging content. These precautionary steps are necessary to provide a needed guide to consumers and for public health benefits. CONCLUSION

The present study shows there is slight but statistically insignificant difference between the values of ascorbic acid reported on the product packaging label and the values determined experimentally. Variation between titrimetric and spectrophotometric methods could be due to sensitivity of the different methods applied although the sensitivity was not determined in this work.

CONFLICT OF INTEREST

None declared REFERENCES

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Article’s citation

Baba A, Ochala AU and Ocheni A (2016). Assessment of ascorbic acid content of common commercial fruit juices in Nigerian market. Ew J Anal & Environ Chem 2(2): 89 - 91.