Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X Vol. 2(1), 20-24, Jan. (2012) Res.J.Chem.Sci. International Science Congress Association 20 Elucidation of Sugar in Edible Fruit – Pineapple (Ananas Comosus) Okonkwo S.I, Ogbuneke R.U. and Uyo B.K.3 Anambra State University Uli, Department of Chemistry, Anambra State, NIGERIA Alvan Ikoku Federal College of Education, Department of Chemistry, Imo State, NIGERIA Federal University of Technology Owerri, Department of Chemical Engineering, Imo State, NIGERIA Available online at: www.isca.in (Received 03rd October 2011, revised 17th Octorber 2011, accepted 22th November 2011) Abstract Sugar present in the juice of pineapple (Ananas Cosmosus) which is edible crystalline carbohydrate mainly sucrose, lactose and fructose was elucidated. Pineapple juice was extracted from the pineapple sample bought from Ekeonunwa market Owerri, Imo State. Qualitative and quantitative analysis were carried out. The qualitative analysis was carried out by using Benedict reagent, Seliwanoff’s reagent, phenylydrazine and thin layer chromatography. The quantitative evaluation was carried out by Dichromate method using glucose and fructose as standards. The results obtained for qualitative analysis showed that the juice contain glucose and fructose. The amount of glucose found was 3.9x10-2g/cm and 1.41x10-2g/cm for fructose in the quantitative analysis. Keywords: Sugar, pineapple, sucrose and fructose. Introduction Sugar is a term for a class of edible crystalline carbohydrate, mainly sucrose, lactose and fructose characterized by a sweet flavor. Sugar is mostly extracted commercially from sugarcane and sugar beet. Glucose, fructose or fruit sugar, high fructose corn syrup are other sugar used in industrial food preparation, but are usually known by more specific names. Nowadays, Brazil has the highest per capital production of sugar. Chemically sugar is one of the carbohydrates and is the source of energy in human diet. Sugar is important as a food and is valued for its sweetness. Sugar was once assumed to raise blood glucose level more quickly than starch because of its simpler chemical structure (with out scientific research) but results from more than twenty studies demonstrated that sugar and starch cause blood glucose to rise at similar rates. This result showed that controlling all carbohydrate is necessary for controlling blood glucose levels in diabetic, the idea behind carbohydrate counting. Many experts believe that eating too much sugar does not cause diabetes, 4,5 though excessive calories from sugar can lead to obesity which may increase the risk of diabetes. However, a 2010 meta-analysis of eleven studies involving 310,819 participants and 15,043 cases of type 2 diabetesfound that “SSBs (Sugar-sweetened beverages) may increase the risk of metabolic syndrome and type 2 diabetes not only through obesity but also by increasing dietary glycemic load” leading to insulin resistance, -cell dysfunction and inflammation. Sugar has been produced in Indian subcontinent since ancient time. It was not plentiful or cheap in early times-honey was more often used for sweetening in most parts of the world. Originally people chewed sugarcane raw to extract its sweetness. Sugarcane was a native of tropical south Asia and Southeast Asia. The term sugar usually refers to sucrose, which is called “table sugar” or “saccharose”. Sucrose is a white crystalline disaccharide. Sucrose is the most popular of the various sugar for flavoring, as well as properties (such as mouth feel, preservation; and texture) of beverage and food. Sugar include monosaccharide (e.g glucose, fructose, galactose), disaccharides (e.g sucrose, lactose maltose), trisaccharides and oligosaccharide in contrast to complex carbohydrate such as polysaccharide. Corn syrups, dextrose, crystalline fructose, and maltose for example are used in manufacturing and preparing food. The international commission form method of sugar Analysis sets standard for the measurement of the purity of refined sugar known as ICUMSA numbers, lower numbers’ indicate a higher level of purity in the refined sugarPineapple (Ananas comosus) is the common name for tropical plant and its edible fruit which are coalesced berries10. The popularity of the pineapple is due to its sweet-sour taste containing 15% sugar, malic and citric fruits acids. It is also high in vitamin C and the essential mineral, manganese11. Its protein-digesting enzyme Bromelain may help digestion after a high protein meal12. Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(1), 20-24, Jan. (2012) Res.J.Chem.SciInternational Science Congress Association 21 The word pineapple in English was first recoded in 1398, when conifer trees (now termed pinecones) the term pine cone for the reproductive organ of cornifer trees was first recorded in 1694. When European explorers discovered this tropical fruit they called them pineapple (term first recorded in that sense in 1664 because of their resemblance to what is now known as the pine cone). In the scientific binomial Ananas Comosus, ananas, the original name of the fruit comes from the Tupi (Rio de Janeiro, Brazil) word Ananas, meaning “excellent fruit12 as recorded by Andre Thevet in 1555, and comosus, “tufted”, refers to the stem of the fruit. Other members of the Ananas gems are often called pine as well by layman. Pineapple is a herbaceous short-lived perennial plant, grows to 1.0 to 1.5 meters (3.3 to 4.9 ft) tall. Pineapple is one of locally available fruit that can be eaten fresh or canned or juice, it is also popularly used in desserts, salads, as a compliment to meat dishes and in fruit cocktail. The nutritional values of pineapple raw per. 100g are Energy 202kj (48kcal), carbohydrate 12.63g, sugars 9.26g, Dietary fiber 14g, fats 0.12g; protein 0.54g. Thiamine, (vitamin B) ,0.079g (6%) Riboflavin (vitamin B), 0.031mg (2%) Niacin (vitamin B),0.489mg (3%), pantholthenic acid (B), 0.205mg (4%), (vitamin B) 0.110mg (8%) folate (vitamin ) 15 (4%), vitamin C 36.2mg (60%). Calcium 13mg (1%), iron 0.28mg (2%) magnesium 12mg (3%), manganese 0.9mg (45%) phosphorus 8mg (1%) potassium 115mg (2%) and zinc 0.10mg (1%) 13. Percentage are relative to US recommendation for adult. In view of it is important to investigate in other to find out the type of sugar and its quantity contained in the juice of pineapple fruit. Material and MethodsSample Collection: Pineapple fruits were bought from Ekeonuwa market in Owerri, Imo State, Nigeria. Sample Preparation: the bark of the pineapple fruits was peeled off; juice was extracted from the pineapple. The juice extracted from the pineapple was used for qualitative and quantitative analysis. The qualitative characterization of sugar in pineapple was conducted using Benedict’s reagent, Seliwanoff’s reagent and phenyl hydrazine. Qualitative examination of the juice from the pineapple was also carried out using thin layer chromatography. The quantitative Estimation of sugar in pineapple juice by Dichromate method was also carried out as follows, using 10cm of prepared pineapple juice. The dichromate was standardized by using 25cm of dichromate, 100cm of 1 molar HSO, 5cm of 85% ortho phosphoric acid. These were poured into a flask and were titrated with Fe (NH). SO from the burette to the purple – bluish green colour. 1g of sugar was poured into 1000cm of water to make sugar solution. 10cm of the sugar solution was taken and 25cm of the standard dichromate solution were added, allowed to stand with occasional shaking for 25 minutes and then 100cm of 1/molar HSO, 5cm of 85% 0rtho phosphoric acid and 3 drops of diphenylamine indicator were added and mixed. These were titrated with Fe (NH). S0 to purple bluish colour. A serial dilution of the glucose were prepared and repeated as in b above with each for the maximum length of time of oxidation. Then a graph of sugar concentrations (from zero sugar concentration). Against difference in volume Fe (NH). S0 were plotted. A 10cm of the prepared pineapple juice were taken, 25cmof dichromate was added and shaked for the maximum length of time of oxidation. A 100cm of 1 molar HS0 and 5cm of 85% ortho phosphoric acid was also added and titrated against the Fe (NH). SO. Then it was extrapolated to find the sugar concentration. Results and Discussions The three reagents that are useful for the characterization of sugar are Benedicts reagent, Selleiwaroff’s reagent and phenylhydrazine. The following results were obtained when the tests were applied to the above mentioned samples of sugar. Table-1 The results of the test with the reagents and the observation made Reagent and test Observations/ Inference Benedicts Reagent Glucose and pineapple showed a positive result of red cuprous oxide precipitate. Selliwanoff’s Reagent Fructose and pineapple juice gave a positive result of red colour. Phenyhydrazine A yellow crystal precipitate was formed and maltose and laclose easily dissolved in hot water. The osazone of glucose and fructose were the same. The pineapple also forms the osazone, while sucrose did not form the osazone. Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(1), 20-24, Jan. (2012) Res.J.Chem.SciInternational Science Congress Association 22 Table-2 Thin layer chromatographic characteristic of the sugars and the pineapple Samples Development system Visualization reaction No of spot f value Glucose butane -1-ol, acetone and water (4:5:1) iodine 1 0.34 Fructose butane -1-ol, acetone and water (4:5:1) Iodine 2 0.393 0.171 Maltose butane -1-ol, acetone and water (4:5:1) Iodine 1 0.21 Lactose butane -1-ol, acetone and water (4:5:1) Iodine 1 0.1 Pineapple Juice butane -1-ol, acetone and water (4:5:1) Iodine 3 0.19 Pineapple Juice butane -1-ol, acetone and water (4:5:1) Iodine 0.30 Table – 3Show the titration value of Fe (NH).S04 against KCr and sugar (glucose) Glucose (g) 3 0.08 1.0 x10 - 2 2.0x1 - 2 3.0x10 - 2 4.0x10 - 2 5.0x10 - 2 g/cm 3 Fe- (NH 3 ). S0 4 32.00 30.60 30.0 29.00 28.00 26.00 Difference 0 1.10 2.0 3.0 4.0 5.1 Glucose Calibration Curve Figure-1 Total Sugar Content (g/cmTable-4 The titration value of Fe (NH). SO against KCr and sugar (fructose) Fructose g/cm 3 0 0.5 x10 - 2 1.0x10 - 2 1.5x10 - 2 2.x10 - 2 Fe- (NH 3 ). 504 32 30.60 29.50 28.30 27.26 Difference 0 1.20 2.43 3.63 4.80  x10 - 2 g/cm 3 Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(1), 20-24, Jan. (2012) Res.J.Chem.SciInternational Science Congress Association 23 Fructose Calibration Curve Figure-2 Total sugar content g/cmTables – 5 Show the titration values of Fe(NH)S0 against pineapple juice pineappleBurette reading 1 st titration (cm 3 ) 2 nd titration (cm 3 ) 3 rd titration (cm 3 ) Final Bur. Reading 28.00 28. 00 28.00 Initial bur. Reading 0.00 0.00 0.00 28.0 28.00 28.00 The difference of the pineapple is 32.00 -28.00 = 4.00. The graphs for glucose and fructose are plotted in the figure-1 and figure-2. The sugar content in pineapple was determined and extrapolated in the calibration curves of glucose and fructose respectively. The work elucidated the type and amount of the sugar in edible fruit-pineapple. The test carried out using the three reagents, Benedicts’, Seliwanoff s and phenyl hydrazine showed that pineapple contain glucose and fructose.The thin layer chromatography result showed the R value of 0.34 and 0.39, 0.17 for glucose and fructose respectively in btane-1-ol, acetone and water which is close to RF value 0.36 and 0.17 of pineapple juice. From literature pineapple contains “sucrose”14 but in the research, TLC and the reagents tests showed that pineapple contains glucose and fructose. This may be probably because of reactions due to ripening and storage. The pineapple juice was strained instead of boiling as given15. The amount of the sugar content in pineapple was determined and extrapolated in the calibration curves for glucose and fructose, the values were 4.00x10-2g/cm and 1.50x10-2g/cm Pineapple being one of the locally available fruits that can be consumed fresh and popularly used in many occasions has been examined and it was found out that it contains glucose with 4.00×10-2g/cm of fructose and 1.50×10-2g/cm3 of glucose. This implies that it contain sugar which is source of energy, but high consumption of sugar raises the blood glucose which may lead to diabetes, excess consumption of the fruit should be avoided and control in other to maintain good health. Conclusion The results obtained in this study showed that pineapple contains sugar (glucose and fructose) which is one of the carbohydrates and source of energy in human diet. Sugar is important as food and it is valued for its sweetness. From the quantitative analysis, it was discovered that the amount of the glucose and fructose present were 4.0×10-2g/cm and 1.450×0-2 g/cm respectively. Therefore excess consumption of pineapple should be avoided since it contains sugar that may cause diabetes, obesity and may increase risk of metabolic syndrome.     x10 - 2 g/cm 3 Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X Vol. 2(1), 20-24, Jan. (2012) Res.J.Chem.SciInternational Science Congress Association 24 References 1.IUPAC Gold Book – Sugars “Gold book. IUPAC Org. http://goldbook.Iupac.org/html.Retriered 2011-02-22, 2009) 2.International Sugar statistic. http://www.Iiiovosugar .com/world of sugar/sugar statistics/international.aspx.accessed 01-30 (2011)3.Beaser R.S. and Campbel A.P., The Joslin guide to diabetes: a program for managing your treatment (2ndedt), Simion and Schuster, 372005) 4.Ab American Dietetic Association. “Nutrion. 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