Studies on Ascorbic acid content of some wild edible fruits from Ahmednagar District , Maharashtra ( India )

Dr. P. P. Sharma Numerous wild edible fruits from different families are distributed in Western Ghat (Maharashtra), India. Tribal people consume these fruits as natural source of food supplement. Ten wild edible fruits of Diospyros melanoxylon, Pithecellobium dulce, Carrisa congesta, Lantana camera var. aculeata, Opuntia stricta, Aegle marmelos, Terminalia catappa, Ziziphus mauritiana and Elaegnus conferta, .Limonia accidisma possess high nutritional potential and medicinal properties. The present communication deals with the investigation of vitamin-C contents of these ten wild edible fruits using standard protocols. The ascorbic acid content was compared with some commonly consumable fruits. Present study focused on the food value and exploration of underutilized edible fruits in Maharashtra, India.


Introduction:-
Nutritional potential of fruits make noteworthy contribution to standard of living and good health in human beings. There is need of identification and exploration of the wild underutilized edible fruits for executing the increasing demand of nutritionally potential diet for growing populations (Andersen et al., 2003;Sena et al., 1998). Since, wild fruits are found to be the most important source of micronutrients; nutritional rich supplements can be fulfilled by fruits. Hence, efforts must be devoted on sustainable use of underutilized wild plants resources as nutrient supplements against enhancing food and nutrition problems in developing countries. As a part of current scenario of safeguarding of good health, worldwide researchers were studying the nutritional potential of various types of wild edible underutilized plants (Lockeett et al., 2000;Ogle et al., 2001).
Enormous literature has evidenced that several wild plant fruits are edible since ages. However, the use of wild fruits as a food has decreased due to improvement and hybridization in commercially cultivated fruit plants. On the other hand increase in urbanization and gradual exploitation of forests is resulting in disappearance of several valuable wild species. Several people in remote areas are still using them as a supplement to complete their basic food requirement. Some are preserved for use during famine period or some time sold in the market. Now a day, the popularity of these wild fruits has declined. Hence, special attention should be focused on maintenance and popularisation of these natural resources as a of future food supply. Therefore, there is need to achieve scientific and systematic knowledge of wild edible fruits for cultivation. Hence, special attention is being focused on the study of vitamin-C content of underutilized wild fruits.
Especially, ascorbic acid (vitamin-C) is considered as a key factor in the quality determination of fruits (Vazhacharickal et al.,2015). It has excellent solubility in water with both acidic and reducing properties. It is being an essential nutrient in humans and it has functions as a cofactor in several enzymatic reactions (Kalt et al., 1999;Padayatty et al., 2003;Gardner et al., 2000). The required vitamin-C intake in humans is approximately 60-95 mgs per day and the maximum intake level is 2000 mgs per day (Carr and Frei, 1999;Levine et al., 1995;Levine et al., 1999;Naidu, 2003). However, overdose of vit-C may cause diarrhoea, iron overload disorders, kidney stone formation and deficiency causes scurvy, muscle pain, skin lesions, fatigue and bleeding (Naidu, 2003;Carr and Frei, 1999;Holick and Chen, 2008;Mayland et al., 2005;Weber et al., 1995;Jacob, 1990;Jacob et al., 1987). It plays an important role in the construction and defence of human connective tissue, immunity, Alzheimer's disease, stroke and coronary heart disease (Padayatty et al., 2003;Morris et al., 1998;Gale et al., 1995).
There are two bioactive forms of vitamin-C are known such as L-ascorbic acid and L-dehydroascorbic acid (DHAA). Mostly, L-ascorbic acid form is often encountered in conjunction with small amounts of dehydroascorbic acid may also present as its primary oxidation product. There are different methods available for determination of ascorbic acid as reported in literature (Christie andWiggins, 1978, Sauberlich et al.,1982;Pachla et al.,1985). The Association of Official Analytical Chemists (AOAC) has designated two official methods for the determination of vitamin C as (a) The dye-titration method (b) The micro-fluorometric method (AOAC, 1984). The dye titration protocol was found to be most suitable in terms of ease of conduction, rapid, use of common desk reagents and large number of samples can be analyzed in a short time. The micro-fluorometric method is more sensitive than redox titrimetic method but requires more sophisticated or expensive equipments and expertise for getting accurate results.

(A) Preparation of the plant materials for chemical analysis:
All ten fruit samples were dried in shade in order to remove residual moisture. The shade dried fruits were ground into powder using grinder, filtered and stored in polythene bags. The stored food powders were used as such for further lipid analysis.

(B) Chemical Analysis:
Determination of Vitamin-C all fruit samples were conducted in Research Laboratory, Department of Botany, Shri Muktanand College, Ganagapur, Dist-Aurangabad by titrimetic method.

(C) Principle:
The ascorbic acid in wild underutilized fruits can be determined by using redox titration method. In general, acid-base titration is not suitable because there are many acids and bases in food material. Hence, the 2,6dichloroindophenol (DCP) dye has been used as colored titrant because it has ability to oxidize only ascorbic acid. It has dark blue in neutral and basic solutions and red in acidic solutions. The oxidation of ascorbic acid and reduction of DPC can be represented in Figure 1. Weigh accurately ascorbic acid (100mg) and dissolve it distilled water (5 ml). Dilute this solution to 100ml with 4% oxalic acid solution in distilled water. Concentration of Ascorbic acid is 1mg/ml.

(E) Preparation of the dye solution:
Weigh accurately 42 mg of sodium bicarbonate (NaHCO 3 ) in 5ml distilled water. To this solution 52 mg of DCPIP (Mol wt. = 268.1g/mol) was added and solution was diluted to 200 ml with distilled water.

(F) Preparation of Sample Solution:
500 ml of fruit powder was mixed with 10 ml distilled water and mixture was stirred for 30 minutes and filtered using Whatman No.1 filter paper (Dilution Factor was 10 ml). (G) General procedure for the determination of ascorbic acid in the fruit sample: (G-1) Determination of V 1 ml (Volume of dye required for 10 ml of standard ascorbic acid solution): Fill the burette with dye solution. 10 ml of ascorbic acid solution was taken in 100 ml conical flask. The ascorbic acid solution was titrated against dye solution from burette. Burette reading (ml) was recorded when solution in the conical flask turns pink and colour was persists for 30 sec. In this way three burette readings were recorded as X 1 (7.4 ml), X 2 (7.5 ml) and X 3 (7.5 ml). From these readings, constant burette reading was recorded as V 1 ml= 7.5 ml).
(G-2) Determination of V 2 ml (Volume of dye required for 5 ml of sample solution):-5 ml of the sample solution was pipette out in a 100 ml conical flask. To this solution 10 ml of 4% oxalic acid and titrated against the dye (V 1 ml). Burette reading (V 2 ml) was recorded when solution in the conical flask turns pink and colour was persists for 30 sec. The amount of the dye consumed is equivalent to the amount of ascorbic acid.

Amount of ascorbic acid in mg/100 gm of fruit sample was determined by following formula
Weight of Vit-C =

Conclusion:
Determination of ascorbic acid content of wild edible fruit was conducted using redox titration method. The ascorbic acid content was further compared with some of the commonly consumable fruits (Ighodalo et al., 1991). The comparative results were represented in Table 2. This indicates the vitamin C potential of wild fruits under investigation were good to excellent for consumption. Hence it will be more beneficial than commonly consumable fruits when vitamin C rich supplement was required.