NGWU, E.K. NWACHI, I.C. DIMGBA, C.S.
Department of Home Science, Nutrition and Dietetics, Faculty of Agriculture, University of Nigeria, Nsukka.
Fruits are generally high in fiber, water, vitamin C and sugars, although this varies widely from traces as in certain citrus fruits to 61% of the fresh weight of the date palm (Hulme, 1970). Fruits also contain various phytochemicals that do not yet have an RDA/RDI listing under most nutritional fact sheets and which research indicates are required for long term cellular health and disease prevention. • Regular consumption of fruits is associated with reduced risk of cancer, cardiovascular disease (especially coronary heart disease), stroke, Alzheimer’s disease, cataracts and some of the functional declines associated with ageing. Health benefits of fruits and vegetables are from additive and synergistic combinations of phytochemicals (Liu, 1978).
Fruits are used to make beverages such as fruit wines and drinks (orange, apple, pine apple juices) or even alcoholic beverages (fruits wines). These amazing and indispensable foods can also be used in manufacture of other edibles (i.e. apart from being eaten raw) like cookies, muffins, yoghurt, ice cream, cakes and pastries.
It has been discovered that many things in fruits which help protect against bowel cancer – including fibre and chemicals known as antioxidants are lost during the juice processing (Philip, 2011). Many fruit juices commercially produced contain only a small percentage of the real fruit juice and many added sweeteners (sucrose or high fructose corn syrup). As a result, fruit juices elevate blood sugar more quickly than whole fruit.
Phytochemicals are biologically active compounds found in plants in small amounts, which are not established nutrients but which nevertheless contribute significantly to protection against degenerative disease (Dreosi, 2000). Some of them function as antioxidants that help delay and inhibit lipid oxidation and when added to foods tend to minimize rancidity, retard the formation of toxic oxidation products, help maintain the nutritional quality and increase their shelf life (Fukumoto and Mazza, 2000). Some phytochemicals with antioxidant activities include carotenoids (found in fruits), flavonoids (found in fruits and vegetables), polyphenols (tea, grapes).
Polyphenols particularly are among the diverse phytochemicals that have the potential in the inhibition of carcinogenesis (Liu, 2004). Saponins are believed to be useful in the human diet for controlling cholesterol, but some including those produced by the soapberry are poisonous if swallowed and can cause urticaria (skin rash) in many people (Otsuka, 2005). The processing of the juices and the use of fruit juice concentrates leads to a remarkable modification of the quality of the fresh products. These could reduce the nutritional value of the packaged drinks. The mixed fruit juices in Nigeria do not have enhanced vitamin and mineral content when compared with the natural counterpart (Dimari and Hati, 2010). This study was therefore designed to evaluate the phytochemical contents and the organoleptic attributes of three fruit pulp blends (apple, pineapple and orange) mixed in different ratios.
MATERIALS AND METHODS
- Collection and preparation of materials.
The ripe fruits (apples, pineapples and oranges) used for the study were bought from local retailers at Ogige market in Nsukka Local Government Area Enugu State. These fruits were washed, peeled (pineapples and oranges), deseeded, cut into smaller pieces and blended separately. After collection of pulp, the various fruit pulps were mixed in various proportions of 40:40:20, 40:20:40, 20:40:40 for the apple pulp, orange pulp and pineapple pulps respectively. The fruit blend mixtures were subjected to both qualitative and quantitative phytochemical tests. These mixtures were also subjected to sensory tests using a nine point hedonic scale.
- Test for tannins:
The method used was that of Boham and Kocipai-Abyazan (Boham &Kocipai-Abyazam, 1974). About 0.5g of the dried samples was boiled in 20ml of water in test tube and then filtered. A few drops of 0.1% ferric chloride was added and observed for brownish green or blue-black coloration.
- Test for saponins:
The method used was that of Harbone (Harbone, 1973). About 2g of the powdered sample was boiled in 20ml of distilled water in a water bath filtered. Ten milliliters of the filtrate was mixed with 5ml of distilled water and shaken vigorously for a stable persistent froth. The frothing was mixed with 3 drops of olive oil and shaken vigorously, then observed for the information of emulsion.
QUANTITATIVE ESTIMATION OFPHYTOCHEMICALS:
- Determination of Total Phenols by Spectrophotometric Method:
The fat free sample was boiled with 50ml of ether for the extraction of the phenolic component for 15min. Five milliliters of the extract was taken into a 50ml flask, then 10ml of distilled water was added. Two milliliters of ammonium hydroxide solution and 5ml of concentrated amyl alcohol were also added. The samples were made up to mark and left to react for 30 minutes for colour development. This was measured at 505nm. The standard curve was prepared using 50, 100, 150, 200, 250mg/l solutions of gallic acid in methanol: water (50:50, v/v).
- Alkaloid determination using Harbone (10) method:
Five grams of the sample was weighed into a 250ml beaker and 200ml of 10% acetic in ethanol was added and covered and allowed to stand for 4h. This was filtered and the extract was concentrated on a water bath to onequarter of the original volume. Concentrated ammonium hydroxide was added dropwise to the extract until the precipitation was complete. The whole solution was allowed to settle and the precipitated was collected and washed with dilute ammonium hydroxide and then filtered. The residue is the alkaloid, which was dried and weighed.
- Flavonoid determination by the method of Boham and Kocipai-Abyazan (Boham &Kocipai-Abyazam):
Ten grams of the pulp sample was extracted repeatedly with 100ml of 80% aqueous methanol at room temperature. The whole solution was filtered whatman filter paper No 42 (125mm). The filtrate was later transferred into a crucible and evaporated into dryness over a water bath and weighed to a constant weight.
- Saponin determination:
The method used was that of Obadoni and Ochuko (Obadim & Ochuko). Twenty grams of samples powder was put into a conical flask and 100ml of 20% aqueous ethanol were added. The samples were heated over a hot water bath for 4h with continuous stirring at about 550C.
- Determination of tannins:
The method employed was that of Edeoga and Gomina (Edeoga & Gomina, 2001). Dried pulp (0.5g) was extracted with 300ml of diethyl ether for 2hours at room temperature. The residue was boiled for 2hours with 100ml of distilled water, and then allowed to cool, and was filtered. The extract was adjusted to a volume of 100ml in a volumetric flask. The content of tannins in the extract was determined colorimetricallly using Folin Dennis Reagent, and by measuring absorbance of the blue complex at 760nm, using tannic acid solution as standard solution.
• Sensory Evaluation:
A 9-point hedonic scale as described by Peryam and Pilgrim (Peryam & Pilgrim, 1950) was adopted to assess consumer’s degree of likeness and general acceptability of the fruit blends. Twenty panelists consisting of students and staff of the department of Home Science, Nutrition and Dietetics were selected for the sensory evaluation. They were oriented in the sensory procedures by the researcher. This sensory test was conducted in the diet therapy laboratory in the Department of Home Science, Nutrition and dietetics, of the University of Nigeria, Nsukka. It was ensured that the laboratory is well lit and has good ventilation. The drinks were appropriately cooled and presented to the panelists simultaneously in clean jugs and disposable cups on a well laid table.
The panelists were given a cup of portable water for rinsing his/her mouth before and after tasting each pulp to prevent carry over taste. Serviette was also made available for cleaning his/her mouth after each taste. Each panelist was given disposable cups and spoons for use in the sensory test. The panelists evaluated the products for colour, flavour, texture, taste and general acceptability with the sample code. Statistical Analysis: The chemical and sensory evaluation results were statistically analyzed using Statistical Package for Social Sciences (SPSS V16). Means -/+ and standard error of the means were calculated.
Analysis of variance (ANOVA) and Duncan’s new multiple range test (DNMRT) were used to determine significant difference of acceptance of P<0.05. RESULTS Table 4.1 shows the phytochemicals present in the different fruit blends. The fruit blend of 40:20:40 ratios for pineapple, apples and oranges respectively had abundant flavonoids, alkaloids and sapiens. Tannins and phenols were abundant in the 20:40:40 fruit blend and flavonoids, alkanoids and saponins were moderately present. The fruit blend of pineapple, apples and oranges in the ratio of 40:40:20 respectively had abundant saponins, moderate flavonoids and small quantities of alkaloids, tannins and phenols.