Banana (Banana Peel)
Peels are often the waste part of various fruits. These wastes have not generally received much attention with a view to being used or recycled rather than discharged. This might be due to their unknown benefit of commercial application.The main by-product of the banana processing industry is the peel, which represents approximately 30% of the fruit. This by-product constitutes an environmental problem because it contains large quantities of nitrogen and phosphorus and its high water content makes it susceptible to modification by microorganisms (R. González-Montelongo et al., 2010). Banana should be considered to be a good source of natural antioxidant for foods and functional food source against cancer and heart disease (Someya, S., Y. Yoshiki and K. Okubo, 2002). Interestingly, the peel and seed fractions of some fruits have higher antioxidant activity than the pulp fractions
Banana fruits are widely available, they have been used as food without apparent toxic affect. The peel could be a potential source of antioxidant and antimicrobial activities .Banana peel is rich in phytochemical compounds, mainly antioxidants (R. González-Montelongo et al., 2010). Banana peels have been used as a home remedy for several skin problems including allergies, bruises and skin irritation. It can help to alleviate several skin conditions including irritation from mosquito bites, treating poison ivy rashes, reducing bruises, getting rid of warts, treating acne and also managing wrinkles. It will not be instantly react to manage the wrinkles, but the skin will look fresher, more toned and healthier.
Potential applications for banana peel depend on its chemical composition. Banana peel is rich in dietary fibre (50% on a dry matter (DW) basis), proteins (7% DW), essential amino acids, polyunsaturated fatty acids and potassium. Banana peel is rich in phytochemical compounds, mainly antioxidants. The total amount of phenolic compounds in banana (Musa acuminata Colla AAA) peel ranges from 0.90 to 3.0 g/100 g DW . Someya et al. (2002) identified gallocatechin at a concentration of 160 mg/100 g DW. Ripe banana peel also contains other compounds, such as the anthocyanins delphinidin and cyaniding, and catecholamines. Furthermore, carotenoids, such as b-carotene, a-carotene and different xanthophylls, have been identified in banana peel in the range of 300-400 lg lutein equivalents/100 g, as well as sterols and triterpenes, such as b-sitosterol, stigmasterol, campesterol, cycloeucalenol, cycloartenol, and 24-methylene cycloartanol. To date, only Someya et al. (2002) have evaluated the antioxidant activity in banana peel, measured as the effect on lipid autoxidation in relation to its gallocatechin content. (R. González-Montelongo et al., 2010)
Antioxidant Activity And Phenolic Content
Antioxidants react as "free radical scavengers" by prevent and repair damage. Antioxidants may also enhance immune defense. Free radicals can attack various substrates in the body and contribute to chronic disease development, for example, oxidatively modified LDL has been hypothesized to be a causative agent in the development of cardiovascular disease . Oxidatively modified DNA may also play an important role in human carcinogenesis. Many nutritional factor are widely considered to be critical for human health. Among them, free radicals have been of concern as one of the factors contributing to chronic degenerative disease (O. Patthamakanokporn et al., 2008).
Bananas peel are a good source of natural antioxidants, which include vitamins A, C, E, and beta carotene. Recently, the demand for natural antioxidants has increased, due to consumer concerns about the safety of synthetic antioxidants (S. Okonogi et al., 2007). Banana peel contains a number of antioxidants and minerals that can help the skin restore itself naturally.Antioxidant is a substance that protect from damage by free radicals or "mopping up" free radicals. In humans, the most common form of free radicals is oxygen. Oxygen molecule (O2) steals electrons from other molecules when it is electrically charged or "radicalized". This may caused damage to the DNA and other molecules. Over time, such damage may become irreversible and lead to disease including cancer.
Several assays have been frequently used to estimate antioxidant capacities in fresh fruits and vegetables and their products and foods for clinical studies including 2,2- azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS, 2,2- diphenyl-picrylhydrazyl (DPPH) , ferric reducing antioxidant power (FRAP), and the oxygen radical absorption capacity (ORAC) . These techniques have shown different results among crop species and across laboratories (K. Thaipong et al., 2006).
Ascorbic acid or Vitamin C is organic acid with antioxidant properties and also water-soluble compound that fulfills several roles in living systems. It is generally recognized as safe substances by FDA. As a potent antioxidant, ascorbic acid has the capacity to eliminate several different reactive oxygen species, keeps the membrane-bound antioxidant a-tocopherol in the reduced state, acts as a cofactor maintaining the activity of a number of enzymes (by keeping metal ions in the reduced state), appears to be the substrate for oxalate and tartrate biosynthesis and has a role in stress resistance (Y. Hernández et al., 2006). Ascorbic acid serves as a reducing agent and may exert a chelating action. Several analytical methods have been reported for the determination of vitamin C using titrimetry, spectrometry and amperometry .Most of these methods may give overestimes due to the presence of oxidizable species other than AA and/or not to measure DHA. For example, the AOAC's official method , based on the titration of AA with 2,6-dichloroindophenol in acidic solution, is not applicable in all the matrices (Y. Hernández et al., 2006). The liquid chromatographic method usually used for the determination of acid ascorbic consisted of an isocratic elution procedure with UV-visible detection is selected in order to avoids the problems of non-specific interference and ion-pair.
The major benefit of ascorbic acid with regard to cancer is it react as anticancer agent. It may be precaution from developing cancer, rather than in therapy. Vitamin C work from inside the cells and protect DNA, the hereditary material in cells from the damage caused by free radicals. It also can reduce the development of nitrosamines from nitrates. Nitrates chemicals that are commonly used for foods processing. Once formed, nitrosamine can become carcinogenic which is cancer-causing.
In this experiment, FRAP method was selected because its relatively simple, easy to standardized and treat samples as reductant in redox- linked calometric method. The FRAP technique showed high reproducibility, was simple, rapidly performed and showed the highest correlation with both ascorbic acid and total phenolics (K. Thaipong et al., 2006). The antioxidant activity of banana peel extract is determined by the ability of the antioxidant in this extract to reduce ferric iron to ferrous in FRAP reagent. "The FRAP values are obtained by comparing the absorbance change at 593 nm in test reaction mixtures with those containing ferrous ions in known concentration. Absorbance changes are linear over a wide concentration range with antioxidant mixtures, including plasma and with solutions containing one antioxidant in purified form."(Benzie and Strain, 1996)
Phenolic compounds must make an important contribution to the flavour to the fruits It is well known that fruits contain various antioxidants, such as vitamin C, vitamin E, and b-carotene. Phenolic compounds is in the category of natural antioxidants and are the most abundant antioxidants in our diet . Phenolic compounds are naturally and commonly found in both edible and inedible plants. The phenolic content and composition in plants are depended on genetic and environmental factors, as well as post harvest processing and storage conditions. For qualitative identification of phenolic compounds, ultraviolet- visible spectrometric were considered as a tool for the identification of phenolics in banana peel extract.
Minerals play a vital role in proper development and good health of the human body and fruits are considered to be chief source of minerals needed in the human diet. Inadequate intake of mineral has been observed to be a major nutritional problems in our environment. Banana has been reported to prevent anaemia by stimulating the production of haemoglobin in the blood. Its role to regulate blood pressure has been assosiated eith the high content of potassium. Peels in conjunction with other substances create a liniment for reducing the acuteness of the arthritis aches and pains. Banana and also banana peel have an impressive potassium content. It is highly recommended by doctors for patients whose potassium is low. State that concentration potassium to be highest (78.10 mg/g), the concentration of calcium, sodium, iron and manganese are 19.20, 24.30, 0.61 and 76.20, respectively (B. A. Anhwange, 2008).
Solvent Extraction and Pretreatment
Selective extraction methods should be practiced since active compounds in plants that exhibit biological activities are usually present in low concentrations. The type and polarity of the solvent used to extract antioxidants from banana peel can affect single electron transfer and hydrogen atom transfer, which are key aspects in the measurements of antioxidant capacity. The polarity of the solvent and that of the different antioxidant compounds affects the efficiency of the extraction and the activity of the obtained extracts. Water, methanol, ethanol, acetone, aqueous solutions of the aforementioned solvents and ethyl acetate are commonly used as extraction solvents (R. González-Montelongo et al., 2010). The recovery of polyphenols from plant materials is influenced by the solubility of the phenolic compounds in the solvent used for the extraction process. Furthermore, solvent polarity will play a key role in increasing phenolic solubility). Acetone (70%) was the most efficient solvent system for the extraction of phenols from pisang mas (M. Alothman et al., 2009).
Drying is the pretreatment process this banana peel extraction. Drying appears to be a potential food preservation option to extend their storage/ shelf-life. It is a complex process involving simultaneous coupled transient heat and mass transfer. In addition, many of the properties of the kiwi fruits, especially the level of vitamin C, are affected by the drying conditions (A. Kaya et al., 2008).