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The present study aims to use microwave power to facilitate the extraction of pectin from dried mango peels, and also to explore the effect of power on some quality parameters of the resultant pectin. Chemical composition of dried mango peels ascertained a high percent of total pectin, being 16.01 % (on dry weight basis). With respect to microwave heating, the optimal experimented power was 600W, and 6 minutes as the best short holding time, which gave 12.80 % yield, 86.54% recovery and 77.20% anhydrogalacturonic acid (AGA) of extracted pectin. Comparing to the commercial pectin, the results of some physico– chemical characterstics of isolated pectin, revealed that the pectin isolated by microwave heating from mango peels, being to some extent analogous to the commercial pectin with respect to its qualities, such as high methoxyl pectin, high degree of estrification (DE), and high percent of AGA besides its high viscosity, followed by the pectin isolated using the conventional method. Statistical analysis of organoleptic data showed no significant differences between strawberry jam prepared by using commercial pectin and that treated with pectin isolated by microwave heating as affecting their texture, color, taste and preference. Besides, high significant differences were detected between various concentrations of added pectin, with respect to the texture alone. Generally, the utilization of pectin isolated from mango peels using microwave heating in jam processing gave high quality attributes resembling that of the commercial pectin when added to strawberry jam and this would also lead to gain economical benefits. INTRODUCTION Mango peels are considered as one of the important wastes in fruit juice industry. These wastes usually cause environmental pollution, so technological attempts would be of value to produce valuable nutritional and economical byproducts from the discarded peels. The total annual production of mango fruits are 375461 tons produced from 81375 fed of fruitful trees. Ismailia alone produces 33.3% of the total Egyptian production followed by El-Sharkia Governorate which produces about 29.8% (Ministry of Agricultural and Land Reclamation, 2004). Mango peels and stones represent 35 to 60% of the total fruit weight depending upon the cultivars and the product made therefrom (Larrauri and Cerezal, 1993 and Larrauri et al 1996). Pectin has become a highly valuable byproduct of fruit juice industry. Pectin, being a natural plant component, has its value not only in food processing, but also in the nutritional and medicinal applications with the great advantage of being legally acceptable. In recent decades, with the increasing emphasis on the favourable functions of pectin in human metabolism, its economical value has increased considerably (Cohn and Cohn, 1996). Pectin is mainly a linear polymer composed of residues of esterfied galacturonic acid which are linked  – (1-4)axial-axial glycosidic bonds. The precise molecular weight, like that of other polysaccharides, is unknown and there may be as many as 1000 monosaccharide residues per molecule. The amount of esterification of the carboxyl groups of the uronic acid residues, present as methyl ester (Robinson, 1987). Assous; Abd El-Wahab and El-Waseif Arab Univ. J. Agric. Sci., 15(2), 2007 396 Pectins are used as gelling agents in jams, and jellies and as a filler or stabilizer in confections, dairy products, fruit preparations, bakery fillings, icings and frostings. Development of pectin-based fat replacers has resulted in a wide range of applications in products such as spread, salad dressing, ice cream (Kalapathy and Proctor, 2001). The use of suitable method of extraction is of importance during pectin production in order to obtain a good yield of pectin having stable properties. Pectin polysaccharides are of high molecular weight and closely connected with the other polymer components in the cell walls which inhibit their release from the cell matrix. Therefore, processing of the plant material is often applied to facilitate pectin extraction (Kratchanova et al 2004). Pectins are commercially produced by acid extraction from citrus peel or apple pomace, followed by filteration and perciptation by 2propanol (Whistler and BeMiller, 1997). The pH value, temperature and extraction time have an effect on the yield and quality of pectin. Conventionally, pectin is extracted in acidic solution at about 90°C for at least 1 hour, and it was normally a time consuming process. (May, 1990 and Pagan et al 2001) Sudhakar and Maini (2000) reported that the method for manufacturing pectin from mango peels was standardized by studying various factors that would govern the recovery and quality of pectin. 0.05M HCl was found to be the best method of extraction for pectin recovery, giving an optimum pectin yield of about 20.8% dry wt, bases. Fishman et al (2006) stated that lime peel pectin extracted by microwave heating was characterized by having high methoxyl pectin with a wide range of molar mass. Panchev et al (1988) used ultrasonic technology to extract apple pectin, and reported that the yield was superior to that obtained by traditional heating extraction. Wang et al (2005) summarized that microwave power reduced the extraction time and displayed a significantly quardatic effect on the yield of pectin, extracted from dried apple pomace, and the greater yield was obtained when about 499.4 W of microwave power was selected. The aim of this work was to study the effect of using microwave heating to extract the pectin from dried mango peels; moreover the effect of addition of the pectin on some properties of processed strawberry jam would be of value. MATERIALS AND METHODS

EFFECT OF MICROWAVE POWER ON QUALITY PARAMETERS OF PECTIN EXTRACTED FROM MANGO PEEL