Pectin from galgal peel

Bioresource Technology 55 (1996) 89-91 0 1996 Elsevier Science Limited

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Short Communication

Pectin from Galgal (Citrus pseudolimon Tan.) Peel
Abstract During the extraction of juice from galgal fruits (Citrus pseudolimon Tan.), peel, which accounts for about 2535% of the weight of thefruit, is thrown away and causes an ecological problem when dumped around the processing plants. A process has been standardized for maximum recovery of pectin from these peels by employing various extractants and varying extractant: peel ratios, extraction times, number of extractions and partkle sizes of the peel, etc. Here, 0.1 N HCl was the best extractant, with a peel to acid ratio of 1:lO foran extraction time of 60 min. Peel in powder form and two extractions helped to maximise recovery of pectin. Alcohol precipitation was better than aluminium-chloride precipitation and there was not much change in the quality parameters during storage of the dry, powdered pectin. Copyright 0 1996 Elsevier Science Ltd.

to isolate the pectin and evaluate its physico-chemical characters, as well asits stability during storage.
METHODS Peels and their stabilization The ripened galgal fruits were procured from Bilas-

pur - a city in Himachal Pradesh in northern India. After the extraction of juice from the fruits, the peels were stored at low temperature (S-UK, RH 75-S%) and also dried in the sun and a cabinet dryer (60°C f 1).
Extraction of pectin

Key words: Galgal peel, extractant,extractions, precipitation, pectin, storage.

INTRODUCTION

Both fresh and dried peels were tried for the extraction of pectin with different organic and inorganic acids: HCl, HN03, citric acid and tartaric acid. Of these acids, the best one was tried for standardizing other conditions. For fresh peel, a ratio of 1:2 of peel and extractant was used, whereas it varied from 1:lO to 1:40 in thecase of dried peel. After heating for 1 h, the extract was separated and cooled. To the extracted solution, two volumes of 0.05 N acidified 95% ethanol was added for precipitation. In another experiment, instead of ethanol 0.75% aluminium chloride (AK&) was used as a precipitant (Joslyn & De Luca, 1957). The precipitate was separated, washed with 65 and 95% ethanol and dried at 40°C. The driedpectin was powdered in a power-driven hammer mill using a 60 mesh screen.
Storage of pectin The pectin powder was stored in airtight glass con-

Galgal (Citrus pseudolimon Tan.), an indigenous variety of lemon, grows well in the low hills and submountainous regions of northern India. The fruit is mostly utilized for pickles, culinary purposes and blending with other fruit juices for the preparationof squashes on a small scale. Peel, which is 25-35% of the weight of the fruit, is thrown away during the processing operations. As with other citrus crops, the peel of galgal is rich in pectin and could be utilized for the extraction of pectin. Pectin has many uses and its isolation from galgal peels would not only help in bringing down the costs of production of galgal products but also managethe disposal of this waste. Hence, the present study was undertaken 89

tainers both at low (4”Cf2) temperatures.

and room (30-35°C)

Physico-chemical analysis of pectin The pectin was analysed for various physico-chemi-

cal and quality characteristics at bimonthly intervals up to 6 months. The moisture, ash, anhydrouronic acid, non-enzymatic browning and jelly grade of the extractedpectin were estimated according to the methods described by Ranganna (1986). The equivalent weight and methoxyl content of the pectin were also determined according to Owens et al. (1952),

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Short communication Table 1. Effect of methods of precipitation and storage on the recovery and quality of pectin AK& precipitation 6 (L.T.) 6.04 0.62 8.91 64.46 75.55 839 215 0 19.20 0.37 8.00 0.90...