EFFECT OF EXTRACTION METHOD OF SOME NATURAL EXTRACTS ON ENZYMATIC BROWNING OF APPLE JUICE

A comparative study concerning the inhibition of the enzymatic browning in apple juices stored for 24 hours at room temperature (25 o C) was carried out between the natural extract of some vegetables and Oyster mushroom with different extraction methods (water, ultra-filtration and alcoholic). The colour changes were assayed quantitatively involved % inhibition using Hunter Lab colorimeter and polyphenoloxidase activities. The results showed that higher inhibition of enzymatic browning was obtained at the end of 24 hour storage period with the extracts of squash, cucumber and pepper followed by mushroom in apple juices. Meanwhile alcoholic and UF extracts were effective in maintaining the storage quality of apple juices. They were found as effective inhibitors. The obtained results confirmed the presence of a proportional relation between the natural vegetable extracts by different extraction methods and their inhibitory effect, whereas the Oyster mushroom extracts in storage time (24 hours) showed an opposite trend. The inhibitory effect of the natural squash extract was comparable with its different extraction method and being higher than pepper and cucumber under all experimental conditions. The natural extracts derived from vegetables were more active than their counterpart derived from mushroom. However, each of them could be considered as potential natural inhibitor having technological and commercial benefits to be applied in processed fruits.