Biochimie et physiologie : accès libre

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Magnitude of Changes in the Activity of Amylases and Cellulase and its Association with the Biochemical Composition during Maturation and Ripening of Banana (Musa spp.)

Theji Mohan, Rajesh PN, Fathimathu Zuhra K and Vijitha K

Introduction: Banana fruit (Musa spp.) is world’s most popular and cheaply available fruit item. Banana fruit maturation and ripening takes place as a result of interplay of several degrading and synthetic enzyme and is responsible for biochemical and morphological variations during fruit maturation and ripening. Objectives: This study was carried out in the “Nendran” variety of Musa spp. to investigate the activity of two major degrading enzymes – amylases and cellulase during fruit maturation and ripening. Amylases (which include both alpha amylase and beta amylase) are the major category of starch degrading enzymes and cellulase is responsible for the cell wall (cellulose) degradation in fruit tissue that results in tissue softening. The changes in the concentration of various biochemical constituents were also investigated. Materials and methods: Fresh samples of fruits (“Nendran”, local name) were collected at particular intervals directly from plants starting from the very young stage (10th day) up to the over ripe stage (102nd day) and were extracted for the crude enzyme preparation. Specific activities of amylases and cellulase were analyzed by standard assay procedures. The concentration of total carbohydrate, starch, cellulose, fructose, total protein and dry recovery percent were also determined. Results and discussion: Significant variations in the specific activity of amylases and cellulase were observed between different periods of maturity. The activity of amylases was found to be very low (4.8 ± 0.26 Units) during the tender stage, remained low up to 90th days (14.00 ± 0.86 Units) of maturation, but when the fruits starts ripening after 90 days it increased to about 10 folds on the 92nd day (103.40 ± 8.20 Units) and then gradually decreased towards the overripe stage ie. on the 102nd day (5.78 ± 0.37 Units). Similarly, the specific activity of cellulase was also significantly changed; the peak activity was observed on the 90th day (769.00 ± 18.54 Units) that was found to be several times high as compared to the tender stages (78.90 ± 3.26 Units on the 10th day and 21.00 ± 1.26 Units on the 20th day), facilitating the process of wall degradation. The activity of amylase and cellulase had significant correlations with the concentrations of related biochemical constituents such as starch and cellulose. Conclusions: Amylases and cellulase had significant roles to play towards the morphological and biochemical transformations associated with the fruit maturation and ripening processes, such as starch accumulation, starch degradation and tissue softening in banana fruit (“Nendran”).