3.5. Conclusion

A procedure for peels on thermally processed (canned) green pears was developed by appropriate zinc treatment during blanching to retain attractive green pigments in the final product. Surface pretreatment before zinc application to remove wax and part of the cuticle layer is essential for the reactions of zinc ions with chlorophyll in the peel tissues. In the developed procedure, zinc ion was used as a processing aid, thus significantly minimizing zinc content in the final products. The degree of green pigment retention depends on zinc concentration in blanching solution and also on blanching time. The green pigments formed were highly stable during storage, not changing for 19 weeks at 38 oC under intensive illumination or for at least 35 weeks at 10 oC.


3.6. Acknowledgement

The authors sincerely appreciate the financial support from the Winter Tree Fruit Research Commission for part of this research and the technical assistance from Mr. Dennis Anderson at Green & Green, Inc., Corvallis, OR.