The quality characteristics and yield of passion fruit peel pectin extracted at pH 2.0 revealed that the pectin had a galacturonic acid content of 69.21 g/100 g d.m., esterification degree of 90.68% d.m. and yield of 5.20 g/100 of peel d.m., which were found to be the highest among the different extraction conditions studied. The galacturonic acid content decreased with increasing pH of extracting medium, which may be due to partial degradation of pectin. It may be concluded that the maximum quality characteristics of pectin can be obtained at pH 2.0 and moderate electric field of 50 V. It is noteworthy that there was a significant difference between these results, thereby indicating that pH by itself may have a dominant effect.
4. Conclusion
Moderate electric field extraction, as an emerging novel technology, was applied to extract pectin from passion fruit peel. Under the conditions applied, the extraction yield of MEF was lower than that of the traditional extraction. The comparison of characteristics in terms of galacturonic acid content and esterification degree of the pectin obtained using different extraction methods indicated that similar values were obtained. The results of the studies demonstrated that MEF is an efficient, timesaving, and eco-friendly method for the extraction of pectin from passion fruit peel, especially for pectin with a high esterification degree and galacturonic acid content higher than 65 g/100 g of pectin. However, a research about the energy expenditure of the two processes as well on the investment costs to implement the novel technology will be interesting to compare these two technologies.
The utilization of moderate electric field like a pre-treatment can be an alternative to increase the yield during the traditional heating, since the moderate electric field induces a damage in cell wall and increases the permeability.
Acknowledgments
The authors acknowledge the financial support received from CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Brasil) as a scholarship to the first author and by the project PNPD (Programa Nacional de Pós-Doutorado) and also from FAPERGS (Fundação de Apoio à Pesquisa do Rio Grande do Sul).