Pectic hydrocolloids from steam exploded lime pectin peel; effect of temperature and time on macromolecular and functional properties

Authors: Cameron, Randall - Randy; Branca, Elena; Dorado, Christina; KIM, YANG - Seoul National University

Submitted to: Journal of Food Science and Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2021
Publication Date: 2/12/2021
Citation: Cameron, R.G., Branca, E.M., Dorado, C., Kim, Y. 2021. Pectic hydrocolloids from steam exploded lime pectin peel; effect of temperature and time on macromolecular and functional properties. Journal of Food Science and Nutrition. https://doi.org/10.1002/fsn3.2158.
DOI: https://doi.org/10.1002/fsn3.2158

Interpretive Summary: Juice extracted citrus peel contains numerous components that could provide higher added value than is currently recovered by processing peel into animal feed. We have developed a process to recover valuable pectin from juice extracted peel using a continuous steam explosion process. Our initial studies demonstrated recoveries of approximately 70% of the pectin in citrus peel as well as other valuable chemicals. However functionality of the recovered pectin was not optimal. In the study reported here we examined the role of temperature and time at temperature on the functional properties of recovered pectin. We were able to model the optimized conditions for % recovery and functionality of the pectin. Our results indicated approximately 130 degrees centigrade for three minutes were the optimal conditions for retaining pectin functionality and 150 degrees centigrade and three minutes were optimal for % recovery.

Technical Abstract: We previously demonstrated the release of pectic hydrocolloids from citrus fruit biomass using a pilot scale, continuous steam explosion process and their recovery with a water wash. Their weight average molecular weight (Mw) and associated intrinsic viscosity (IV) were low suggesting fragmentation was due to process temperature and/or time-at-temperature. We tested this hypothesis on stabilized lime pectin peel (Citrus spp.) using a static, batch steam explosion system. Temperatures of 120 °C - 150 °C were tested at 1 - 3 min hold times. Galacturonic acid recovery and Mw ranged from 20% - 75% and 136 – 207 kDa. Intrinsic viscosity ranged from 1.81 – 5.86 dL· g-1. Degree of methylesterification ranged from 65.0 – 74.7. Tan (d) values of sugar acid gels for 120 – 140 °C treatments were less than 1.0 indicating more gel-like than liquid-like properties. Ideal optimization analysis was performed to determine the optimum conditions for percent recovery and intrinsic viscosity.