ARS | Publication request: Hydrolytic and oxidate stability of L-(+) -ascorbic acid supported in pectin films: Influence of the macromolecular structure and calcium presence

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 26, 2012
Publication Date: April 26, 2012
Citation: Pérez, C.D., Fissore, E.N., Gerschenson, L.N., Cameron, R.G., Rojas, A.M. 2012. Hydrolytic and oxidate stability of L-(+) -ascorbic acid supported in pectin films: Influence of the macromolecular structure and calcium presence. Journal of Agricultural and Food Chemistry. 60:5414-5422.

Interpretive Summary: In many industries, various compounds and ingredients used exhibit significant decrease or degradation in their desired properties due to oxidation and/or hydrolysis. L-(+)-ascorbic acid (AA) is a reducing agent and also a water soluble vitamin and antioxidant used for pharmaceutical and food preservation and/or supplementation. In recent years, there has been an enormous demand for natural antioxidants mainly because of adverse toxicological reports on many synthetic compounds. AA is unstable to hydrolysis and oxidation and its degradation also leads to browning. AA carried into edible films may constitute another form of natural antioxidant protection at interfaces and of AA stabilization with controlled delivery. Dietary fiber inclusion in food formulations also confers the functional label to the product. Pectins are soluble dietary fibers mainly present in the primary cell walls and middle lamella of plants, being then renewable as well as biodegradable polymers. Enzymatic engineering of the pectin nanostructure for tailoring functionality can expand the role of pectin as a food-formulating agent and the use of in situ modification in prepared foods, and produce the pectin nanostructures required for specific demands in film/membrane development. The objective of the present work was to explore the influence of the macromolecular structure on the hydrolytic stability of AA when supported in pectin films.

Technical Abstract: The hydrolytic and oxidative stability of L-(+)-ascorbic acid (AA) into plasticized pectin films were separately studied in view of preserving vitamin C activity and/or to achieve localized antioxidant activity at pharmaceutical and food interfaces. Films were made with each one of the enzymatically tailored pectins (50, 70 and 80% DM)1 or commercial high methoxyl pectin (HMP; 72% DM). Since AA stability was dependent on water availability in the network, pectin nanostructure affected the AA kinetics. Higher AA retention and lower browning rates were achieved in HMP films, and calcium presence in them stabilized AA because of higher water immobilization. Air storage did not change AA decay and browning rates in HMP films but they significantly increased in Ca-HMP films. It was concluded that the ability of the polymeric network to immobilize water seems to be the main factor to consider in order to succeed in retaining AA into film materials.