Polyphenolic fractions improve the oxidative stability of microencapsulated linseed oil
Polyphenolic fractions improve the oxidative stability of microencapsulated linseed oil
Year: 2012
Authors: Rubilar, M. Morales, E. Saez, R. Acevedo, F. Palma, B. Villarroel, M. Shene, C.
Publication Name: Eur. J. Lipid Sci. Technol.
Publication Details: DOI: 10.1002/ejlt.201100230
Abstract:
The main objective of this study was to evaluate the effect of incorporating polyphenolic-enriched fractions from murta leaves on the oxidative stability of linseed oil microencapsulated by spray drying. For this purpose, polyphenol-enriched fractions from murta leaves were separated by gel permeation chromatography and chemically characterized. The oxidative stability of microencapsulated linseed oil (MLO) with antioxidants was evaluated in storage conditions at 258C for 40 days. The antioxidant effects of the polyphenolic fractions and commercial antioxidants (BHT and trolox) on microencapsulated oil were evaluated by the value of conjugated dienes, peroxide, and p-anisidine. In the initiation step of the oxidation, no significant oxidation delay (p>0.05) in MLO containing fractions F6, F8, or BHT and trolox was observed. However, in the termination step of the oxidation, the addition of fractions F6, F8, and BHT and trolox decreases significantly (p>0.05) the rancidity in MLO. Furthermore, the results of this study demonstrated the importance of the addition of natural antioxidants such as fractions of murta leaf extract in microencapsulated linseed oil to increase its resistance to oxidation. Practical applications: For incorporating linseed oil, a source of omega-3 fatty acids, in the diet it is necessary to protect it against oxidative rancidity, the main cause of deterioration that affects food with a high unsaturated fat content. Microencapsulation is effective in retarding or suppressing the oxidation of unsaturated fatty acids and natural plants extracts are effective in inhibiting the lipid oxidation of microencapsulated oil. The use of process technology and a natural additive is expected to increase storage stability and enable its use in dry foods such as instant products. Linseed oil can be used in human nutrition as well as in animal feed as a replacement for fish oil. (Authors abstract)
Lipids in seed oils are important functional components of foods and have a significant effect on their quality, although they constitute only a minor component. Lipid peroxidation is one of the primary mechanisms of quality deterioration in foods. The changes in quality can be manifested by deterioration in flavor, color, texture, nutritive value, and the production of toxic compounds. Few studies address the effects of storage on linseed (flaxseed) oil composition. In general, long-term storage and heat promote the auto oxidation of fats, as well as decreases in the amounts of tocopherols and vitamin E in linseed oil. The potential antioxidant activity of polyphenolic compounds has been reported for a number of natural plant extracts including grapes, almond hulls (Prunus amygdalus), green teas, berries, and murta fruits. Murta is a wild shrub growing in the Coast and pre-Andean mountains of southern Chile. Murta extracts have shown high levels of flavonols like rutin and myricetin, substances with antioxidant activity. Another approach to protect lipid from oxidation is through microencapsulation, which offers several advantages including retarding auto-oxidation; enhancing stability; controlling lipid-soluble flavor release; masking the bitter taste of lipid soluble substances; and protecting dissolved substances against enzyme hydrolysis. Few studies have combined polyphenolic compounds and microcapsules for the prevention of lipid oxidation. The main objective of this study was to evaluate the effect of the incorporation of polyphenolic-enriched fractions from murta leaf on the oxidative stability of linseed oil microencapsulated by spray drying. It was found that fraction F6 of the murta leaf reached an increase in the oxidative stability of MLO with values comparable to those reached with trolox and BHT. In this fraction, vanillic, caffeic, sinapic, ferulic, p-coumaric acids, and (gamma)epicatechin were identified by LC-MS-MS. The high antioxidant activity of fractions and commercial fractions in microencapsulated systems was attributed mainly to their low polarity. According to the polar paradox, the use of lipophilic antioxidants is recommended for microencapsulation. The low polarity of an antioxidant seems to be crucial for a suitable antioxidant performance in microencapsulated systems. The results of this study demonstrated the importance of the addition of natural antioxidants in MLO and the possibility of using fractions of murta leaf extract to increase its resistance to oxidation. The results presented for evaluation of lipid oxidation in microencapsulated oils correspond to overall oil. (Editors comments)
Lipids in seed oils are important functional components of foods and have a significant effect on their quality, although they constitute only a minor component. Lipid peroxidation is one of the primary mechanisms of quality deterioration in foods. The changes in quality can be manifested by deterioration in flavor, color, texture, nutritive value, and the production of toxic compounds. Few studies address the effects of storage on linseed (flaxseed) oil composition. In general, long-term storage and heat promote the auto oxidation of fats, as well as decreases in the amounts of tocopherols and vitamin E in linseed oil. The potential antioxidant activity of polyphenolic compounds has been reported for a number of natural plant extracts including grapes, almond hulls (Prunus amygdalus), green teas, berries, and murta fruits. Murta is a wild shrub growing in the Coast and pre-Andean mountains of southern Chile. Murta extracts have shown high levels of flavonols like rutin and myricetin, substances with antioxidant activity. Another approach to protect lipid from oxidation is through microencapsulation, which offers several advantages including retarding auto-oxidation; enhancing stability; controlling lipid-soluble flavor release; masking the bitter taste of lipid soluble substances; and protecting dissolved substances against enzyme hydrolysis. Few studies have combined polyphenolic compounds and microcapsules for the prevention of lipid oxidation. The main objective of this study was to evaluate the effect of the incorporation of polyphenolic-enriched fractions from murta leaf on the oxidative stability of linseed oil microencapsulated by spray drying. It was found that fraction F6 of the murta leaf reached an increase in the oxidative stability of MLO with values comparable to those reached with trolox and BHT. In this fraction, vanillic, caffeic, sinapic, ferulic, p-coumaric acids, and (gamma)epicatechin were identified by LC-MS-MS. The high antioxidant activity of fractions and commercial fractions in microencapsulated systems was attributed mainly to their low polarity. According to the polar paradox, the use of lipophilic antioxidants is recommended for microencapsulation. The low polarity of an antioxidant seems to be crucial for a suitable antioxidant performance in microencapsulated systems. The results of this study demonstrated the importance of the addition of natural antioxidants in MLO and the possibility of using fractions of murta leaf extract to increase its resistance to oxidation. The results presented for evaluation of lipid oxidation in microencapsulated oils correspond to overall oil. (Editors comments)
