According to the European Food Safety Agency, human dietary intake of long chain n-3 fatty acids (EPA and DHA) is lower than that recommended (250 mg/d), so the Food Industry is interested to produce functional foods enriched with these fatty acids (FA). However, enriching food with EPA and DHA may increase the risk of lipid oxidation and off-flavour development. Microcapsules (MC) obtained by spray-drying may help to avoid this issue, by including fish oil (FO) in a dry powder ready to be integrated into the food. Recently, several dairy products have been proposed as functional foods, by enriching milk with functional lipids or probiotic and pre- biotic substances. The aim of this work was to evaluate the FA and volatile compounds (VOCs) profile and the lipid oxidation of yoghurt enriched with fish oil MC. Four types of MC containing FO were produced using whey protein isolate plus gum arabic (GA) or maltodextrin (MD), with (GAQ; MDQ) or without quercetin as antioxidant. MC were used to obtain four different types of yoghurt that were compared with non-enriched yoghurt (CY) or with yoghurt enriched with unprotected FO (CO), during a 21 days stor- age period at 4°C. FA composition of yoghurts was determined by gas chromatography (GC) analysis, while the oxidative stability was characterized through the analysis of thiobarbituric acid reac- tive substances (TBARS). Volatile compounds were determined by solid phase microextraction (SPME) coupled with GC/MS. The VOCs composition was evaluated by a multivariate analysis. Yoghurts enriched with 15 g/L of MC resulted in a significant increase of EPA (0.082 to 2.012 g/100 g total lipids) and DHA (0.011 to 1.649 g/100 total lipids), irrespective of the presence of quercetin as an antioxidant. At the end of the storage period, the value of TBARS significantly increased only in CO and CY samples, suggest- ing a protective role of MC against FA oxidation. Nevertheless, the MD yoghurt was associated with an oxidative aromatic profile,(2- hexenal, 2-methyl furan) whereas the presence of quercetin elim- inated this aspect. GA, GAQ and MDQ yoghurt were associated with an acid flavour profile. CO and CY yoghurts were associated with sweet and fruit flavour profiles (2-nonanone). In conclusion, MC could be an effective strategy to enrich yoghurt with n-3 PUFA and simultaneously preserve FO from oxidation, however some differ- ences in the oxidative stability and VOCs profile were observed depending on the properties of the MC wall.

Microencapsulated fish oil to enrich yoghurt with omega-3 fatty acids: evaluation of fatty acid composition and volatile compounds

CIUCCI, FRANCESCA;SERRA, ANDREA;CONTE, GIUSEPPE;MELE, MARCELLO
2015

Abstract

According to the European Food Safety Agency, human dietary intake of long chain n-3 fatty acids (EPA and DHA) is lower than that recommended (250 mg/d), so the Food Industry is interested to produce functional foods enriched with these fatty acids (FA). However, enriching food with EPA and DHA may increase the risk of lipid oxidation and off-flavour development. Microcapsules (MC) obtained by spray-drying may help to avoid this issue, by including fish oil (FO) in a dry powder ready to be integrated into the food. Recently, several dairy products have been proposed as functional foods, by enriching milk with functional lipids or probiotic and pre- biotic substances. The aim of this work was to evaluate the FA and volatile compounds (VOCs) profile and the lipid oxidation of yoghurt enriched with fish oil MC. Four types of MC containing FO were produced using whey protein isolate plus gum arabic (GA) or maltodextrin (MD), with (GAQ; MDQ) or without quercetin as antioxidant. MC were used to obtain four different types of yoghurt that were compared with non-enriched yoghurt (CY) or with yoghurt enriched with unprotected FO (CO), during a 21 days stor- age period at 4°C. FA composition of yoghurts was determined by gas chromatography (GC) analysis, while the oxidative stability was characterized through the analysis of thiobarbituric acid reac- tive substances (TBARS). Volatile compounds were determined by solid phase microextraction (SPME) coupled with GC/MS. The VOCs composition was evaluated by a multivariate analysis. Yoghurts enriched with 15 g/L of MC resulted in a significant increase of EPA (0.082 to 2.012 g/100 g total lipids) and DHA (0.011 to 1.649 g/100 total lipids), irrespective of the presence of quercetin as an antioxidant. At the end of the storage period, the value of TBARS significantly increased only in CO and CY samples, suggest- ing a protective role of MC against FA oxidation. Nevertheless, the MD yoghurt was associated with an oxidative aromatic profile,(2- hexenal, 2-methyl furan) whereas the presence of quercetin elim- inated this aspect. GA, GAQ and MDQ yoghurt were associated with an acid flavour profile. CO and CY yoghurts were associated with sweet and fruit flavour profiles (2-nonanone). In conclusion, MC could be an effective strategy to enrich yoghurt with n-3 PUFA and simultaneously preserve FO from oxidation, however some differ- ences in the oxidative stability and VOCs profile were observed depending on the properties of the MC wall.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/753433
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