Evaluation of sacha inchi oil oxidative stability as bulk oil and in an emulsion

Details

Supervisors

Larondelle, Yvan

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en sciences agronomiques, à finalité spécialisée

Abstract

Sacha inchi also known as Plukenetia volubilis, is a plant native to the tropical part of South America and its seeds are characterized by a high content of polyunsaturated fatty acids, mainly 𝛼-linolenic (ALA) and linoleic acids. These recent years, with the current trend in the search for "superfoods", great attention has been paid to sacha inchi as a new source of ALA. ALA is an essential fatty acid for humans and Belgian citizens consume on average only 70% of its daily recommendation. Sacha inchi oil, which contains almost 50% of ALA, appears to be a good candidate to reach this daily recommendation. However, polyunsaturated fatty acids such as ALA present an increased sensitivity to oxidation. This work focused on the sacha inchi oil oxidative stability and it was divided in two parts, the first one on bulk oil and the second one on a mayonnaise developed specially for this work and containing a mixture of sacha inchi and rapeseed oils (15:85, w/w). For this purpose, different accelerated aging experiments were conducted by storing at 60°C and 30°C the bulk oil and mayonnaise, respectively. In these experiments, liposoluble green tea extract (GTES), green tea extract powder (GTE) and Phytrox were used as antioxidants to evaluate their ability to extend the shelf life of the oil by protecting it from oxidation. The peroxide value and para-anisidine value were measured and reflected the respective progress of primary and secondary oxidation. Other parameters such as tocopherol or catechin contents were also measured. In the first part, the sacha inchi oil showed to be sensitive to oxidation. However, the supplementation with GTE and Phytrox allowed to significantly (p < 0.05) and strongly decrease the oxidation level. GTES also significantly decreased the oxidation level of the oil but to a lesser extent. A significant depletion in total tocopherol content initially present in the oil was also observed in the oil without antioxidant and with added GTES, while the total tocopherol content of the oils with added GTE and Phytrox remained stable. In the oil containing GTE, a significant decrease in the total catechin content was also observed. In the second part, none of the mayonnaises exceeded the oxidation limits after 28 days of storage at 30°C. The addition of GTE and Phytrox significantly decreased the oxidation level while the addition of GTES did not protect the mayonnaise from oxidation. The developed mayonnaise contains 83 mg ALA per gram of mayonnaise and represents a real opportunity to increase the ALA intake of the Belgian citizens who consume a lot of sauce. However, during a sensory analysis, mayonnaises containing SIO scored lower than a mayonnaise containing only rapeseed oil. For such a product to end up on the market one day, it would be necessary to improve the recipe and to carry out more in-depth market analyses.