Modification of the Nutritional Quality and Oxidative Stability of Lupin (Lupinus mutabilis Sweet) and Sacha Inchi (Plukenetia volubilis L.) Oil Blends.

Andean lupin (Lupinus mutabilis) oil is rich in monounsaturated (54.2%) and polyunsaturated (28.5%) fatty acids but has a ω-3:ω-6 ratio (1:9.2) above the recommended values for human health. Sacha inchi (Plukenetia volubilis) oil presents a high polyunsaturated fatty acid content (linolenic 47.2% and linoleic 34.7%), along a ω-3:ω-6 ratio (1:0.74) good for human consumption. The objective of this research was to study the physico-chemical properties and oxidative stability of tarwi and sacha inchi oil blends (1:4, 1:3, 1:1, 3:1 and 4:1 w:w) with suitable ω-3:ω-6 ratios. All blends showed ω-3:ω-6 ratios between 1:0.8 and 1:1.9, acceptable from a nutritional point of view, and high total tocopherols' content (1834-688 mg/kg), thanks to sacha inchi. The oxidative stability index (OSI) of the mixtures by the Rancimat method at 120 °C ranged from 0.46 to 8.80 h. The shelf-life of 1:1 tarwi/sacha inchi oil blend was 1.26 years; its entropy (-17.43 J/mol), enthalpy (107.04 kJ/mol), activation energy (110.24 kJ/mol) and Gibbs energy (113.76 kJ/mol) suggest low oxidation reaction rates and good stability. Hence, balanced blends of tarwi/sacha inchi oils can achieve optimal nutritional properties and enhanced shelf-life.

Changes in stability, tocopherols, fatty acids and antioxidant capacity of sacha inchi (Plukenetia volubilis) oil during French fries deep-frying.

Sacha inchi (Plukenetia volubilis) oil (SI) is appreciated for its nutritional and sensorial characteristics. The aim of this study was to evaluate SI changes during French fries deep-frying at 170 °C or 180 °C up to 119 and 50 min, respectively; commercial soybean oil (SO) was tested as control. SI had high α-linolenic acid (53.8%), linoleic acid (33.4%) and total tocopherols (2540.1 mg/kg). During frying tocopherol content, oil stability and antioxidant capacity (ABTS, DPPH) decreased following zero-order kinetics; γ-tocopherol showed the strongest decrease. Notwithstanding the high SI unsaturation and the commercial antioxidant (TBHQ) in SO, SI showed slightly higher or similar hydrolysis (free fatty acids and diacylglycerols), similar primary (K232, oxidized-triacylglycerols) and lower secondary (K268, triacylglycerol oligopolymers) oxidation. Because of the high tocopherol content, SI showed lower degradation than SO. Thus, SI is suitable for short-term deep-frying; additionally, it may enhance the nutritional value and the flavour of fried foods.