Bioactive oleogel from supercritical carbon dioxide extracted walnut (Juglans regia L.) oil as a butter substitute and utilization of the spent residue in cookie formulations

Abstract

The scope of the work presented in this paper is based on the principles of circular economy. Functional oleogels were prepared from pre-optimized supercritically extracted walnut oil (350 bar/40 °C/90 min) as a butter alternative that can meet more than 50% of the Required Dietary Allowance of ω-3 fatty acids per serving of 5.75 g. The spent residue of walnut kernel after supercritical extraction was incorporated in cookie formulations to replace wheat flour as a valorization approach. Carnauba and beeswax were used as oleogelator in the oleogels so prepared by optimizing the rheological and textural parameters of the oleogels. Prior to this development, the yield, fatty acid composition, tocopherol content, antioxidant activity as well as total polyphenolic content (TPC) was compared with conventional soxhlet using n-hexane for extraction. Cookies were formulated by replacing 15% w/w refined flour with the protein and fiber-rich spent residue with good overall acceptability (7) when compared to control (8) and textural properties like hardness (4125 g) and fracturability (8 mm). The oleogels could be vulnerable to oxidation during storage and hence their stability as well as the cookies needs further evaluation. Approaches to increase the same are also warranted. The approach so presented can have positive implications for both economy as well as the environment.