Exploring cold-pressed beech (Fagus sylvatica L.) kernels by-products as a sustainable alternative to almond flour in macaron production

This study investigates the viability of cold-pressed beechnut oil cakes as sustainable substitutes for almond flour in macaron production, while exploring the influence of aged egg whites on the rheological and textural characteristics of the batter and final product. Beechnut oil cakes, both crude (CBKC) and thermally-treated (TTBKC), were incorporated in varying proportions (25%, 50%, 75%, and 100%) in macarons formulations. Variations in chemical composition between the two types of oil cakes were observed in the content of fat, protein, and carbohydrates. Following fat extraction of oil cakes applying Soxhlet extraction, the resultant oil was analyzed for fatty acid composition, which revealed a predominance of mono- and polyunsaturated fatty acids. Phenolic compounds identified in beechnut oil cakes comprise flavonols, hydroxybenzoic acids, ellagitannins, and gallotannins. Lutein is the most abundant carotenoid identified in oil cakes. Aging egg whites is critical for stable macaron shells; however, using additional egg whites reduced the batters' textural qualities compared to conventional formulations. All formulations presented elastic behavior, independent of variations in flour type and concentration. Almond complete replacement with thermally-treated beechnut oil cake flour, retains macaron textural qualities and exhibits similar hardness. The sensory evaluation indicates that the samples with 25% and 50% TTBKC substitution received the highest appreciation scores.