An innovative approach for lipid-rich food preservation: peanut skin microcapsules

This study evaluates the microencapsulation of peanut skin phenolic compounds by spray drying, assessing their physicochemical properties and storage stability and the protective effect against oxidative deterioration in walnut kernels. Extraction yield, total phenolic content, and HPLC-ESI-MS/MS analysis were performed on peanut skin crude extract (PCE). Microencapsulation of PCE with 10%, 20%, and 30% maltodextrin via spray drying was conducted. The drying yield, phenolic encapsulation efficiency, moisture content, morphology, particle size, and stability during dry storage (23°C) and in water (23 and 100°C) were assessed for the microcapsules. PCE contained 950.29 mg GAE/g of total polyphenolic compounds, primarily hydroxycinnamic acid-derived phenolic acids and procyanidins. Microcapsules with 20% maltodextrin exhibited the best properties (drying yield, encapsulation efficiency, and stability). These microcapsules were incorporated into an edible chickpea-based coating, which was applied to walnuts and stored at 40°C for 15 days. Peroxide value, conjugated dienes, volatile compounds, and fatty acid profile were analyzed on samples from storage. The chickpea-based coating combined with PCE microcapsules effectively preserves walnut quality during storage, offering a viable and natural alternative to synthetic antioxidants such as BHT, addressing current concerns in food preservation. PRACTICAL APPLICATION: Peanut skins are a byproduct of the peanut industry with low commercial value. These skins are rich in polyphenols, which exhibit potent antioxidant activity. This study investigates the microencapsulation of polyphenolic peanut extract and its incorporation into a chickpea-based edible coating. The prepared coating demonstrated a remarkable protective effect against lipid oxidation in walnuts, extending their shelf life. These findings present a sustainable strategy that adds value to agro-industrial residues and aligns with circular economy principles. This innovation offers a natural and effective solution to enhance the stability and quality of lipid-rich foods.