Development of food-grade microemulsions (F‒G μEms) for green extraction of bioactive compounds from Jalapeño waste (Capsicum annum var. Hot)

Jalapeño peppers, a key crop in Mexico, have a short postharvest life, leading to food waste and loss of bioactive compounds. While conventional solvent extraction is used to recover these compounds, it often relies on toxic, environmentally harmful solvents. In this context, we aimed to formulate a series of eco-friendly food-grade microemulsions (F‒G μEms) and assess the use of these solvent-free systems to extract polyphenols and capsaicinoids from Jalapeño waste. The basic formula of these F‒G μEms included d-limonene, Tween 80, and may have acetic acid (AcLiTw) or not (LiTw). The results showed that the acidic and non-acidic microemulsions were thermodynamically stable after 10.8 ± 0.69 and 13.98 ± 0.21 days at 35 °C, respectively. The use of AcLiTw as a solvent significantly enhanced (p < 0.05) the extraction of total polyphenols, achieving approximately 27% improvement compared to ethanol. The AcLiTw microemulsion extracted substantially higher amounts of vanillic acid and rutin, achieving increases of 0.4-fold and 4.4-fold, respectively, compared to LiTw. AcLiTw was twice as effective (p < 0.05) in extracting vanillin (≈67 mg/kg dw for ethanol extraction and LiTw, compared to 101.72 mg/kg dw for AcLiTw) and was the only formulation capable of extracting catechin from jalapeño waste (183.9 mg/kg dw). Finally, both LiTw and AcLiTw successfully extracted capsaicinoids from Jalapeño peppers (1131.01 and 5977.41 mg/kg dw, respectively), although in lesser amounts than ethanol (17569.02 mg/kg dw).