Evaluation of peanut skin subcritical extract as a natural antioxidant for preserving a high-fat food product.

RODRÍGUEZ-RUIZ, CAROLINA; MARTÍNEZ, MARCELA; MAESTRI, DAMIÁN; VELEZ, ALEXIS; BODOIRA, ROMINA

Congreso; 11th World Congress of Chemical Engineering; 2023

Preservation procedures are commonly used in the food industry to guarantee a product´s quality. One of these procedures consists in adding components that prevent or retard the degradation processes, prolonging their shelf life. The decrease of quality in products with high-fat content, such as mayonnaise, is mainly caused by oxidative processes. Currently, the antioxidants (AOs) used for food applications are mainly synthetic substances (TBHQ, BHT, BHA), which have been questioned for their safety. In this regard, the need of using innocuous natural AOs obtained through the application of clean technologies with low environmental impact is increasing. Peanut skin (PS) is a by-product of low added value that has abundant bioactive phenolic substances with a high antioxidant capacity, both in vitro and applied to certain foods. Subcritical extraction uses water or ethanol + water mixtures at temperatures between 100 - 374 °C, and pressures above atmospheric to keep it in a liquid state. It is a green, environmentally friendly, safe, and fast extraction technique that achieves high extraction yields of medium and high polarity compounds from a solid matrix.Considering this background and the antioxidant effectiveness of a PS extract observed in an O/W model emulsion [1], a storage test with mayonnaise was carried out using this extract as a natural antioxidant to retard lipid degradation processes.The PS extract was obtained with ethanol-water (40:60) under subcritical conditions (200°C, 7 MPa, and a solvent flow of 7 g/min) using semi-continuous extraction equipment. The extract was processed until obtaining a dry extract (PSE). The mayonnaise was made with refined soybean oil without additives (65%). The PSE was incorporated into the aqueous phase in concentrations of 1 and 2 mg PSE/g fat matter, mayonnaise without any antioxidant was used as a negative control, and the addition of BHT-EDTA at the concentrations allowed by the Argentinian Food Code was used as a positive control. The color and other physical parameters were measured for all treatments (four in total).For the storage test, 30 g of mayonnaise from each treatment (in duplicate) were placed in 50 mL amber bottles, covered with film, and stored at shelf temperature (25°C) for six months. A sample was taken without replacement every month. The oil was extracted by stirring at room temperature using 30 mL of chloroform: methanol (1:1). Subsequently, the evolution in the peroxide index (PI) and acidity index (AI) was measured by volumetric analysis. The control mayonnaise presented a pH of 5,10 and water activity of 0,914 at 24,7°C. The color parameters, according to the CIELAB system, showed differences between the treatments. Previous tests under accelerated conditions (40°C) allow considering the PSE as a replacement for synthetic antioxidants in commercial high-fat products.