Valorization of spent coffee ground as a natural antioxidant and its use for sunflower oil shelf‐life extension

Abstract

In the present paper, spent coffee grounds (SCG) were investigated for their antioxidant capacity, chemical profiling, and their potential to extend the shelf‐life of refined sunflower oil (RSO). Ethanolic SCG extract (SCGE) ability to enhance RSO oxidation, during accelerated aging conditions, was examined at 60°C for 120 days. To this end, oxidative stability was evaluated for RSO added with SCGE (at 0.01%, 0.02%, and 0.03%) in the presence of a negative control (RSO without SCGE) and a positive one consisting in vitamin E (VE, a synthetic antioxidant) using the same concentrations (0.01%–0.03%). Our outcomes reveal that SCG were an important source of oil, protein, carbohydrates, minerals, pigments, phenolics, and flavonoid compounds, and they have high antioxidant capacity. SCGE at 0.03% increased RSO oxidative stability by reducing free fatty acids (FFA), peroxide value (PV), and conjugated dienes (CD) and trienes (CT) compared to the unenriched oil. However, both SCGE and VE had no significant effect (p < 0.05) on the fatty acids profile and iodine value. Furthermore, RSO enriched with SCGE had overall acceptability in the sensory evaluation. In conclusion, SCGE improved RSO oxidative stability, and therefore, it could be used as an efficient natural antioxidant to substitute VE during industrial processes.Practical Application: It is widely accepted that synthetic antioxidants may be harmful to human health. In such a context, plant‐based natural antioxidants proved to be an excellent alternative. The valorization of SCG as a natural antioxidant may represent a cost‐effective and sustainable approach for the food industry. The addition of used coffee grounds to refined sunflower oil could enhance its shelf‐life, offering a potential alternative to synthetic antioxidants. This may also help to reduce the quantity of coffee waste produced, promoting a circular economy.

Improvement of the oxidative stability of edible oils through enzymatic esterification with hydroxytyrosol‐rich extract

“…Previous studies recorded similar observations regarding the resistance of edible oils to thermal degradation. [19,40,41] Previous studies recorded similar results. [19,40] For instance, Chandrasekar et al [40] showed that incorporated rutin esters delayed the progress of the oxidation of sardine oil compared to the untreated or enriched sardine oil.…”

“…Vegetable oils commonly contain adequate levels of pigments, for example, chlorophylls, pheophytins, and carotenoids, which are related to their characteristic color and also contribute to their stability against rancidity due to their known antioxidant activity. [19,41] The relative content of pigments during the thermo-induced oxidation was assessed by fluorescence spectroscopy. Figures S5 and S6 depict the relative decrease in pigments' content, which is associated with the emission peak at 670 nm.…”

Advances in the Use of Four Synthetic Antioxidants as Food Additives for Enhancing the Oxidative Stability of Refined Sunflower Oil (Helianthus annuus L.)

“…The determination of the oil pigment content followed the protocol outlined by [24]. In a 25 mL volumetric flask, approximately 7.5 g of each oil sample was placed and then diluted with cyclohexane to reach a volume of 25 mL.…”

“…The chlorophyll and pheophytin profile may experience further modifications, with pheophytinization leading to a decrease in chlorophyll levels [86]. Bijla et al claimed that enrichment with 0.01, 0.02, and 0.03% vitamin E led to a reduction in chlorophyll levels by approximately 45% over four months of accelerated storage [24]. Carotenoids, meanwhile, are tetra-terpenoids that can give orange, red, and yellow hues, playing a vital role in the coloration of oils.…”

“…However, both the proportions in which antioxidants are added to foods and tolerance thresholds (acceptable quantities) are subject to significant variations. For example, TBHQ can be used alone or in combination with BHA and/or BHT up to a maximum limit of 200 ppm [24].…”