Improving the quality of used frying niger seed oil with adsorbent treatment

Abstract

High temperature continuous deep fat frying of foods will result in the frying oil and food quality deterioration. Although the quality can be retained by using fresh oil, this approach will increase the production cost. In this study, quality improvement of used niger seed oil using adsorbent treatment was evaluated. Each adsorbent was mixed with 20 h used niger seed oil (15% w/v) at 150 °C and stirred for 30 min. The oil was recovered through centrifugation at 4200 rpm for 15 min. The tested chemical parameters of the oil increased after 20 h of frying (acid value (AV) (2.24–8.31) mg KOH/gm oil, free fatty acid (FFA) (1.13–4.17) %, and peroxide value (PV) (1.00–13.97 mEq oxygen/Kg of oil). The improvement in free fatty acid, peroxide value and oil recovery upon treatment of the fried oil with ash, bentonite, bleaching earth, silca gel and magnesium oxide (MgO) was (61, 57, 80), (66, 43, 88), (56, 21, 85), (61, 50, 70), and (73, 64, 40) % respectively. Ash and MgO effectively improved the physico-chemical characteristics of the used oil. Thus, the two were selected for further optimization of effective concentration and to evaluate their synergetic effect. Treatments with 2.5, 5.0, 7.5, 10.0, 12.5 and 15.0 % of ash reduced the AV of the fried oil by 26, 39, 46, 53, 53 and 60 % respectively (p < 0.05). Also the combination of ash and MgO (1:1) improved the physico-chemical properties of the frying oil to nearly fresh quality.

Optimizing niger seed (Guizotia abyssinica) oil quality: A comprehensive analysis of infrared‐heat induced changes in bioactive profile, physiochemical attributes, and oxidative stability

“…The unprocessed NSO exhibited viscosity of 51.13 mPa s (Table 1). The prior research by Nuru and Getachew (2021) documented higher viscosity (54.50 mPa s) for fresh NSO from Ethiopia. The degree of unsaturation, density, molecular weight, and melting point influences viscosity of edible oils (Kaur et al., 2021).…”

“…The unprocessed NSO displayed AV of 0.48 mg KOH/g, p ‐AV of 0.17 and PV of 2.97 meq O 2 /kg (Table 1). Bhatnagar and Gopala Krishna (2014) reported lower PV (2.2 meq O 2 /kg) while Nuru and Getachew (2021) reported a relatively higher AV (2.24 mg KOH/g) for cold pressed NSO of Indian and Ethiopian origin, respectively. The IRH influenced the AV, p‐ AV, and PV of NSO.…”

Iodine values, peroxide values and acid values of Bohai algae oil compared with other oils during the cooking

“…Iodine values (IVs), peroxide values (POVs) and acid values (AVs) are often used as the indicators for the oxidative stability of fats and oils [ 17 , 22 ]. They are becoming significance for the assessment of quality and stability of oils [ 16 , 17 ].…”

Utilization of activated carbons produced from some natural materials in the purification of used frying oil

“…p-AV of oil was 21.8 mmol/kg at 40°C, it declined to 19.7 mmol/kg at 80°C. The literature reported a decrease in oxidation products of UO after adsorbent treatment (Bhattacharya et al, 2008;Ismail & Ali, 2015;Ismail et al, 2017;Lin et al, 2001;Nuru & Getachew, 2021).…”

“…Similarly, Maskan and Bağcı (2003) utilized commercial magnesium silicate (florosil), activated charcoal, bentonite, natural earth (pekmez earth) as adsorbents for the purification of the UO. Nuru and Getachew (2021) reported that FFAs and peroxide value of UO were decreased after treatment with 15% (w/v) ash, bentonite, bleaching earth, silica gel, and magnesium oxide (MgO) at 150°C for 20 hr. Moreover, a blend of MgO and ash (1:1) improved the physicochemical properties of the frying oil to a point, which is close to fresh quality.…”