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. 2019 Jun 6;7(7):2302-2311.
doi: 10.1002/fsn3.1072. eCollection 2019 Jul.

Evaluating the rancidity and quality of discarded oils in fast food restaurants

Fatemeh Esfarjani  1 , Khadijeh Khoshtinat  2 , Aziz Zargaraan  3 , Fatemeh Mohammadi-Nasrabadi  1 , Yeganeh Salmani  1 , Zahra Saghafi  2 , Hedayat Hosseini  2 , Manochehr Bahmaei  3
Affiliations

Evaluating the rancidity and quality of discarded oils in fast food restaurants

Fatemeh Esfarjani et al. Food Sci Nutr. .

Abstract

This cross-sectional study attempts to determine the rancidity and quality of discarded oils in fast food restaurants. Samples of the discarded frying oils were collected randomly from 50 fast food restaurants in Tehran, Iran. Their physicochemical properties were assessed and compared to the standard values. The means (±SD) of the physicochemical indicators of the rancidity in the discarded oils were as follows: peroxide value, 3.06 (0.51) (mEq/kg); free fatty acids content, 1.52 (2.26) (%); p-anisidine value, 57.63 (4.02) (mEq/kg); total oxidation value, 64.53 (4.15); total polar compounds (TPC), 20.19 (1.02) (%); viscosity, 107.87 (2.35) (cp); and red color, 9.64 (0.84). Positive correlations were found between the TPC, viscosity, and red color (p ≤ 0.01) of the oil samples. The majority of discarded oil from fast food restaurants were overdegraded containing hazardous secondary oxidative products, and also, the consumption of nonstandard frying oil has increased in fast food restaurants. Policymakers should develop guidelines to determine whether and when frying oils should be discarded and consider the consumption of overdegraded oils as a public health hazard.

Keywords: discarded oils; fast food restaurants; quality assessment; rancidity.

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Conflict of interest statement

The authors declare that they have no conflicts of interest to disclose. This study received no specific grant from any funding sources (commercial or nonprofit sectors).

Figures

Figure 1
Figure 1
The mean of fatty acids in the discarded frying oil samples compared to the standards of the Iranian National Standardization Organization
Figure 2
Figure 2
The mean of heavy metals in the discarded frying oils compared to the standards of the Iranian National Standardization Organization
Figure 3
Figure 3
Rancidity measurements of the discarded frying oil samples from fast food restaurants. (a) Total polar compound; (b) peroxide value; (c) p‐anisidine value; and (d) free fatty acid
See this image and copyright information in PMC

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