Quality control of used deep‐frying oils

Abstract

Quality of deep-fried food is inseparably attached to the quality of the used deep-frying oil. Taste, flavor, shelf life, consumer acceptance, and safety of fried food essentially depend on frying oil quality. Evaluation of frying oil quality therefore is an important issue for both frying operators and official food control agencies. Organoleptic evaluation is an essential step in the monitoring of frying fat quality. Several official laboratory methods are available to support the sensory evaluation. Total polar materials (TPM) and polymer TAGs (PTG) are the most reliable parameters for this purpose. Recommended and widely accepted limits are 24% for TPM and 12% for PTG. When oxidative alterations strongly predominate over thermal alterations, sensory defects can appear before TPM and PTG reach recommended values. In that case additional parameters like anisidine value, carbonyl value, or epoxy fatty acids should be considered. A number of physical and chemical rapid methods are available. Despite the limited informative value and the possibility of error of rapid tests, they are essential for fryer operators, because they deliver information about fat quality in real-time. Most reliable for most applications are quick tests measuring TPM. A unique and powerful tool for the simultaneous detection of multiple parameters corresponding to thermal and oxidative alterations is near infrared spectroscopy (NIRS), which will become more and more important in future.

Application of Rosemary (rosmarinus officinalis l.) Based Natural Antioxidant During Deep Fat Frying of Noodle

“…Each sampling was done in triplicate and each experiment was repeated three times. The principles of Testo 265 cooking oil tester is to measure the changes of dielectric constant in the oil samples, the concentration of which is highly correlated with the concentration of total polar matter (Stier, 2004;Stier, 2013, Weisshaar, 2014.…”

“…Consequently, the higher the amount of polar compounds in oil, the worse is its quality (Gharachorloo et al, 2010). Recommendations of the 3rd International Symposium on Deep-Fat Frying in 2000 have defined TPC Value less than 25% as criteria for the assessment of used frying oils and frying fats (Weisshaar, 2014).…”

High-performance size-exclusion chromatography studies on the formation and distribution of polar compounds in camellia seed oil during heating

“…Other researchers reported that the recommended and widely accepted limits are 12% for TGP (Weisshaar, 2014). Further harmonization of regulations on the quality control of oxidized oil is desirable.…”

Oxidative stability of crude palm oil after deep frying akara (Fried Bean Paste)

“…According to Bansal et al (2010), there are some disadvantages in the use of Testo 270, which included the presence of water, salt, minerals, long warm up time and the need of daily calibration factors that affect the polarity of a sample and can give false information on the TPC. Nevertheless, in these methods, there are problems in determining the actual level of oil degradation as it depends on the food-oil combination used and is severely affected by the food moisture retained by the frying oil (Bansal et al, 2010;Weisshaar, 2014). In the specific case of the CPD, the presence of largest content of water, impurities minerals may to be responsible for the results obtained, since the other cited studies analyzed refined oils Akusu et al (2000), Szydłowska-Czerniak et al (2013).…”

“…Also to be considered is that the process of deep frying akara is discontinued, often done in open areas, using enameled pots with large diameter without any temperature control, factors that tend to accelerate the oxidative processes. Coupled with the practice of the "Baianas de acarajés" of replace the volume of the frying oil with both new and reused oil (Weisshaar, 2014) that can also affect this variability, which means that 36.95% of the samples have been completely oxidized (Table 1).…”