Review of Rapid Tests Available for Measuring the Quality Changes in Frying Oils and Comparison with Standard Methods

Abstract

Repeated use of oils and fats for frying of food brings about many changes in their physical and chemical properties. Due to increasing health concerns, the assessment of the quality of reused oils has received much attention, since such assessment is useful in determining the discarding point of the oils. The official analytical methods used in laboratories for this purpose need skill, time, and a large consumption of solvents. To make the oil testing simpler, several rapid test kits have been developed based on either physical parameters (such as viscosity or dielectric changes) or chemical parameters (such as free fatty acids, oxidized fatty acids, or carbonyl compounds). These test kits usually comprise a portable instrument or colorimetric reaction sticks, capable of providing a direct or indirect measurement of a single parameter. The review presented in this paper evaluates the use of such rapid test kits and highlights the need to develop multi-parameter test kits in order to establish the quality of reused oil and the point at which it should be discarded. The review also encompasses pertinent details on the standard analytical methods, and deterioration of frying oils that occur during and after their use and the associated health consequences.

Evaluation of commercially available rapid test kits for the determination of oil quality in deep-frying operations

“…The official analytical procedures used in the laboratories to assess the quality of reused oils are, however, time consuming and costly, and hence, the commercially available rapid test kits are gaining attention in the food industry (Bansal et al, 2010). These test kits measure the quality of deep-frying oils by analysing either chemical parameters, e.g.…”

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

“…These results differ from those found by Dsawa et al (2012), who showed a correlation coefficient of r = 0.90 and R 2 of 80.5% from the Test 265 and the official methodology in 59 samples of palm olein and cotton oil in discarded frying oil. 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).…”

“…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).…”

Enzymatic interesterification on the physicochemical properties of <em>Moringa oleifera</em> seed oil blended with palm olein and virgin coconut oil

“…Because the eating habits of most Malaysian people are based on deep fried foods, oxidative-resistant low saturated oils are needed. It has been previously reported that more than 90% of the lipids in fried food came from the frying oil (Pérez-Camino et al, 1991) due to the interactions between food and frying oil (Bansal et al, 2010). Abdulkarim et al (2007a) and Tsaknis and Lalas (2002) reported that MoO has greater frying stability over other conventional frying oils such as canola oil, soybean oil and palm olein.…”

“…Two vegetable oils, palm olein (PO) and Virgin coconut oil (VCO) have been selected to be interesterified with MoO in order to evaluate the effect of lipase on their characteristics. PO, which is the most commonly used oil for frying foods in the Southeast Asia region (Bansal et al, 2010), is a liquid fraction of palm oil and contains a high proportion of saturated fatty acids that contributes to related health disorders. Because the eating habits of most Malaysian people are based on deep fried foods, oxidative-resistant low saturated oils are needed.…”