Chemical and physical parameters as quality indicators of used frying fats

The level of polar compounds is a good indicator of oil quality and it is the basis of the international regulations limiting the use of degraded frying fats/oils for human consumption. According to ISO 8420:2002 standard, polar compound content is determined by adsorption chromatography extraction followed by gravimetric quantification. This simple and accurate method is time-consuming and considerable amounts of silica-gel and solvents are needed. This study aims at developing a fast and reliable alternative method for polar compound quantification in frying oils, using HPTLC-densitometry. This technique was tested for soybean, sunflower and peanut oils, heated at 180 degrees C, and for frying oil samples. This technique proved to be fast, accurate and repeatable. Practical applications: The developed method is adequate for rapid screening of unknown oil samples, with respect to their level of polar compounds. Using HPTLC-densitometry to evaluate polar compound content in oils, the number of samples to be analyzed by the ISO standard method may be considerably reduced to those having values close to the maximum allowed. Thus, the proposed methodology allows for a reduction in time and chemicals used, with economic and environmental benefits

Section: Introductionmentioning

confidence: 99%

Rapid quantification of polar compounds in thermo‐oxidized oils by HPTLC‐densitometry

Correia¹,

Dubreucq

Ferreira‐Dias

et al. 2014

“…Frying oils with 24-27% TPC content should be discarded due to negative influences on the flavor and nutritional value of the fried food. [3,4] AOCS Official Method Cd 20-91 [5] and IUPAC Method 2.507 [6] for the TPC determination are well accepted due to good accuracy and precision. [7] However, these standard methods are time-consuming and labor-intensive, and often require many chemicals which are harmful to the health.…”

Section: Introductionmentioning

confidence: 99%

Rapid Measuring Flavor Quality Changes of Frying Rapeseed Oils using a Flash Gas Chromatography Electronic Nose

Huang

et al. 2019

A flash gas chromatography electronic nose (FGC E‐nose) is applied to measure flavor quality changes and monitor the oxidation process of rapeseed oils during frying. Partial least squares regression (PLS) is applied to determine the relationship between total polar compounds (TPC) and some volatile compounds determined by FGC E‐nose in frying rapeseed oils. Qualitative differentiation between frying oil samples with different frying time is analyzed by principal component analysis (PCA) and hierarchical cluster analysis (HCA). The PCA and HCA results show that the FGC E‐nose could be used to discriminate oil samples with different frying time. The results show a good linear relationship (R2 = 0.98; SD = 1.433) between TPC in oil samples measured by AOCS method and that predicted by the FGC E‐nose responses using PLS method. Thus, this study indicates that the FGC E‐nose method could be available for rapid at‐ or on‐line implementation in oxidation control of frying oils. Practical Applications: Standard methods for determining the TPC of frying oil samples are labor‐intensive and require toxic chemicals. The volatile compounds determined by FGC E‐nose show a good linear relationship with TPC in frying rapeseed oil samples. The FGC E‐nose technique is suitable to monitor the frying process and the proposed method has the potential to be a more rapid and convenient tool for quality control of frying oils. A flash gas chromatography electronic nose (FGC E‐nose) is applied to measure flavor quality changes and monitor the oxidation process of rapeseed oils during frying. Partial least squares regression is applied to determine the relationship between total polar compounds and some volatile compounds determined by FGC E‐nose in frying rapeseed oils.

“…Several analytical indices for monitoring the degradation level of frying oils have been proposed: para-anisidine value (AnV), acid value (AV), total polar compounds (TPC), and di-and polymerized triacyl-glycerols (DPTG) [6,7]. Determination of polar compounds is now considered to be one of the most reliable tests for assessing deterioration [8].…”

Section: Introductionmentioning

confidence: 99%

A new analytical and statistical approach to predict the sensory properties of deep frying fats and oils to determine the point of discard during processing

Gertz¹,

Aladedunye²,

Matthäus

2017

Self Cite

The aim of this work was to explore the feasibility and limits of analytical criteria to assess the sensory properties of used frying oils and different fried food. Over a period of 2 years, 148 used frying oils collected in restaurants bakeries, fish caterers, and industrial plants were analyzed for a wide range of parameters, including sensory tests, total polar compounds (TPC), dimerized and polymerized triacyl‐glycerols (DPTG), monomeric oxidized triacyl‐glycerols (MONOX), acid value (AV), para‐anisidine‐value (AnV), and iodine value (IV). All methods were judged for their relevance, concerning the sensory quality of used frying oils categorizing the qualities as good or bad. The binary results were statistically evaluated using logit regression. The statistical evaluation of the tests was used to calculate the probability of occurrence of off‐flavors which allows determining the point of discard and finally the point where the oil is certainly totally abused. All levels of degradation for used frying oils regardless of oil type and kind of food being fried can be statistically described and used to develop a simple equation using the TPC and AV value as variables (y = 117–8 × AV − 3 × TPC) to find the point of disposal and to monitor the degradation process. The new criterion has been proven in the controlling of various industrial frying processes, restaurants and bakeries and kitchen frying. Practical applications: A simple equation of linear regression using AV and TPC as variables (y = 117–8 × AV − 3 × TPC) has been developed to monitor the level of degradation and to determine the point of disposal of used frying fats and oils much more reliable than using only one of the recommended parameters (TPC, AV, or PTG). This criterion is independent of fat composition, food to be fried, or frying process conditions and effectively helps to overcome the limitations of TPC and other major regulatory parameters related to the frying/baking industry. The good correlation of the results of the equation with the sensory quality of the fried food provides a powerful predictive tool for accurate calculation of the oil disposal point. This is useful since the quality of the fried food strongly depends on the quality of the frying oil that is absorbed by the food and becomes a major ingredient in the final product. This tool can easily be used to improve frying oil quality which finally improves the quality of the food to be fried. With continuous improvement this tool can become useful in reducing time and costs required for a human sensory panel. Physical and chemical changes of oils during different frying processes affect the development of color, flavor, and taste of the oil and also the structure of the food being fried. A new analytical approach applicable for all types of frying oil from different sources (bakeries, fisheries, restaurants, and industrial fryers) is proposed to predict the sensory quality of the oil using the content of total polar compounds and acid value resulting in the probability of the poin...