The year 1973 marked the first of nine International Symposia on Deep Frying that have been organized by the German Society for Fat Science. These programs have been held in Europe, Asia and USA. The first symposia focused on analytical methods and chemical criteria (free fatty acids, petrol ether insoluble oxidized compounds, smoke point) for the evaluation of used frying oil quality were discussed and finally proposed with the aim to improve the quality of fried products.
These first meetings provided the impetus for the establishment of regulatory guidelines for the production of safe and wholesome foods in foodservice and restaurant frying. Thereafter, focus was on more practical and less time-consuming methods such as Total Polar Compounds or Polymerized Triacylglycerols, which are much faster, more reliable and better predictors of oil and food quality. Later, in the nineties simple color tests to evaluate the quality of the used frying fat were propagated, and at the International Frying Symposium in 2000 semi-quantitative and quantitative tests were presented from different suppliers for the first time.
Since the beginning of the 21st century, much has changed in the area of deep-fat frying. The physical and chemical changes that occur during the frying process are now better understood as are the dynamics of heat and mass transfer. This understanding served as a prerequisite for the later development of mitigation strategies for the formation of acrylamide in fried food, first detected in 2002 and to better explain the role of water in the frying process. Water had long been suspected to be responsible for the hydrolysis of fat or oil during frying, and the new work clearly demonstrated that this was the case.
New processes and additives to improve the stability of the frying medium during the process have also been introduced and new frying media have been developed with view on health aspects or due to stability reasons.
In the meantime, there was very rapid development in instrumental analytics, data processing and the application of statistics to better understand the frying process. Analytical methods such as gas and liquid chromatography or NIR and NMR spectroscopy have been utilized which allowed the simultaneous determination of not only a huge number of compounds at the same time but also helped oil chemists determine their role in the frying process. The result is the availability of a large quantity of data that consequently help to better describe the structural changes of fats and oils during frying. In combination with chemometrics, these data provided the data to develop safer and more accurate recommendations regarding the usability of used frying oils.
As a result of the heating process during deep frying, several contaminants are formed in the frying medium which are either transferred to the food being fried or formed in those foods. Fresh frying medium can contribute to the amount of contaminants. The discussion about trans-fatty acids is more than 30 years old, but still topical. Recently, regulation (EU) 2019/649 to limit the trans-fatty acid content of food was introduced. As noted earlier, acrylamide in carbohydrate-based food was first announced in 2002, and at the end of 2017 regulation (EU) 2017/2158 establishing mitigation measures and benchmark levels for the reduction of the presence of acrylamide in food was published. For 3-monochloro-propane-1,2-diol (MCPD) and glycidyl fatty acid ester, other heat-induced contaminants, the knowledge about the formation during deep frying is rare, but in 2018 regulation (EU) 2018/290 has been published to limit the amount of glycidyl esters in fats and oils, and baby food, but not in formulated foods. Due to the sensitivity of edible oils to heat and oxygen a huge number of degradation products resulting from the frying medium are formed. Among these compounds are 4-hydroxy nonenal or acrolein, being suspected to impair human health.
Among the analytical parameters used to evaluate the quality of used frying oils or fried food is sensory evaluation. In fact, one of the recommendations made at a past frying symposium was that the sensory qualities of the food is the most important aspect to describe the quality of used frying oil or fried food. Although no standardized method for the sensory evaluation of used frying oils is available, there are several general methods describing general aspects and procedures. One important aim of this symposium is to provide the participants with some experiences in the application of the sensory assessment in a practical course.
The technical program of the 10th International Symposium on Deep frying will cover all the aspects necessary for a better insight into the frying process, the analytical and sensory methods and the evaluation regarding safety and quality of the final product. Thus, the 10th International Symposium on Deep-fat frying is intended for all persons from industrial food producers, foodservice and restaurant operations, sciences, official and commercial laboratories, marketing and consumers and suppliers who are involved into the production of fried food, research on the frying process or the assessment of used frying oils or interested in deep-fat frying in general.
The aim of the symposium is to provide the participants with new information on frying and to discuss the latest findings. This comprehensive knowledge provided during the 2-days symposium will give a solid basis for the production of high-quality products and better foods. We look forward to welcoming you in Hagen, on March 8 – 10, 2020.
Christian Gertz Rick Stier Bertrand Matthäus
Hagen, Germany San Francisco, CA/USA Detmold, Germany