Influence of the frying process on the real fat intake

Abstract

As shown in the former presentation, one fact about repeated frying is that there comes a moment, when the oil used is no longer suitable for frying, that is discarded. The amount may be quite large depending, among other factors, on the composition of the oil itself and on that of the foodstuffs fried. This can be of practical significance for the total lipid intake, since the unsuitable oil is no longer ingested. It is difficult to know the amount of oil discarded for this reason and there is no scientific information in the literature on this subject. In this paper we try to know the quantitative and qualitative importance of the oil proceeding of repeated frying (RF) which normally is discarded in relation to the total fat intake (Fl) in Madrid, as well at domestic level (96 families) as in catering (hospitals, restaurants and schools). For this purpose discarded oils proceeding of the frying of food were collected in the usual quantity, variety and conditions (only olive and sunflower oils were used), both in the households and in the institutions. In the oils, raw and discarded, we also determined their composition in fatty acids. Our results show that at domestic level, although the dispersion is big, the average values of the discarded oil are the 19.3 ± 18.4% of the inventoried oil. However, in the institutional frying, in which, of course, industrial fryer are utilised, the proportion of discarded oil was much bigger, some time doubling the quantity discarded at domestic level. Curiously, the discarded oils proceeding either from the households or from catering do not show significative differences regarding their composition in fatty acids with respect to raw oil. The reason is that the oils are discarded due to subjective reasons, although they probably might be utilised again. At this moment, we are trying to confirm this last statement. In conclusion, if you do not take into consideration this percentage of losses, when utilising the inventory as measure technique of the intake of an individual person or a collective, you would overestimate the consumption approximately in 19-20%, and this error would be bigger when some meals are consumed in catering. This obviously would have a repercussion on the estimation of the fat intake, and therefore, of caloric intake and of the indices related to it, as shown in this presentation.