Taiwan Food and Drug Administration (TFDA) has discovered target compounds for the identification of animal fats adulterated with vegetable ingredient-contained cooked oils by liquid chromatography tandem-mass spectrometry (LC-MS/MS). This result has been published in the journal “Food Control” in 2017. This is the first time using target compounds for the identification of adulterated animal fats by chemical analysis techniques.

Edible animal fats, such as lard and tallow, are widely used in pan-frying, stir-frying and deep-frying due to a desirable flavor which differs from that of vegetable oils, particularly in Asian countries. In 2014, a Taiwanese trader was discovered to have added cooked oil to lard in order to reduce production costs. It caused great economic loss to catering industry, affected public health, and highlighted the importance of analytical methods which can reliably identify adulterated animal fats.

Since the oil refining process reduces the values of most common quality indexes in these adulterated animal fats, there are currently no effective methods to discriminate between refined cooked oils and natural edible oils. Phytosterols are sterols in plants, and the contents of major phytosterols are not significantly affected by the oil refining process. Therefore, TFDA established an analytical method by detecting four common phytosterols (campesterol, stigmasterol, β-sitosterol and β-sitostanol) using LC-MS/MS for the determination of adulterated animal fats contaminated with cooked oils.

The phytosterol contents in inspected lard samples from companies that had been found guilty of adulterating lard in 2014 were higher than that found in homemade and commercial lard samples. In these inspected lard samples, the phytosterol contents in crude lard were higher than those in refined lard samples. Findings from this study suggest that phytosterols could be great candidates for the determination of adulterated animal fats.

This method is useful to screen out the animal fats which were most likely adulterated with refined cooked oils and could be used in conjunction with other analytical methods and adulteration inspections to strengthen judgments made in a court of law and to improve the quality of animal fats.

TFDA shows the outstanding technology after years of development. The authority will use this novel analytical method to monitor the crude lards in origins accompany with inspection result to prevent animal fats from adulterating with cooked oils. TFDA continuously develops new analytical methods for food management to protect the public health.