Scope extension validation of a LC-MS method for the inspection of preservatives in butter

Abstract

Butters are considered as “natural products” by many consumers, once they are obtained from milkfat without adding of any additive, except sodium chloride, starter cultures and natural dyes. The main goals of this study were to extend the scope of a previously developed method, including a new analyte (benzoic acid) and new matrices (butter and margarine), and thus evaluate the content of preservatives in national and imported butters traded in Brazil. Samples (n = 51) from inspected establishments in Argentina (n = 2), Brazil (n = 40), France (n = 7) and Uruguay (n = 2) were assessed by liquid chromatography-tandem mass spectrometry. Two screening inspection rounds were carried out between November, 2015 and January, 2016. Non-compliance rates were 36.4% in 2015 and 22.2% in 2016 for Brazilian butters. It was shown that preservatives are irregularly added to butters by many factories, contrary to regulation, and without proper declaration on labeling. The limits of quantitation (LOQ) were set to 25.00 mg kg−1 (benzoic acid), 1.25 mg kg−1 (natamycin), 3.13 mg kg−1 (nisin) and 2.50 mg kg−1 (sorbic acid). Except nisin, any of the researched preservatives was detected in a total of 12 samples, in concentrations that ranged from <LOQ–235.67 mg kg−1 (benzoic acid), 8.26–35.60 mg kg−1 (natamycin) and 4.52–1007.17 mg kg−1 (sorbic acid). The method was also checked on margarine samples, revealing concentrations that ranged from 43.72 to 359.17 mg kg−1 (benzoic acid) and from 509.00 to 1102.67 mg kg−1 (sorbic acid), respectively. Our findings demonstrate that there is a need for stricter control in butter processing, with the aim to ensure food safety and to safeguard consumers.