A polypeptide made up of 34 amino acids, nisin (nisin A) is a type of bacteriocin - a protein or peptide naturally produced by bacteria to inhibit the growth of other bacteria - and is used by food manufacturers to extend shelf life.
In a manufacturing setting, it is produced via fermentation by Lactococcus lactis subsp. Lactis and is already authorised in the EU as an antimicrobial agent in a range of foods, such as ripe and processed cheese.
This latest opinion, published in the open source EFSA Journal yesterday (11 December), okayed the preservative in two new food groups – unripened cheese and heat-treated meat – and increased the acceptable daily intake (ADI) from 0.13 mg per kilo body weight per day to 1 mg.
It recommended manufacturers can use nisin in unripened cheese, at a maximum level of 12 mg per kilo and in heat-treated meat products at a maximum level of 25 mg per kilo.
For this opinion, which was requested by DuPont Nutrition Biosciences in March last year, the Panel on Food Additives and Nutrient Sources Added to Food (ANS) took into account data used in the previous evaluation from 2006 as well as an additional subchronic toxicity study.
They found no adverse effects in rats given nisin A for 90 days and therefore established a ‘no observed adverse effect level’ (NOAEL) of 225 mg nisin A per kilo bodyweight per day.
Using this NOAEL, as well as estimates for exposure through dietary sources, the scientists set the new ADI of 1 mg.
Food preservatives linked to AMR?
However, the scientists note they did not consider the possibility that using nisin in food induces antimicrobial resistance (AMR) as well as a possible “modulating effect” on the gut microbiota.
This was a deliberate decision as they were deemed to fall outside the remit of the ANS Panel and the scope of this mandate.
Although the Panel noted that these uncertainties around residual nisin activity and the microbiome “would not alter the conclusions on the terms of reference”, it nonetheless recommended a separate evaluation of these risks.
Using the EFSA Comprehensive Database, it calculated that nisin exposure ranges from 4 μg/kg bw per day in infants to 163 μg/kg bw per day in toddlers at the mean exposure level and from 29 μg/kg bw per day in elderly to 238 μg/kg bw per day in children at the high exposure level.
The main food category currently accounting for total exposure in all population groups is meat products. This would not change with the proposed extended use, the Panel noted, with exposure for all groups remaining below the ADI.
In 2008, EFSA said nisin could be used in liquid eggs without posing a safety concern.