Safety evaluation of certain food additives - ipcs inchem

112 PHOSPHOLIPASE C EXPRESSED IN PICHIA PASTORIS
3. DIETARY EXPOSURE
3.1 Intended use, use levels and residual level
The refining of raw vegetable oil following treatment with phospholipase C
can proceed by a chemical process or a physical process, although the chemical
process is more prevalent (Allen, 1997). In the chemical process, the phospholipase
C enzyme preparation is added to the refining process of vegetable oils at the first
step, which is referred to as the degumming step, and is followed by the additional
steps of bleaching and then deodorization.
The enzyme preparation is added to the unrefined vegetable oil, such as
rapeseed, corn or sunflower, at levels no higher than necessary to achieve the
intended effect. These levels are generally in the range of 100–1000 mg of enzyme
preparation per kilogram of vegetable oil, depending on the oil to be treated and the
reaction conditions (General Standard for Food Additives [GSFA] food category
02.1.2, vegetable oils and fats). This is equivalent to approximately 10 mg of purified
phospholipase C per kilogram. The reported percentage of TOS in the commercial
products is 7%.
As indicated in the submission report, the level of phospholipase C
significantly decreases with each step in the process, regardless of whether the
process uses chemical or physical processing techniques. No enzyme was found
in any of the samples besides the initial sample, suggesting that the enzyme is
actually degraded in these refining steps and not just denatured. The level of
residual phospholipase C in the final degummed vegetable oil is estimated to be
below the detection limit of the assay, set at 1 μg/kg.
3.2 Assessment of per capita dietary exposure based on data from food
balance sheets
An international assessment based on data from food balance sheets was
performed by the Committee according to the 13 Consumption Cluster Diets of the
Global Environment Monitoring System – Food Contamination Monitoring and
Assessment Programme (GEMS/Food) categorization (Annex 1, reference 177). In
this assessment, per capita daily consumption of vegetable oils and fats—including
olive, coconut, cotton seed, groundnut, linseed, maize, palm kernel, rape seed,
sesame seed, soya bean, sunflower and other oils of vegetable origin, butter of
karité and margarine—from the 13 cluster diets was combined with the maximum
use level recommended by the petitioner, 1000 mg of the commercial enzyme
preparation (7% TOS) per kilogram of vegetable oil.
Thus, if it is assumed that the enzyme is not removed from the oil and if per
capita vegetable oil consumption is considered to range from 9 g/day (cluster A) to
68 g/day (cluster B), per capita dietary exposure to phospholipase C from P.
pastoris would be estimated to range from 0.011 to 0.079 mg TOS/kg bw per day
for a 60-kg body weight adult.