Safety evaluation of certain food additives
Chemical and technical considerations
tải về 1.44 Mb. Chế độ xem pdf
|
| 1.2
Chemical and technical considerations Branching glycosyltransferase is secreted during fermentation into the fermentation broth and is subsequently purified and concentrated. The final product is formulated with sorbitol, glycerol and water and standardized to a desired activity. The total organic solids (TOS) content of the branching glycosyltransferase preparation is approximately 4%. The branching glycosyltransferase enzyme preparation complies with the General Specifications and Considerations for Enzyme Preparations Used in Food Processing (FAO/WHO, 2006). The branching glycosyltransferase preparation is intended for use in the production of modified starch with improved functional properties, such as higher solubility, lower viscosity and reduced retrogradation (undesirable structural changes). The recommended use levels range from 0.4 to 40 kg of the enzyme preparation per tonne of starch dry substance. The branching glycosyltransferase is likely to be inactivated and/or removed during starch processing steps. The enzyme is not added directly to food, and any carryover to food products formulated with modified starch is expected to be very low. 2. BIOLOGICAL DATA 2.1 Biochemical aspects Branching glycosyltransferase has been evaluated for potential allergenicity using bioinformatics criteria recommended in the report of the Joint Food and Agriculture Organization of the United Nations (FAO)/World Health Organization 4 BRANCHING GLYCOSYLTRANSFERASE FROM RHODOTHERMUS OBAMENSIS (WHO) Expert Consultation on Allergenicity of Foods Derived from Biotechnology (FAO/WHO, 2001). An amino acid sequence homology search between branching glycosyltransferase and known allergens listed in the allergen database at http://fermi.utmb.edu/SDAP/index.html was conducted. No homology was found for sequence fragments of six contiguous amino acids. However, when using a sliding window of 80 amino acids, a 35% match was found to sequences of Asp o 21 allergen, which is the Į-amylase from Aspergillus oryzae (TAKA amylase A). However, the sequence alignment of the two enzymes showed that there are large differences in the loop regions, and the overall identity is only about 32%. As the two enzymes belong to the same family of glycosylhydrolases (Family 13; http://www.cazy.org/fam/GH13_3D.html ), some homology is not surprising. Although Į-amylase from A. oryzae is an occupational allergen (Skamstrup Hansen et al., 1999), allergy symptoms after ingestion of the enzyme were reported only for four individuals. Three of these individuals consumed bread baked with the enzyme (Baur & Czuppon, 1995; Kanny & Moneret-Vautrin, 1995; Moreno-Ancillo et al., 2004), and one had a positive response to the oral challenge with Į-amylase (Losada et al., 1992). In other studies conducted with patients with documented occupational or other allergies, no cases of food allergy to Į-amylase from A. oryzae or other commercial enzymes used in food were identified (Skamstrup Hansen et al., 1999; Bindslev-Jensen et al., 2006). Thus, food allergy to Į-amylase from A. oryzae is extremely rare. Moreover, branching glycosyltransferase is a bacterial protein, whereas nearly all known allergens listed in allergen databases are eukaryotic proteins. Therefore, despite certain homology to Į-amylase from A. oryzae, branching glycosyltransferase does not seem to have the characteristics of a potential food allergen. tải về 1.44 Mb. Chia sẻ với bạn bè của bạn:
|