Takanashi et al. 2018 — Aluminium in baking-powder-containing processed foods, Japan 2015–2016
A survey by the Tokyo Metropolitan Institute of Public Health measured aluminium (Al) content in 123 processed-food products (confectionery, bakery goods, flour-processed foods, and powder mixes) that potentially used alum-containing baking powder. Al was detected in 41 of the 123 samples at concentrations from 0.01 to 0.40 mg/g; 4 of those 41 samples were found at levels where consuming a single serving once per week would exceed Japan’s Provisional Tolerable Weekly Intake (PTWI) for young children (body weight 16 kg). The study found that non-Japanese confectionery categories had declining detection rates since prior surveys (80% in 2009 down to 14% in 2015–2016), consistent with industry efforts to substitute Al-free leavening agents, while Japanese confectionery (wagashi) categories remained high at 56% detection, suggesting the Al-reduction effort had not reached that segment.
Key numbers
- Total samples: 123 products across 4 groups (bakery products, confectionery, flour-processed foods, powder mixes)
- Al detected: 41 of 123 products (33%)
- Detection range: 0.01–0.40 mg/g (wet weight)
- Highest values: imagawayaki (Japanese pancake) at 0.40 mg/g; takoyaki (octopus ball) imported from China at 0.38 mg/g
- LOQ: 0.01 mg/g
- Detection rate by group: bakery products 13% (2/15); confectionery 35% (25/71); flour-processed foods 60% (12/20); powder mixes 12% (2/17)
- Four samples exceeded the child PTWI (32 mg/week for 16 kg child) at one serving per week: Chinese deep-fried bread (0.22 mg/g × 192 g/serving = 42 mg), takoyaki-1 (43 mg), takoyaki-2 (40 mg), takoyaki-3 (38 mg)
- Five additional samples approached the PTWI (imagawayaki, chijimi, takoyaki-4 through -6 at 23–30 mg)
- PTWI used: 2 mg/kg body weight/week (JECFA 2011); Japan’s Food Safety Commission set TWI at 2.1 mg/kg bw/week in December 2017
- Imported takoyaki tended to have higher Al than domestic products (0.09–0.38 mg/g vs. 0.01–0.10 mg/g); all Al-positive imported takoyaki were Chinese-origin
- Analysis method: ICP-OES (Perkin Elmer Optima 7300DV) following microwave acid digestion; conforms to MHLW food additives testing guidelines; r² > 0.999 calibration linearity confirmed
Methods (brief)
Microwave acid digestion of approximately 0.5 g sample in HNO3/water, filtered through 0.45 µm, measured by inductively coupled plasma optical emission spectrometry (ICP-OES). LOQ 0.01 mg/g. Validated per MHLW Guidelines for Evaluation of Analytical Methods for Metal in Foods (2008). Frozen foods were thawed per package instructions before sampling. Conducted by Tokyo Metropolitan Institute of Public Health with Tokyo Metropolitan Bureau of Social Welfare and Public Health oversight.
Implications
Certification: Al in baking-powder-dependent products is a function of whether the manufacturer uses alum (potassium aluminium sulfate) vs. Al-free leavening acid. HMT&C product standards for baked goods should flag Al as a process-additive analyte, not merely a soil-contamination analyte. A supplier-specification lever exists: requiring Al-free leavening agents in certified products is feasible given that major confectionery producers in Japan already made this switch by 2015.
Courses: Useful illustration that heavy-metal exposure from food additives is mechanistically distinct from soil-uptake contamination, and that regulatory notice (JECFA’s 2011 PTWI revision) can drive voluntary reformulation within a few years in some segments but not others.
App: Baking-powder ingredient listing on a label is a proxy marker for potential Al content in confectionery and bakery products. Products listing “alum,” “potassium alum,” “aluminium potassium sulfate,” or just “leavening agent” without specification should be flagged as Al-risk products pending speciation data.