UC Irvine

Objective

Assessment of the quantity and chemical type of phosphorus (P) content in cooked ham products with or without preservatives using a novel biochemical procedure.

Methods

We examined the quantity and types of P in 40 samples of cooked ham, including 20 without and 20 with P-containing preservatives, which were purchased randomly from a grocery store in Italy. Food samples were analyzed for dry matter, nitrogen, fat, and P content. Novel spectrophotometric methods were used to measure total P and 3 different P subtypes, that is, water-soluble (inorganic) P including added preservatives and natural P derived from phospholipids and phosphoproteins, separately.

Results

Compared with hams without preservatives, hams with P-containing preservatives had significantly lower dry matter and protein and fat contents. There was 66% more inorganic P (IP) in ham with preservatives than in samples without preservatives (169 ± 36 vs. 102 ± 16 mg/100 g, P < .001, respectively). There were no significant differences in P contents derived from proteins or lipids. The P-to-protein ratio was higher in ham samples with preservatives than in those without preservatives (16.1 ± 4.0 and 9.8 ± 0.8 mg/g, P < .001). The sum of measured IP and P from phospholipids and phosphoproteins was 91% ± 4% of measured total P (207.1 ± 50.7 vs. 227.2 ± 54.4 mg/100 g), indicating a small portion of unspecified P and/or under measurement.

Conclusions

Novel differential dietary P measurement detects added P-containing preservatives. Cooked ham with preservatives has 66% more measurable IP and 64% higher P-to-protein ratio than ham without preservatives. The contribution of food added with P-containing preservatives to global dietary P burden can negatively influence chronic kidney disease outcome and counteract the efficacy of P-binder medications: this is an important topic that warrants additional investigations.