Simultaneous and rapid determination of added phosphorus(V) compounds in meat samples by capillary isotachophoresis

Quantitative assessment of phosphate food additive in frozen and chilled chicken using spectrophotometric approach combined with graphitic digestion

A new method based on spectrophotometry combined with graphitic digestion was developed for quantitative assessment of phosphate in frozen and chilled chicken meat. Digestion reagents comprising HNO₃ (conc.) & H₂SO₄ (conc.) and HNO₃ (5 M) & H₂SO₄ (conc.) were found to have optimal composition, affording similar recovery values of 100% and 99%, respectively, with excellent linearity (R² > 0.999) and good limit of detection (LOD = 0.032 mg/L) and limit of quantification (LOQ = 0.10 mg/L), whereas other reagents offered lower recoveries (0-1.73%). Phosphate was found in concentrations of 3.38-5.90 g/kg and 3.96-26.94 g/kg in frozen and chilled chicken, respectively. Chilled chicken contained higher amounts of phosphate (>20 g/kg) than recommended by the European Commission (EC, 5 g/kg), either alone or in a mixture of processed meat products. This method is simple, cost-effective, and can be used as an alternative for analyzing phosphate in various samples comprising a similar matrix.

Physiochemical Changes and Optimization of Phosphate-Treated Shrimp (Litopenaeus vannamei ) Using Response Surface Methodology

The objective of this study was to determine the factors responsible for the changed physiochemical properties of unpeeled shrimp treated in cold phosphate solution (2~4°C) with the intervention of 4 factors: phosphate concentration, dipping time, rotation speed, and volume of brine solution. Response surface analysis was used to characterize the effect of the phosphate treatment on shrimps by running 33 treatments for optimizing the experiment. For each treatment, phosphate amount, moisture content, and weight gain were measured. The results showed that phosphate concentration is the most important factor than other factors for facilitating phosphate penetration in the meat of the shrimp and for getting the best result. The optimum condition of phosphate-treated shrimp in this study was 110 to 120 min dipping time, 500 to 550 mL brine solution for 100 g shrimp sample, and 190 to 210 rpm agitation speed. The studied conditions can be applied in fisheries and other food industries for good phosphate treatments.

Determination of polyphosphates in fish and shrimp muscles by capillary electrophoresis with indirect UV detection after phosphatase inhibition using high pressure pretreatment

A method was proposed for the determination of polyphosphates (P2O7(4-), P3O10(5-) and (PO3)3(3-)) in fish and shrimp muscles by capillary electrophoresis with indirect UV detection after phosphatase inhibition using high pressure pretreatment (HPP). Separation parameters were optimized and the effects of HPP on deactivation of enzyme were investigated. Well resolution was obtained with 10 mM adenosine 5'-phosphate (ATP) in 16 mM disodium hydrogen phosphate combining with 32 mM citric acid buffer (pH = 6.4) containing 0.1 mM cetyltrimethyl ammonium bromide, and phosphatase was effectively inhibited by HPP at 400 MPa for 10 min. Method was validated with LOD (0.23-0.33 mg g(-1)) and LOQ (0.77-1.0 mg g(-1)). Recovery of P2O7(4-), P3O10(5-) and (PO3)3(3-) in the fortified samples were in the range of 91.6-100.1%, 97.6-104.6% and 79.1-88.1%, respectively, and the corresponding RSD ranged from 1.1% to 6.8%. Finally, the method was applied in the determination of polyphosphates in food samples collected from local markets.

Development and analytical evaluation of a spectrophotometric procedure for the quantification of different types of phosphorus in meat products

Phosphorus is an important natural nutrient, but high dietary phosphorus intake, including that sourced from added preservatives, is of great concern in renal patients. In this context a reliable analytical method able to quantify differential phosphorus in food could be a valuable tool for monitoring diet composition This paper presents a novel analytical procedure to quantify the following kinds of phosphorus in cooked ham: total (TP), inorganic (IP), from phospholipids (PL), and from phosphoproteins (PP). This technique is based on a suitable sample preparation followed by spectrophotometric analyses. Analytical performances of each method were evaluated, taking advantage also of food industry certified material and in-house reference samples. Limit of detection and limit of quantification values for TP, IP, PP-derived, and PL-derived phosphorus were 13 and 37, 11 and 33, 2 and 20, and 6 and 16 mg P/100 g fresh mass, respectively. Similar results were obtained when this procedure was used to quantify different types of phosphorus present in cooked ham samples. In conclusion, this procedure is effective for quantifying the content of different types of phosphorus present in cooked ham, which can be contributed by different phosphorus-containing ingredients and additives. To the best of the authors' knowledge, this is the first time that simultaneous determination of TP, IP, PL, and PP in cooked ham has been reported.

Novel differential measurement of natural and added phosphorus in cooked ham with or without preservatives

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.

Phosphate additives determination in meat products by 31-phosphorus nuclear magnetic resonance using new internal reference standard: hexamethylphosphoroamide

New (31)P NMR internal reference standard - hexamethylphosphoroamide (HMPA) was applied for determination of added polyphosphates and their ionic forms in raw pork meat and meat products. Phosphate species were determined after extraction with a boric acid buffer (pH=9) and EDTA solution, using internal standard (HMPA) procedure. Hexamethylphosophoroamide was also used as the NMR reference standard. Linear correlations between phosphates and polyphosphate concentrations and (31)P NMR signal areas were found in the range 81-5236 mg P/dm(3), presenting 95-99% recovery and variation coefficient (CV) ≤ 5%. Studied HMPA procedure revealed shorter analysis time and the same recovery (>95%) and precision (CV=1.3-2.7%) in comparison to MDPA method. Results of phosphate determination by both (31)P NMR methods were tested against the molybdenumvanadate yellow spectrophotometric method (standard PN-ISO 13730, 1999) using standard reference material (certified phosphate solution).

Extra-phosphate load from food additives in commonly eaten foods: a real and insidious danger for renal patients

BACKGROUND

Restriction of dietary phosphorus is a major aspect of patient care in those with renal disease. Restriction of dietary phosphorus is necessary to control for phosphate balance during both conservative therapy and dialysis treatment. The extra amount of phosphorus which is consumed as a result of phosphate-containing food additives is a real challenge for patients with renal disease and for dieticians because it represents a "hidden" phosphate load. The objective of this study was to measure phosphorus content in foods, common protein sources in particular, and comprised both those which included a listing of phosphate additives and those which did not.

METHODS

Determinations of dry matter, nitrogen, total and soluble phosphate ions were carried out in 60 samples of foods, namely cooked ham, roast breast turkey, and roast breast chicken, of which, 30 were with declared phosphate additives and the other 30 similar items were without additives.

RESULTS

Total phosphorus (290 ± 40 mg/100 g vs. 185 ± 23 mg/100 g, P < .001) and soluble phosphorus (164 ± 25 mg/100 g vs. 100 ± 19 mg/100 g, P < .001) content were higher in products containing additives than in foods without additives. No difference was detected between the 2 groups regarding dry matter (27.2 ± 2.0 g/100 g vs. 26.7 ± 1.9 g/100 g) or total nitrogen (3.15 ± 0.40 g/100 g vs. 3.19 ± 0.40 g/100 g). Consequently, phosphorus intake per gram of protein was much greater in the foods containing phosphorus additives (15.0 ± 3.1 mg/g vs. 9.3 ± 0.7 mg/g, P < .001).

CONCLUSIONS

Our results show that those foods which contain phosphate additives have a phosphorus content nearly 70% higher than the samples which did not contain additives. This creates a special concern because this extra amount of phosphorus is almost completely absorbed by the intestinal tract. These hidden phosphates worsen phosphate balance control and increase the need for phosphate binders and related costs. Information and educational programs are essential to make patients with renal disease aware of the existence of foods with phosphate additives. Moreover, these facts highlight the need for national and international authorities to devote more attention to food labels which should clearly report the amount of natural or added phosphorus.

Recent advances in the application of capillary electromigration methods for food analysis and Foodomics

The use of capillary electromigration methods to analyze foods and food components is reviewed in this work. Papers that were published during the period April 2007 to March 2009 are included following the previous review by García-Cañas and Cifuentes (Electrophoresis, 2008, 29, 294-309). These works include the analysis of amino acids, biogenic amines, peptides, proteins, DNAs, carbohydrates, phenols, polyphenols, pigments, toxins, pesticides, vitamins, additives, small organic and inorganic ions and other compounds found in foods and beverages, as well as those applications of CE for monitoring food interactions and food processing. The use of microchips, CE-MS, chiral-CE as well as other foreseen trends in food analysis are also discussed including their possibilities in the very new field of Foodomics.