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

Insights into the impact of complex phosphates on acid-induced milk fan gel properties: Texture, rheological, microstructure, and molecular forces

Milk fan cheese, a type of stretched -cheese, presents challenges in its stretch-forming. This study investigated the impacts of complex phosphates (sodium tripolyphosphate and sodium dihydrogen phosphate, STPP-DSP) on the gelling properties of acid-induced milk fan gel and the mechanisms contributing to its stretch-forming. The treatment of milk fan gel with STPP-DSP resulted in improved functional and textural properties compared with the control group. In particular, drawing length increased significantly from 69.67 nm to 80.33 nm, and adhesiveness increased from 1737.89 g/mm to 1969.79 g/mm. The addition of STPP-DSP also led to increased viscosity, elastic modulus (G'), and viscous modulus (G"). Microstructural analysis revealed the formation of a fibrous structure within the gel after STPP-DSP treatment, facilitating uniform embedding of fat globules and emulsification. Structural analysis showed that the addition of STPP-DSP increased β-fold and decreased random coiling of the gel, facilitating the unfolding of protein structures. Additionally, UV absorption spectroscopy and excitation-emission matrix spectroscopy results indicated the formation of a chelate between STPP-DSP and milk fan gel, increasing protein-protein molecular interactions. Evidence from differential scanning calorimetry and x-ray diffraction demonstrated the formation of sodium caseinate chelate. Fourier transform infrared spectroscopy and zeta potential analysis revealed that the sodium caseinate chelate formed through hydrophobicity, hydrogen bonding, and electrostatic forces. These findings provided theoretical insights into how phosphates can improve the stretch-forming of milk fan gel, facilitating the application of phosphate additives in stretched -cheese processing.

Determination of phosphate in food based on molybdenum yellow derivatization coupled with resonance Rayleigh scattering method

This paper proposed a rapid, selective and sensitive molybdenum yellow derivatization coupled with Resonance Rayleigh scattering (MYD-RRS) method for detection of phosphate. Under the acidic condition, phosphate can be selectively transformed to Keggin type of phosphomolybdic acid (PMA, i.e., PMo12O403-) through molybdenum yellow derivatization reaction prior to RRS detection. The PMA can further react with cationic methyl violet (MV) to form larger PMA-MV ion association complexes, generating significant RRS signal. The concentration of phosphate was linearly related to the RRS signal in the range of 8-200 ng/mL, with the determining coefficient (R2) of 0.9973 and the detection limit of 4 ng/mL. The analytical procedure can be completed within 10 min and the RRS signal intensity can remain stable more than 4 h. The method showed good stability toward temperature and time, and good anti-interference capability. The method was applied to the determination of phosphate in real food samples with the recovery of 85-117% and RSD of 1-5.2%. With the advantages of rapidness, high sensitivity and good selectivity, the MYD-RRS method exhibits great potential to the determination of phosphate in food. It also provides an instructive strategy for detection of analytes with weak RRS signal.

Ratiometric fluorescent detection of total phosphates in frozen shrimp samples using catalytic active Zr(IV) modified gold nanoclusters

Phosphate salts are important food additives in a variety of foods. In this study, the Zr(IV) modified gold nanoclusters (Au NCs) were prepared for ratiometric fluorescent sensing of phosphate additives in seafood samples. Compared with bare Au NCs, the synthesized Zr(IV)/Au NCs showed stronger orange fluorescence at 610 nm. On the other hand, the Zr(IV)/Au NCs retained the phosphatase-like activity of Zr(IV) ions and could catalyze the hydrolysis of fluorescent substrate 4-methylumbelliferyl phosphate to produce blue emission at 450 nm. The addition of phosphate salts could effectively inhibit the catalytic activity of Zr(IV)/Au NCs, resulting the fluorescence decrease at 450 nm. However, the fluorescence at 610 nm almost unchanged upon the addition of phosphates. Based on this finding, the ratiometric detection of phosphates using the fluorescence intensity ratio (I₄₅₀/I₆₁₀) was demonstrated. The method has been further applied for sensing total phosphates in frozen shrimp samples with satisfactory results.

Study on adsorption and recovery utilization of phosphorus using alkali melting-hydrothermal treated oil-based drilling cutting ash

Oil-based drill cutting ash (OBDCA) was treated by alkali melting-hydrothermal method and used as novel adsorbent (AM-HT-OBDCA) for the recovery of phosphorus (P) in water body. The experiment parameter for preparation of AM-HT-OBDCA was optimized, including alkali melting ratio (M_OBDCA: M_NaOH), alkali melting temperature and hydrothermal temperature. The adsorption process of phosphorus on AM-HT-OBDCA was fit well with the pseudo-second-order model and the Langmuir model. The calculated theoretic adsorption capacity of phosphorus on AM-HT-OBDCA was 62.9 mg/g. The adsorption behavior was spontaneous and endothermic. The effect of pH value and interfering ions on the adsorption of phosphorus in AM-HT-OBDCA was investigated. The main existing form of adsorbed phosphorus on AM-HT-OBDCA was sodium hydroxide extraction form phosphorus (NaOH-P), including iron form phosphorus (Fe-P) and aluminum form phosphorus (Al-P). Precipitation and ligand exchange were the main mechanisms of phosphorus adsorption on AM-HT-OBDCA. The AM-HT-OBDCA used for phosphorus adsorption (AM-HT-OBDCA-P) could be further utilized as fertilizer to promote plant growth. The results of this study provide fundamental data and evaluation support for resource utilization of OBDCA. These results will also provide a reference for the adsorption and recovery utilization of phosphorus using solid waste-based adsorbent.