Pet Food Testing

Xiaolu, Liu, et al. Microchemical Journal (2024): 110903.

Rapid analysis of pet food to control its nutritional quality is of great interest to the pet food industry. The objective of this study is to test the effectiveness of near-infrared hyperspectral imaging (HSI) in determining the chemical composition of cat and dog food, and to assess the impact of mixed models and feature wavelengths on the performance of quantitative models.

A total of 70 cat food samples and 36 dog food samples were characterized for moisture, crude protein (CP), crude fat (CF), crude fiber (CFe), crude ash (CA), calcium (Ca), and total phosphorus (TP) using reference methods. Partial least squares regression (PLSR) was employed to establish quantitative models involving cat food and mixed models. The competitive adaptive reweighted sampling (CARS) algorithm was used to select feature wavelengths.

The results indicate that, except for CFe, the performance of the cat food model is similar to that of the mixed model. When using the selected feature wavelengths, the mixed model predictions for CP, CF, moisture, and CFe were optimal, with R²p ranging from 0.73 to 0.96 and RPD ranging from 2.22 to 5.20. However, the predictions for TP, CA, and Ca did not meet practical requirements. The optimal quantitative model can visually display the distribution of chemical composition in the samples. The findings of this study provide theoretical and technical support for rapid online quality control of pet food.

Davies, Mike, et al. Scientific Reports 7.1 (2017): 17107.

The mineral content of complete pet foods is regulated to ensure the health of companion animal populations. However, the compliance with these regulatory guidelines has not been previously analyzed.

In this study, the mineral composition of complete wet (n = 97) and dry (n = 80) dog and cat foods sold in the UK was measured to assess compliance with EU guidelines. Most foods complied with at least 8 out of 11 guidelines (99% for dry food and 83% for wet food), but many products failed to provide minimum nutritional levels (e.g., 20% of wet foods were deficient in Cu) or exceeded maximum nutritional levels (e.g., 76% of wet foods exceeded Se). Only 6% (6/97) of wet foods and 38% (30/80) of dry foods fully met the requirements.

Some foods (20-30% of all analyzed products) exhibited mineral imbalances, such as lacking the recommended Ca:P ratio (which should be between 1:1 and 2:1). Foods high in fish content contained significant levels of undesirable metal elements, such as arsenic. This study highlights that a wide range of popular pet foods sold in the UK generally do not comply with EU guidelines, with 94% of wet foods and 61% of dry foods failing to meet the standards. Feeding these pet foods exclusively over the long term may adversely affect the overall health of companion animals.

Guirado-Moreno, José Carlos, et al. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 284 (2023): 121820.

In response to concerns about environmental impact and human health, countries such as China and the European Union have set maximum zinc levels in animal feed at 150-250 mg/kg and 100-150 mg/kg, respectively.

We report an innovative method for measuring Zn(II) concentrations in commercial pet food samples, including both wet and dry foods. This method is based on a colorimetric sensing polymer synthesized from commercial monomers and a 0.5% synthetic monomer featuring a quinoline sensing core (N-(8-(2-azidoacetyl)quinolin-5-yl)methacrylamide). The sensing polymer, acting as a crosslinked membrane, was obtained through thermal initiation of the bulk radical polymerization of 100 μm thick monomers and was pressed into sensing disks with a diameter of Ø6 mm.

When the disks are immersed in a Zn(II)-containing aqueous solution, fluorescence is activated, allowing the cation to be titrated using the G parameter from digital photos taken of the disks. The limits of detection and quantification were found to be 29 µg/L and 87 µg/L, respectively. Furthermore, we measured Zn(II) concentrations even in the presence of other cations, with no significant interference detected.

In subsequent steps, we extracted Zn(II) from 15 commercial pet food samples using a simple extraction procedure that involved contacting the extractant with our sensing disks. The concentrations of Zn(II) obtained ranged from 19 to 198 mg/kg.