Identification of adulterated milk based on auto-correlation spectra.

A qualitative analysis of melamine-adulterated milk was proposed based on two-trace two-dimensional (2T2D) auto-correlation spectra. The concentration of melamine was used as external perturbation, and 40 adulterated samples of each brand with different concentrations of melamine (0.01 g/L to 1 g/L) were configured. Four brands of milk were used to configure experimental samples, including Guangming brand, Mengniu brand, Sanyuan brand and Wandashan brand. Spectroscopic data of pure milk and melamine-adulterated milk were measured by infrared (IR) (80-4000 cm-1) spectrophotometer. 2T2D auto-correlation spectral technology combined with least squares support vector machine (LS-SVM) method was used for qualitative analysis. The two strongest auto-correlation peaks in the auto-correlation spectra were selected for modeling. For Guangming brand, the intensities of auto-correlation at two wave numbers 2898 cm-1 and 2972 cm-1 were selected as independent variables. For Mengniu brand, the intensities of auto-correlation at two wave numbers 2852 cm-1 and 2920 cm-1 were selected. For Sanyuan brand, the intensities of auto-correlation at two wave numbers 2900 cm-1 and 2974 cm-1 were selected. For Wandashan brand, the intensities of auto-correlation at two wave numbers 2900 cm-1 and 2974 cm-1 were selected. For four brands fused together, the intensities of auto-correlation at two wave numbers 2900 cm-1 and 2974 cm-1 were selected. For each brand, the accuracy of qualitative analysis was 100 %. For four brands fused together, the accuracy of qualitative analysis was 99.05 %. In this way, it greatly reduced the amount of data to be processed. This study showed that 2T2D auto-correlation spectral technology combined with LS-SVM method was perfect for the discrimination of melamine-adulterated milk.

Development of weaning food with prebiotic effects based on roasted or extruded quinoa and millet flour.

Weaning is the gradual process of introducing solids or semisolid foods into an infant's diet, in order to ensure their healthy growth. This study developed two kinds of formula weaning food based on roasted or extruded quinoa and millet flour, and evaluated their quality. A fructo-oligosaccharide (FOS)/galacto-oligosaccharide (GOS) mix was added to provide the prebiotic potential. The protein contents of the roasted quinoa-millet complementary food (RQMCF) and extruded quinoa-millet complementary food (EQMCF) were 16.7% and 17.74% higher, respectively, than that of commercial millet complementary food (CMCF). Both RQMCF and EQMCF provided sufficient levels of energy and minerals. Extrusion provided the foods with a lower viscosity, and higher solubility and water absorption ability than roasting. In vitro digestion results showed that EQMCF exhibited the highest starch and protein digestibility (89.76% and 88.72%, respectively) followed by RQMCF (87.75% and 86.63%) and CMCF (83.35% and 81.54%). The digestas of RQMCF and EQMCF after in vitro digestion exhibited prebiotic effects by promoting the growth of the probiotics (Lactobacillus plantarum and Lactobacillus delbrueckii). These results will contribute to developing complementary weaning foods for infants. PRACTICAL APPLICATION: This study has shown that extrusion is an efficient and stable processing method for producing infant complementary foods with low density, balanced nutrition, and high levels of starch and protein digestibility. Extruded quinoa-millet prebiotic complementary food can also promote the proliferation of probiotics. This will provide a new direction for developing novel infant formula weaning foods.

[Analysis of Three Polycyclic Aromatic Hydrocarbons in Solution Based on Two-Dimensional Fluorescence Correlation Spectroscopy].

Polycyclic aromatic hydrocarbons (PAHs) are listed as the priority pollutants. It is difficult to resolve effectively the peaks of PAHs by conventional one-dimensional fluorescence spectroscopy due to its low content and the overlapping fluorescence three mixed ystems and a total of 27 samples, are to be prepared with different concentrations of three PAHs. Concentrations of three PAHS are monotonically increasing or decreasing in each mixed system. Then the 2D fluorescence correlation spectrum of each mixed systems will be calculated under the perturbation of the concentration of anthracene, phenanthrene and pyrene in solution. There are seven strong autopeaks at 425, 402, 381, 373, 365, 393 and 347 nm in synchronous 2D correlation spectrum. The fluorescence peak of phenanthrene at 347 nm is uncovered in three mixed systems, so the band at 347 nm is to be used as clues for further assignment. According to positive or negative cross peaks at 347 nm in synchronous 2D correlation spectrum, we can know that the peaks at 402, 381, 425 and 452 nm are assigned to anthracene, the peaks at 373 and 393 nm are assigned to pyrene, and the peaks at 365, 356 and 347 nm are assigned to phenanthrene. The fluorescence peak of phenanthrene at 385 nm is shown in asynchronous 2D correlation spectrum; it means the spectral resolution of asynchronous spectrum is better than the synchronous spectrum. The results are that it is feasible to analyze serious overlapping multi-component PAHs using two-dimensional fluorescence correlation spectroscopy, which can be extended to the detection of other pollutants in the air.

[Progress in Application of Two-Dimensional Correlation Spectroscopy for Detection of Food Quality].

In recent years, the food safety and quality has always been a serious issue. Therefore, it is urgent to develop a rapid and widely available method to determine the quality of food. Due to high spectral resolution, good spectral selectivity and good ability of spectrogram analysis, the technology of two-dimensional (2D) correlation spectroscopy is an effective method for solving three major problems encountered by the conventional one-dimensional (1D) spectrum: low selectivity of the spectra, difficulty in extracting the information of the spectral feature and difficulty in spectrogram analysis. Therefore, 2D correlation spectroscopy, which is suited to distinguish similar samples hardly distinguished by the conventional 1D spectroscopy, has been successfully applied in many complex biological systems. The developmental process, the experimental way to obtain spectrum, the fundamental mathematical principle and the properties of 2D correlation spectroscopy were introduced in this paper. At the same time, it is pointed out that the origin of weak characteristic bands of substance can be verified in terms of the positive or negative corss peaks in synchronous 2D correlation spectrum combined with the existence or inexistence of corss peaks in asynchronous 2D correlation spectrum. The application of 2D near-infrared, mid-infrared, fluorescence, and raman correlation spectroscopy in the detection of food quality and adulteration, concentrated specifically on diary product, wine, oil, meat, honey, and rice were reviewed. Finally, the limitations and future development prospects were pointed out.

[Discrimination of adulterated milk based on Euclidian distances between two-dimensional infrared correlation spectra].

Based on Euclidian distances between synchronous two-dimensional infrared correlation spectra, in terms of the average Euclidian distances between unknown samples and "extreme samples", and average intra- and inter-Euclidian distances of samples in the calibration set, a new method for the discrimination of adulterated milk was proposed. Sixteen pure milk samples were collected and 16 adulterated milk samples with urea (0.01-0.3 g x L(-1)), and 16 adulterated milk samples with melamine (0.01-0.3 g x L(-1)) samples were prepared, respectively. The IR absorption spectra of all samples were measured at room temperature. The synchronous two-dimensional correlation spectra were generated from concentration-dependent spectral variation of adulterant in milk. The Euclidian distances were calculated between synchronous two-dimensional infrared correlation spectra of all samples. Then, the classification models were built respectively for adulterated milk with urea, and adiulterated milk with melamine. The "extreme samples", average intra- and inter-Euclidian distances were determined. Finally, the unknown samples in prediction set were predicted using constructed models in terms of classification rules of adulterated milk. The classification accuracy rates for pure milk and adulterated milk were 100%. The effectiveness of the proposed method was verified. The results obtained in this study revealed that synchronous two-dimensional infrared correlation spectra in combination with Euclidian distance has a feasible potential to discriminate adulterated milk and pure milk.