Analytical Method for Differentiation of Chilled and Frozen-Thawed Chicken Meat
Abstract : Chilled and frozen chicken breast and thigh meat were stored at +4±1 oC and - 20±1 oC, respectively. Maillard reaction between ribose and meat proteins of the chicken samples was initiated. The changes in the ribose-induced Maillard reaction rate during chilled and frozen storage of chicken meat were evaluated on the bases of corrected absorbance values (A420*) and bovine melanoidin equivalent values (mg BME/g). Application of BME as a measure of ribose-induced Maillard reaction rate enables comparability of the data obtained by different spectrophotometers. It was found that the BME values of chicken meat frozen stored for more than 15 days were significantly (P<0.05) lower than BME values of chilled-stored samples. According to the suggested threshold limit values the chicken thigh and breast meat with BME values lower than 30 mg BME/g and 51 mg BME/g, respectively could be classified as frozen-thawed.
Discrimination between fresh, chilled, and frozen/thawed chicken based on its skin's spectrochemical and optical properties
Monitoring of the spectrochemical and optical properties of biomaterials has been widely utilized in many biomedical applications for both diagnosis and therapy. Recently, these nondestructive, noninvasive technologies have been used to inspect the quality and safety of food products. In this work, samples from chicken breast skin were investigated spectrochemically and optically to distinguish between fresh, frozen/thawed, and chilled chicken to reveal the adulteration of fresh meat and commercial fraud. Spectrochemical analysis was carried out using the Laser-Induced Fluorescence (LIF) technique. In the LIF setup used, a diode-pumped solid-state laser was used as a pump laser at λ = 266 nm. The LIF spectra were then analyzed statistically using the principal component analysis (PCA) method, while optical analysis was conducted via measurement of the parameters of the absorption and scattering of laser light (λ = 405 nm) on the chicken's skin. The optical absorption and scattering coefficients were acquired using an integrating sphere with a combination of the Beer–Lambert law and the Kubelka–Munk mathematical model. The spatial distribution of light at the sample surface was modeled using Monte-Carlo simulation and finite element solution of the diffusion equation to visualize the results. The potential of the LIF technique combined with principal component analysis in discriminating between the three chicken categories was validated by measuring the optical parameters as well as the simulation model. Besides, the discriminative ability of the proposed method was evaluated using receiver operating characteristic (ROC) curves, which showed sensitivity in discriminating fresh and frozen samples of 0.82 and 0.74 in fresh-chilled separation. These investigations demonstrate the capability of using LIF and proper software for in situ commercial fraud detection, i.e., in supermarkets and/or meat supplier centers.
Soil organic matter and microbiological development of technosols in the South Wales Coalfield
Abstract Degraded land (formerly ‘reclaimed’) after surface-coal-mining is a serious problem in South Wales. This project uses forestation to foster soil development on opencast coal-mine spoil technosols. It compares records of humification and the soil microbiological system (microcoenosis) using paired data from the same plantings in 1998 and 2018. Statistical analysis finds no significant difference between samples collected under trees planted by the pit-planting versus trench planting method or trees planted using organic or mineral fertilizer. However, there are strong significant differences in both soil organic matter and microflora components and significant correlations with time since tree planting. Most components of the soil organic carbon (TOC) and the microflora increase, often significantly. However, compared to 2018, 1998 samples contain significantly greater maximum levels of Insoluble Carbon while the microflora had significantly more Ammonifying bacteria. Decreases in Insoluble Carbon explain the relatively small increase in TOC between 1998 and 2018. The % extracted with 0.1 N H2SO4 is significantly larger in 2018, suggesting active weathering. Similarly, both the maxima and minima of total Humic and Fulvic acids content, extracted with 0.1 M Na4P2O7 + 0.1 M NaOH, are significantly greater in 2018. Total microflora shows significant positive correlations with time-since-tree-planting as do the proportions of bacilli and actinomycetes but the correlation with ammonifying bacteria is negative. In 1998, the microflora was dominated by non-spore-forming bacteria while, in 2018, bacilli and actinomycetes prevail; both are involved in the transformation of complex organic compounds and humification. This indicates active transformation of more complex organic compounds and advancing humification. In sum, forestation of these degraded, formerly reclaimed, opencast coal-mine spoils has resulted in a massive increase in both the size and functioning of the soil organic system.