| Popis: |
Splits, slits and cracks are a continuing problem in the US Swiss Cheese industry and cause downgrading of the cheese, bringing economic loss. The defects generally occur during secondary fermentation in cold storage, which is known to be an issue caused by many factors. Many chemical and physical changes can be indicators to help predicting the defects. Various techniques have been applied to test different compounds in cheese. HPLC is one of the reference methods which have been applied in cheese chemistry for the past decades. Its application involves in the qualification and quantification of organic acids, amino acids and peptides, and sugars in dairy products. However, limited research has been conducted on a rapid and easy testing regimen to investigate split defects in Swiss-type cheese. For over fifty years, researchers have investigated the application of Fourier Transform Infrared (FTIR) Spectroscopy in various food samples, including cheeses and other dairy products because FTIR spectroscopy gives fast, simple and comprehensive detection of chemical compounds. There is great potential for applying FTIR spectroscopy in developing a rapid test method to detect and predict the occurrence of split defects.In this study, initially four pairs of cheese samples were analyzed using a standard HPLC methodology, to assess the capability of this method in chemical detection addressing the defects, and to provide a reference to later FTIR results. Four pairs of cheeses, each pair from its own vat, were chosen for this analysis. Each pair of cheeses contained one defective item and one non-defective item. Three major organic acids (oxalic, pyruvic and lactic acid) in the Swiss cheese extract were detected. Oxalic Acid concentration remained constant over the samples and the concentrations of the two remaining acids were determined by standard curves. The HPLC results showed a lower level of lactic acid concentration and also a higher ratio of pyruvic acid to lactic acid in cheeses with split defects than cheeses with good grades. At the same time, Fourier Transform Infrared (FTIR) supported HPLC results. The spectra information showed significant difference between the pair members in the wavenumbers range corresponding to these organic acids. Modification of the sampling method was applied, with the FTIR analysis being used on a further nine individual cheese samples. The sampling was done from different areas of split, “eye” and “blind” from each cheese. This allowed FTIR spectra to give more significant differentiation between defective and non-defective samples. Better differentiation was attained following modification of the sampling method, with a shift of significant wavenumber ranges, from organic acid bands to amino acid bands. Results showed the application of FTIR in Swiss-type Cheese has great potential, targeting different compounds to address split defects. |
