Vývoj množství kyselin a hodnoty pH u jablečných pyré a moštů z jablek odrůdy 'Golden Delicious' během skladování s možností predikce daných parametrů pomocí near infrared spektrometrie [Monitoring development of titrable acid and pH values in purees and juice of apple variety 'Golden Delicious' during storage with the possibility of predicting the parameters by near infrared spectroscopy]

Apples as a biological material are differently affected by variety, location of origin, season, as well as type and length of storage. To produce fruit products, processors require constant parameters of the input raw material to obtain the same quality. Various destructive and time-consuming methods are used for control of fruit properties. Near infrared (NIR) spectroscopy can be a fast, cheap, and non-destructive alternative. Apples ripen during storage, their quality parameters are changing, and they can only be used for processing during a certain period of time. NIR spectroscopy appears to be a good alternative enabling quick measurement of required parameters in a large number of samples. For this reason, calibration models were created to determine the titrable acidity and pH of apple juice and puree prepared from the apple variety ´Golden Delicious´. These main quality parameter exhibited a coefficient of determination with R2 cal values of 0.959 for acidity and 0.927 for pH. These values appear as promising results. However, the external validation proved the insufficient accuracy of the given models for these quality parameters in combination with the tested material for routine use. Therefore, it is necessary to continue to expand the set of calibration samples and input data.