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The analytical performance of the newly proposed laser-based photoacoustic spectroscopy (PAS) and of optothermal window (OW) method for quantification of total anthocyanin concentration (TAC) in five sour cherry varieties is compared to that of the spectrophotometry (SP). High performance liquid chromatography (HPLC) was used to identify and quantify specific anthocyanins. Both, PAS and OW are direct methods that unlike SP and HPLC obviate the need for the extraction of analyte. The outcome of the study leads to the conclusion that PAS and OW are both suitable for quick screening of TAC in sour cherries. The correlation between the two methods and SP is linear with R(2)=0.9887 for PAS and R(2)=0.9918 for OW, respectively. Both methods are capable of the rapid determination of TAC in sour cherries without a need for a laborious sample pretreatment., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Sour cherry juices made from two sour cherry cultivars (Érdi bőtermő and Kántorjánosi 3) were investigated to determine their total anthocyanin content and half-life of anthocyanins during heat treatment at different temperatures (70, 80 and 90 °C) for 4 h. Before the heat treatment, Érdi bőtermő juice had higher anthocyanin concentration (812 mg/L) than Kántorjánosi 3 juice (513 mg/L). The greatest heat sensitivity of anthocyanins was measured at 90 °C, while the treatments at 80 and 70 °C caused lower thermal degradation. The loss of anthocyanins in Érdi bőtermő juice aft er treatment was 38, 29 and 18%, respectively, while in Kántorjánosi 3 juice losses of 46, 29 and 19% were observed, respectively. At 90 °C sour cherry Érdi bőtermő juice had higher half-life (t1/2) of anthocyanins, while the Kántorjánosi 3 juice had higher t1/2 values at 70 °C. Cyanidin-3-glucosyl-rutinoside was present in higher concentrations in both cultivars (Érdi bőtermő: 348 and Kántorjánosi 3: 200 mg/L) than cyanidin-3-rutinoside (177 and 121 mg/L) before treatment. However, during the experiment, cyanidin-3-rutinoside was proved to be more resistant to heat. Comparing the two varieties, both investigated pigment compounds were more stable in Kántorjánosi 3 than in Érdi bőtermő. Degradation rate of anthocyanins was cultivar-dependent characteristic, which should be taken into account in the food production. [ABSTRACT FROM AUTHOR]