Changes in glucose, fructose, sucrose and total sugar content in the juice obtained from the harvested strawberries were determined according to the method developed by Akšić et al. [31 (link)] Lyophilized strawberry fruit samples were powdered using a mortar and pestle. Then, they were weighed to 0.1 g. A total of 5 mL of ultrapure water (Millipore Corp., Bedford, MA, USA) was added to each sample. The reaction mixture was placed in an ultrasonic bath and sonicated at 80 °C for 15 min, and then centrifuged at 5500 rpm for 15 min and filtered prior to HPLC analysis. (Whatman nylon syringe filters, 0.45 µm, 13 mm, diameter). The high-performance liquid chromatographic apparatus (Shimadzu LC 20A vp, Kyoto, Japan) consisted of an in-line degasser, pump and controller coupled to a refractive index detector (Shimadzu RID 20A vp) equipped with an automatic injector (20 µL injection volume) interfaced to a PC running Class VP chromatography manager software (Shimadzu, Japan).
Separations were performed on a 300 mm × 7.8 mm i.d., 5 µm, reverse-phase Ultrasphere Coregel-87 C analytical column (Transgenomic, Omaha, NE, USA) operating at 70 °C with a flow rate of 0.6 mL min−1. Elution was isocratic ultrapure water. Individual sugars were calculated based on their standards and expressed in mg/100 g of dry weight (DW).
Separations were performed on a 300 mm × 7.8 mm i.d., 5 µm, reverse-phase Ultrasphere Coregel-87 C analytical column (Transgenomic, Omaha, NE, USA) operating at 70 °C with a flow rate of 0.6 mL min−1. Elution was isocratic ultrapure water. Individual sugars were calculated based on their standards and expressed in mg/100 g of dry weight (DW).
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