Total titratable acidity (TTA) was determined on 10 g of samples homogenized with 90 mL of distilled water using a Stomacher apparatus (Seward, London, UK), and expressed as the amount (mL) of 0.1 M NaOH to reach a pH of 8.3. The value of pH was measured by a Foodtrode electrode (Hamilton, Bonaduz, Switzerland). Chemical analyses concerning total proteins, fat content, and dry matter were determined by MilkoScan™ FT6000 (Foss Electric A/S, Hillerod, Denmark), based on Fourier-transformed infrared technology [26 (link)].
Carbohydrates were determined in water-soluble extract (W-SE) by HPLC analysis. Two grams of freeze-dried fruit powder were extracted with 20 mL of water/perchloric acid (95:5, v:v). In an ice bath, the mixture was sonicated (amplitude 60) with a macro-probe (Vibra-Cell sonicator; Sonic and Materials Inc., Danbury, CT, USA) for 1 min (two cycles, 30 s/cycle, 5 min interval between cycles). The suspension was stirred at room temperature for 1 h, kept at 4 °C overnight, and centrifuged for 10 min at 10,000 rpm. W-SE was filtered and stored at −20 °C until further use. A Spherisorb column (Waters, Milford, CT, USA) and a Perkin Elmer 200a refractive index detector were used to determine the concentrations of glucose, fructose, mannitol, and sucrose [25 (link)]. Carbohydrates standards were purchased from Sigma-Aldrich (Steinheim, Germany).
Carbohydrates were determined in water-soluble extract (W-SE) by HPLC analysis. Two grams of freeze-dried fruit powder were extracted with 20 mL of water/perchloric acid (95:5, v:v). In an ice bath, the mixture was sonicated (amplitude 60) with a macro-probe (Vibra-Cell sonicator; Sonic and Materials Inc., Danbury, CT, USA) for 1 min (two cycles, 30 s/cycle, 5 min interval between cycles). The suspension was stirred at room temperature for 1 h, kept at 4 °C overnight, and centrifuged for 10 min at 10,000 rpm. W-SE was filtered and stored at −20 °C until further use. A Spherisorb column (Waters, Milford, CT, USA) and a Perkin Elmer 200a refractive index detector were used to determine the concentrations of glucose, fructose, mannitol, and sucrose [25 (link)]. Carbohydrates standards were purchased from Sigma-Aldrich (Steinheim, Germany).
Free full text: Click here
