Changes of Chemical Components during Fermentation of Pear Wine

We used pears to manufacture wine, and analyzed changes in pH, acidity and ethanol and sugar content during fermentation. Pear wine with added ginger (to improve quality) did not differ from ginger-free wine in pH or acidity level. The ethanol content of pear wine was the highest (13.0%, v/v) inpear wine with 0.1% (w/v) added ginger compared to pear wine with no ginger, and sensory tests examining taste and color yielded the highest scores for pear wine with 0.2% (w/v) ginger. To assess storage stability, pear wine was treated for 30 minutes at , , , or . Unheated pear wine showed rapid changes in pH and acidity level after 30 days of storage, whereas pear wine treated for 30 minutes at did not show such changes. Total organic acid levels in pear wine increased by 0.71% and 0.89% (v/v), respectively. The free sugar level in pear wine decreased from 12.05% to 3.13% (w/v). Turning to phenolic compounds, caffeic acid, catechin, and epicatechin contents in pears were 1.64, 1.40, and 0.23 mg/100mL, respectively, with diverse compositions. Caffeic acid levels in pear wine decreased sharply to 0.12 mg/100 mL upon fermentation, whereas free catechin inpear wine increased to 1.16 mg/100 mL compared with 0.28 mg/100 mL in pears. Free arbutin increased from 8.34 mg/100 mL in pears to 10.39 mg/100 mL in pear wine. The free amino acid content of pear wine was 118.5 g/100 mL, but the levels of serine, alanine, glutamic acid, and aspartic acid decreased sharply upon fermentation, with corresponding increases in tyrosine, GABA, lysine, and arginine.