Harvest of Sangiovese grapes: the influence of material other than grape and unripe berries on wine quality

The grape harvest period and applied methods determine the levels of unripe berries (substandard berries, SSB) and material other than grape (MOG) in grape must. This study describes, in a full-factorial experiment at the industrial scale, the impact of different levels of MOG and SSB on the chemical composition and the sensorial properties of Sangiovese wines. The addition to the grape juice of 30 g/kg MOG led to significant changes in chemical composition, altering key components such as titratable acidity, lactic acid level, flavonoids concentration and color-related parameters. Sensorial parameters were also modified, as demonstrated by statistically significant differences both in astringency and in the concentration of volatile organic compounds. The threshold level for unripe (SSB) berries was arbitrarily defined as below 21.5 °Bx. In the experimental vineyard used here, 19–36% of grapes were unripe, depending on the harvest zone. The level of SSB influenced some important chemical and sensorial characteristics. Changes in SSB content altered ethanol concentration, titratable acidity, malic and lactic acid levels, a range of polyphenol-related parameters, certain volatile organic compound concentrations, as well as color and bitterness.