Nondestructive Determination of ‘golden Delicious’ Apple Quality and Harvest Maturity

The usefulness of nondestructive methods for measuring chlorophyll content in skin of ‘Golden Delicious’ apples and for evaluating quality parameters and fruit maturity using optical reflectance spectrometry was studied. The fruit weight, firmness, total soluble solids content and titratable acidity during vegetation period and short-term storage at 10°C of ‘Golden Delicious’ apples were measured. Additionally, internal ethylene concentration and chlorophyll a and chlorophyll b contents were analyzed as indicators of fruit maturation. The quality parameters were measured using standard destructive methods and non-destructively using Chlorophyll Content Meter CCM-200 and CP Pigment Analyzer PA1101. The results of measurement using CCM-200 were expressed as Chlorophyll Index. Spectra collected from CP PA1101 were used for calculating two indices: normalized difference vegetation index NDVI=(I780-I660)/(I780+I660) and normalized anthocyanin index NAI=(I780-I570)/(I780+I570). Chlorophyll content, fruit firmness, and acidity decreased during vegetative and postharvest period. The indices obtained from nondestructive measurements also decreased. Good correlations between NAI and fruit firmness, chlorophyll content and titratable acidity were noticed. The results of the experiment indicate a big potential of using NAI index for sorting ‘Golden Delicious’ apples according to their ripening stage (based on ethylene evolution).