Peach Quality: Determination of Physical and Chemical Attributes for Quality Evaluation of Fresh Peaches

Quality is a major driver of fruit consumption. In peach quality, attributes of appearance, sugar and acid content, and texture/firmness have generally been assessed. The use of these parameters can help to better understand and differentiate the complexity of peach varieties taste and consumer eating experience. These parameters will help growers to classify the different peach cultivars grown. Fifty varieties of commercially ripe fruit were harvested and stored in a cool room for 5-7 days at (5 ± 2°C), followed by 2-3 days at room temperature (21 ± 1°C). Individual sugar and acids were analyzed for the different varieties using HPLC in the Agricultural and Environmental Services Laboratories at the University of Georgia, Athens, GA. ºBrix, total titratable acidity (TTA), texture (puncture, compression and Kramer), and colorimeter values were measured at the University of Georgia, Griffin Campus, Griffin, GA. Statistical significance differences between varieties were observed for all the quality parameters being evaluated (P<0.05). Among varieties, fruit texture measurements of compression, puncture, and Kramer shear tests, were strongly associated with peach flesh type. A higher firmness force (kgf) was found in non-melting peach varieties and a low firmness force (kgf) in melting varieties. ‘Springprince’, a non-melting clingstone peach, was found to have the highest firmness among all texture tests. Puncture values ranged from 1.69 kgf in ‘Springprince’ to 0.19 kgf in ‘All-Star’, a melting freestone peach. Compression values ranged from 11.60 kgf in ‘Springprince’ to 0.38 kgf in ‘Goldprince’, a melting clingstone peach. Kramer values ranged from 2.03 kgf per gram in ‘Springprince’ to 0.19 kgf per gram in ‘All-Star.’ Among varieties, ºBrix values ranged from 7.8 to 15.6 for ‘Brittney Lane’ and ‘Summerflame’, respectively. Sucrose levels comprised the large percentage of total sugars in comparison with glucose and fructose. TTA values ranged from 0.18% for ‘May Sweet’ to 1.11% in ‘Flavorich.’ The organic acids commonly found among peach varieties were citric acid, succinic acid, and malic acid. There was no correlation between texture forces and ºBrix, TTA, juiciness, or individual sugars and acids. Similarly, juiciness, TTA, and ºBrix were not correlated. ºBrix was correlated with total sugars (R² = 0.617). TTA was highly correlated with citric acid (R² = 0.757) and slightly correlated with ascorbic acid (R² = 0.265). The results of these analyses will be used to develop an index of peach quality to be used in conjunction with sensory attributes to identify peach characteristics associated with likeness.