Using Chlorophyll Fluorescence for the Rapid, Nondestructive Assessment of Fruit Quality

The high level of competition in domestic and international markets for stored apple fruit requires high quality packed fruit. Segregating high- and low-quality fruit based on internal quality is key to consumer satisfaction and is an important component of quality control of the final pack-out.  Nondestructive technology based on one or more of the attributes of quality for sorting the whole population is desirable to reduce losses and improve the quality of fruit delivered to the consumer. Considerable research has been conducted in developing technologies to nondestructively assess, grade, and sort fruit for internal quality of apple fruit. However, technologies for sorting apple fruit for internal quality are still not available. Chlorophyll fluorescence (CF) has been used as a measure of chloroplast function and, indirectly, the physiological status of whole plants and plant organs. Changes in chlorophyll fluorescence of many fruit during ripening, senescence, and stress have been reported. In this talk, investigations on the changes in apple fruit chlorophyll fluorescence and its relationship not only limited to firmness and ground color, but also to other internal quality parameter such as SS, TA, and aroma production during ripening as well as response to stress will be introduced and discussed. Our studies indicate that the ripening process is complex and dynamic, but that CF may provide a meaningful nondestructive tool to monitor these changes. It is possible to use different CF parameters to predict fruit quality indices such as Fv, Fm, Fv/Fm, or Fv/Fo. The relationships that have been found so far may be improved by further analysis of data and mathematical modeling.  The further defining of the relationship between CF and firmness, TA, and SS/TA is promising and may lead to the development of a nondestructive fruit quality detector to sort fruit based on eating quality prior to fruit being shipped to the consumers.