Non Technical Summary
Economic losses due to inadequate ripeness detection in the orchard and post-harvest continue to plague the apple industry. It is anticipated that the in-orchard/packinghouse sensor approach will significantly reduce the waste/spoilage-to-edible-fruit ratio, thereby increasing fruit quality and availability and resultant consumer demand at the domestic retail level as well as in the export market. This ripeness detection system translates the natural plant ripening hormone ethylene into a colorimetric visual aid readily seen and "read" by the apple worker in the field. This approach utilizes an easily implemented ripeness detection device activated at the front end of the marketing pipeline, the critical point where fruit quality determination begins and where significant cost controls can be readily implemented.

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
204	1110	2000	50%
404	7210	2020	50%

Knowledge Area
204 - Plant Product Quality and Utility (Preharvest); 404 - Instrumentation and Control Systems;

Subject Of Investigation
7210 - Remote sensing equipment and technology; 1110 - Apple;

Field Of Science
2020 - Engineering; 2000 - Chemistry;

Goals / Objectives
The overall objective of Phase I is to further test and record sensor performance from a relatively fast response (less than two hours) to a longer, integrated measurement in which color change develops over the span of weeks to months and to evaluate the translation of this tuned response from the laboratory to the field, packinghouse, and storage. Objectives include the evaluation of sensor performance for apples in-orchard (fast response) and post-harvest (slow response); estimation of ripeness detection limits; determination of reagent sensitivity to interfering compounds (CO2, CO, H2O, or volatiles released by the apples); determination of level of sensitivity that can be achieved for ethylene detection; and assessment of the potential for application to other climacteric fruits including peaches and pears. A further objective is to assess the viability of the approach based on the experimental results.

Project Methods
Sensor formulations will be developed with varying proportions and amounts of two different types of reagents so as to develop a panel of devices with high sensitivity and with long time responses. Solution volumes, pH, salt content, and the final dryness of the device will be varied. Support materials including several commercial and modified membranes along with activated silica will be employed. Varying these reagent proportions, membrane materials, and volume of reagents can alter both the sensitivity of the device and the timing of the response. Sensor evaluation will be performed in a number of ways. Initial testing of formulations will be performed on ethylene obtained from a tank (rather than from fruits), diluted to concentrations ranging from 0.1 to 50 ppm. Stickers will be placed in chambers of 1 L each into which will be injected a dilute amount of ethylene so as to meet the target concentration. Digital images will be taken for each sticker before introduction of ethylene, immediately after, and at varying times based on formulation. A high degree of reproducibility is critical and so at least 5-10 replicates will be performed for each condition with measurements taken at precise timing. Images will be processed using Adobe Photoshop in order to quantitatively assess the intensity and color of change in the reagents. Dose response curves will be generated in this manner. The limit of detection for each time of analysis will be determined for each preparation. Performance of each will be compared to the desired goals of the two device formulations.Testing of fast and slow responding devices will be performed first on commercial apples obtained from grocery stores but will quickly move to apples that have a well-characterized history. Initial studies will be done with apples on the tree and then with apples post-harvest. The performance metric will be to correlate sensor response to the amount of ethylene being released by the apples as quantified both by destructive testing (needles used to collect interior samples then analyzed by gas chromatography) and by head space analysis using a commercial ethylene sensor in a closed chamber.