2007 Annual Report 1a.Objectives (from AD-416) The objective of this cooperative research project is to evaluate the aroma profile of the core accessions and other lines of interest to help define the diversity of this important quality characteristic. Since fruit will be harvested at a specific maturity stage in order to control for stage of development, the fruit will be appropriate for additional assessments related to storability. These include an analysis of the rate of textural change at 0°C in air and assessment of susceptibility to physiological disorders including greasiness, superficial scald, and chilling injury. In addition, this information will be interlaced with an ongoing microarray study to help identify genes regulating aroma volatile biosynthesis, textural shifts, and disorder development. We will also assess the possibility of developing fruit aroma descriptors. 1b.Approach (from AD-416) The Cooperator (Michigan State University) will collect as much postharvest information about the members of the NPGS, Geneva Malus core collection as is practicable with the primary intent of capturing the diversity of aroma profiles for the collection. To obtain accessions at approximately the same stage of fruit development, fruit maturity will be tracked once per week on fruit sent to MSU via overnight shipments from the NPGS, Geneva. Physiological measures of maturity will include internal ethylene concentration and starch pattern staining. We anticipate as many as 20 accessions, 5 fruit per accession, to be evaluated each week beginning in August 2005. Once it is recognized that the ethylene climacteric is impending or just initiated, we will arrange for the harvest and shipment of sufficient fruit for analysis and storage the following week. For aroma analysis, we intend to hold the fruit so harvested for 7 days at room temperature prior to analysis to allow fruit to fully engage the volatile biosynthetic machinery. For storage analyses, a portion of the fruit will be placed into 0°C refrigerated air storage immediately upon receipt. Fruit texture will be determined initially and once per month for a period of three to 6 months, depending on the rate of deterioration of the fruit. On each analysis date, external fruit quality attributes (e.g., soft scald and superficial scald incidence and severity and greasiness) will be determined. After 2, 4, and 6 months storage, a subset of 10 fruit will be destructively assessed for internal quality defects (e.g., soggy breakdown and senescent breakdown). 3.Progress Report This report serves to document research conducted under a Specific Cooperative Agreement between ARS and Michigan State University. Additional details of the research can be found in the report for the parent project 1910-21000-015-00D "Conservation and Utilization of the Genetic Resources of Apples, Grapes, and Tart Cherries." 184 lines from the Geneva Malus core collection including several Kazakhstan apples were evaluated. They were collected at a mature stage. Measurements were, weight, internal ethylene concentration, starch index, firmness, °Brix, taste (classified as tart, astringent, sweet, nutty, floral, fruity, bland, acid, lemon, alcohol, spicy, anise, and other unusual notes), and volatile compounds. Fruit with a mass greater than 50 g were stored in 0°C and assayed for firmness retention and physiological disorders after 3 and 6 months. Fruit mass ranged from 0.3g to 342.3g, small fruit had higher Brix than large fruit, however, they tended to be tart, astringent, have a less complex volatile profile and lower total volatiles. The internal ethylene concentration increased as fruit size increased. Some of the early-ripening varieties had relatively high concentrations compared to late ones. Medium-sized fruit had higher firmness, averaging 20-23 lbs compared to large fruit, which averaged 16 lbs. Unusual flavor and scent tended to be found in the 10 to 100 g classes of fruits. Large fruit had more diversity in and a higher production of esters and alcohols, but not peculiar aromas. Commercial apples were generally balanced with sweetness, acidity, floral, and fruity. Sweet cultivars tended to have a bland taste. In terms of storability, some fruit retained significant levels of starch; common disorders included soft scald, internal browning, bitter pit, sun scald, senescence breakdown, and superficial scald. Unusual taste/aromas included broccoli-like, tomato-like, and butter (crayon)-like. Of 90 possible esters that could be formed, a total of 67 different esters were detected in the 184 lines of apple fruit evaluated. Ester subgroups tended to be unevenly distributed within the matrix. The average abundance tended to be greatest for esters containing alcohol and acid subgroups composed of 4 and 6 carbons or subgroups derived from 2-methylbutanoate (from isoleucine metabolism). Esters containing unsaturated subgroups were relatively rare. Small fruit also tended to produce unsaturated alcohol precursors for the esters, whereas larger fruit tended to form esters containing straight chain subgroups longer than 6 carbons. While there were some exceptions, larger fruit also tended to have a greater diversity of esters. Cluster analysis of the esters across the 184 lines suggests that several classes of esters are independently regulated or co-regulated. Clusters included:. 1)methyl and ethyl esters,. 2)propyl esters,. 3)acetate esters. 4)butyl and hexyl esters, and heptyl and octyl esters. The data from these evaluations will be summarized and added to the GRIN database in the current fiscal year. Monitoring activities for this project include annual reports and communications by phone and email.