2005 Annual Report
1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter?
Major postharvest losses of fresh produce occur during cold storage. Additional losses result from processing and marketing of fresh-cut produce. Deterioration of fresh and fresh-cut produce during cold storage can be prevented, or at least diminished. Major problems of fresh-cut products are physiological deterioration, browning and microbial decay at the cut surfaces. We are using several natural products and antioxidants such as methyl jasmonate, amino acids, organic acids, and calcium salts and chelates to alleviate temperature stress and to inhibit enzymatic browning and texture deterioration. This results in a slowdown of microbial growth as well as decreasing the rate of physiological deterioration of cold temperature-sensitive produce. Texture is a critical quality factor for fresh fruits and vegetables because it relates to consumer acceptability, microbial contamination, and senescence. Most existing instrumental texture measurements were developed for intact fruits or vegetables and are not readily adaptable to fresh-cut sliced or diced products, so new methods must be developed. The changes in texture of fresh-cut produce in response to preparation and storage are not well documented. We are investigating the mechanical properties that change after a fruit or vegetable is cut and stored and how those changes relate to sensory assessments of quality and consumer acceptability. Based on changes in those characteristics, effective instrumental measurements can be developed for routine inspection and for physiological studies. We are also investigating the impact of changes in volatile aroma compounds during storage on sensory acceptability of fresh-cut fruit.
Postharvest losses of fresh produce range from 10 to 50% depending upon commodity and storage facilities. Further losses result from fresh-cut processing and marketing where shelf-life of various items will range from three days to three weeks. Extension of shelf-life would be beneficial with some fresh-cut products as would development of methods to allow use of other produce now considered too sensitive for current processing and storage procedures. As an example, the application of natural antioxidants could open up a market for fresh-cut fruit slices allowing development of new value-added products. One specific problem area being addressed is the prevention of tissue browning that detracts from appearance and reduces market value of fresh-cut produce. Microbial growth on fresh and fresh-cut produce not only affects quality, but also reduces shelf-life of the products. Better methods of preventing browning and reducing decay are urgently needed if postharvest quality of fresh and fresh-cut fruits and vegetables is to be improved. Texture is frequently the quality attribute limiting the acceptability of fresh fruits and vegetables by the consumer. Cutting and packaging of produce can cause texture breakdown and cause certain quality-related volatiles to either decrease or increase, and these changes may alter consumer acceptability. Because it is such a new industry, there are no established, traditional measurements of quality of fresh-cut products other than sensory (appearance, feel, and taste). Rapid, accurate, and reproducible grading methods will systematize the measurement of quality of these value-added products.
The proposed research falls within Component 1 of NP-306 on "Quality Characterization, Preservation, and Enhancement." The project focuses on Category 1 (Fruits, Vegetables, Tree Nuts, and Sugar Crops) and addresses Problem Area 1a, "Definition and Basis for Quality" and Problem Area 1d, "Preservation and/or Enhancement of Quality and Marketability."
2.List the milestones (indicators of progress) from your Project Plan.
Milestones are from a new project approved by OSQR and having a start date of 09/25/04.
Year (FY 2005):
Better tasting fresh-cut apple cultivars selected.
Orange-fleshed fresh-cut honeydew evaluated.
Approximately ten GRAS substances evaluated.
Texture panel trained.
Crispness and crunchiness defined.
Year 2-3 (FY 2006-2007):
Alternative processing protocols formulated.
Food-safe product developed.
Alternative sanitation technologies developed.
Effective antimicrobial substances and dosages identified.
MAP technologies optimized for fresh-cut apples.
Sensory and instrumental texture of ~30 commodities measured.
Sensory and instrumental measurements made on fresh-cut apple and melon products.
Year 4-5 (FY 2008-2009):
GRAS treatments optimized.
Combination processing and MAP strategies established.
Statistical models for hardness, crispness, crunchiness, and toughness in high-moisture products developed and validated.
Instrumental texture measurement methods for fresh-cuts recommended.
Models proposed for predicting sweetness, sourness, and acceptability of fresh-cut apple and melon from instrumental measurements.
4a.What was the single most significant accomplishment this past year?
Found that certain natural volatiles such as methyl jasmonate and essential oil of tea tree are effective in increasing the antioxidant capacity, antioxidant enzyme activities, and/or free radical scavenging activities in fruit of raspberry, strawberry and blackberry genotypes. In addition, these natural products also retarded decay of berry fruits during storage. Therefore, the nutritional values and the shelf-life of these berry fruits can be improved by postharvest exposure to certain natural volatile compounds. This information should benefit both the berry industry and consumers.
4b.List other significant accomplishments, if any.
Maintaining the analytical, sensory and microbial quality of fresh-cut melons after processing and throughout distribution and marketing is a major challenge facing the fresh-cut fruit industry. In 2003 and 2004, fresh-cut chunks of orange and green fleshed honeydews and an orange-fleshed cantaloupe were compared after storage for 0 to 11 days in air at 5 degrees C. Quality characteristics (firmness, SSC, beta-carotene, aromatic volatiles, surface color) of fresh-cut chunks from all genotypes were well maintained even though microbial populations increased especially on cantaloupe chunks. Consumers liked the flavor, texture, sweetness and overall eating quality of the orange-fleshed honeydews as well as or better than those of cantaloupe and green-fleshed honeydew. The best orange-fleshed honeydew genotypes for color development, appearance, flavor, and overall eating quality were identified. The results indicated that orange-fleshed honeydews are well suited for fresh-cut processing, and will enable melon growers and fresh-cut processors to provide a better tasting product, which should enhance fresh-cut melon sales.
4c.List any significant activities that support special target populations.
5.Describe the major accomplishments over the life of the project, including their predicted or actual impact.
While this project is in its first year, significant accomplishments have been achieved in identifying the best apple and melon cultivars for fresh-cut processing. In addition, alternative processing aids have been developed and cultivars selected that maintain the microbial quality and/or food safety of these fresh-cut fruit products better than that attained using current commercial practices.
Many GRAS substances have been evaluated for their effectiveness in reducing decay, alleviating chilling injury, and extending storage life. Several of these naturally occurring compounds, including methyl jasmonate, methyl salicylate, tea tree oil, allyl isothiocyanate, acetic acid, and ethanol have been identified to be effective in maintaining the quality of various commodities. The mechanisms of how these compounds exert their effects and their potential benefits to the produce industry will be investigated.
The optimal times to treatment intact apples with 1-methylcyclopropene (1-MCP), a gas used commercially to maintain apple quality during storage, has been determined along with recommended dosages for four cultivars of apples. Appropriately timed 1-MCP application(s) maintain quality and shelf-life of intact apples as controlled atmosphere storage, but cannot inhibit postharvest decays in apples as well as controlled atmospheres. The apple industry has been alerted to combine an antifungal treatment with the 1-MCP treatment if necessary to control decay during storage of 1-MCP-treated fruit.
6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?
Confidentiality Agreements have been made with a Vegetable Seed Co. and its Research Partners regarding quality and shelf-life evaluations of orange-fleshed hybrid melons specifically being developed for the fresh-cut fruit industry.
7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below).
Saftner, R., J. Abbott, and G. Lester. National Mall Outreach Activity, May 2005. Eating quality of Fresh-cut Fruit
Saftner, R., A. Bhagwat, and J. Abbott. BARC Public Field Day, June 2005. Fresh-cut Apple Products Processed with Commercial and Low pH Processing Formulations.
Erkan, M., Wang, C.Y. 2005. Hot water and curing treatments reduce chilling injury and maintain postharvest quality of 'valencia' oranges. International Journal of Food Science and Technology. 40:91-96.
Ayala-Zavala, J.F., Wang, S.Y., Wang, C.Y., Gonzalez-Aguilar, G., Montoya, L.C. 2004. Effect of storage temperatures on antioxidant capacity and aroma compounds in strawberry fruit. Swiss Society of Food Science and Technology. 37:687-695.
Gonzalez-Aguilar, G., Wang, C.Y., Buta, J.G. 2004. Uv-c irradiation prevents breakdown and chilling injury of peaches during cold storage. Journal of the Science of Food and Agriculture. 84:415-422
Gonzalez-Aguilar, G.A., Ruiz, S., Vasquez, S., Wang, C.Y. 2005. Biochemical changes in pineapple slices treated with antibrowning agents. Journal of Agricultural and Food Chemistry. 40:377-384.
Kim, J., Luo, Y., Tao, Y., Saftner, R.A., Gross, K.C. 2005. Effect of initial oxygen concentration and film oxygen transmission rate on the quality of fresh-cut romaine lettuce. Journal of the Science of Food and Agriculture. 85:1622-1630
Saftner, R.A., Abbott, J.A., Bhagwat, A.A., Vinyard, B.T. 2005. Quality measurement of intact and fresh-cut slices of, `fuji', `granny smith', `pink lady' and `goldrush' apples. Journal of Food Science. 70:S317-324.