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Bill B. Dean and Eugene M. Kupferman

Shelf life of perishable commodities is a function of time by temperature effects on the composite kinetic reactions within each commodity. Empirical tests to approximate shelf life have limited value, particularly in long-distance shipment when less than ideal storage conditions occur, such as for the export market. Time temperature monitors (TTMs) have been developed for monitoring storage temperatures and predicting remaining shelf life. Kinetics curves for ripening of pears, yellow color development in broccoli and browning of mushrooms were compared to kinetics properties of available TTMs at 5, 10, and 20°C. Each commodity deteriorated or ripened at rates corresponding to a different TTM. At 20°C, broccoli kinetics were similar to TTM MC 60 or 67, pears to MC 74, and mushrooms MC 66. Customized TTMs and application of this technology will be discussed.

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Bill B. Dean and Eugene M. Kupferman

Shelf life of perishable commodities is a function of time by temperature effects on the composite kinetic reactions within each commodity. Empirical tests to approximate shelf life have limited value, particularly in long-distance shipment when less than ideal storage conditions occur, such as for the export market. Time temperature monitors (TTMs) have been developed for monitoring storage temperatures and predicting remaining shelf life. Kinetics curves for ripening of pears, yellow color development in broccoli and browning of mushrooms were compared to kinetics properties of available TTMs at 5, 10, and 20°C. Each commodity deteriorated or ripened at rates corresponding to a different TTM. At 20°C, broccoli kinetics were similar to TTM MC 60 or 67, pears to MC 74, and mushrooms MC 66. Customized TTMs and application of this technology will be discussed.

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R. Karina Gallardo, Eugene Kupferman and Ann Colonna

In light of increasing consumer demand for optimal fresh fruit quality, experience attributes are crucial to ensure repeated purchases and price premiums. Challenges in offering consistent quality throughout the marketing year make ‘Anjou’ pears an interesting case in which to analyze the effects of experience quality attributes on willingness to pay. We analyzed data from choice experiments conducted along with sensory tests at two different times during the marketing year. Results indicate that individuals are willing to discount between 15.43 cents/kg to 37.48 cents/kg for a one-unit increase in pear firmness and pay between 19.84 cents/kg to 24.25 cents/kg for a one-unit increase in soluble solid concentration. This information would help the industry assign priority to the factors likely enhancing the characteristics leading to repeated sales at price premiums. Also, this information is valuable to related sciences because it provides market information for focusing research portfolios on quality characteristics likely to increase pears’ commercial viability.

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Dan D. MacLean, Dennis P. Murr, Jennifer R. DeEll and Eugene Kupferman

The ethylene antagonist 1-methylcyclopropene (1-MCP) was investigated for its potential impact on the transcription of key flavonoid biosynthetic (PAL and CHS) and ethylene perception (ERS1) genes during the postharvest storage of pear (Pyrus × communis L.). Optimally harvested red and green `d'Anjou' fruit were treated with 1 μL·L-1 1-MCP for 24 h at 0 °C to 1 °C, and subsequently placed in cold storage (0–1 °C, 90–95% RH). Fruit were removed every 21 days for 126 days, and evaluated for firmness, TSS, and ethylene and volatile production for up to 10 days (≈21 °C). Tissue samples were collected for Northern blot analysis and determination of flavonoid and chlorogenic acid content. PAL content increased during the 1-week simulated marketing period irrespective of storage duration, which coincided with an increase in respiration and ethylene content. Although it was still detectable, total PAL content was dramatically reduced by the 1-MCP treatment. CHS was abundant immediately after harvest and after removal from storage, but declined rapidly thereafter, and was not detectable after 1 week at room temperature. The 1-MCP treatment further exacerbated this decreasing trend in CHS content. ERS1 content appears to be stable throughout storage and the simulated marketing period, with levels lower in 1-MCP-treated fruit. These results suggest that 1-MCP significantly inhibits the transcription of key flavonoid and ethylene regulatory enzymes, possibly compromising the nutraceutical content of pear fruit. The increase in PAL with the concomitant decrease of CHS after removal from storage suggests a diversion of carbon from flavonoid compounds into simple phenols, such as chlorogenic acid.

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James F. Thompson, Joseph A. Grant, Eugene M. Kupferman and Jerry Knutson

Damage (pitting and bruising) to sweet cherries during packing line operations was evaluated in a 3-year study conducted in California, Washington, and Oregon. A large percentage of cherries sampled before packing developed damage symptoms (28% in 1992 and 35% in 1993 and 1994), suggesting that damage is imparted during growing, harvest, or transport to the packing house. Packing line operations caused an average of 39% pitting and 10% bruising. The greatest damage was imparted by cluster cutters (20% pitting) and shower type hydrocoolers (19% pitting). Results from this study demonstrate that packing line damage can be reduced by slowing fruit speed in cluster cutters, operating cluster cutters at high fruit-throughput rates, and reducing water drop height in shower hydrocoolers.