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  • Author or Editor: Cindy Tong x
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Anthocyanins are a class of flavonoids that are responsible for pigments in flowers, fruit, and potato periderm. Developing `Norland' potatoes synthesize anthocyanins in periderm tissue when the tubers are mere swollen stolon tips. As the tubers enlarge, anthocyanin accumulation seems to stop, and anthocyanins synthesized early in development seem to be diluted as the tubers enlarge. Expression of dihydroflavonol reductase (DFR) limits anthocyanin synthesis in grape and maize fruit, and in petunia and snapdragon flowers. However, DFR expression in periderm tissue occurred throughout tuber development (Hung et al., 1999). To determine if expression of late anthocyanin pathway genes limit anthocyanin synthesis in developing potato tubers, we performed RNA gel blot analyses. Expression of leucoanthocyanidin dioxygenase and UDP glucose: flavonoid 3-O-glucosyl transferase was observed in swollen stolon tips but not in periderm of later tuber development stages. Surprisingly, expression was also observed in cortex tissue, although that tissue remained white throughout tuber growth.

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Determining consumers' preferences and willingness to pay (WTP) for organically grown and locally grown fresh produce is very important for stakeholders because it helps them figure out what type of fresh produce to grow and sell, what to emphasize in marketing efforts, and what are reasonable prices to charge. However, the literature that studies and compares consumers' preference and WTP for both organically and locally grown fresh produce is sparse. The objective of this study was to investigate consumers' WTP for organically grown and locally grown fresh produce and the marketing segmentation of these two types of produce. We combined a hypothetical experiment and nonhypothetical choice mechanism to investigate consumers' WTP for the attributes organic, local, and organic plus local for fresh produce. We found that when real products were used in the hypothetical experiment, the hypothetical bias (the difference between what people say they will pay and what they would actually pay) was not high. We found that consumers' WTP for the organic attribute was about the same as their WTP for the local attribute. Consumers' sociodemographics affected their choice between organically grown and locally grown produce. Furthermore, we found that consumers patronized different retail venues to purchase fresh produce with different attributes. The findings of the research have great importance for fresh produce stakeholders to make correct production and marketing decisions; the findings also contribute to experimental method choice in consumers' WTP research.

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We used choice experiments to investigate consumers’ preferences and willingness to pay (WTP) for various apple (Malus ×domestica) varieties. The experiments also asked consumers to evaluate a series of quality attributes by allowing them to taste apples. The choice experiments were conducted in real markets where consumers were making fruit purchases to eliminate any decontextualized biases. The objectives of this study were to determine how much consumers are willing to pay for 13 new and existing apple varieties and learn what quality attributes consumers’ like or dislike in new vs. older apple varieties. Results show that compared with other apple varieties, participants were willing to pay the highest prices for ‘SweeTango®’, followed by ‘Zestar!™’ and ‘Honeycrisp’. Frequent and infrequent buyers were willing to pay significantly different amounts for most of the studied varieties. In addition to WTP estimates, our study also shows what quality attributes consumers consider as improvements compared with existing varieties. Combined with objective measures of these quality attributes, our transdisciplinary study will help apple breeders make more targeted breeding decisions by better understanding what quality attributes consumers like or dislike about the studied varieties.

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To learn what areas should be emphasized in future educational good agricultural practices (GAPs) training efforts, a survey on usage of GAPs was mailed to 855 vegetable growers in Minnesota. We received a 32% response rate and a 43% cooperation rate. Over 65% of respondents reported compliance to proper worker hygiene practices, harvest container and tool sanitization and cleaning, water treatment to reduce the potential for microbial contamination, and protection of growing and stored vegetables from contamination. Small acreages and a diverse array of vegetables are typical characteristics of the majority of Minnesota vegetable farms. Seventy-seven percent of respondents farmed 15 acres or less. Most farms grew 10 or more different vegetable crops, and farmers markets, u-pick operations, and roadside stands were the most common marketing outlets. Overall responses to this study indicated that farmers currently believe they adhere to many recommended food safety best practices, but are lagging in key areas such as treating wash and processing water, taking measures to keep animals out of production fields, and cleaning and disinfecting harvesting tools and containers on a scheduled basis.

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External bruising to potato tubers can result in a blue-black discoloration in the tuber flesh called potato blackspot (PBS). Three potato cultivars used in the Minnesota chipping industry (Atlantic, Frito Lay 1533, and Norchip) were tested for their susceptibility to PBS and compared to Russet Burbank. Tubers were bruised on the stem end using a spring-loaded bruiser and stored at 10°C from 1 to 3 days. PBS was evaluated 24, 48, and 72 hours after bruising. Percentage of bruised tubers showing PBS and Hunter L values of the bruised flesh were used to assess susceptibility. Percentage data showed that the order of most to least susceptible to PBS was Atlantic > Russet Burbank ≥ Frito Lay 1533 > Norchip. L values were not indicative of percentage of tubers showing PBS and may not be accurate measurements of susceptibility to PBS. Atlantic and Russet Burbank tubers were also bruised and stored at 25°C to determine whether a higher storage temperature affected PBS development Atlantic tubers stored at 25°C showed less PBS than those stored at 10°C at each evaluation time. Russet Burbank tubers stored at 25°C exhibited less PBS than those at 10°C at 48 and 72 hr after bruising but not at 24 hr.

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Abstract

Respiration, ethylene production, firmness, polygalacturonase activity, cell wall composition, and soluble uronide content were measured during ripening of two tomato (Lycopersicon esculentum Mill.) genotypes, ‘Manapal’ and dark green (dg). Respiration rates and cell wall uronide contents of the two genotypes were similar. Climacteric ethylene production rates of dg fruit were about half that of ‘Manapal’ fruit. Firmness and polygalacturonase activity of dg tomatoes were similar to that of ‘Manapal’ fruit until 55 days postpollination, when dg fruit were twice as firm as ‘Manapal’ fruit and exhibited greater polygalacturonase activity. Soluble uronide content did not differ between the two genotypes, except at 50 days postpollination, when that of dg fruit was 60% that of ‘Manapal’ fruit. Cell wall uronide content of dg fruit was 1.5 times greater than ‘Manapal’ fruit at 55 days postpollination. Although dg fruit contained larger, absolute amounts of cell wall noncellulosic neutral sugars than ‘Manapal’ fruit, net changes in sugar composition were similar throughout ripening. Also, ratios of cell wall arabinosyl or galactosyl residues to cell wall galacturonic acid were similar in both genotypes. These data suggest that firmness differences between dg and ‘Manapal’ fruit are not due to differing activities of polygalacturonase or changes in cell wall composition during ripening, but to other factors that may affect solubilization of cell wall uronides.

Open Access

During storage, many apple (Malus ×domestica Borkh.) genotypes lose their desirable textural qualities, but some like `Honeycrisp', maintain their sensory Crispness and Firmness. To understand this differential response of genotypes to postharvest changes in texture, reliable and quantifiable methods of texture measurement are needed. This study integrated data from a snapping test, confocal laser scanning microscopy (CLSM), and sensory panels to study postharvest textural changes and to predict sensory textural attributes of Firmness, Crispness, Mealiness, and Juiciness. Three separate analyses on fresh, stored, and combined fresh and stored fruit data yielded different predictors for the same sensory attributes. Change in Crispness during storage was successfully predicted by change in Work during storage. Cell number and size were related to fresh fruit texture and its maintenance during storage. Unique textural properties of `Honeycrisp' were found to be inherited by its progeny.

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We evaluated regional variation in the Delta Absorbance Meter® index of absorbance difference (IAD) as a measure of harvest maturity and for predicting the occurrence of storage disorders in ‘McIntosh’ apples [Malus ×sylvestris (L.) var. domestica (Borkh.) Mansf.] in 2016 and ‘Honeycrisp’ apples in 2016 and 2017. Apples were grown in Maine (ME), Minnesota (MN), and Ontario (ON), and they were harvested from one orchard in each region, and two to three times each year, followed by cold storage at 0.5 °C for 2 months in 2016 and 4 months in 2017. In 2016, ‘Honeycrisp’ IAD values were similar in ME and ON, but lower than in MN. In 2017, IAD was greater in ME than in the other two regions during the first harvest, and it similar to MN in the latter two harvests and lower in ON than in the other regions. In ‘Honeycrisp’ apples, IAD was more strongly related to starch pattern index (SPI), internal ethylene concentration, and fruit peel blush than to chlorophyll or soluble solids concentration. Soft scald incidence (SSI) of ‘Honeycrisp’ fruit was greater in ME than in MN and ON in both years. In ME, SSI was related to IAD at harvest in both years, but with an inverse relationship with the first harvest and a positive relationship in the second harvest. A positive relationship also occurred in ON in 2017. SSI was not related to IAD at harvest in MN in both years and ON in 2016. Regional similarities in patterns of change in ‘Honeycrisp’ fruit IAD were not consistent from year to year, and this indicates that a single IAD standard should not be used to assess fruit maturity in different regions. In ‘McIntosh’, IAD values were variable among the three regions and were not related to other maturity indicators. IAD was not useful for measuring maturity in ‘McIntosh’ apples, but it was weakly related to core browning incidence.

Open Access

It has been reported that 90-day old fruit of rin mutant tomato plants treated with nutrient solution containing 1 g EDTA/L attain 98% red coloration of untreated wild-type fruit. We grew rin plants in sand and watered with half-strength Hoagland's solution until flowering. After flowering, plants were watered until run-off daily with full-strength Hoagland's solution (control), full-strength Hoagland's solution with 135 μ M or 2.5 mM Na2EDTA, or full-strength Hoagland's solution lacking calcium. We did not observe any red fruit or measure any differences in ethylene production or soluble polyuronides content. Analyses of pericarp ion content indicated that fruit from plants treated with 2.5 mM Na2EDTA had higher concentrations of sodium and manganese than control fruit. Fruit from plants treated with solution lacking calcium developed blossom end rot and had less calcium and iron than control fruit.

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