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Elizabeth A. Baldwin

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Elizabeth A. Baldwin and Russell Pressey

Exopolygalacturonase (exo-PG) (EC 3.2.1.67) was investigated for ability to induce ethylene production in green cherry tomatoes (Lycopersicon esculentum Mill.). The fruit were vacuum-infiltrated with various levels of exo-PG from green tomato fruit, squash flower, or oak pollen and compared to boiled enzyme or salt controls for ethylene production. In all cases, fruit treated with active enzymes produced significantly higher levels of ethylene than did control fruit. The ethylene response was evident 2 hours after treatment and was transient in nature, returning to basal levels by 22 hours. The amount of ethylene produced did not appear to be influenced by the source of exo-PG.

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Elizabeth A. Baldwin and Bruce Wood

Unsaturated fatty acid oxidation results in rancid off-flavors in pecan [Carya illinoinensis(Wangenh.) K. Koch] kernels, which shortens shelf life under ambient conditions. For this reason kernels are stored under costly refrigeration. Edible coatings [hydroxypropyl cellulose (HPC) and carboxymethyl cellulose (CMC), plus various additives] were used to restrict oxygen contact with kernel associated fats by acting as a barrier to gas exchange. Fresh pecans were acquired from orchards, air-dried, shelled, and treated with various coating formulations. The kernels were then drained, dried, and stored several months in open air or perforated zip-lock plastic bags at 20 to 25 °C and periodically evaluated by 18 to 20 sensory panelists using a 9-point hedonic scale for appearance, shine, off-flavor or overall flavor, and texture. Coated kernels generally scored lower for off-flavor, and higher for overall flavor. Preliminary coatings resulted in a less preferred appearance, but modifications to formulations of subsequent coatings resulted in either improved appearance or had no effect on appearance of kernels compared with uncoated control. Coatings with CMC imparted a shine to coated kernels, but did not generally affect texture. Hexanal accumulation, a good indicator of rancidity, of the homogenate of kernels stored at ambient temperatures for 5 and 9 months was lower in kernels coated with CMC than in the uncoated control, with CMC coatings including α-tocopherol being most effective. Thus, CMC-based coatings exhibit potential for extending the shelf life of pecan kernels.

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J. W. Scott and Elizabeth A. Baldwin

Fruit of 10 tomato (Lycopersicon esculentum Mill.) cultigens, including five typical fresh market F1's, two rin/ + F1's, two very firm (ultrafirm) inbreds, and an antisense PG F1, were harvested at mature green, breaker, and table ripe stages of development, passed over a grader and taken to a lab (21°C) for analyses of soluble solids, titratable acidity and firmness at the table ripe stage. Shelf life was also measured. Cultigens varied in response to both solids and acids at the three harvest stages, thus there was no clear effect of harvest stage on these variables. The rin /+ F1's and ultrafirm inbreds were significantly firmer than the other cultigens at the table ripe and breaker stages. Shelf life tended to decrease with maturity at harvest. One rin /+ F1 had the greatest shelf life at all harvest stages. Ultrafirm and antisense PG cultigens had greater shelf life than the other six cultigens at the table ripe stage.

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Elizabeth A. Baldwin and Myrna O. Nisperos-Carriedo

Edible lipid and composite films were tested for their ability to retain flavor volatiles in `Pineapple' orange fruits stored at 21° using a headspace analysis technique. Volatiles, considered to be important to fresh orange flavor, were quantified and acetaldehyde, ethyl acetate, ethyl butyrate and methyl butyrate increased progressively during storage in coated fruits. Acetaldehyde increased by the second day of storage in uncoated fruits but declined thereafter, `Sunny' tomato fruits were harvested at the green or breaker stage of maturity and ripened at 32.5, 21.0 and 12.9°C. Some fruit from the higher and lower storage temperatures were moved to 21° after one week. In most cases major or important flavor volatiles were highest in fruit transferred to or continuously stored at 21.0°C followed by 12.9 and 32.5°C. Fruit harvested at the breaker stage generally had higher volatile levels compared to those harvested green.

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Elizabeth A. Baldwin and Myrna O. Nisperos-Carriedo

Edible lipid and composite films were tested for their ability to retain flavor volatiles in `Pineapple' orange fruits stored at 21° using a headspace analysis technique. Volatiles, considered to be important to fresh orange flavor, were quantified and acetaldehyde, ethyl acetate, ethyl butyrate and methyl butyrate increased progressively during storage in coated fruits. Acetaldehyde increased by the second day of storage in uncoated fruits but declined thereafter, `Sunny' tomato fruits were harvested at the green or breaker stage of maturity and ripened at 32.5, 21.0 and 12.9°C. Some fruit from the higher and lower storage temperatures were moved to 21° after one week. In most cases major or important flavor volatiles were highest in fruit transferred to or continuously stored at 21.0°C followed by 12.9 and 32.5°C. Fruit harvested at the breaker stage generally had higher volatile levels compared to those harvested green.

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Fernando Maul, Steven A. Sargent, Elizabeth A. Baldwin and Charles Sims

`Agriset-761' and `CPT-5' tomato fruits were harvested at green stage and subsequently exposed to a postharvest exogenous ethylene-air mixture (100 ppm C2H4 at 20°C). Tomatoes with visual symptoms of ripening (breaker stage = <10% red coloration) were removed from ethylene treatment after 1, 3, and 5 days and were transferred to 20°C and 85% RH. At “table-ripe” stage (full red coloration and 4-mm fruit deformation after 5 sec@9.8N), whole fruit samples were analyzed for difference/discrimination sensory evaluations, aroma volatile profiles, and chemical composition. Flavor of fruits gassed for 1 day was rated significantly different than that of fruits gassed for 3 or 5 days (n = 25 panelists) for both cultivars. Several panelists noted the perception of “rancid” and “metallic” tastes, and “lingering” aftertaste in fruits gassed for 5 days. Chemical composition assays showed that flavor differences could be partially due to a significant increase in pH values between fruits gassed for 1 and 5 days (4.23 and 4.34, respectively for `Agriset-761') and a significant decrease in titratable acidity (0.91% and 0.73%, respectively, for `Agriset-761'; 1.04% and 0.86%, respectively, for `CPT-5'). No significant differences in soluble solids content or total sugars were found in any treatments for either cultivar. `Agriset-761' showed significant increases in the concentrations of acetone, hexanal, 2+3 methylbutanol, and a decrease in 2-isobutylthiazole, whereas, `CPT-5' fruits showed significant increases in hexanal, 2+3 methylbutanol, trans-2-heptenal, 6-methyl-5-hepten-2-one, 2-isobutylthiazole, β-ionone, geranylacetone, and a decrease is ethanol concentration. In both cultivars, these significant differences in important aroma volatile compounds could be of enormous relevance in the perception of off-flavor/off-odors.

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Jinhe Bai, Elizabeth A. Baldwin and Robert H. Hagenmaier

Zein, starch, polyvinyl acetate (PVA), carnauba, and carnauba-polysaccharide (CPS) coatings were compared with a commercial shellac coating using controlled atmosphere stored 'Delicious' apples (Malus ×domestica Borkh). Coated apples were stored in air at 2 °C for 2 weeks and then removed to 21 °C for an additional two weeks to simulate marketing conditions. Gloss, internal O2 and CO2 partial pressures, weight loss, flesh firmness, and contents of sugars, acids and volatiles were measured on 0, 2, and 4 weeks after coating treatment. Starch- and carnauba-coated apples had high initial gloss, similar to that found for shellac-coated fruit. Gloss of all coated fruit decreased similarly during the 4-week evaluation period, although all of the coated fruit were glossier than uncoated controls. For uncoated apples, the differences of O2 and CO2 partial pressure between internal and ambient atmosphere were ≈1 kPa at 2 °C, and these increased by a further 2 kPa after transfer to 21 °C. Fruit coated with shellac and starch had >10 kPa CO2, and <10 kPa O2 at 21 °C. Zein-, PVA- and carnauba-coated apples showed a less modified internal atmosphere (6-7 kPa CO2, 11-15 kPa O2). Internal partial pressures of O2 and CO2 were inversely related for most coatings, except for the CPS coating, for which partial pressures of both CO2 and O2 were low. Carnauba-, PVA-, and shellac-coated fruit lost less weight than uncoated fruit. Starch-, shellac-, and CPS-coated fruit were firmer than those from other coating treatments, and all coated fruit were firmer than uncoated control. Titratable acidity was higher in the fruit coated with CPS, starch, and shellac than in uncoated control. Ethyl alcohol and ethyl esters accumulated in starch-, shellac-, and CPS-coated fruit kept at 2 °C, but, levels of these volatiles decreased after transfer of fruit to 21 °C. Carnauba, PVA and zein coatings compared favorably to shellac for gloss and other quality characteristics.

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Libin Wang, Elizabeth A. Baldwin, Zhifang Yu and Jinhe Bai

Both refrigeration and blanching of red-stage tomatoes are common practices in Japan home kitchens and in food service operations. However, little is reported on the impact of such practices on aroma profiles in tomato fruits. In this study, ‘FL 47’ tomatoes at red stage were dipped in 50 °C hot water for 5 minutes or exposed to 5 °C for 4 days to simulate consumer handling of tomato in food service or home kitchens, respectively. Of the 42 volatile compounds detected, refrigeration generally suppressed production of aldehydes, alcohols, oxygen-containing heterocyclic compounds, and nitrogen- and oxygen-containing heterocyclic compounds, including the following abundant and/or important volatiles: pentanal, 3-methylbutanal, 2-methylbutanal, hexanal, cis-3-hexenal, trans-2-hexenal, 2-phenylacetaldehyde, pentanol, 3-methylbutanol, 2-phenylethanol, 1-penten-3-one, geranial, and geranylacetone. On the other hand, the production of aldehydes, alcohols, hydrocarbons, oxygen-containing heterocyclic compounds, and nitrogen- and oxygen-containing heterocyclic compounds was reduced by blanching, associated with low concentrations of 2-methylbutanal, pentanal, cis-3-hexenal, trans-2-hexenal, 2-phenylacetaldehyde, pentanol, 2-methylbutanol, and 2-phenylethanol. These results indicate that a short blanching or refrigeration of tomatoes substantially impacts tomato aroma quality.