The antioxidant properties of blueberries have been examined only in ripe fruit, although fruit of different maturities are used in processed food products. In this study, highbush blueberry cultivars Bergitta, Bluegold, and Nelson highbush blueberry fruit at different stages of ripeness were examined to characterize differences in oxygen radical absorbing capacity (ORAC) and the phenolic components responsible for ORAC. Underripe fruit at different stages of maturity were also stored at 20 °C for up to 8 days to assess changes in ORAC and phenolic content. Anthocyanin content was substantially higher in fruit of more advanced stages of ripeness. In contrast, the phenolic content and ORAC were lower in the riper fruit. Anthocyanins continued to form during storage, although rate of pigment formation declined after about 4 days. Less anthocyanin pigment was formed in the less ripe fruit. After 8 days of storage, the anthocyanin content of fruit harvested 5% to 50% or 50% to 95% blue exceeded that of ripe fruit. Up to 60% of the total phenolic content could be accounted for by anthocyanins. ORAC was positively correlated with total phenolic content (R 2 = 0.78), but not with anthocyanin content.
Wilhelmina Kalt, Christopher Lawand, Daniel A.J. Ryan, Jane E. McDonald, Horst Donner, and Charles F. Forney
Charles F. Forney, Jun Song, Lihua Fan, Paul D. Hildebrand, and Michael A. Jordan
Fresh broccoli (Brassica oleracea L. Italica group) florets untreated or treated with 1 μL·L-1 1-methylcyclopropene (1-MCP) for 14 h, were stored at 12 °C with 0, 200, or 700 nL·L-1 ozone. Senescence parameters were evaluated after 0, 1, 2, 5, 8, or 12 days of storage. Treatment with 1-MCP delayed the yellowing of florets, and at day 5 the hue angle of 1-MCP treated florets was 116° (green) compared to 102° (yellow) for the control. Respiration rates of florets were reduced by 1-MCP for the first 5 days. The 1-MCP treatment maintained higher chlorophyll fluorescence expressed as Fv/Fm during 12 days of storage. Also, 1-MCP reduced dimethyl trisulfide production, which contributes to off-odor development in broccoli florets. Compared with the controls, florets stored in 200 nL·L-1 ozone had less mold growth and yellowed more slowly, but no differences were observed in respiration, ethylene production, or Fv/Fm. Florets stored in 700 nL·L-1 ozone were greener than florets held in air or 200 nL·L-1 ozone. Interestingly, chlorophyll fluorescence of the florets stored in 700 nL·L-1 ozone decreased significantly and at day 12, Fv/Fm was only 30% of its initial value. Ozone at 700 nL·L-1 stimulated respiration and ethylene production of florets after 1 day of storage, and caused visible damage in the form of increased weight loss and browning of the floret stem ends. Treatment of broccoli with 1-MCP alone or in combination with 200 nL·L-1 ozone maintained the quality and extended the shelf life of broccoli florets.
Charles F. Forney, Roger E. Rij, Ricardo Denis-Arrue, and Joseph L. Smilanick
The potential use of vapor phase hydrogen peroxide (VPHP) to prevent decay caused by Botrytis cinerea Pers. ex Fr. in table grapes (Vitis vinifera L.) was investigated. `Thompson Seedless' and `Red Globe' grapes, inoculated with Botrytis cinerea spores, were placed in polyethylene bags and flushed for 10 minutes with VPHP generated from a 30% to 35% solution of liquid hydrogen peroxide at 40C. Immediately after treatment, bags were sealed and held at 10C. Vapor phase hydrogen peroxide significantly reduced the number of terminable Botrytis spores on grapes. The number of terminable spores on `Thompson Seedless' and `Red Globe' grapes had been reduced 81% and 62%, respectively, 24 hours following treatment. The incidence of decay on inoculated `Thompson Seedless' and `Red Globe' grapes was reduced 33% and 16%, respectively, after 8 days of storage at 10C compared with control fruit. Vapor phase hydrogen peroxide reduced the decay of noninoculated `Thompson Seedless' and `Red Globe' grapes 73% and 28%, respectively, after 12 days of storage at 10C. Treatment with VPHP did not affect grape color or soluble solids content.